New Year, New Ideas (or not!)

I don't think I am capable of "Original Thought".

Every time I think I have discovered something new, I realise that I am re-inventing the wheel.

Please don't think I am bitter about this, if I have a philosophy in life it would be a misquote (no blasphemy intended!) of one of the "Ten Commandments" (or to be more specific the Tenth Commandment) in that I do not (or at least try very hard not to) covet what another has.

Wives, possessions, original ideas, it's all the same thing to me!  Coveting like resistance (misquoting the Borg this time) is futile.

A couple of weeks ago, a professional colleague who works at our Head Office, unlike me who works "out in the field" mentioned something called an "Arduino" to me, and I had to confess that I'd never heard of it.

Anyway, to cut a long story short I looked "Arduino" up on the web, got very excited (!) at what I saw, bought one, faffed about with it and began asking friends and other colleagues if they knew about this wonderful piece of gadgetry, and it seems that I was the only one who thought it was something "new"!

Largely thanks to my friend and mentor, Ron Taylor (G4GXO) of Cumbria Designs, I had been introduced to the world of microcontrollers some little time ago, in connection with the "Eden 9" project.  For those who don't know, the Arduino is essentially a "mini microcontroller development board" based around an Atmel microcontroller, and as such could be described as a "microcontroller on steroids".

Further research, and reading of other bloggers' output revealed that Arduino isn't the only contender in this market place, Julian,  G4ILO has blogged about the "Gadget Gangster Propeller USB" platform, which seems, at least to the casual observer to be more or less the same thing but done with different hardware.

The unfortunate thing for me is that I now have ANOTHER interest to compete for my limited free time with QRSS, meteor observations, Digimodes, Classic Rigs, etc etc.   If only I could afford to retire from the Day Job and play with all these new toys!

RC-14 - An Old Project Revisited

Way back in June 1987, the RSGB published an article in RadCom describing the "RC-14", a relatively simple "beginners" single band (20m) direct conversion receiver.    This was "kitted" by the then popular "Cirkit" emporium, and was offered at an attractive price to RSGB members.

This was, in my view a very well designed piece of equipment, and contained only three integrated circuits (one of the famous and rather splendid Plessey "SL" ICs and a couple of op amps configured as active filters with characteristics very similar to those of a high-performance crystal SSB filter) plus a varactor-tuned VFO, and the end result was a very pleasing receiver.

I built the receiver not long after it was published using the approved kit, and adapted it to my "bespoke" requirements - I disliked the flimsy enclosure provided and moved it to a more mechanically sound but less aesthetically pleasing aluminium die-cast box, and replaced the linear slider tuning pot (remember it was a varactor based design) with a rotary multiturn unit, albeit at great expense, and used it for a while (as you do) and moved on . . .

My version of the RSGB RC-14

Recently, I have become interested in the "QRSS" aspect of the hobby which is based around the transmission of very low power, low signalling rate beacon signals for extended periods which are received at various locations around the globe using PC-based "grabber" software.

Participation in this requires either the setting up of a "grabber" receiving station, or the use of a low power "MEPT" (Manned Experimental Propagation Transmitter), or in some cases both, though not necessarily at the same time!

Over the last few weeks I have been doing either and even occasionally both (!) using conventional equipment, and by "conventional" I mean "High Performance Japanese Transceivers", certainly as the receiving station, but it occurred to me recently that it was possible overkill using such high-spec equipment to perform such relatively mundane tasks.   In a flash of inspiration (or something!) I remembered my RC-14, and began to wonder if that could be dragooned into service as a QRSS receiver.

The built-in VFO, though adequate for general receiving purposes was certainly not of the required specification as a QRSS receiver, where frequency stability is a primary requirement, but the substitution of the built-in VFO with a crystal-based, or even synthesiser-based local oscillator would seem to be a Good Idea.

If you are following the argument, then by now you will surely have picked up on the mental thread . . .

And so, another project is born!

TS-180S - this is getting ridiculous!

I knew it was a mistake putting the lid on properly.

Having restored the functionality of the frequency display I decided to run the radio for a few hours over the weekend to evaluate performance further.   Still no tx, of course or any PLL locking on 28MHz but I knew that already ...

I was listening to a QSO on 7MHz this morning between a very strong Belgian station and a string of UK stations, most of whom I could hear reasonably well when I realised that the frequency seemed to be locked on to 7.150.0MHz.  Tuning either side by a kHz or two made no difference to the display.   I had a funny feeling about this, so I tuned up and down the band to find that lo and behold that the display was only displaying frequency to a 10kHz resolution!

To see whether this was a heat related issue I switched the radio off and let it cool down for half an hour or so, but on re-powering the fault was still present, so I have concluded that I have ANOTHER dead chip!  More than likely a duff 7490 in the counter chain, and that's TTL not CMOS, so another theory goes down the pan.

It is now only sheer stubbornness which is sustaining my interest in this project.  In all the years of building and repairing equipment, I don't think I've ever come across a project like this.   Trying to fix up a radio with numerous faults is one thing (and what I thought I was dealing with here), but fixing one which keeps breaking seemingly randomly whilst under repair is quite something else.   It's a case of either "nolum illigitimus carborundum", or chuck the bloody thing in the (recycling) bin!  I don't give up easily though.  What kind of trauma has this radio suffered in the past?   It's anybody's guess.