Author Archives: Colin Shaw

Transceiver new build 1

The workshop clean up was delayed, I just had to get the VFO working. When I built the kit a few months back I did not solder one of the headers! Found that this afternoon, soldered it and all was well.

First job was to setup the IF at signal frequency + 9Mhz. Then a quick run through to see if all the functions were working as they should.

I like the minimal display. It would be even better to be able to go back to using one the old Eddystone slow motion drives like this one on a G2DAF RX from 1963. No water falls, flashing lights, bleeps, tones or warning messages on screen. Don’t get me wrong there is a place for all of that but sometimes I just want a radio that is simple and easy to operate without the need for an A4 ring binder full of instructions.

G2DAF RX at the national radio museum

At the end of the afternoon this is what I had; a VFO covering all bands from 160M – 10M with the IF set to 9Mhz and giving about 80mV P-P of sine wave ready to go straight into the mixer.

Building an HF Transciever

Over the years I have built a lot of gear from simple test equipment to an eight band CW transceiver using reclaimed parts. Technology moves on and I now have three commercial SDR rigs. The performance of modern transceivers is amazing but I feel something has been lost; it’s all done in software which feels a bit cold, clinical even.

A few years back I followed a series of articles in RadCom written by Eamon Skelton, EI9GQ, where he described how he built a transceiver mainly from discrete components. I bought the book a couple of years ago and now feel I want to make my version of his project.

Why now? It is mainly the availability of cheap test equipment like spectrum analysers, VNAs, GPS locked frequency meters and wide band noise sources which work well with SDR receivers like the RSP1A.

Not long ago all we had were grid dip oscillators, drifting sig gens and frequency counters with dubious accuracy.

I have made a start and almost fallen at the first hurdle! Instead of making a 9Mhz, 2.4Khz wide SSB filter I have bought one from Spectrum Communications. That will save buying lots of 9Mhz crystals and spending hours matching them to get a good shape.

I have already built a VFO based on a synthesiser chip. There are some things it is not worth trying to replicate and a drifting VFO is top of the list. I did build a free running 8 Mhz VFO in the early 1970s that was multiplied by 18 to drive an old Pye valve TX on 2M. It took hours to sort out the drift but eventually it was rock solid. The key was an Oxley Tempatrimmer. The fixed vanes of the capacitor were fixed to a bimetalic strip so as as the temperature varied the capacitance changed. They are impossible to find these days.

Watch this space as I will post progress reports as each stage is completed. The first thing to do is tidy up the workshop, I may be some time…

IC-705 and a new portable antenna

Although I still make stuff it is getting harder especially with small components. Last year I was told that I have rare form of cataracts. That makes working on circuits boards difficult. When the current pandemic is over maybe they will be able to replace to duff components and restore the circuit to its original condition.

This is all leading up the to be the excuse for buying an IC-705! It’s an exceptional radio with amazing performance which is hard to believe for an old timer brought up on HF receivers that occupied a full 19 inch rack.

 

Above left – Marconi HR11 telegraphy receivers with the boss pretending to tune one and above right, Plessey PVR800s telephony receivers. The first transistorised professional RX for the HF point-to-point service. Pics from around 1968 at PO radio station Bearley.

The IC-705 which I can hold in one hand!

So now the work is on perfecting the HF /P antenna. I have gone back to an end fed half wave made from a homebrew system that breaks down into 1m long sections. The aim is to cover 40m-10m with different lengths of wire wound on a reel, after removing the washing line. See Steve Nichols, G0KYA,  post on his blog here.

I also have a couple of light weight fibreglass poles and a drive over support just to make everything more flexible. That will allow me to operate from the car/micro camper.

 

 

Norcal-40A

Had this kits for a while. Built it but at the first attempt it did not work. Tried again a couple of weeks back and got it going! Must admit to getting the biggest kick from making something and then having a QSO.

Had a bit of trouble with the faulty, cheap, trimmer caps and idiotic SOIC to pin converters for the NE612s but after going back the the DIL versions all was OK. It still needs tweaking and putting in a box.

Could not resist trying on an antenna, heard a MM station, gave him a call and he came straight back!

10 July 20
It’s in a box, just needs wiring up.

Hammarlund SP600-JX6

There used to be a large scrap yard not far from where I grew up in South Warwickshire. It had regular lorry loads of government electronic scrap plus some from local USAF bases. On one visit in the late 1960s or early 1970s I found a Hammarlund SP600-JX6 and the boss said “that’s a radio I want £5 for it.”

I found a broken 6C4 valve, replaced it and it worked! It was a fantastic RX and I used it for a few years and then sold it for £60 when I got married.

My dream rig

It has to be Collins S line not to collect and put on shelf but to use daily.

To me this is the pinnacle of radio design both technically and aesthetically and pure Collins quality. It takes me back to times when radios had to be operated manually, no computers, no DSP.

One day perhaps but not so many days left, I need to start buying lottery tickets.

FMT Morse Tutor boxed up and working

The Morse tutor is complete. I chose a plastic box that was only just big enough, I like a challenge and this certainly was one! It all worked out OK in the end but was a real fiddle to get the measurements right.

What I learned apart from home construction is fun:
1. A nice bezel hides a lot of mistakes!
2. Covering a plastic box in masking tape prevents it being scratched when drilling and filing.
3. Removing the glue after covering a box in masking tape is not easy.
4. Red is always the positive wire on battery connectors!

Phoenix Kits Online

CWops CW Academy

It was around 60 years ago that I realised there was a radio amateur living across the road, he was Jim G3LIO, an ex Navy WT operator.  When I passed the RAE in in 1972 Jim advised me to learn Morse, but I resisted and became a G8. He was right of course; it would have been much easier to train a younger brain.

In 2000 I started learning Morse and managed to pass a 5WPM test at the Harrogate Morse Camp which gave me a class A/B license and the M5 call. A couple of months later I went to take a 12WPM test at a local rally but the examiner never turned up and the Morse requirement was dropped a few days later.

Eventually I did a 15WPM proficiency test at the Newark Ham Fest but lack of confidence was still a big issue. After that I decided that my operating would be 100% CW and it was. Things slowly improved but only with straight keys.

Now my resolve it to get to 25WPM and use a paddle by my next big birthday! I have signed up for training at the CWops CW Academy  which should start in a couple of months.

FMT Morse Tutor MK3 kit

I can’t think of a better way to spend a wet and windy Sunday afternoon than building a Morse tutor! It is from Phoenix Kits Online and grew out of a FISTS CW Club Project designed by Paul, M0BMN.

Twenty years ago I learned Morse using an MFJ-418 Morse code trainer. While it was good the design was a outdated which made repetitive – the character generated were not random.

The kit was easy to build. It too around a couple of hours and worked first time. Now all I need is a box.

As I have been away from Morse for a while I wanted to get back up to speed. What is really pleasing is that the code has stuck in my aging brain so maybe with a bit of practice I will be back on the air soon.

A 2m transverter

I know you can’t really call this homebrew as all it needs is the two boards mounting in a box and wiring up. It was fun though, and irritating as it was a bit of a tight fit. The relay board was tested and the PTT line works. Now it needs a bit of RF from the G90 to see if there is output on 2M. If all is OK then I will need to find/make an antenna.