70cms activity?

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G0DJA
Posts: 110
Joined: Fri Mar 28, 2008 2:35 pm

70cms activity?

Post by G0DJA » Fri Apr 18, 2008 6:46 pm

I've not seen or heard much about ATV on 70cms these days. I know there were problems with bandwidth, especially with colour, but I wonder if there's any activity these days?

I know a station near me was using some gear that they'd had for a while a week or so back, so I guess there's still some equipment about, but I wonder if anyone ever sees any stuff for sale now-a-days?

I remember that Microwave Modules used to sell a transmitter and receiver, maybe even a transceiver. Did Wood & Douglas ever do a 70cm unit? I guess they probably did.

So, if only to activate the band in a contest for extra points, I wonder what gear I should look out for, and what to avoid like the plague?

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G8ADM
Posts: 116
Joined: Sat Feb 23, 2008 7:14 pm

Re: 70cms activity?

Post by G8ADM » Sat Apr 19, 2008 9:26 am

Digital transmission has bought 70cm ATV back to life.
It is easily possible to transmit high quality pictures and stereo sound in a 2 MHz bandwidth.
So we transmit on 436 MHz and we remain within 435 to 437 MHz
Also only about a tenth of the power is required for the same range.
Using 150W I can work 80 miles or more under flat conditions over a restricted path.
London to Portsmouth for example is easily workable.
See the Digital TV section at the top for more info.

As far as Analogue AM transmission on 70cm is concerned.
It really only appears during contests using such equipment as the Microwave Modules or home made equipment.
It is very difficult to keep within the 70cm band using AM.

I hope this is of interest,
Regards,
Dave. G8ADM

G0DJA
Posts: 110
Joined: Fri Mar 28, 2008 2:35 pm

Re: 70cms activity?

Post by G0DJA » Sat Apr 19, 2008 9:43 am

Thanks for the reply Dave, and the information.

I did look at the Digital area of the forums when I 1st signed up, so I'll go back and do a bit more reading up on the subject of DATV.

Does anyone know if there are any DATV users in the Derbyshire/Nottingham/Sheffield areas?

Thanks - Dave (G0DJA)

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