Showing posts with label Kit Building. Show all posts
Showing posts with label Kit Building. Show all posts
Monday, January 13, 2014
News for kit builders
Tuesday, March 12, 2013
Iler 40 arrives!
It took its time getting here, but the Iler 40 QRP SSB transceiver kit from Spain has finally arrived! Opening the package confirmed my expectations that this is a very high quality kit indeed.
The printed circuit board is top quality and screen printed with plated through holes. Quite a contrast to some kits of UK origin that look as if the board has been etched and drilled in someone's garage.
The components of each type are individually bagged. The CD containing PDF manuals in both English and Spanish has a custom colour printed label. A quick glance inside showed that the assembly instructions have been professionally produced and are of the a similar standard as the manuals for kits by Heathkit and Elecraft - if not better. Javier has even included data sheets for all the active components making this the most fully documented kit I've ever encountered. I'm going to enjoy building this.
It's going to be a while before I can get started, though. There are some major home improvements going on at the moment chez G4ILO and with all the hammering and sawing I'll have to wait for a peaceful and relaxed atmosphere. I also need to print off a copy of the 39-page assembly manual so I can cross steps off as I go along - and as you may have read our printer doesn't want to play ball.
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| Iler 40 kit contents |
The components of each type are individually bagged. The CD containing PDF manuals in both English and Spanish has a custom colour printed label. A quick glance inside showed that the assembly instructions have been professionally produced and are of the a similar standard as the manuals for kits by Heathkit and Elecraft - if not better. Javier has even included data sheets for all the active components making this the most fully documented kit I've ever encountered. I'm going to enjoy building this.
It's going to be a while before I can get started, though. There are some major home improvements going on at the moment chez G4ILO and with all the hammering and sawing I'll have to wait for a peaceful and relaxed atmosphere. I also need to print off a copy of the 39-page assembly manual so I can cross steps off as I go along - and as you may have read our printer doesn't want to play ball.
Monday, February 25, 2013
A 40m transceiver kit
It has been a while since my soldering iron has been warmed up and I have been feeling the urge to build something. The challenge of building something from scratch has usually proved too much, so I have decided to build a kit. I've read a lot of good things about the "Iler 40" and its 20m brother so I decided to get one.
I thought that this kit was sold on Ebay but a search for "Iler 20" came up blank. A more generic search produced some interesting hits including this 40m transceiver kit from a UK seller. This kit is quite a bit cheaper than the Iler kits but without any reviews it is a bit of an unknown quantity. I eventually found that the Iler kits can be bought from the maker's own site. The excellent reviews plus a higher output (4w vs 1w) were the decider. I was a bit unsure of which version to go for but I eventually plumped for the 40m version. More to follow once it gets here.
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| Iler 40 transceiver (EA9GCY photo) |
Tuesday, July 17, 2012
New WSPR / QRSS beacon kit
Hans Summers (G0UPL) and Steve Farthing (G0XAR) have recently begun selling a new kit for a QRPp (150mW) beacon that can generate Hellschreiber, various QRSS modes and best of all WSPR. Unlike the ones now sitting unused in a drawer in G4ILO's shack which have my details programmed in, the Ultimate QRSS Transmitter Kit has a user interface with an LCD panel that allows you to input your own callsign, locator and power output. This means it has resale value - when you get bored you can sell it on and the new owner can program it with his own details.
At the moment, kits are only available for the 30m, 40m and 80m bands, though they can also generate an audio signal that can be used to drive an SSB transmitter.
I asked Hans if they were going to offer a version for 20m, which has become one of the most popular WSPR bands. His reply was that the kits will actually work fine on any frequency between 1MHz and 20MHz, they just require a different crystal and different components in the low pass filter.
A 20m beacon for WSPR would need a 14.097MHz crystal. I searched my junkbox and couldn't find one. Nor could I find a source for one and having one specially made would be expensive. Perhaps if there is enough demand for a 20m version it will be worth Hans and Steve's while to have a batch made which will be cheaper.
I asked Hans if they were going to offer a version for 20m, which has become one of the most popular WSPR bands. His reply was that the kits will actually work fine on any frequency between 1MHz and 20MHz, they just require a different crystal and different components in the low pass filter.
A 20m beacon for WSPR would need a 14.097MHz crystal. I searched my junkbox and couldn't find one. Nor could I find a source for one and having one specially made would be expensive. Perhaps if there is enough demand for a 20m version it will be worth Hans and Steve's while to have a batch made which will be cheaper.
Friday, April 06, 2012
OAFS redux
A couple of days ago I decided to take another look at the Spectrum Communications Off-Air Frequency Standard (OAFS). It had been suggested that its failure to work might be the result of a solder bridge or similar error. I had a good look at the board using a high power magnifier and found a pair of pads that were suspiciously linked to ground. A moment's work with the desoldering braid and sure enough there was a solder bridge exactly the width of a PCB track.
Having found a fault I was optimistic that the board would work. The setup adjustments were completed OK. But instead of hearing BBC Radio 4 in the speaker as the instruction sheet suggested I received a loud heterodyne with some speech faintly in the background, like listening to an AM signal in SSB mode with the BFO a couple of kHz off-tune.
I was looking at the Spectrum Communications advert in Practical Wireless to check how the ferrite rod was mounted and noticed that the description said "Background heterodyne whistle at 2kHz confirms lock condition." That is exactly what I was getting. Odd that the instructions didn't mention it though. Nevertheless I gave a cheer and went ahead with installing the board in its box.
My happiness was short-lived when I put my frequency counter on the output. It was 10MHz sure enough, but it was not phase locked to anything. I was only receiving the output of the uncontrolled 10MHz crystal oscillator which could be tuned a few tens of Hz either side of 10.000MHz. No adjustment I could make would cause lock to occur.
Comments made to my original post about this suggested that I might have problems with the OAFS as I am not in a good location to receive a strong signal from BBC Radio 4. I'm unhappy with the amount of time I've wasted on this. I think it would be best to write it off and forget about it. I'd rather not be bugged by it or have it taking up scarce space in the G4ILO shack. If anyone would like to have it and see if they can make it work then it's yours for the cost of the postage.
Having found a fault I was optimistic that the board would work. The setup adjustments were completed OK. But instead of hearing BBC Radio 4 in the speaker as the instruction sheet suggested I received a loud heterodyne with some speech faintly in the background, like listening to an AM signal in SSB mode with the BFO a couple of kHz off-tune.
I was looking at the Spectrum Communications advert in Practical Wireless to check how the ferrite rod was mounted and noticed that the description said "Background heterodyne whistle at 2kHz confirms lock condition." That is exactly what I was getting. Odd that the instructions didn't mention it though. Nevertheless I gave a cheer and went ahead with installing the board in its box.
My happiness was short-lived when I put my frequency counter on the output. It was 10MHz sure enough, but it was not phase locked to anything. I was only receiving the output of the uncontrolled 10MHz crystal oscillator which could be tuned a few tens of Hz either side of 10.000MHz. No adjustment I could make would cause lock to occur.
Comments made to my original post about this suggested that I might have problems with the OAFS as I am not in a good location to receive a strong signal from BBC Radio 4. I'm unhappy with the amount of time I've wasted on this. I think it would be best to write it off and forget about it. I'd rather not be bugged by it or have it taking up scarce space in the G4ILO shack. If anyone would like to have it and see if they can make it work then it's yours for the cost of the postage.
Monday, August 15, 2011
Should I or shouldn't I?
Regular readers of my blog will know of my fondness for handheld radios. I'm finding this one very hard to resist even though I have an FT-817 and so no need for another handheld 20m/40m radio. At this point in my life I'm not even sure if building it is still within my capabilities. If I did try, it would be the most difficult kit I have attempted since my Elecraft K2, and I built that 12 years ago when my eyes were a lot sharper and I was not suffering the after effects of a brain operation. Should I or shouldn't I?
The TJ2A looks like an updated and improved version of the Mizuho HF handhelds that were produced during the late 1970s which still fetch a tidy sum whenever they change hands on eBay. Like the Mizuhos, the TJ2A is VXO controlled and covers a portion of each of the two bands, though you can install alternative crystals if you would prefer to have full coverage of one band in two ranges. You could also choose other bands by changing the VXO crystal and bandpass filters.
The building instructions are on the web and it looks as if the kit uses mostly through hole components but there are some SMD transistors. It isn't perfect. There is mention of warm-up drift in the first 5 minutes after switching on or changing bands. There is also a mod already to stop BFO leakthrough into the IF stages. And there doesn't appear to be any high SWR protection for the PA so using the rig with handheld antennas - or any type of antenna that presents a mismatch prior to tune-up - might be problematic.
But it looks really cute. And it's a kit. There are few things in ham radio more rewarding than hearing the first signals, then making the first contact, on a radio you built yourself. Should I or shouldn't I?
Thursday, August 11, 2011
Whispering with a VCXO-AXE
My VCXO-AXE WSPR transmitter kit from W5OLF came this morning. It was two weeks in the post, doubtless due to Customs which had opened the package. I wasted no time in building it, though it did take me somewhat longer to complete than it took AE5X.
The kit itself has been impressively put together. The PCB is extremely high quality and the instructions are almost of Elecraft standard. If the horrible Spectrum Communications Off-Air Frequency Standard kit had been produced to this level of quality it might not have turned out to be a failure for me. If American kit makers can produce nice silk screened and solder masked boards, why do ours make us struggle with boards that look like they were made by hand on somebody's kitchen table?
The VCXO-AXE kit uses almost all through hole components and there is plenty of space around the solder lands. I doubt that anyone would have any trouble building this. The one part that induced a feeling of terror when I saw it was the VCXO itself.
As described, it is a "larger surface mount component." But what I didn't expect was that it didn't have any pins or legs that stick out to solder to. Instead, you have to solder it so the solder goes under or up the side of the chip. You need a very fine tipped soldering iron for this. I couldn't really see if I had successfully soldered the chip or not, so I took a couple of pictures.
The result is not very pretty, but it must have been OK because the transmitter eventually worked!
When ordering, I specified my call, locator and the supply voltage I would be using (12V, as I planned to power the transmitter off a pack of 10 NiMH batteries.) The PICAXE controller chip came programmed with this information and a power level of 33dBm - 2 watts.
On a freshly charged battery pack I was actually getting nearer 3 watts output once the PA tuning capacitor had been peaked up, but after the first few transmissions the power did drop off a bit to become nearer the advertised 2 watts.
I hooked the VCXO-AXE up to my attic MFJ magnetic loop, watched the radio-controlled clock in the shack until it rolled over to an even minute, pressed the transmit button and a couple of minutes later had my first WSPR spots.
Soon after that I had several more. No great DX, but perhaps that is just down to conditions at the moment.
The instructions warn that second harmonic suppression of this transmitter is not great and an external low pass filter is advised. However, the magnetic loop (either the MFJ or my portable Wonder Loop) has a very high Q which I am sure does a good job of attenuating out of band harmonics on its own.
My next move will be to build the little transmitter into a plastic box and use it as a hand held portable WSPR rig. It would be fun to try making a 30m base loaded whip - which should also be fairly high Q - and see how well that works. So expect some WSPRing from various locations around Cockermouth some time soon!
This was a fun project and a good morale booster to prove to myself that I can still build stuff - and with an SMT part in it, too! Thanks to Jay W5OLF for making the kit available. A 20m version would be nice, as well!
If you want to buy one of these kits for yourself you have to look on eBay, though as of right now there doesn't seem to be any for sale.
The kit itself has been impressively put together. The PCB is extremely high quality and the instructions are almost of Elecraft standard. If the horrible Spectrum Communications Off-Air Frequency Standard kit had been produced to this level of quality it might not have turned out to be a failure for me. If American kit makers can produce nice silk screened and solder masked boards, why do ours make us struggle with boards that look like they were made by hand on somebody's kitchen table?
The VCXO-AXE kit uses almost all through hole components and there is plenty of space around the solder lands. I doubt that anyone would have any trouble building this. The one part that induced a feeling of terror when I saw it was the VCXO itself.
As described, it is a "larger surface mount component." But what I didn't expect was that it didn't have any pins or legs that stick out to solder to. Instead, you have to solder it so the solder goes under or up the side of the chip. You need a very fine tipped soldering iron for this. I couldn't really see if I had successfully soldered the chip or not, so I took a couple of pictures.
The result is not very pretty, but it must have been OK because the transmitter eventually worked!
When ordering, I specified my call, locator and the supply voltage I would be using (12V, as I planned to power the transmitter off a pack of 10 NiMH batteries.) The PICAXE controller chip came programmed with this information and a power level of 33dBm - 2 watts.
On a freshly charged battery pack I was actually getting nearer 3 watts output once the PA tuning capacitor had been peaked up, but after the first few transmissions the power did drop off a bit to become nearer the advertised 2 watts.
I hooked the VCXO-AXE up to my attic MFJ magnetic loop, watched the radio-controlled clock in the shack until it rolled over to an even minute, pressed the transmit button and a couple of minutes later had my first WSPR spots.
Soon after that I had several more. No great DX, but perhaps that is just down to conditions at the moment.
The instructions warn that second harmonic suppression of this transmitter is not great and an external low pass filter is advised. However, the magnetic loop (either the MFJ or my portable Wonder Loop) has a very high Q which I am sure does a good job of attenuating out of band harmonics on its own.
My next move will be to build the little transmitter into a plastic box and use it as a hand held portable WSPR rig. It would be fun to try making a 30m base loaded whip - which should also be fairly high Q - and see how well that works. So expect some WSPRing from various locations around Cockermouth some time soon!
This was a fun project and a good morale booster to prove to myself that I can still build stuff - and with an SMT part in it, too! Thanks to Jay W5OLF for making the kit available. A 20m version would be nice, as well!
If you want to buy one of these kits for yourself you have to look on eBay, though as of right now there doesn't seem to be any for sale.
Monday, July 18, 2011
OAFS failure
One of the things I had intended to do this year was install the external frequency reference module in my Elecraft K3 in order to get the best possible frequency accuracy for digital modes. To this end I had ordered an Off-Air Frequency Standard (OAFS) kit from Spectrum Communications so as to avoid wearing out my rubidium frequency standard. I had completed populating the OAFS board a couple of weeks before I ended up in hospital. So I thought I would try to see if it worked, as that would simply involve connecting up a speaker, ferrite rod antenna and power supply.
It began to look as if the predictions of the couple of people who commented or emailed when I first posted about the OAFS were going to be right. I could hear BBC Radio 4 long wave in the loudspeaker but it was very weak, presumably (as I had been advised) due to North Cumbria being a poor location to receive the transmission. When I checked the frequency of the phase locked loop it remained steadfastly on 216.4kHz regardless of the setting of the trimpot.
The instructions supplied with the kit suggested that it might be necessary to change a resistor value if the loop will not lock on to 198kHz so I wrote to Tony Nailer at Spectrum to see if he had a suggestion. Unfortunately his reply was that if the loop will not change frequency with the pot there must be a solder bridge or other assembly error. I checked my soldering as best I could and re-did any joints that looked suspect but the way my eyes are now any sort of cross checking between the schematic and the circuit board to look for errors is impossible.
I haven't really figured out what is wrong with my eyes but it is as if they no longer have the ability to vary focus. I can only see clearly what is at the exact focal point of whatever spectacles I am wearing. When something is out of focus my head swims and I have to close my eyes for a few minutes to steady it again. So any sort of constructional work now is well-nigh impossible.
Tony offered to get the OAFS working for me for a fee if I sent it to him, but at this point I think it would be a waste of money. I can't see myself installing the frequency reference boards in my K3 now even if I still had the same interest in doing so. So I think the OAFS is destined for the G4ILO junkbox.
It began to look as if the predictions of the couple of people who commented or emailed when I first posted about the OAFS were going to be right. I could hear BBC Radio 4 long wave in the loudspeaker but it was very weak, presumably (as I had been advised) due to North Cumbria being a poor location to receive the transmission. When I checked the frequency of the phase locked loop it remained steadfastly on 216.4kHz regardless of the setting of the trimpot.
The instructions supplied with the kit suggested that it might be necessary to change a resistor value if the loop will not lock on to 198kHz so I wrote to Tony Nailer at Spectrum to see if he had a suggestion. Unfortunately his reply was that if the loop will not change frequency with the pot there must be a solder bridge or other assembly error. I checked my soldering as best I could and re-did any joints that looked suspect but the way my eyes are now any sort of cross checking between the schematic and the circuit board to look for errors is impossible.
I haven't really figured out what is wrong with my eyes but it is as if they no longer have the ability to vary focus. I can only see clearly what is at the exact focal point of whatever spectacles I am wearing. When something is out of focus my head swims and I have to close my eyes for a few minutes to steady it again. So any sort of constructional work now is well-nigh impossible.
Tony offered to get the OAFS working for me for a fee if I sent it to him, but at this point I think it would be a waste of money. I can't see myself installing the frequency reference boards in my K3 now even if I still had the same interest in doing so. So I think the OAFS is destined for the G4ILO junkbox.
Wednesday, May 11, 2011
Home-build D-Star radio
Years ago, after I built my Elecraft K2 I had the idea that I would only use home-built radio equipment. However I found that it was no longer possible to buy a kit to build a 2m FM radio. This afternoon I visited a site mentioned by Tim, G4VXE in his latest blog posting and was intrigued to find that a Dutch group is working on a design for a VHF/UHF transceiver kit. Not only that, it is apparently being developed in consultation with Elecraft and is built into an Elecraft EC-1 (K2) enclosure!
The basic kit will be for an analogue FM transceiver with modules for 2m, 70cm and 23cm (it isn't clear to me whether you must choose one of these bands or whether you can fit all of the modules.) But with the addition of another module it can also become a D-Star transceiver!
Now I have never made any secret of my dislike of D-Star, mainly due to the fact that one manufacturer has a monopoly on the provision of radios. But a home-brew D-Star transceiver that doesn't require you to buy anything from Icom and would sit neatly alongside my K2 in a matching enclosure could just be the thing that makes me swallow my objections. Yes, it will still have an AMBE chip containing the proprietary codec. But most of my radios contain chips with proprietary firmware so I don't think that's a good enough reason for continuing to avoid D-Star.
The basic kit will be for an analogue FM transceiver with modules for 2m, 70cm and 23cm (it isn't clear to me whether you must choose one of these bands or whether you can fit all of the modules.) But with the addition of another module it can also become a D-Star transceiver!
Now I have never made any secret of my dislike of D-Star, mainly due to the fact that one manufacturer has a monopoly on the provision of radios. But a home-brew D-Star transceiver that doesn't require you to buy anything from Icom and would sit neatly alongside my K2 in a matching enclosure could just be the thing that makes me swallow my objections. Yes, it will still have an AMBE chip containing the proprietary codec. But most of my radios contain chips with proprietary firmware so I don't think that's a good enough reason for continuing to avoid D-Star.
Friday, October 15, 2010
QRSS beacon progress
Yesterday I finished building the QRSS beacon kit board. The keyer chip sends the wrong callsign but it that was no reason not to build the kit. It's a very easy kit to build although there are no fewer than five toroids to wind which is a lot for such a simple project. Some people hate winding toroids though I find them easy to do and can't see what all the fuss is about.
The only other slight difficulty with the kit is that the potentiometer for setting the output power has leads that are too big for the holes in the PCB. This is mentioned in the instructions, where it is recommended to use component lead offcuts to extend the originals. My junk box was supplemented a few months ago with a Maplin bargain pack of assorted potentiometers and lo and behold it yielded a wirewound trimpot of exactly the right value that perfectly fitted the PCB holes. So I used that instead.
When the board was finished I powered it up using my bench power supply and PM20 QRP absorption wattmeter. In the photo I have breadboarded a regulator from 9V down to 5V as I was toying with the idea of running the beacon from a rechargeable PP3 battery (the board will fit into a case I have which has an integral PP3 battery holder) and wanted to see how much heat the regulator would dissipate.
I found that I could get a maximum of just under 100mW from the beacon with about 120mA current drawn. This is a little less than the specification. The instructions suggest that a bit more than 100mW should be possible, but the shortfall isn't enough to worry about. For longer battery life I will run the beacon at 50mW which draws a current of around 65mA.
To get the transmitter on frequency and set up the mark/space frequency shift I used my K3 and QRSS VD software. The signal, even on the dummy load of the power meter, was very loud which was helpful getting it into the ball park. I had to disconnect the antenna, switch in the attenuator and back off the RF gain to reduce the signal to a level where I could fine-tune the frequency and see what the signal would look like on the air.
And here it is, sending G4LIO! It's a bit frustrating not being able to connect it to an antenna and put it on the air because of the wrong callsign. I've been promised a new chip and I practically snatched the post out of the hands of the postwoman but it hasn't come yet. In the meantime I can think about putting the beacon into a nice box. Forget winding toroids, for me that is the hardest and least enjoyable part of any constructional project!
The only other slight difficulty with the kit is that the potentiometer for setting the output power has leads that are too big for the holes in the PCB. This is mentioned in the instructions, where it is recommended to use component lead offcuts to extend the originals. My junk box was supplemented a few months ago with a Maplin bargain pack of assorted potentiometers and lo and behold it yielded a wirewound trimpot of exactly the right value that perfectly fitted the PCB holes. So I used that instead.
When the board was finished I powered it up using my bench power supply and PM20 QRP absorption wattmeter. In the photo I have breadboarded a regulator from 9V down to 5V as I was toying with the idea of running the beacon from a rechargeable PP3 battery (the board will fit into a case I have which has an integral PP3 battery holder) and wanted to see how much heat the regulator would dissipate.
I found that I could get a maximum of just under 100mW from the beacon with about 120mA current drawn. This is a little less than the specification. The instructions suggest that a bit more than 100mW should be possible, but the shortfall isn't enough to worry about. For longer battery life I will run the beacon at 50mW which draws a current of around 65mA.
To get the transmitter on frequency and set up the mark/space frequency shift I used my K3 and QRSS VD software. The signal, even on the dummy load of the power meter, was very loud which was helpful getting it into the ball park. I had to disconnect the antenna, switch in the attenuator and back off the RF gain to reduce the signal to a level where I could fine-tune the frequency and see what the signal would look like on the air.
And here it is, sending G4LIO! It's a bit frustrating not being able to connect it to an antenna and put it on the air because of the wrong callsign. I've been promised a new chip and I practically snatched the post out of the hands of the postwoman but it hasn't come yet. In the meantime I can think about putting the beacon into a nice box. Forget winding toroids, for me that is the hardest and least enjoyable part of any constructional project!
Tuesday, October 12, 2010
QRSS Keyer
I have operated most of the reverse beacon and weak signal modes but one that I have never tried is QRSS. "QRS" is the Morse Q code for "send slowly" so QRSS means send very slowly indeed. QRSS beacons send your call using very, very slow Morse, which listeners receive using a "grabber", which is a slow moving waterfall display. If you're lucky, they will email you a reception report, but you can also look for your signal yourself on one of the various online grabbers.
One day I planned to build my own QRSS beacon. When I found out that Hans Summers G0UPL had produced a QRSS beacon kit I was disappointed to learn that all the kits had been sold at the US Dayton hamfest. However I recently discovered that he had made a new batch of kits and not wanting to wait and find out they were all sold at the G-QRP Convention I ordered one at the weekend. The order process was extremely professional (amateur components suppliers who expect you to email your order and credit card details please note) and the kit arrived this morning.
I opened the envelope and was very impressed to find that the package included a printed copy of the instructions as I had expected to have to print them myself from the website. The PCB is of very high quality. But as I tipped the parts on to the workbench my heart immediately sank.
Because the microcontroller chip which keys the transmitter and has been preprogrammed with my callsign was wrapped in a slip of paper on which was written G4LIO, a transposition of my call that often afflicts people on the air as well - I don't know why. The incorrect call was also written on the jiffy bag the kit came in. I checked the emailed copy of the order and the mistake was not mine.
After an exchange of emails with Hans I installed the chip in its socket, applied power and connected an earpiece to pin 2 which produces an audio tone to verify whether the chip had been programmed incorrectly. It sent G4LIO. :-( Why is it always me that gets the kits with the missing or faulty parts?
One day I planned to build my own QRSS beacon. When I found out that Hans Summers G0UPL had produced a QRSS beacon kit I was disappointed to learn that all the kits had been sold at the US Dayton hamfest. However I recently discovered that he had made a new batch of kits and not wanting to wait and find out they were all sold at the G-QRP Convention I ordered one at the weekend. The order process was extremely professional (amateur components suppliers who expect you to email your order and credit card details please note) and the kit arrived this morning.
I opened the envelope and was very impressed to find that the package included a printed copy of the instructions as I had expected to have to print them myself from the website. The PCB is of very high quality. But as I tipped the parts on to the workbench my heart immediately sank.
Because the microcontroller chip which keys the transmitter and has been preprogrammed with my callsign was wrapped in a slip of paper on which was written G4LIO, a transposition of my call that often afflicts people on the air as well - I don't know why. The incorrect call was also written on the jiffy bag the kit came in. I checked the emailed copy of the order and the mistake was not mine.
After an exchange of emails with Hans I installed the chip in its socket, applied power and connected an earpiece to pin 2 which produces an audio tone to verify whether the chip had been programmed incorrectly. It sent G4LIO. :-( Why is it always me that gets the kits with the missing or faulty parts?
Tuesday, March 09, 2010
No shame, no pride
A few weeks ago fellow blogger Dominic M1KTA wrote that he was selling off some unwanted projects from his shack, including some unbuilt or part-completed kits. A little while ago he wrote: "I have decided to stop selling off project builds now and I am keeping hold of everything until a rally when I can sell them in person as I have had a complete nightmare after selling one of the projects over the internet to someone I believed was capable of finishing it and has demanded I rebuild and re-align it after they hacked about with it themselves to the point where it no longer functions, they melted the pcb connectors and filed away part of the pcb and at least one track in the process to attempt to squeeze it into a box that was too small and demanded a paypal refund. I am never again selling a 'built' project over the internet it is too risky for me."
I have bought things before, either at rallies (hamfests) or from ads in RadCom, that were found not to work and sometimes revealed some astonishingly ham-fisted handiwork inside. The purpose of some modifications defied understanding. I either fixed them myself or wrote it off to experience.
The idea that someone could buy an unfinished kit and then try to make the seller liable for their inability to complete it just beggars belief. It seems some members of this hobby have no shame and no pride.
I told Dom he should publish the callsign of this so-called amateur as a warning to other sellers to steer clear. I know I would.
I have bought things before, either at rallies (hamfests) or from ads in RadCom, that were found not to work and sometimes revealed some astonishingly ham-fisted handiwork inside. The purpose of some modifications defied understanding. I either fixed them myself or wrote it off to experience.
The idea that someone could buy an unfinished kit and then try to make the seller liable for their inability to complete it just beggars belief. It seems some members of this hobby have no shame and no pride.
I told Dom he should publish the callsign of this so-called amateur as a warning to other sellers to steer clear. I know I would.
Tuesday, December 29, 2009
Change of resistance
I hate getting old! Last night my lower back was in agony from the couple of hours I spent hunched over the desk working on the SoftRock 6.2 Lite kit. So I didn't plan on doing any constructional work today. However, Maurice G4DVM read of my problem with the kit and asked me to send him some voltage measurements. It also occurred to me that I had tested the circuit with the power supply set to 9V instead of 12V. So I connected the kit to a 12V power supply, switched on the FT-817 (which was still set to 8.191MHz from yesterday) and this time a carrier signal was heard!
I started taking voltage measurements anyway and observed that the voltage on pin 2 of U2 was low: 0.79V compared to the 2.47V obtained by the author of the instructions. Pin 3 was 1.23V compared to 3.21V expected. More importantly I observed that the oscillator signal stopped as soon as the test probe touched the pad. Around this time I observed that oscillation also stopped if I touched the case of the crystal and it didn't always start up again afterwards. So I probably wasn't mistaken that I didn't detect the local oscillator signal yesterday.
According to the instructions, R6 (which has something to do with the bias of Q2) is not used in most versions of the SoftRock except for 40m. It is supposed to be used in the version for the K3 IF, and the value supplied is 22K. I thought it would be an easy test to remove it - just snip the exposed lead (since it is mounted on end.) If that didn't help I could always solder the ends back together again.
With R6 open circuit there was no local oscillator at all. I then decided to try a lower value. The instructions say a value from 12K to 22K may be used "as appropriate". I found a 15K resistor and tacked it across the pads on the underside of the board. I had a local oscillator again and this time it didn't stop when I touched the case of the crystal!
I absolutely hate replacing components in circuit boards with plated through holes. Removing the snipped in half 22K resistor from the circuit board was easy. But clearing the holes to allow the 15K resistor to be inserted in its place was a job I dreaded. Ironically it would have been easier if the SoftRock kit was all SMT - apart from the fact that I wouldn't have had a 15K SMT resistor to try.
I have a spring-loaded desoldering gun, but I didn't think I could use it as it was designed for larger boards with more space between the components and the holes. I have desoldering braid too, but most times I have used it I ended up lifting pads and traces on the board. I made a real mess of modifying the KSB2 board in my early model Elecraft K2. The board works, but it is a good job no-one can see it.
In the end I did the job using a couple of stainless steel needles from Olga's sewing kit. I heated up a hole and quickly pushed a needle through, then cleaned up the solder that was pushed through. It took a couple of attempts to clean the holes sufficiently for the replacement resistor's leads to pass through.
By the time I had finished the modification and checked that I still had an 8.191MHz signal my back was painful again. So much as I would have liked to finish the SoftRock and see if it works I shall have to pack it and my tools away and leave it for a few days. I hate getting old!
I started taking voltage measurements anyway and observed that the voltage on pin 2 of U2 was low: 0.79V compared to the 2.47V obtained by the author of the instructions. Pin 3 was 1.23V compared to 3.21V expected. More importantly I observed that the oscillator signal stopped as soon as the test probe touched the pad. Around this time I observed that oscillation also stopped if I touched the case of the crystal and it didn't always start up again afterwards. So I probably wasn't mistaken that I didn't detect the local oscillator signal yesterday.According to the instructions, R6 (which has something to do with the bias of Q2) is not used in most versions of the SoftRock except for 40m. It is supposed to be used in the version for the K3 IF, and the value supplied is 22K. I thought it would be an easy test to remove it - just snip the exposed lead (since it is mounted on end.) If that didn't help I could always solder the ends back together again.
With R6 open circuit there was no local oscillator at all. I then decided to try a lower value. The instructions say a value from 12K to 22K may be used "as appropriate". I found a 15K resistor and tacked it across the pads on the underside of the board. I had a local oscillator again and this time it didn't stop when I touched the case of the crystal!
I absolutely hate replacing components in circuit boards with plated through holes. Removing the snipped in half 22K resistor from the circuit board was easy. But clearing the holes to allow the 15K resistor to be inserted in its place was a job I dreaded. Ironically it would have been easier if the SoftRock kit was all SMT - apart from the fact that I wouldn't have had a 15K SMT resistor to try.
I have a spring-loaded desoldering gun, but I didn't think I could use it as it was designed for larger boards with more space between the components and the holes. I have desoldering braid too, but most times I have used it I ended up lifting pads and traces on the board. I made a real mess of modifying the KSB2 board in my early model Elecraft K2. The board works, but it is a good job no-one can see it.
In the end I did the job using a couple of stainless steel needles from Olga's sewing kit. I heated up a hole and quickly pushed a needle through, then cleaned up the solder that was pushed through. It took a couple of attempts to clean the holes sufficiently for the replacement resistor's leads to pass through.
By the time I had finished the modification and checked that I still had an 8.191MHz signal my back was painful again. So much as I would have liked to finish the SoftRock and see if it works I shall have to pack it and my tools away and leave it for a few days. I hate getting old!
Monday, December 28, 2009
On the rocks
A disappointing day in the G4ILO shack. I did some more work on the SoftRock 6.2 Lite kit which I was hoping to make into a panadapter for my K3. But the project has hit the rocks as the local oscillator doesn't work and I don't know what to do about it.
I started off by adding the components for the regulated power supply. That checked out fine - not much to go wrong there, really.
Next I built the crystal oscillator part of the circuit. That also worked fine - I could hear a strong signal just below 32.768MHz on my FT-817 receiver.
The stage after that was the divider circuit, which is supposed to divide the oscillator frequency by 4 to give the 8.192MHz local oscillator required by the K3 version of the SoftRock. I didn't need to add any components for that, as I'd already soldered in all the SMT components and this stage just involved adding the divider ICs. So I tuned down to 8.192MHz and heard nothing.
The current consumption of the SoftRock was correct for this stage, but some of the voltages on pins of U2 were not correct. There was zero volts on pin 2 where there should have been a reading. I checked the board carefully but I could not see any solder bridges or anything else I have done wrong. I don't have an oscilloscope so I can't see what is happening.
I don't know what is wrong, and I don't know what to do. Perhaps it was a mistake to solder all the SMT parts first, but I really would not have liked to do it after the through-hole components were added, making access difficult. Perhaps my anti-static precautions weren't good enough. I did use an anti-static mat and wrist band, but I'm getting pretty absent minded these days and there were times I forgot to connect the ground strap to the wrist band before handling the board.
I don't have any replacement divider ICs to try, and to be honest I find the board too small to work on. I doubt that I could remove a chip without lifting the PCB pads at the same time. I don't know why the SoftRock couldn't have been designed using all through-hole parts with socketed ICs, on a larger board. It doesn't appear to use any components that aren't available in leaded versions, and it would have made the project easier to build and easier to troubleshoot for most people.
The SoftRock has gone into the box of projects that didn't work, along with my short-lived enthusiasm for SMT construction.
I started off by adding the components for the regulated power supply. That checked out fine - not much to go wrong there, really.Next I built the crystal oscillator part of the circuit. That also worked fine - I could hear a strong signal just below 32.768MHz on my FT-817 receiver.
The stage after that was the divider circuit, which is supposed to divide the oscillator frequency by 4 to give the 8.192MHz local oscillator required by the K3 version of the SoftRock. I didn't need to add any components for that, as I'd already soldered in all the SMT components and this stage just involved adding the divider ICs. So I tuned down to 8.192MHz and heard nothing.
The current consumption of the SoftRock was correct for this stage, but some of the voltages on pins of U2 were not correct. There was zero volts on pin 2 where there should have been a reading. I checked the board carefully but I could not see any solder bridges or anything else I have done wrong. I don't have an oscilloscope so I can't see what is happening.
I don't know what is wrong, and I don't know what to do. Perhaps it was a mistake to solder all the SMT parts first, but I really would not have liked to do it after the through-hole components were added, making access difficult. Perhaps my anti-static precautions weren't good enough. I did use an anti-static mat and wrist band, but I'm getting pretty absent minded these days and there were times I forgot to connect the ground strap to the wrist band before handling the board.
I don't have any replacement divider ICs to try, and to be honest I find the board too small to work on. I doubt that I could remove a chip without lifting the PCB pads at the same time. I don't know why the SoftRock couldn't have been designed using all through-hole parts with socketed ICs, on a larger board. It doesn't appear to use any components that aren't available in leaded versions, and it would have made the project easier to build and easier to troubleshoot for most people.
The SoftRock has gone into the box of projects that didn't work, along with my short-lived enthusiasm for SMT construction.
Wednesday, December 23, 2009
Breaking my SMT duck
It was nagging at me like a persistent toothache. The SoftRock kit was sitting in an envelope with all the parts sorted and the instructions printed, waiting for me to start building. But the anxiety about soldering the SMT parts made me put off starting. Finally, this afternoon, I decided to bite the bullet and make a start.
The first snag was my soldering iron. The regular sized bit had seized on to the shaft of my Antex TCS. I could not get it off, so I could not replace it with the small one I had bought for just this task. In the end I decided to use my 40 year old Antex Model C. Years ago I bought a fine tipped bit for it which I had always found to be too feeble for any projects I had built. Miraculously I had not managed to lose it during all that time, so at long last it was to be of some use!
I made the decision to mount all the SMT parts first, instead of building the board stage by stage. I thought that would make the task easier by keeping the board flat and not restricting access to the SMT pads in any way. I decided to start with what I thought would be the easiest parts: the 0.1uF SMT capacitors. There are 10 of those in the SoftRock 2, and 11 were supplied, so I had one spare!
Things did not start well. For the first one I made the mistake of deciding to tin (apply solder to) the two pads before soldering. This made the pads uneven which made it even more difficult to hold the capacitor in position for soldering than it normally is. At the first attempt the capacitor was standing a bit proud of the board at the other end. I applied some pressure with tweezers to try to level it out. Only after I had soldered both ends and then inspected my work did I see that I had cracked the component. So I had to remove it and start again - my one spare lost before I had even started!
I nearly gave up at this point. I had spent about 15 minutes trying various ways to hold the component still so I could fix it with a dab of solder at one end. "OK", I thought, "SMT is not for me. This is no fun at all." I was close to packing the SoftRock all away and giving the kit to someone else. But then I thought "what the hell." There was nothing to lose by trying. The kit hadn't even cost me anything, thanks to the generosity of Craig VK3HE. So I tried again.
Eventually I hit on a technique that worked. I used a bronze bladed trimmer tool with BluTack on the end to pick up an SMT part and hold it in position. The BluTack was necessary because otherwise the slight tremor in my hands would jiggle the capacitor out of position. Then I would fix one end in place with a blob of solder from the fine tipped bit. Next I would solder the other end of the part. Then finally I would go back to the first end and try to make a better job of it.
I should point out that this was only possible with the aid of a headset with magnifying lenses that I bought on eBay several years ago. It took nearly an hour to solder in all 10 capacitors, and my back was protesting a bit at all the bending close to the desk to get the board in focus with the high magnification lenses I was using. Only one capacitor pinged off into my lap and fortunately I immediately saw it. If I had lost one in the carpet that would have been that.
I was going to quit while I was ahead but I was fired up and wondering how I would manage with the SMT ICs in the kit. There are four of them. The instructions say to use electrostatic precautions so before I could carry on I had to unroll the electrostatic mat and ground it using the negative terminal of my shack power supply.
Amazingly, I found the SMT ICs easier to install than the small capacitors. Contrary to all the advice found on the web I did not use flux and desoldering braid. I soldered each leg of each IC individually, just as I would do with through-hole components. The fine-tipped soldering iron bit made this possible, as did use of some 0.2mm diameter solder that I had purchased on eBay. Thanks to the fantastic macro facility of my new £25 digital camera you can have a good look at the result.
I used a couple of small balls of BluTack to anchor the PCB to the work surface, then picked up the IC with tweezers and dropped it on to the board. Then I nudged it into the correct position using one end of the bronze tipped trimming tool. I held the IC in position using the other blade of the trimming tool which had some BluTack wrapped round it, and quickly tacked one corner leg to the board with solder.
Next I rotated the board so I was looking at the other side of the IC, checked that all the pins still lined up with the pads, and tacked the opposite corner leg into position. I then soldered all of the pins individually by applying the fine tipped bit and fine 0.2mm solder.
I mounted all 4 ICs in less than an hour and did not create a single solder bridge, which is better than I usually manage soldering regular sized through-hole parts! I am over the moon to have broken my duck and overcome my fears of working with SMT components, though my back is telling me that two hours of this in one session is more than enough!
The first snag was my soldering iron. The regular sized bit had seized on to the shaft of my Antex TCS. I could not get it off, so I could not replace it with the small one I had bought for just this task. In the end I decided to use my 40 year old Antex Model C. Years ago I bought a fine tipped bit for it which I had always found to be too feeble for any projects I had built. Miraculously I had not managed to lose it during all that time, so at long last it was to be of some use!I made the decision to mount all the SMT parts first, instead of building the board stage by stage. I thought that would make the task easier by keeping the board flat and not restricting access to the SMT pads in any way. I decided to start with what I thought would be the easiest parts: the 0.1uF SMT capacitors. There are 10 of those in the SoftRock 2, and 11 were supplied, so I had one spare!
Things did not start well. For the first one I made the mistake of deciding to tin (apply solder to) the two pads before soldering. This made the pads uneven which made it even more difficult to hold the capacitor in position for soldering than it normally is. At the first attempt the capacitor was standing a bit proud of the board at the other end. I applied some pressure with tweezers to try to level it out. Only after I had soldered both ends and then inspected my work did I see that I had cracked the component. So I had to remove it and start again - my one spare lost before I had even started!
I nearly gave up at this point. I had spent about 15 minutes trying various ways to hold the component still so I could fix it with a dab of solder at one end. "OK", I thought, "SMT is not for me. This is no fun at all." I was close to packing the SoftRock all away and giving the kit to someone else. But then I thought "what the hell." There was nothing to lose by trying. The kit hadn't even cost me anything, thanks to the generosity of Craig VK3HE. So I tried again.
Eventually I hit on a technique that worked. I used a bronze bladed trimmer tool with BluTack on the end to pick up an SMT part and hold it in position. The BluTack was necessary because otherwise the slight tremor in my hands would jiggle the capacitor out of position. Then I would fix one end in place with a blob of solder from the fine tipped bit. Next I would solder the other end of the part. Then finally I would go back to the first end and try to make a better job of it.I should point out that this was only possible with the aid of a headset with magnifying lenses that I bought on eBay several years ago. It took nearly an hour to solder in all 10 capacitors, and my back was protesting a bit at all the bending close to the desk to get the board in focus with the high magnification lenses I was using. Only one capacitor pinged off into my lap and fortunately I immediately saw it. If I had lost one in the carpet that would have been that.
I was going to quit while I was ahead but I was fired up and wondering how I would manage with the SMT ICs in the kit. There are four of them. The instructions say to use electrostatic precautions so before I could carry on I had to unroll the electrostatic mat and ground it using the negative terminal of my shack power supply.
Amazingly, I found the SMT ICs easier to install than the small capacitors. Contrary to all the advice found on the web I did not use flux and desoldering braid. I soldered each leg of each IC individually, just as I would do with through-hole components. The fine-tipped soldering iron bit made this possible, as did use of some 0.2mm diameter solder that I had purchased on eBay. Thanks to the fantastic macro facility of my new £25 digital camera you can have a good look at the result.
I used a couple of small balls of BluTack to anchor the PCB to the work surface, then picked up the IC with tweezers and dropped it on to the board. Then I nudged it into the correct position using one end of the bronze tipped trimming tool. I held the IC in position using the other blade of the trimming tool which had some BluTack wrapped round it, and quickly tacked one corner leg to the board with solder.
Next I rotated the board so I was looking at the other side of the IC, checked that all the pins still lined up with the pads, and tacked the opposite corner leg into position. I then soldered all of the pins individually by applying the fine tipped bit and fine 0.2mm solder.
I mounted all 4 ICs in less than an hour and did not create a single solder bridge, which is better than I usually manage soldering regular sized through-hole parts! I am over the moon to have broken my duck and overcome my fears of working with SMT components, though my back is telling me that two hours of this in one session is more than enough!
Friday, December 11, 2009
Preparing to build the SoftRock
I spent a couple of hours yesterday evening preparing to build the SoftRock 6.2 Lite kit that I hope to use as a panadapter for my K3. I started by printing out all the detailed build notes at WB5RVZ's SoftRock page. This describes building the receiver in seven separate stages, starting with the power supply and ending with the external connections. Each stage has its own bill of materials or components list, so I then checked the supplied components and put them into individual small polythene bags, one for each stage.
When I got to the local oscillator stage I realized that I didn't have a crystal. An email to the Elecraft reflector produced the information that the crystal used for the K3 panadapter version is a 32.768MHz. Even better, it produced an offer from Alan G4LWA to send me one he had that was surplus to requirements. Aren't hams a great bunch?
I'm also missing an unusual component, a 4.7uF ceramic capacitor listed in the operational amplifiers stage as Cxx with the note "for audio test". I can't see where on the board that goes and on a scan through the instructions I couldn't see any mention of it. I'm sure I have a 4.7uF electrolytic capacitor in my parts box which will hopefully do, but I think I'll have to solve this problem when I come to it.
I'm a bit apprehensive at building this kit. I'm going to take it very slowly, in stages, no more than one every few days, not least because I can easily set off my back problems by spending too long hunched over the desk which is necessary to see what I am doing using my magnifier headset.
There are about 4 SMT ICs to be soldered in, and ten SMT capacitors. At the moment, the capacitors look more scary than the ICs. I can't even see how to get them off the backing strip without them pinging off to be lost forever in the carpet. At least the ICs are big enough to hold on to.
Although building the receiver in stages makes a lot of sense, I'm wondering if it would be easier to solder all the SMT parts on first. I think it would be easier to do while I can put the board flat on the bench. As soon as any through-hole parts are on there they will restrict access and make it harder to keep the board in a stable position. I need to think about what is the best way to proceed before I can actually start.
When I got to the local oscillator stage I realized that I didn't have a crystal. An email to the Elecraft reflector produced the information that the crystal used for the K3 panadapter version is a 32.768MHz. Even better, it produced an offer from Alan G4LWA to send me one he had that was surplus to requirements. Aren't hams a great bunch?
I'm also missing an unusual component, a 4.7uF ceramic capacitor listed in the operational amplifiers stage as Cxx with the note "for audio test". I can't see where on the board that goes and on a scan through the instructions I couldn't see any mention of it. I'm sure I have a 4.7uF electrolytic capacitor in my parts box which will hopefully do, but I think I'll have to solve this problem when I come to it.
I'm a bit apprehensive at building this kit. I'm going to take it very slowly, in stages, no more than one every few days, not least because I can easily set off my back problems by spending too long hunched over the desk which is necessary to see what I am doing using my magnifier headset.
There are about 4 SMT ICs to be soldered in, and ten SMT capacitors. At the moment, the capacitors look more scary than the ICs. I can't even see how to get them off the backing strip without them pinging off to be lost forever in the carpet. At least the ICs are big enough to hold on to.
Although building the receiver in stages makes a lot of sense, I'm wondering if it would be easier to solder all the SMT parts on first. I think it would be easier to do while I can put the board flat on the bench. As soon as any through-hole parts are on there they will restrict access and make it harder to keep the board in a stable position. I need to think about what is the best way to proceed before I can actually start.
Saturday, December 05, 2009
Between a SoftRock and a hard place
A couple of weeks ago I posted a message on the Elecraft reflector to the effect that if anyone was using a SoftRock SDR kit as a panadapter for the K3 and was planning on replacing it with the Elecraft P3 panadapter that is shortly going to be available, I was interested in experimenting with it and would give the SoftRock a good home. Craig, VK3HE replied that he had a kit which was mine for free if I would send my address. I thanked him very much, sent my address and a small jiffy bad with an Australian stamp plopped on to my doormat this morning. Thanks again, Craig!
What I hadn't expected, since I'd anticipated that someone would be replacing a SoftRock they'd built and used, was that "kit" meant it was an unbuilt SoftRock 6.2 Lite kit! Inside the jiffy bag was a polythene bag containing one of the most densely packed printed circuit boards I'd ever seen. There hardly seems space for all the components, which include a few SMT parts. This is going to be a baptism of fire for sure!
However, no building instructions were included. I guessed there was a PDF file on the web that can be downloaded and printed out, but so far I have been unable to find it. I went to the SoftRock Radio website and clicked on the Documentation link and bizarrely, it opened some pages about installing WordPress! This reminded me that during a couple of other wet weekends in the last couple of years I had toyed with the idea of building a SoftRock kit and couldn't even find on the website where to order one!
Google found some pages by Jack Smith that describe building a Softrock and even using it as a panadapter which are going to be required reading, but he doesn't mention where he found the instructions on how to build it. Hopefully one of my more savvy blog readers will help me out here. Otherwise I'll probably have to send Jack an email and ask where he found them.
What I hadn't expected, since I'd anticipated that someone would be replacing a SoftRock they'd built and used, was that "kit" meant it was an unbuilt SoftRock 6.2 Lite kit! Inside the jiffy bag was a polythene bag containing one of the most densely packed printed circuit boards I'd ever seen. There hardly seems space for all the components, which include a few SMT parts. This is going to be a baptism of fire for sure!
However, no building instructions were included. I guessed there was a PDF file on the web that can be downloaded and printed out, but so far I have been unable to find it. I went to the SoftRock Radio website and clicked on the Documentation link and bizarrely, it opened some pages about installing WordPress! This reminded me that during a couple of other wet weekends in the last couple of years I had toyed with the idea of building a SoftRock kit and couldn't even find on the website where to order one!
Google found some pages by Jack Smith that describe building a Softrock and even using it as a panadapter which are going to be required reading, but he doesn't mention where he found the instructions on how to build it. Hopefully one of my more savvy blog readers will help me out here. Otherwise I'll probably have to send Jack an email and ask where he found them.
Tuesday, November 10, 2009
Building the Dixie Pixie
Jorge KI4SGU has started a new blog specifically to document building a QRP PIXIE2 transceiver Manhattan style. It promises to be a good read and I for one will be following it with interest.
I've been intending to build one of these little Pixies myself for a long time but I have never got around to ordering up the parts needed. Or rather, I have never managed to put my mind to deciding what other parts to buy at the same time to make up a worthwhile order.
I've been intending to build one of these little Pixies myself for a long time but I have never got around to ordering up the parts needed. Or rather, I have never managed to put my mind to deciding what other parts to buy at the same time to make up a worthwhile order.
Tuesday, November 03, 2009
Tempting Sienna
Ham radio kit builders in the USA have another full-featured HF transceiver kit to choose from - the DZKit Sienna.
Announced over a year ago, the first kits seem to be finding their way to builders now, and reports are starting to appear on the web in builders' blogs. Here you can see some pictures of a Sienna in various stages of construction.
The Sienna appears more complicated to build than an Elecraft K3, but involves some real construction. Some boards use SMT parts, but they are preloaded. The Sienna is modular, and can be built as a receiver, QRP transceiver or with 100W PA. It is available with or without a front panel (for computer control) and may even be built with an internal PC running HRD.
Unlike the Elecraft K3 the Sienna is not a software defined radio. The circuit design appears to be an entirely analogue, triple conversion design with a 20KHz roofing filter at the first IF. I can't imagine that the performance comes anywhere near that of the K3, but I wouldn't be surprised if it sounds better.
DZKit doesn't have a forum where one can see what builders and users are saying about the radio but you can download construction manuals to get an idea of what is involved. I'd be lying if I said I wasn't tempted to order one, but I'd have to sell the K3 to afford it and the K3 is working really well now.
Announced over a year ago, the first kits seem to be finding their way to builders now, and reports are starting to appear on the web in builders' blogs. Here you can see some pictures of a Sienna in various stages of construction.
The Sienna appears more complicated to build than an Elecraft K3, but involves some real construction. Some boards use SMT parts, but they are preloaded. The Sienna is modular, and can be built as a receiver, QRP transceiver or with 100W PA. It is available with or without a front panel (for computer control) and may even be built with an internal PC running HRD.
Unlike the Elecraft K3 the Sienna is not a software defined radio. The circuit design appears to be an entirely analogue, triple conversion design with a 20KHz roofing filter at the first IF. I can't imagine that the performance comes anywhere near that of the K3, but I wouldn't be surprised if it sounds better.
DZKit doesn't have a forum where one can see what builders and users are saying about the radio but you can download construction manuals to get an idea of what is involved. I'd be lying if I said I wasn't tempted to order one, but I'd have to sell the K3 to afford it and the K3 is working really well now.
Monday, October 19, 2009
DC20B osc mod failure
For about three months I have had an annoying nagging at the back of my mind that my DC20B 20m QRP transceiver kit has been laying in the junk box, almost but not quite working. The main problem with it is that the transceiver is operating on a frequency of 14.062MHz, which means that it cannot be used to call people working on the QRP frequency of 14.060MHz. For some people who have good antennas and prefer to call CQ that might actually be an advantage. But personally I prefer to reply to others whom I hear calling, and I rarely hear anyone calling that far up the band except during a contest.
Shown above is the schematic of the DC20B oscillator circuit. Q9, a 2N7000, is a transistor switch which is on during transmit, shorting out the frequency trimming components CT2 and C36. Effectively the crystal X1 is connected directly between the base of Q8 and ground and there is no way of varying the frequency. CT2 and C36 are used to shift the oscillator frequency 600Hz higher during receive so that a station that replies exactly on your frequency can easily be copied. (Incidentally, while doing this I noticed that the ground pads for C36 are not actually connected to ground on the circuit board. One more thing to add to the catalogue of faults with this kit.)
I tried replacing the crystal supplied by QRP Kits with another 14.060MHz crystal from another source, but that made no difference. The frequency was still 2KHz too high. So I tried modifying the oscillator circuit.
With the tuning trimmer in parallel with the crystal I was able to get the frequency down to 14.060MHz. Very little capacitance was needed, though. Too much and the crystal stopped oscillating.
My attempt to shift the oscillator frequency between transmit and receive by switching an additional capacitor using Q9 was a failure however. My test meter showed Q9 was indeed switching, but even during receive when the transistor switch was "off" the additional capacitor was loading the circuit. Presumably the capacitance through the 2N7000 is large in relation to the capacitance I was trying to switch (a few pF) so that even during receive most of the extra capacitance is still in circuit.
In order to test the shift between transmit and receive I connected my QRP power meter to the antenna socket to provide a dummy load and I discovered more bad news. In this circuit configuration the output power was only tens of milliwatts instead of the couple of watts that the transceiver produced with the original oscillator circuit. I restored the original circuit just to verify that the PA hadn't failed (it hadn't). At this point I was out of ideas and returned the DC20B to the junk box.
I think this kit is a lost cause, but perhaps someone reading this will know what to do to get it working on 14.060MHz and still get the full power output.
Shown above is the schematic of the DC20B oscillator circuit. Q9, a 2N7000, is a transistor switch which is on during transmit, shorting out the frequency trimming components CT2 and C36. Effectively the crystal X1 is connected directly between the base of Q8 and ground and there is no way of varying the frequency. CT2 and C36 are used to shift the oscillator frequency 600Hz higher during receive so that a station that replies exactly on your frequency can easily be copied. (Incidentally, while doing this I noticed that the ground pads for C36 are not actually connected to ground on the circuit board. One more thing to add to the catalogue of faults with this kit.)I tried replacing the crystal supplied by QRP Kits with another 14.060MHz crystal from another source, but that made no difference. The frequency was still 2KHz too high. So I tried modifying the oscillator circuit.
With the tuning trimmer in parallel with the crystal I was able to get the frequency down to 14.060MHz. Very little capacitance was needed, though. Too much and the crystal stopped oscillating.My attempt to shift the oscillator frequency between transmit and receive by switching an additional capacitor using Q9 was a failure however. My test meter showed Q9 was indeed switching, but even during receive when the transistor switch was "off" the additional capacitor was loading the circuit. Presumably the capacitance through the 2N7000 is large in relation to the capacitance I was trying to switch (a few pF) so that even during receive most of the extra capacitance is still in circuit.
In order to test the shift between transmit and receive I connected my QRP power meter to the antenna socket to provide a dummy load and I discovered more bad news. In this circuit configuration the output power was only tens of milliwatts instead of the couple of watts that the transceiver produced with the original oscillator circuit. I restored the original circuit just to verify that the PA hadn't failed (it hadn't). At this point I was out of ideas and returned the DC20B to the junk box.
I think this kit is a lost cause, but perhaps someone reading this will know what to do to get it working on 14.060MHz and still get the full power output.
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