Category Archives: Uncategorized

Hi-Fi SSB?

A few years back it was fashionable to use ‘HiFi SSB’. The idea was to transmit a much wider AF frequency range with the emphasis on getting more bass response. I remember hearing a station who was proud of his studio mike and loads of processing gear. His signal had lots of bass and extend higher frequencies. His bandwidth was nearer 8Khz than the usual 2.4Khz. He said he did not care because he had spent a lot of money getting ‘better’ audio.

Years back I was taught that the frequency range for intelligible speech was 300hz – 3.4Khz.  I find that lots of bass makes signals harder to copy, especially when they are weak. Which is exactly why the military and aviation communications limit the bass response.

Why spend lots of money on expensive ‘studio’ microphones and other fancy audio stuff when all it does is make your signal less readable? Is it the just the dealers making money again? Is it the desire to be different or ‘one-upmanship’? Or is it a lack of understanding of what radio communication is about?

Home construction, QRP, solar power 8 months on

When I came back to amateur radio in March 2018, I set myself some aims, more aspirations really.  I said that I wanted the station to be QRP, all homebrew and solar powered.

I have always enjoyed making stuff and now I have finally retired I have a lot of time to do just that. Second, I have previously thrown money at the hobby, got on the air and become bored.

QRP? Life is too short say the kilowatt cynics. Over the years I have enjoyed using a lot of small, home made radios with spectacular results. It takes more effort to winkle a signal out of the noise, but the rewards are bigger. Like many things in life it takes effort and patience to get results but the reward are higher.

uBITX

As the solar power I am trying to reduce my carbon footprint as I fear we are on the brink of a climate catastrophe.  You may not agree but I would urge you to read the evidence, from climate scientists, not newspaper articles, who agree that there is a big problem. Besides saving energy in the home saves money!

80w folding solar panels

So, 8 months on I am back on the air with a uBITX with the mods to reduce spurious emission and harmonics. Next is the AGC board. Using a LiPo battery I can get near 20W output but that is trimmed down to 5W. I also have a 20M QSX and am eagerly awaiting the launch of the multiband QSX.

20m QCX

The auto antenna tuner is nearly finished but in the mean time I have a 9:1 balun at the bottom of the antenna and an L match at the radio end. I can get below 1.5:1 from 106m to 10m which is fine for now.

The only thing to sort out now is a more permanent solar panel battery charging facility. I have the gear from ‘the van’ but want something more permanent.

80M DX on the uBITX

This is a recording of W1MBB on 3.798Mhz at 0754 this morning. My antenna is a long wire strung between two trees with a homemade tuner. I also heard a ZL this morning.

 

So, what does this prove? That the uBITX receiver works well although I must add the AGC board! That there is DX out there if you know where to look. That amateur radio need not cost a lot. And, most of all, there is nothing to beat the kick of building a radio and using it on the air.

I know I could never work him on the uBITX but I also know that using higher bands it is perfectly possible to work across the pond on 2W of CW.

HF radio communication is not dead!

It seems that the US have tested HF radio as a means of long-distance communication of speech and data. Maybe they have realised that satellites and fibre optic cables are not as safe as they thought.

Satellites are easy to take out as the Chinese demonstrated a while back. There was also a report in the UK press recently about the vulnerability of underwater fibre optic cables.

It is interesting how things go around in circles. It is only ~30 years since the UK closed its point-to-point HF radio system. Now we are looking at HF again for strategic communications. It will be interesting to see what happens.

See the full article here

 

A lost age – marine HF radio

My first job was as an apprentice at a Post Office HF radio station, Bearley near Stratford-upon-Avon. It was part of the HF point-to-point system that provided worldwide telecommunications. It was state of the art in 1967 and scrapped in 1980.

The station had 50 of the first professional, transistorised communications receivers,  Plessey PVR800s. The early versions had some germanium transistors which proved to be unreliable. They were replaced by the ultra modern silicon types!

They were used for telephony, 4 voice channels on double side band reduced carrier. The audio was inverted so that short wave listeners could not eaves drop.

There were also 50 Marconi HR11, valve telegraphy receivers. Each had the capability running 48 telex services on one radio channel using time division multiplex.

As services were transferred to satellites the station took over the maintenance of UK coast stations used for marine communications. They also suffered the same fate. Eventually all HF communications was taken over by satellites and the point-to-point and coast station were closed down. This Post Office film from 1979 shows something of what HF coastal communications in the “good old days”.

It was then end of an era and still saddens me to think that all the old skills have been lost, particularly commercial Morse.

If you want to read more about the HF point-to-point HF radio network, then see this book by Paul Hawkins who worked at the Dorchester TX station. (click the image >)

Remember, radio amateurs still use Morse!

Also see the Radio Officers Association