DATV on 70MHz.

The place to discuss reduced bandwidth fast scan amateur television on 70cms and below
G1BVI
Posts: 155
Joined: Wed Aug 02, 2017 7:32 am

Re: DATV on 70MHz.and 70 MHz amp module

Post by G1BVI » Sat Sep 15, 2018 3:56 pm

For anyone intererested Anglia have 2 modules left at the time of writing this..

http://www.anglia-live.com/Products/275 ... Z-30W-125V

73

Nick

radiogareth
Posts: 335
Joined: Wed Jan 06, 2016 9:46 am

Re: DATV on 70MHz.

Post by radiogareth » Tue Sep 03, 2019 9:45 am

Finally, I'm building up my Module amp for 4. using the RA30H0680M module. Just wondering how much drive I'll need for maxing it out on DATV? So I googled it...
http://www.mitsubishielectric.com/semic ... 0608m1.pdf which shows that 50 mW should fully drive it, so for DATV probably not much more than half that. Single stage amp after my portsdown/limeSDR/pluto should do that then :-)
Gareth

radiogareth
Posts: 335
Joined: Wed Jan 06, 2016 9:46 am

Re: DATV on 70MHz.

Post by radiogareth » Mon Sep 09, 2019 3:57 pm

The Amp module passes all its tests and delivers an indicated 50 watts at least on carrier only. Suitable attenuation (-11dB on my Portsdown modulator) then into a +20dB modamp seemed to drive it without the shoulders getting worse.

Adding a decent power lead(longer) seems to have induced a pulsing instability. Current draw drops from 5 amps or so, to 0.9 amps.

Its uncased at the moment. Should I add ferrite filtering on the DC power leads, and more 10/100nf decoupling capacitors where DC feeds in.

Gareth

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