Friday, August 31, 2012

Our Jubilee

I'm not doing much radio today as Olga and I celebrate our 10th wedding anniversary.


Some of you might like to see a picture of us taken today in our present to each other - a new kitchen!

Thank you, Olga, for a wonderful ten years. I hope the next ten will be even better!

Thursday, August 30, 2012

Buzz off

Ever since I received the Elecraft KX3 it has suffered from poor loudspeaker audio. It buzzed and distorted at any but the lowest volume level. Various suggestions were made and considered but the culprit seemed to be the loudspeaker itself. Elecraft spotted my description of the problem on the KX3 Yahoo group and offered to send a new speaker. After confirming to my satisfaction that the speaker was indeed the culprit I accepted the offer. The replacement came in the post this morning.

The culprit(s) revealed

It didn't take long to plug the new speaker into the KX3. To my dismay, that buzzed and distorted too. It didn't seem to be quite as bad as the original, though, so I decided to install it. That was when I hit a snag: the holes in the speaker chassis had not been tapped to take the mounting screws. I was stymied.

Thinking I would have to put the old speaker back, I had a good look at it. That's when I noticed a split ring lock washer stuck to the magnet where it joined the speaker cone. Aha! I thought. The culprit! As I was soldering the speaker leads back on I noticed something else that should not have been there. A second lock washer! I fished it out with the end of a jeweller's screwdriver and put it with the other one.

I hoped that would be the solution and prepared to reinstall the original speaker. While I was thinking about that I was examining the replacement I had been sent and I noticed what looked like the edge of another split ring lock washer. After a bit of fiddling with the jeweller's screwdriver I managed to fish it out. Yes. it was a split ring lock washer, stuck to the magnet of the replacement speaker!

I'm sure some of you are thinking that my shack must be a tip with bits of hardware strewn all over the place, but I assure you that isn't. I can easily see how a small part could get dropped inside the KX3 during assembly and migrate to the speaker's powerful magnet. But how one came to be stuck to the inside of the replacement in a sealed envelope straight from Elecraft will probably forever be a mystery.

I'm happy to report that the audio from the KX3 is now perfect at any reasonable volume, with the original speaker reinstalled in it. If any UK KX3 owner needs a replacement speaker then it's yours for the asking. But you'll have to tap threads for the mounting screws into it.

Tuesday, August 28, 2012

UHF DVAP Dongle on the way?

Rumour has it that a 70cm version of the DVAP Dongle is on the way. Rumour also suggests that the price will be the same as for the 2m dongle. For those who would like to use Icom's new ID-31 D-Star handie and have no UHF D-Star repeaters in range, the wait may soon be over.

Sunday, August 26, 2012

Robust Packet Radio

A couple of days ago Chris, HB9DDF sent me an email asking how to configure APRSIS32 to work with the SCS Tracker / DSP TNC. Digging through my configuration files to get the information he needed I thought: why not put the 30m APRS gateway back online? It had been off since I went into hospital last year and the K2 and magnetic loop were hardly ever used.
SCS Tracker DSP TNC and Elecraft K2 at G4ILO
I don't know if propagation is lousy or whether things have changed since I was last on HF APRS but there seemed to be a lot less activity on the 30m APRS frequency today. An hour went by without my receiving anything. I did, however, hear quite often the "whooshing" sound of Robust Packet Radio (RPR) stations a few hundred Hz down. So I decided to configure the TNC to work in RPR mode.

Robust Packet is a mode obtainable in 300baud and 600baud versions that has been designed to take advantage of the capabilities of digital signal processing (DSP) in order to obtain reliable communication over a normal less than perfect HF path. To anyone who has experience only of traditional 300baud FSK packet RPR has too be seen to be believed. Packet after packet was decoded and displayed by APRSIS32 while conventional packet transmissions on the adjacent channel just flickered the DCD lamp and were discarded due to errors.

Robust Packet is a proprietary mode developed by SCS and is only supported by SCS TNCs. As far as I know no description exists that would enable someone to develop a PC implementation that uses a sound card. In that respect it is pretty much like Icom and D-Star. I would much rather use an open standard.
G4ILO-10 joins the Robust Packet Network
But RPR works where the old-fangled 300baud FSK invented to work on the analogue modems of 30 years ago doesn't. I think it is in keeping with the spirit of ham radio to use state of the art technology where it provides clear benefits to communication.

So G4ILO is now part of the Robust Packet Network.

Saturday, August 25, 2012

Info needed

Ed, PE5ED and Wijn are developing a project called the IARL. They are trying to collect as much data as they can on repeaters and beacons. This will be freely available via the website and also through an app for smartphones.

They already have quite a lot of information for western Europe though I have already spotted a couple of errors relating to local repeaters. If you can help with corrections or sources of data they would like to hear from you.