[Drake] Drake R4B Passband Tuning Problem Additional

[Bob Scott]

Adjusting the 5595 Khz oscillator appears to have resolved the  
problem.  I had to hold the frequency counter probe near the lead  
going to pin 1 of V3 to keep from loading the circuit.  I just  
finished peaking the passband tuning and the receiver is performing  
much better.  I will probably go through the rest of the alignment  
since I have the receiver opened up.

Thank you again for the help.

73, Bob Scott W4ZY
Woodbridge, VA



On Oct 5, 2008, at 7:03 PM, Rodger wrote:

> Bob,
>
> Also, be sure you correctly adjusted the 5595 Khz. oscillator and  
> the 50 Khz. IF transformers as problems here will show up when you  
> try to do the passband tuner alignment.   Either use a frequency  
> counter or check the 5595 Khz. oscillator signal in another receiver  
> to make sure it is very close to correct.  Although the 50 Khz. IF  
> transformers tune fairly broadly the passband tuner does not so if  
> your mixer oscillator signal is wrong this will create a problem  
> when trying to align the final IF.
>
> 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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>>
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