[Drake] R4B noise

[ed brooks]

Kinda what I expected - not to be able to find a 4-section can.  We'll 
put some axials underneath.  Good time to replace the power diode for 
the marker oscillator, too, as it is defective.  

Nope, don't have C90A.  Screen bypass on the 6EH5 is C172, (according to 
the schematic - might be different in the radio itself)  

Thanks folks -- I was really wondering if my eyes were deceiving me!  
Ed, W5HTW


Garey Barrell wrote:

> Ed -
>
> C90A is a screen bypass on the 6EH5 audio output tube.   Depending 
> upon your serial number, and which schematic you have, it may or may 
> not be there!
>
> GOOD multi-section FP style cans are getting very hard to find.  
> You'll probably end up having to stuff one or more sections under the 
> chassis.  Fortunately there is plenty of room!
>
> 73, Garey - K4OAH
> Atlanta
>
>
> ed brooks wrote:
>
>> My R4B is starting to sound a wee dab raspy.   So far I haven't 
>> opened the cover (if I had I would just trace out the wiring) but was 
>> browsing the schematic to see what filters are in the line.  Seems 
>> C90 is the can of suspicion.  But on the schematic I find C90B, C90C 
>> and C90D.  I have searched with these old eyes for C90A and can't 
>> find it. Guess I could get out the magnifying glass.  But section A 
>> may not even be used.  B, C, and D, are all 100 mf at 200 v.  If A is 
>> used, (and it may not be) can some one help me avoid eye strain and 
>> tell me in what circuit?!!  Or will I be relegated to pulling the 
>> covers and tracing the circuit?  And where can I find a suitable 
>> replacement can if it turns out that is what is needed?  (Surplus 
>> Sales didn't list any such animal under four section cans.) Thanks
>> Ed, W5HTW
>>
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>
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