[ARC5] Fw: Oscillation at high gain

Mon, 04 Mar 2002 08:54:52 -0600

Sounds like it might be an open bypass cap.  Have you replaced any of 
the caps in the set?  You could also pull tubes until the oscillation 
stops.  That should help to isolate which stage it is in.  Start with 
the RF amp tube and work your way to the 12A6.  Since the tubes are in 
series you would have to put around 84 ohms at 2 watts across the 
filament pins of the tube you pull to keep its pair going.

Sean

COWARD,JAY (A-SanJose,ex1) wrote:

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> -----Original Message-----
> From: COWARD,JAY (A-SanJose,ex1) <[email protected]>
> To: '[email protected]' <[email protected]>
> Sent: Sat Mar 02 19:32:01 2002
> Subject: Oscillation at high gain
> 
> Hello gang,
>  Have been busy getting all my receivers up and running.So far I have
> R-23,24,25,26,27 and CBY-46104 all working and all the dynamotors spinning
> nicely.Mostly the work was lubeing the dyno bearings.A few 12SK7's were
> weak.Had a bunch of good ones on hand so that was no problem.
>  The one I am having difficulty is a CBY-46106 6-9.1 ARA unit.When I turn
> the gain up it goes into oscillations. Anyone else run into this?This rx
> looks brand new except its been slid in and out of a rack a few times.None
> of the screws are bunged up so it still has factory air inside.Any clues?
>  Regards,
>           Jay
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