Quad 2/Quad II tuner problem

[Nigel Cook]

Repairing this hybrid tuner of about 1968,valve/tube tuner
and transistor stereo decoder in 2 separate sections.
I have the schematics but more a general query.
The problem was lack of stereo which I have
realigned (for strong signals) but I think the main problem is
lack of signal to decode. Output for
stations 96 MHz to 100 MHz strong but 100 to 104 MHz
output is much reduced.
Is this more likely due to loss of gain in one or more of the valves
or drift of RF/IF alignment ?


e-mail (removing .....) diverse2@tcp.co.u.....k
electronic hints and repair briefs , schematics/manuals list on
http://homepages.tcp.co.uk/~diverse

Nigel,Diverse Devices,Southampton,England

 

[ajb]

On Wed, 13 Aug 2003 15:08:08 +0100, "Nigel Cook"
<diverse2@tcp.co.antispam.uk> wrote:

Repairing this hybrid tuner of about 1968,valve/tube tuner
and transistor stereo decoder in 2 separate sections.
I have the schematics but more a general query.
The problem was lack of stereo which I have
realigned (for strong signals) but I think the main problem is
lack of signal to decode. Output for
stations 96 MHz to 100 MHz strong but 100 to 104 MHz
output is much reduced.
Is this more likely due to loss of gain in one or more of the valves
or drift of RF/IF alignment ?

Hello Nigel

Possibly both but alignment will certainly need doing. You will also
find that various small capacitors which live inside the screening
cans tend to drift in value with time and temperature in an
unpredictable manner. Best to replace anything dubious and realign
carefully right through properly. Realigning for strong signals will
also tend to give variation over the waveband and other subtle odd
effects, even dead spots.

This tuner will give excellent results but I'm afraid there's no real
substitute for proper realignment by the book; however this will repay
dividends in full measure..... Its a very nice tuner.

Good luck

Anthony
--

Just because I'm paranoid it doesn't mean
they're not out to get me...