"Hot" SB-303

[John Campbell]

Hi Bill...It sounds to me like your AGC problem could be an open capacitor
in the agc time delay circuit. When you go to "slow" agc, you switch in an
extra capacitor to slow down the agc time-constant. I'll bet that you
probably don't notice much difference between fast-agc and turning the agc
completely off with respect to audio quality. You said that you checked the
voltages, but pay special attention to the bias voltage adjustment as this
directly affects agc operation. Make sure it is within specs. As for the
volume control, the sb-303 needs an audio taper (log taper) pot. If somebody
installed a linear taper pot, it would behave as you describe. You say that
it's the correct part number, so I must assume that the pot may be defective
and should be replaced. Believe it or not, I actually found a replacement at
Radio Shack (of all places). If I recall correctly, it's a 10K log taper
pot.
                          Good Luck.....John  <<w8jnc>>



>From: The Boutwells Bill & Mary <boutwell at THE-BRIDGE.NET>
>Reply-To: The Boutwells Bill & Mary <boutwell at THE-BRIDGE.NET>
>To: HEATH at LISTSERV.TEMPE.GOV
>Subject: "Hot" SB-303
>Date: Mon, 10 Apr 2000 22:04:02 -0500
>
>My SB-303 seems to be running too "hot" (not temperature).  I have a fair
>amount of background noise and most signals have barely understandable
>audio with the AGC in the "fast" position.  It sounds like the audio is
>"over driven", if that makes any sense.  The audio sounds fine in the
>"slow" AGC position.  Voltages seem to check out.  Another symptom that may
>be relavent (or just another problem) is the AF/volume control seems to
>have a dead area.  When the volume is turned up, it jumps up too quickly
>when I compare it to another SB-303 I have.  The volume control is the
>correct Heath part number.  Everything else works great.  Good sensitivity.
>  Any ideas?
>
>Tnx   Bill, KB0BK
>

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