[Drake] Drake R4B Passband Tuning Problem

[Bob Scott]

Thanks Rodger.

Yes, the slugs appear to move in and out.  I am not seeing an S-meter  
reading to use as an indicator.  I will check the oscillator.  I did  
not try a full alignment and perhaps I should.  I just noticed the  
problem with the passband and focused on that.  I will be out of town  
the next couple of weekends, but when I get back on it, I will let you  
know what I find.  Thanks again for the help.

73, Bob Scott W4ZY
Woodbridge, VA



On Oct 5, 2008, at 6:47 PM, Rodger wrote:

> 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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>
>