[Drake] Drake R4B Passband Tuning Problem

[Rodger]

Bob,

The passband tuner is used for all selectivity positions.  Do all of the 
slugs appear to move in and out normally as you rotate the passband 
tuner knob? 

You should notice a very sharp peak when the individual slugs are 
properly adjusted.  Tuned to the calibrator signal on the 80 meter band 
are you able to get any S meter reading in the .4 position?  If so use 
the S meter to peak the slugs just to make sure there isn't a 
measurement issue at TP-2.

I have most of the Drake receivers including all variants of the 4 line, 
a 1-A and a 2-B and the only time I have had to repair a passband tuner 
was when a previous owner had apparently gotten frustrated and attacked 
it with a pair of vise grips.  That doesn't mean things never go wrong 
inside the passband tuner but they do seem pretty robust.

Let me know your answers to the previous questions in my email and I 
will try to help direct you further.

73, Rodger WQ9E

Bob Scott wrote:
> I have an R4B that I bought awhile ago and am just starting to look 
> at.  It seems to have a problem with the passband tuning.
>
> If I am reading the schematic correctly, if the passband selector is 
> in the 4.8 position, the passband tuning circuit is bypassed.  
> Otherwise, one of the tuned circuits is selected.
>
> If I select the 4.8 position, I get lots of signal/audio.  If I switch 
> to the 2.4 or narrower positions the signal level drops dramatically.  
> If I try the passband tuning alignment procedure, I do not get much of 
> a change in the voltage level at TP-2 which makes me think there is a 
> problem in that area.
>
> If anyone has any experience working on this receiver and can give me 
> some ideas, I would be grateful.  My electronic skills are a bit 
> rusty, but I would really like to fix this vs sending it out for 
> repair/alignment.
>
> 73, Bob Scott W4ZY
> Woodbridge, VA
>
>
>
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