Saturday, May 16, 2009

Receiving GB3VHF

I have always had rather a soft spot for the 2 metre band. It was the band that got me interested in getting my own ham radio license. I had built radios and other things in my teens and listened on the short wave bands, but I was never particularly interested in being able to transmit.

Then one day, wanting something different to build, I decided to construct a 2 metre super-regenerative receiver from a design in Practical Wireless. Using it, I heard stations fairly local to me having interesting conversations in English. And that was the motivation that led to me coming on the air as G8ILO in 1974.

In those days, 2 metres was not the busy band it is in parts of the country today. There were no ready-built rigs at all. Most of the operation was on AM using home-built crystal controlled transmitters, or modified ex-taxi radios. For receive people used a down-converter and short wave receiver. You would call CQ and then tune a chunk of the band, low to high, listening for any replies.

A lot of the time, there was nothing to hear on two metres at all. Except that at the time, I lived about 30 miles from the Wrotham beacon, GB3VHF. That was something I could always hear. So I got very used to hearing dah-dah-dit dah-dit-dit-dit dit-dit-dit-dah-dah dit-dit-dit-dah dit-dit-dit-dit dit-dit-dah-dit daaaaaah ...

Up here in the back of beyond I'm about as far from the Wrotham beacon as it's possible to get and still be in England, and I'm screened by the Cumbrian Mountains from the rest of the country. The only SSB activity I have heard so far has been someone operating from one of the Lake District mountains that I can almost see from the window. So at the moment I have no idea whether this QTH has any potential for working VHF at all.

Turning the pages of the latest RadCom a couple of days ago I saw on the Data page a screenshot of GB3VHF being received using the WSJT software. Apparently, GB3VHF gives its call and locator once every two minutes in JT65B mode. So I thought I would give it a try.

The picture above shows GB3VHF being received using the Moxon Rectangle I constructed a couple of days ago, which is still clamped to a shelf just above the shack door. I don't hear it every time. I guess I get a decode about once every ten minutes or so. I was going to upload an MP3 of the audio that was recorded during that one minute period, but you can't hear anything at all except noise.

It would be interesting to know if there are any other 2 metre beacons that transmit using JT65B which I could try to copy. And how far afield GB3VHF can be received using this mode. But if all I can receive from here on 2m is a distant beacon buried deep in the noise, it probably isn't worth spending much more time and effort on the band.

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