[Drake] R4B Receiver

Mon, 10 Nov 2003 07:24:52 -0600

Paul, that sure sounds like a capacitor.  Probably not an electrolytic
unless it's used for interstage coupling or bypassing.  As the voltages
apparently read normal I'd suspect that a disk is opening up rather than
shorting.  I think I'd start off replacing C167 ( .1uf disk between vol
control and base of Q7), C185 ( .01 uf disk between Q7 and V7).  I think I'd
add C187 to that list now ( .1uf disk before vol. control).

I can't recall having any particular problems with caps in my R-4B but I
have in the T-4XB

If I recall, the tube runs hot in mine as well so that's probably normal.

Dan W. Dooley WB5TKA
 email: [email protected]
 http://www.dooleystreasurechest.com

----- Original Message ----- 
From: "Paul Manno" <[email protected]>
To: <[email protected]>
Sent: Sunday, November 09, 2003 9:31 PM
Subject: [Drake] R4B Receiver

> Hello all,
>
> I recently received an R4B receiver with a low-audio condition.  All tubes
> have been checked swapped and replaced, the voltages seem correct to the
> manual data at the audio stage (transistor and 6EH5).  Speaker is 4 ohm.
>
> After the unit is first turned on after a long (few days) off-time, audio
> output is near normal for a few minutes then the audio drops suddenly to
> about 25% former volume with no pop or crackle.  After that, if the audio
> gain control is turned up past the 3:00 position, audio becomes distorted
> but rcvr never attains the first-on volume level.  It appears someone has
> already replaced the 10uf electrolytic in the 6EH5 cathode circuit.
>
> The RF seems to behave normally (S-meter shows same signal levels) before
> and after the audio volume drop.  I have observed the 6EH5 seems to run
> very warm but I don't know if that's just the tube.
>
> I do appreciate your suggestions where to start looking.
>
> Tnx and 73,
> -- Paul, KG4UVU
>
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