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Forum 141

System A on 70cm

Black & White Television

Last Post by Doz 11 years ago

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Doz

(@doz)

Posts: 1491

Prominent Member Registered

Topic starter

Ok, in between waiting for bits for the G8, I've been conjuring up a modulator to put some system A on 70cm.

Ran some encouraging tests on 436MHz last night, with just a few mW. Limiting the video bandwidth to 1.9MHz keeps it out of the way of any repeaters.

I'm using an old topfold receive converter feeding a Sony 9-90 frigged for 405 lines on UHF (both buttons in!)

Anyone local-ish to Cheltenham there to receive?

Posted : 04/01/2013 12:40 pm

Anonymous

(@anonymous)

Posts: 16868

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I suspect easy to make a converter from 70cm to Band I. Some Analogue voltage tuned UHF tuner heads could perhaps be tweeked as a 435MHz to 42MHz out on the IF out?

I'm too far away and don't have 405.

Posted : 04/01/2013 2:03 pm

Doz

(@doz)

Posts: 1491

Prominent Member Registered

Topic starter

Shouldn't be too tricky.

Gave the little transmitter the beans this evening. Makes 10 watts on peak white. I'll go and borrow the spectrum analyser from work in the morning and see how it looks before connecting it to an antenna.

It's all going to remind me a little of Max Headroom's "Big Time Television" , where "two's company, and three's an audience"!

Best knock up a test card C with my call sign on it.

Posted : 04/01/2013 11:14 pm