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Old 21st Feb 2021, 2:10 am   #125
Helder Crespo
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Join Date: Sep 2019
Location: Crystal Palace, Bromley, London, UK.
Posts: 417
Default Re: My first telly TV22

Quote:
Originally Posted by beery View Post
Hi Helder,
I don't think you will notice much difference in the bandwidth on this set between 6 dB and 12 dB attenuation, but some sets do start to show a bit of grainy noise in the picture at 12 dB.
A set with too much signal will tend to have vision on sound and possibly sound on vision as well.
The only y reason I tend to go for 6 dB is that it gives me enough signal to feed into an inductive Y splitter and run two sets at once.

BTW, some set designs only applied the contrast/gain control to one stage which gives the effect (when staggered RF/IF tuning is used) of reducing the bandwidth as the contrast is increased. This makes for a set with a wide service area, but the effect on the resolution was definitely noticeable.

Cheers
Andy
Hi Andy. Many thanks for your detailed explanation. I hadn't thought about vision on sound and sound on vision. I will test the attenuators again next time I'm in London as one of the limitations I found when adjusting the oscillator + rf + aerial coils was that best resolution resulted in sound on vision, so the attenuated signal may give me a bit more margin.
Cheers
Helder

Last edited by Helder Crespo; 21st Feb 2021 at 2:24 am.
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