Buying batteries on Ebay

Yesterday I wanted to experiment with using a ferrite rod antenna for WSPR. I was using my AA-200 antenna analyzer to try to tune the antenna when it suddenly restarted. I switched it off and on again and as soon as I chose any function the analyzer restarted again.

The last time I used the AA-200 I remember the batteries ran out so I charged it. It appears that after 6 years of use the rechargeable battery pack won't hold a charge.

AA-200 antenna analyzer and open battery pack

I'm useless at taking things apart but Olga managed to open the battery pack to reveal a shrink wrapped pack of 4 AA cells. I could have ordered a replacement from Strikalite but their price was £20. I found an Ebay seller in Hong Kong whose price was a quarter of that. So for the sake of a few days wait I could save myself £15.

I ordered the battery pack, but this morning there were two emails in my inbox saying "We are sorry to tell you that we are not allowed to dispatch batteries recently for the customs are very strict on exporting batteries." Is this something new? It's the first I have heard of it. I've certainly bought battery packs (including batteries for handheld transceivers)from China on Ebay before.

The seller has refunded my money (or at least he has said he will.) In the meantime I found a UK seller of Chinese batteries, Vapextech UK, which, while not as cheap as the Hong Kong seller, is still a third of the price of Strikalite. Having said that, Strikalite is still a good firm to go to if you want to refurbish a ham radio battery pack and like me you are useless at taking battery packs apart.

A good deal(er)

If you are a UK amateur and you like Chinese radios you'd probably never think of buying them from anywhere other than direct from China or Hong Kong, most likely using eBay. Ham radio dealers in Britain are widely regarded (rightly or wrongly) as rip-off merchants who work out the price by replacing the dollar with a pound sign and then adding on a bit more for good measure. Their pleas that the UK price includes VAT and the cost of providing a warranty usually fall on deaf ears.

In one of the discussion groups someone mentioned buying a radio from a British firm called Sinotel UK. I went to their web site and saw that they carried several models of hand-helds from China, including a new one I hadn't seen before: a TYT UVF9 (pictured right.) But what particularly caught my attention was their prices, which were little more than what I have been paying buying on eBay. Their cheapest model, the Vero Telecom UV-X4 (similar to the Baofeng UV-3R) was just £29.99 (yes, a brand new dual band radio for 30 quid.) A UV-5R eas £34.99. The radio that had caught my eye, the TYT UVF9, was £47.99. It would cost me $68.50 from 409shop and I'd have to wait a couple of weeks for it.

I am not associated with Sinotel UK and have not even bought anything from them but if I want yet another Chinese handy to add to my collection I probably will.

Fake or genuine?

Buying radio gear on eBay is like gambling. It's addictive, but often you lose. You win often enough to keep you coming back in the hope of finding that absolute bargain.

Is the antenna on the right a fake?

I thought that I would buy a dual-band handheld antenna that was long enough to have a bit of gain but not too long to use in the shack. (I have several gain antennas but at over a metre in length they are not suitable for indoor use.) I have a Nagoya NA-701 which works very well for its length (22cm) so I thought I would get a NA-771 which is 40cm in length and ought to perform a couple of dBs better. I know only too well that there are a lot of fake antennas on eBay so I bought this one from 409shop, or rather from radiobanker which is one of the eBay IDs used by 409shop. The general consensus is that 409shop is a trustworthy trader and doesn't sell fake stuff.

When the antenna arrived I was concerned to see that instead of the silver-on-black label showing the make and model number the details were printed on in blue. I have had other fake antennas with printed-on labels, even ones with the same shade of blue so it was not a good omen. When I tried the antenna on one of my handies I found that it performed no better than the much shorter NA-701.

SWR of the alleged NA-771

I put it on my AA-200 antenna analyzer and found that the SWR at 145.000MHz was about 4:1. There were two dips to the HF of the 2m band, the best of which was at 195.000MHz with 2.7:1. This is not the worst I have found but it explains why the antenna did not perform optimally.

SWR of Nagoya NA-701

For comparison I looked at the SWR of the NA-701 with the silver-on-black label. This was a really good match - better than 1.5:1 at 150.000MHz though closer to 2:1 at 145.000MHz. Given that the resonance at any given time will be affected by conditions surrounding the hand-held antenna that's close enough.

So is the NA-771 from radiobanker a fake or not? The plastic sleeve the antenna came in bears a silver hologram label that says "Nagoya", and the name "Reuex Industrial Co. Ltd." That is the name of the company that manufactures Nagoya antennas and apparently they do use blue lettering.

So I conclude that this antenna is probably genuine and performs as well as it was meant to, which unfortunately happens to be not as well as I hoped. The Nagoya NA-771 is not worth its extra length.

FYI using an SWR/power meter I measured the SWR of the two antennas at 433.000MHz to be: NA-701 3.4:1, NA-771 4:1.

Yet another fake Diamond antenna

I ordered a Nagoya NA-771 antenna on eBay. I was impressed with the shorter NA-701 and wanted something with a bit more gain that was not poke-you-in-the-eye long. The NA-771 had mostly good reviews on eHam.

I ordered from an eBay seller that shipped from the UK. The price was £4.99. When it arrived, I found the packaging and the antenna itself claimed to be a Diamond RH-771 not a Nagoya NA-771.

But this is clearly another fake Diamond. The lettering is white whereas the real Diamond product is lettered in blue. The lettering also contains nonsense. It claims "144/430 MHz & VDE BAND HECEMNG COVERAGE JAPAN." Eh??? Perhaps it was supposed to say wide band general coverage? And the antenna is only 36cm long whereas the real RH-771 (and the NA-771) are supposed to be 39-40cm long.

None of this would matter if the antenna was any use, but in fact its resonant frequency is just below 120MHz. At 145MHz the SWR is more than 4 to 1 and it radiates a poorer signal than the shorter Nagoya NA-701 antenna.

Anyone want an air band antenna? Yours for a fiver. And can anyone recommend a seller that has the genuine Nagoya NA-771?

No charge

The object on the left of the picture is a 9600mAh external back-up battery for MP3 players, mobile phones and other 5V devices. I bought it on eBay (where else?) for $55.99 including shipping with the intention of using it to power my HTC Touch Pro smartphone so that it could run all day using GPS and internet connected apps like the APRS client APRSISCE. Previously I hadn't been able to make much use of such applications when out and about on foot because if I was away from a power supply for more than a couple of hours the end result was a dead battery and a phone that could not be used to make phone calls.

The product arrived after a couple of weeks wait rather poorly packed in a jiffy bag containing the battery back-up unit, a 5V USB charger with the usual two-prong fold-out mains plug, and a USB cable with coiled lead and interchangeable power connectors. There was no box, nor any instructions so I had to figure things out for myself. Clearly the DC IN port was meant for the charger, the USB socket marked DC OUT was the output and the slide switch next to it turned the output on and off. The four LEDs showed the battery state for a few seconds after the POWER button to the left of it was pressed, and the charging state whilst charging.

There was no cable for charging, so I presumed I had to use the USB lead supplied for output and one of the interchangeable connectors. One of them did fit, though not very well, poorly enough in fact that it pulled out of the socket if there was the slightest tension on the coiled cable.

I started charging the power pack. Two lights lit up on the charger and the charge status showed two of the four LEDs lit. Next time I looked at it all the LEDs were off. Surely the batteries could not have charged so quickly? Eventually I measured the output from the charger and found it was about 0.25V. Clearly the charger had failed.

I sent an email to the eBay seller who was anxious enough about the possibility of receiving negative feedback to immediately promise to send a replacement. Meanwhile I found that the charger which came with my HTC phone had a USB output so I charged the battery pack with that. With hindsight that was rather foolhardy and I ought to have attempted to measure the current drawn first, but I got away with it. Though rated at 1.0 Amp output the HTC charger got fairly warm, but eventually the charge level reached full and the charger got cold again so I assume that it finished charging and the pack was fully charged.

The charger that came with the battery pack is labelled as an "MP3 Power Supply" and the output is rated at: DC 200mA +/- 30mA. Even the 1500mAh battery in the little Baofeng radio takes more than 400mA on charge. I managed to find a cable that would enable me to charge the battery pack from my workbench variable metered power supply and even when the battery pack is only half discharged it is drawing a current of almost 800mA. So I think the charger supplied simply blew up! I'm just hoping the eBay seller will provide a more adequate charger as a replacement. Sure, I can use my existing HTC phone charger. It may even be more convenient than having separate chargers for the two devices. But it would be nice to receive what one paid for.

By the way, if you ever wondered what is inside those Chinese wall-wart power supplies, how come they are so light, here are some pictures of the innards of the one that failed.

The answer, it seems, is not much. Call me old fashioned, but I'm just a bit apprehensive about having just a handful of components between my equipment and the 230V mains!

It's a pity that this problem has occurred because I would have liked to have been able to recommend this battery pack to other users of APRSISCE on Windows Mobile. My initial test on the workbench suggest that this battery pack is more than capable of powering the phone with GPS and mobile data connection active during a day's outing. The battery pack itself seems well made and I would guess that it is probably supplied by its Chinese manufacturer in a nice box with instructions and an adequately rated charger. The trouble in this case would seem to be caused by a cheapskate eBay seller.

Another eBay dud

It's the same on 433MHz as well.
In fact I couldn't find any frequency at which this so-called antenna is resonant!

Antenna analyzer from China

An antenna analyzer is a very useful piece of equipment and I have never regretted buying my AA-200, though I probably wouldn't get one now with the current model priced at £410.00. Even the basic MFJ-259B which is not exactly renowned for its quality construction will set you back £260.00. So I was interested to discover that the Chinese have entered the market with the Feature Tech AW07A which can be bought on eBay for a much more reasonable £160.00.

The unit can measure RF impedance and SWR from 1.8 to 490MHz (making it more directly comparable to the MFJ-269B model) as well as measuring capacitance and inductance. It may be used as a non-precision signal source and frequency counter, and with the addition of an inductor may be used as a dip meter. It looks like a nice addition to any amateur's toolkit.

Dead mic

When using a hand held radio with a long whip antenna for more gain I often prefer to use a speaker mic so I can hold the radio in a steady, upright position. I have a speaker mic for the Kenwood TH-F7E (which fits the old TH-205E as well) and I have one for the Motorola GP300. But needless to say neither of them fit the Intek H-520 Plus 10m rig because the wiring and pin spacing is different. The official Intek speaker mic is rather expensive so I looked on eBay and found a speaker mic for "Alinco Icom Standard 2-pin" with the correct pin spacing for less than £7 including postage from Hong Kong.

When it arrived I decided to check what the audio sounded like by listening on the K3 while I made a call. The mic keyed the radio up but there was no audio. To make troubleshooting easier I swapped the antenna for a dummy load and audio was then heard!

I then tried a variety of different antennas and power levels and was soon pulling my hair out. I would hear audio with the dummy load connected and none as soon as I switched to an antenna. Eventually I tried the very short antenna supplied with the H-520 on the lowest power setting, 0.1W and I heard audio. It was looking very much as if the presence of radiated RF was somehow interfering with the audio. But the amount of RF required to cause the problem must be small as 0.1W on any of the larger antennas resulted in no audio from the speaker mic.

I didn't know whether the RF was causing a problem with the microphone or the radio. I tried clamp-on ferrites at both the mic end of the cable and the plug end but neither made any difference so I was none the wiser. This particular made-in-China speaker mic is held together with screws that require a nonstandard five pointed key to undo so I couldn't look inside to see if it used screened cable. I decided to give up on that speaker mic and do what I could have done in the first place if I hadn't thought spending seven quid would be an easier solution.

In my junk box was the business end of another cheap Chinese speaker mic from which the cable had been 'borrowed.' I noticed in the past that the curly cables used for these speaker mics are often not screened. I happened to have a length of stereo audio cable with each channel separately screened. I wired this up to the spare speaker mic and attached suitable 2.5mm and 3.5mm jack plugs to the other end. When I tested it I now had transmit audio even on high power with the 4 foot telescopic whip!

At this time I don't really know whether the mic I bought was at fault because I don't have another radio that uses the same size plug spacing to test it with. Given that I have been less than impressed with other aspects of the H-520's performance I wouldn't be surprised if it wasn't the radio that has inadequate filtering for RF picked up on the speaker mic cable.

More eBay purchase woes

I'm not paranoid, but I think everyone is out to get me!

I ordered some connectors from eBay seller m0jpm and, because I have been thinking about getting a radio that has N type connectors on it, I decided to order a couple of BNC to N-type adapters so I could use the much easier to obtain BNC plugs on my antenna cables. The listing I ordered from is shown below.

The package arrived this morning and when I opened it, to my dismay I found that the adapters were the reverse of what I wanted. As you can see, they are for attaching N-type plugs to BNC sockets.

It has sometimes happened that I ordered the wrong thing by mistake, so I was relieved when I checked the eBay listing and saw that this time it was the seller's mistake not mine. But my relief turned to anger when I emailed the seller to inform him of the error and received the reply: Dear g4ilo, Hi we have send you what you have ordered, as this is the only n-type to bnc we have listed. but if you not happy send it back for a refund.

Is it really necessary to insult my intelligence by telling me "we have send (sic) you what you have ordered"? I will send the adapters back for a refund (and no doubt be out of pocket for the postage) because they are no use to me. But I shan't be buying anything from m0jpm again.

In a comment to my previous post Ricardo CT2GQV said that I should give up buying on the Internet. I wish I could, but if I did I would have to give up the hobby because it is not possible to buy radio stuff round here.

The battery charger that wasn't

I've bought loads of radio and electronic stuff from Hong Kong and China on eBay and most of it has been okay. But I've had the occasional duff purchase, like the stubby dual band antenna allegedly made by Diamond which I'm pretty sure was a fake.

I bought a Motorola GP300 radio body at the Blackpool rally a couple of weeks ago but I needed accessories like a battery pack, charger and speaker mic. Ebay was the obvious place to look for them. The 1800mAH NiMH battery pack was fine, and a good price. The speaker mic is obviously a clone of the original Motorola design but a lot less solidly made, but I have received good audio reports using it so no complaints there. However I was a bit suspicious about the "overnight charger" purchased from RadioFactory because after 6 hours of charging the battery pack was really hot.

The GP300 battery ran out while I was on Watch Hill this afternoon so I need to charge it back up, but before I do I thought I would take a look inside. The case is conveniently designed so that you can pull it apart after pushing back four flexible plastic clips. The circuit board then just lifts out. I got quite a surprise after I did!

The top of the circuit board is printed with component outlines but most of the components marked are not present, and many of the components that are there don't correspond with the outlines. In the middle of the board is an unidentified component that looks as if it has overheated.

On the underside of the board, again, most of the components that are supposed to be there are missing. Some of the tracks are bridged together with solder blobs or a wire link. I haven't got the time or, more importantly, the clarity of mind to work out exactly what the circuit on the board actually is, but it doesn't look much like something capable of charging a 7.2V battery pack from a 12V wall wart.

I'm not quite sure what to do about this. I have the plastic case and the charger contacts, which as I know from the charger I made for the TH-205E are the hardest parts of a battery charger to make. So I could simply make up another constant current charger circuit on Veroboard and put it into the existing case. Or I could simply cut my losses and buy another Motorola charger from a reputable source. I'm sure that one of my readers will know of one.

eBay bargain

Whilst buying on eBay can sometimes result in a piece of junk, it can also produce the occasional lucky find. The radio pictured on the right is my latest auction success which arrived this morning. It is a Trio / Kenwood TH-205E of 1986 vintage which was being sold as for spares or repair. It cost me all of ten quid ($15 for my US readers), four of which were for postage.

When it arrived it was a bit oily, for some reason, but a wipe over with some tissues took care of that. From the front it looks almost like new - no scratches or signs of wear on the markings or buttons. The rig has obviously had an active life though as on the back the paint has worn away and the serial number plate and the warning notice on the battery pack have been polished almost clean of lettering.

The seller stated that they could not get the radio to charge up, which is no surprise, as for 24 year old NiCads to still retain a charge would be nothing short of a miracle. I applied 9V of external power, switched on, and was pleased to see "144.000" appear on the display and hear the hiss of an unsquelched receiver from the speaker. My initial delight at having acquired a worker was short-lived, however, as the frequency display failed to respond to the up/down buttons and the squelch did not seem to work either.

After a while spent pressing buttons in the faint hope of getting the frequency to change, it suddenly did increment a few steps and the squelch also operated. Then the radio gradually became more responsive to the buttons and I was eventually able to persuade it up into the 145.500 region. I connected my QRP power meter and was delighted to observe that the TH-205E was putting out a good 5W in the high power position and 1W in low power. I could also receive the signal on the TH-F7E standing nearby, which was somewhat dwarfed by its older sibling. I'd forgotten hand-helds were still this chunky in 1986!

I connected an antenna and found that I could receive all the local repeaters, so sensitivity is acceptable. The TH-205E will only do 5kHz steps so it isn't suitable for 12.5KHz channeling, but the receiver is broad enough to receive the GB3LA repeater on 145.7125 when tuned to 145.710 with perfect audio. There is no CTCSS, though there is a tone-burst switch (which I haven't tested.)

Apart from the up/down frequency selectors the only other front panel button that appears to work is the Lamp button which backlights the LCD display. I can't activate the repeater offset or program or recall any of the three frequency memories. Possibly these buttons will eventually spring to life after repeated pressing. Otherwise it may require a look inside to see if it is possible to clean the switch contacts. But to be honest I'm not all that bothered, as I'm unlikely to be using the TH-205E on any repeaters.

The most I hoped for when bidding for this was a radio that could easily be got working and could then be put to use as a dedicated rig for APRS on 144.800 or something similar. The least I expected was something I could cannibalize for £10 worth of useful parts. So already I have got more than I hoped for!

Chinese crap

Several months ago I had a plan to build a project using Manhattan style construction so I decided to get a tool to make myself some Manhattan pads. Constructors in the US can buy a nice hand punch from Harbor Freight for $25 - that's less than £18. Over here the nearest equivalent cost around £90 from a tool supplier, except on eBay. I bought the eBay one, but even that cost over £30 including postage.

In the end, apart from punching a couple of test pads using the 7mm punch that was already fitted when I opened the box, I didn't use it. Until this afternoon, when I wanted to make some smaller pads. That was when I discovered what a shoddy piece of manufacturing this eBay hole punch is.

The 7mm die was a bit stiff to remove but came out with the aid of a screwdriver in the slots provided. The 4.5mm one I put in would bind at each turn and got more and more stiff. Eventually it wouldn't budge, so I put the screwdriver blade in sideways to get a bit of leverage. There was a crack and a whole piece of the die broke off! I guess it was made by the same firm that makes K3 knobs for Elecraft!

It's far enough in that I can make 4.5mm pads, but not only does it not want to go in any further but it also doesn't want to come out. I might be able to get it out with some Mole grips but this is probably the most useful size and I might never be able to get it back in again next time I need it. Crap!

A new toy

There was a knock on the door this morning and the postman asked me to sign for a parcel from overseas. The customs declaration amusingly - if appropriately - described the item as "Toy". It was the UNI-T UT-81B Oscilloscope Digital Multimeter that I ordered last weekend from eBay seller hk360radio in Hong Kong.

My first thought on opening the box was: "Wow! All this for a hundred quid? Amazing!" Inside the zip-up fabric carry case was the scope/multimeter, test probes, a BNC oscilloscope probe adapter, an opto-isolated USB cable for connecting the instrument to a PC, a two-pin wall-wart power supply and a two-pin to UK three-pin mains adapter, manual and CD containing the PC software.

The instrument is both a multimeter and a storage oscilloscope. The multimeter is auto-ranging, so the control switch simply selects the function: voltage, current, resistance etc. It measures DC voltages to 1000V, AC to 750V, current to 10A, resistance to 10M, capacitance to 100u and frequency to 10MHz. There is also a continuity tester. It can read volts down to 100uV and current down to 0.1uA. The frequency counter accuracy isn't good enough to calibrate your radio, but it's still quite handy.

Many years ago, back before I had a ham radio license, I had an oscilloscope that I built from a design in Radio Constructor magazine. It only covered up to about 200kHz and wasn't calibrated. I had to sell it when I left my parents home and had nowhere to keep so much electronic stuff, and I haven't had one since. But there have often been occasions when I wished I had one, so that was one of the main reasons for buying the UT-81B.

The oscilloscope bandwidth of the UT-81B model is quoted as 8MHz, so I can't use it as a monitor scope for the whole of HF, but it covers up to 40m at least. I was very keen to try this. I connected my FT-817 up to my QRP power meter via a T-piece and connected a cable between that and the oscilloscope. When I spoke into the microphone I could see the modulation envelope on the display.

I was interested to see whether the horizontal scan rate was fast enough that I could see the actual RF waveform. I increased the timebase speed until I was able to see the display above of the carrier wave from the FT-817 in CW mode. The sample rate is given as 40MHz and you can just see that the waveform is a little jagged. You can see that the scope has also displayed the frequency to within 1kHz. There is a full range of trigger functions and also a manual hold you can press to capture the display, which I used to take the photo above.

There is a Windows software application that connects to the instrument via a USB port. It can log measurements over time and also capture scope displays and save them to a bitmap (BMP) file. I was able to capture the waveform shown in the photo. However it was not able to capture an RF modulation envelope when sampling the RF at a much slower time base setting. I just got a thin wiggly line that seemed to bear no relation to the envelope displayed on the scope itself. Not a major issue, though.

I am really delighted with my new "toy", which cost me £95.50 plus £13 for the shipping (and no tax.)

No crystals

I have been awaiting the arrival of the postman for the last week with eager anticipation and growing frustration. I have been expecting a set of QRP CW frequency crystals that I ordered on eBay almost a fortnight ago in order to try to make a contact using my little XBM80-2 transceiver. The only 40m crystals I have are for 7.040 which were fine for testing the radio but that frequency is in the middle of the 40m data segment so I can't go on the air using it. I don't have any 80m crystals at all, and I want to try the circuit on that band - which Roger designed it for - before coming to a decision as to which band to build it for.

I ordered the crystals from an eBay trader named spratreader because he offers a set of 5 crystals for £6.95 post paid whereas just two crystals plus postage from the G-QRP club would cost £4.60 - and I'd have the hassle of going to the post office to get stamps because they won't accept PayPal for anything less than a fiver. I've had crystals from spratreader before and they came quite promptly, so I'm not blaming him for the problem. Unfortunately I didn't order 80m crystals in the previous set, nor did I realise that the 40m crystals were not for the European QRP CW frequency - perhaps they'll come in handy one day for a WSPR beacon.

My order was delayed because spratreader was on holiday. He informed me last Thursday that they had been sent, so I began staking out the postman. After a week nothing had arrived, so I sent an email right after the post came this morning to say that I still hadn't got them. I'd hoped that replacements might be sent today, but I'm still waiting for a reply to my email. So it's looking less and less likely that I'll be able to test the XBM-80 this weekend. It's really frustrating, though with the ARRL DX CW contest on this weekend probably isn't a good time to try making a contact with 100mW anyway.

HT Saver

One of my ham radio pet hates are those SMA sockets used to mount the antennas on all modern VHF/UHF handheld radios. They are very fragile, and not designed for the repeated changing of antennas that most of us go in for. I don't see any justification for using them except on those very slim credit card sized handhelds which are pretty fragile devices anyway. But all the manufacturers now use them so we're stuck with them.

With the Kenwood TH-F6A / TH-F7E you really have no choice to switch antennas if you want to make use of the shortwave receive capability because the VHF/UHF antennas are useless on shortwave. Last week I made a shortwave receive antenna for it which I called the Wonder Whip. This antenna works on 2m and 70cm transmit as well, but it is a bit long to leave on the radio when carrying it so I still need to remove it quite frequently.

I made the Wonder Whip on a BNC connector so I needed to use a BNC to SMA adapter to use it on the radio. The trouble with the readily obtainable BNC to SMA adapters is that they do not have a large base that clamps down on to the body of the radio for extra support like the supplied antenna does. This means the SMA adapter takes the full force of any sideways knocks. It is very easy to snap off, as many HT owners have found to their cost. So when I saw some SMA to BNC adapters with a large base being sold very cheaply on eBay by a Hong Kong trader called PartsPipe I ordered a couple of them. The pair cost less than £5 including postage and they arrived in just over a week which is one of the quickest shipments I've had from the Far East.

To my disappointment I found that when screwed on to the TH-F7E as far as it would go there was a gap of about one millimetre between the base of the adapter and the radio. Fortunately I found a steel washer that slips over the SMA antenna connector and fills the gap. I will probably be able to get a matching brass washer at a local DIY store but the steel one will do for the moment. Now any BNC antennas will be fully supported by the body of the radio.

If I use only BNC base antennas from now on I can leave the adapter permanently in place and will not have to keep connecting and removing things from the SMA socket, which I think is rated for only something like 100 connections. I think this is a much better solution: BNC connectors are more robust and in the unlikely event you do get a problem you can just replace the inexpensive adapter - which is why I got two of them!

Now I just have to decide what to do with my arsenal of SMA-based antennas. Probably flog them on eBay!

Fake Diamond

A few weeks ago I wrote about the Diamond SRH805S stubby helical antenna I bought on eBay to use with my VX-8E. Its performance turned out to be much worse than expected and the antenna was not even resonant in the 2m band according to my antenna analyzer. Having looked at it a bit more closely I now believe the antenna I bought is not a real Diamond SRH805S at all.

The pictures above show, from left to right, the antenna I bought, an unbranded "short dual band SMA antenna" advertised by an eBay seller from Hong Kong, and a picture of a genuine Diamond SRH805S taken by an owner. You can see that the fake antenna and the unbranded antenna look identical apart from the "Diamond" labelling on the fake. There is a wide knurled brass band on the fake and the unbranded antennas, where the real Diamond has just a narrow smooth band. The fake and the unbranded antennas both have a double groove molded into the case, the real Diamond doesn't. The picture of the unbranded antenna gives its height as 52mm, matching exactly the one I have, while another picture I found of the Diamond SRH805S shows the height to be only 45mm.

The word "Diamond" on the fake antenna is not in the same font as on the real antenna, which uses a bolder font matching that used in Diamond company advertising and on the packaging. The labelling on the real antenna is blue while the fake is white. To be fair, I have found an image on a Canadian radio dealer's site where the labelling is white. It is also written top to bottom rather than bottom to top and has an aircraft logo on it. This may be a picture of an older version of the antenna.

The fake antenna came in a genuine-looking plastic case with a yellow back and a clear front. The forgers appear to have reproduced the lettering exactly. But on the genuine antenna cases the model number SRH805S is written in red. The genuine Diamond antenna comes with a rubber washer to seal between the antenna and the radio body if there is a gap. It also includes a printed sheet giving the specification of the product - the fake didn't.

One clue to the fact the antenna I bought was a fake is the price. I paid £6.99 including postage from Hong Kong for this antenna, which is about the same as the unbranded SMA antenna. Hams in the Far East have often told me prices there are a lot less than they are here so I was not as suspicious as perhaps I should have been.

Radioworld in the UK advertises the Diamond SRH805S for £25.96, while some Chinese and Hong Kong eBay sellers have what appear to be the genuine item (but could just be a better fake) for around £20 including postage. A Polish dealer (allegro.pl) is advertising what from the picture looks exactly like the antenna I bought for the zloty equivalent of about £14. A UK dealer (www.dvdongle.co.uk) is advertising a Diamond SRH805S for £13.99 but no picture is shown. In view of what I have discovered I would be interested to see what it looked like.

It might come as a bit of a surprise to many people that there are fake ham radio products on sale. I wonder how often these fake products are being passed off as the real thing for the full price?

What I want to do now is figure out how to get inside this antenna, preferably without resorting to use of a hacksaw, and see if I can tweak it down on to the 2m band and make something useful out of it.

Dud Diamond

As regular readers will know, I recently bought a Yaesu VX-8E with GPS and APRS which I use so that my XYL and others can see where I am when I'm out with a radio. Because the rubber duck antenna is a bit long for convenient use when the radio is clipped to my belt or in a pocket, I thought I would try one of the very small stubby antennas. There is not much choice of alternative HT antennas from suppliers in the UK and the prices of those that are available are absurdly high, but I saw a Diamond SRH-805S being sold for the bargain price of £6.99 including postage from an eBay seller in Hong Kong, so I decided to order one.


I put the antenna on the VX-8E and went for a stroll into town half a mile away as the crow flies but with a lot of buildings in the way. With the radio in my top pocket running 5W my position beacons were received back in my shack quite well except for when I was inside a shop, so I was fairly pleased. However on Sunday I took the radio up the local SOTA summit Watch Hill and was unable to access a single repeater. A repeater that was end-stop on the rubber duck was about S3 on the stubby.

Back in the shack I investigated further, which resulted in a "shoot-out" between all the portable whip antennas I have. I used my K3 with transverter as the test receiver, as it has a direct dBm display of received signal strength. As best as I could measure, the SRH-805S is 13 - 15dB down on the VX-8R rubber duck. I expected it to be worse, but not that bad!

I then attached the antenna to my RigExpert AA-200 antenna analyzer and found that the SRH-805S was giving an apparently infinite SWR! After some tests to check that the antenna was actually making contact with the centre pin of the connector, I had the idea of increasing the sweep range and then saw that the antenna did have a sharp resonance, but it was centred at about 169MHz!

I wasn't able to check performance on 70cm as there is no 433MHz activity round here and my antenna analyzer only goes up to 200MHz. But I tried the SRH-805S on my FT-817 and on both 2m and 70cm the radio displays the warning HIGH SWR! So this stubby antenna is completely useless on either of the two amateur bands it is supposed to cover.

It's quite annoying as the antenna obviously is resonant, just on the wrong frequency, and on that frequency it might actually work quite well. But there isn't much I can do. It would have been better if I had bought this antenna in the UK because I could have sent it back to the retailer as "unfit for purpose." Instead I ended up with a £7 piece of junk.

At least my tests produced one useful result: I found that the rubber duck on the VX-8E works just as well as any of the longer SMA whip antennas I have including a 19 inch telescopic whip. So I can save myself the bother of carrying those around.

New arrival from China

A knock on the door this afternoon heralded the arrival of my latest QRP radio - an HB-1A 3-band (40/30/20m) CW transceiver from China.

Shipment had taken just over a week and, unlike products ordered from the USA, there was no customs charge or VAT to pay, so the radio cost me a total of £165.

Opening the box revealed the radio extremely well packed in expanded polystyrene, plus a photo-printed card with a picture of BG2FX in his lab - presumably the builder. There was no manual, but the eBay listing had linked to an English language manual in PDF form that I could print out.

The radio itself seems very well made, the impression of solidity created by the heavy steel case which is well-painted in a black crackle finish. As this is intended to be a portable radio, an aluminium case would have saved a bit of weight.

Unscrewing two screws and removing the bottom of the case revealed a bit of a surprise - the two 4 x AA cell battery holders were not connected together or to the plug that connects them to the circuit board. I will have to solder together and insulate the wires myself. Four rubber stick-on feet were also inside the case, which I fitted to the bottom of the case before reattaching it.

Applying 12V DC from my shack power supply I was pleased to find that the HB-1A worked perfectly. There is no loudspeaker, output is headphones only, and best results were obtained using a pair of MP3 player style ear buds. The receiver is no match for a K2, but it is quite lively. Selectivity is reasonable and adjustable in three steps - 900Hz, 700Hz and 400Hz for CW - but stopband performance is quite poor: I could hear strong CW signals a few kHz away.

Although this is a CW-only transceiver it can receive LSB and USB as well. Tuning is continuous from below 40m to above 20m so you can even receive shortwave broadcasters by zero-beating the carrier. There is no bandswitch, but the HB-1A has 20 programmable memories which are pre-loaded with useful frequencies in each band such as the QRP CW frequencies - and the broadcast frequencies of Radio China!

The front panel key jack can accept either a straight key or a paddle. This is detected at power-on. However, for a straight key to be detected the center contact of the stereo jack must be grounded. Other radios I have go into continuous key-down unless this contact is open-circuited. Why can't there be a standard?

I was pleased to see that I got a genuine 5W output for 12V DC input. At 9V DC I measured 3W output. I haven't tried batteries yet as I have not yet wired up the internal battery holders.

The battery holders are a tight fit between components on the circuit board and there is no facility for charging rechargeable cells whilst they are installed. I will find removing the bottom of the case, removing the batteries to recharge them and then reinstalling them a bit of a nuisance, so I will be looking to install a socket so that they can be charged in situ.

Despite calling CQ on both 20m and 40m I haven't managed to have any contacts yet - I guess conditions aren't all that good right now.

With a power consumption less than half that of the FT-817 the HB-1A should give decent battery endurance on a set of rechargeable NiMH cells. This is going to be used as a portable HF rig, so the search is on for a small and equally robust Morse key for it. I'm trying to think how I can adapt the DinKey - which turned out to be such a disappointment when used with the FT-817 - so it can be plugged in to the 3.5mm key socket of the HB-1A.

That's all I have to say about this little Chinese radio for now, but I'm sure you'll be hearing more about it once I get everything set up for operation in the field - assuming that the weather plays ball!

Pet ferrites

Ferrites are my friends. You can never have enough clamp-on ferrite RFI filters. Unfortunately just about every radio and components stockist charges a ridiculously high price for them, like £2.50 (about $4) each, which makes it expensive to keep a stock of them. However, a few weeks ago I found an eBay seller in China that was selling packs of 6 or 10 clamp-on RFI ferrites at a much more acceptable price, so I sent off for a bunch of them.

This afternoon the K3 was sitting scanning 2m 144.250-144.350 while I was working, and I noticed a 3 S-point increase in the background noise level. My wife had just switched on her laptop, so I thought that might be the culprit, and sure enough we soon found that the noise was being radiated by the power supply cable. Even if the power supply was off and the computer was running from its battery, the noise level jumped up when the power cable was connected. One turn of the cable through a clamp-on ferrite was all it took to fix it. (Most PC power supplies seem to have a moulded-on ferrite at this point, but curiously not this one.)

A few weeks ago I used clamp-on ferrites to cure a problem with my Elecraft K3 transmitting a poor PSK31 signal (high IMD) on 10m. What seemed to be happening was that RF was getting picked up on the shield of my 2m antenna and coupled back to the K3, causing the problem. I dare say the real cause is a poor RF ground, but it's hard to get good grounding at 28MHz when you're about a quarter wave above ground already. Anyway, fitting clamp-on ferrites to the antenna cables and any other long cables that seemed to be contributing to the problem seem to have cured the trouble.

Clamp-on ferrites have also been quite effective at keeping RF out of the computer. The mouse would freeze when 100W is used on some bands, but looping the USB cable through a ferrite soon fixed it. Without having a box of ferrites sitting patiently in the cupboard, I might have wasted a lot of time trying to find another solution.

eBay ads

A few ham radio sites and blogs I've looked at recently had ads in the sidebar for ham radio equipment being offered at eBay. I thought this would be rather a nice addition to my own site, but I haven't figured out how to get them. After Googling "eBay ads" I subscribed to the eBay Partner Program, which appeared to be the thing to do. However, the ads I got were not terribly interesting from a ham radio point of view.

After a bit of further investigation it seems that the eBay auction ads I have seen are coming from Google. I have had Google ads on my site for years but have never seen an ad showing ham radio items from eBay displayed there. It's a bit of a mystery.

Postscript: Mystery solved. I finally got the auction ads to appear by telling Google I wanted image ads only, not text and image ads.