[Drake] TR4C weak audio and poor sensitivity

[Dick KF4NS]

Thanks for the suggestion Guillermo. The calibrator is very strong on
both sidebands but the S-meter reads lower in the sideband 'X'
position. (S9+20 and S9+30).

I moved the C130 control away from 9mhz zero beat and the sidebands
are more equal now but there is still considerable attenuation (signal
and audio) in the 'X' position.

There was an easy way to compensate for this in my Heathkit HW-100,
by simply  padding the sideband crystals with a capacitor in parallel
or series to move the carrier closer or away to/from the center of the
filter passband. Since the theory is different in the Drake circuitry,
I would not have any idea how, if even possible, that could be
applied.This is my first attempt to work on a Drake so I am still 
learning.

73, Dick KF4NS
St Petersburg, FL 33714 USA
Keep The Glow!
------------------------------

Message: 3
Date: Wed, 16 Jun 2010 21:00:03 -0300
From: GGLL <nagato at arnet.com.ar>
Subject: Re: [Drake] TR4C weak audio and poor sensitivity
To: Drake <drake at mailman.qth.net>
Message-ID: <4C196583.4040602 at arnet.com.ar>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

What about performing an elementary sweep with the calibrator signal
(at the "best" band) that is, rocking VFO knob from zero beat upto
highest pitch and noting the Smeter readings?.

Regards
Guillermo - LU8EYW.

El 16/06/2010 20:26, Dick KF4NS escribi?:
> During the restoration I discovered what may be my worst nightmare.
> The sensitivity and weak audio changes from band to band when I
> switch
> sidebands. That to me says it is likely to be one of the filters.
>
> Example: on 20M the trouble is on USB and on 15M it switches to LSB,
> in other words the trouble is always when the sideband switch is in
> the X position.
>
> All tubes have been tested and shorted/weak tubes replaces with new
> ones (pretested).
>
> The contacts of all switches have been cleaned and the sideband
> switch
> tested for continuity.
>
> The 9mhz osc was adjusted for zero beat with C130 injecting a
> calibrated signal to grid 1 of V12.
>
> I have no idea if it may be an alignment problem caused by changing
> several tubes so please clue me in if that would cause this trouble.
>
> 73, Dick KF4NS
> St Petersburg, FL 33714 USA
> Keep The Glow!