(no subject)


From: Larry East (LVE1@inel.gov)
Date: Mon Aug 07 1995 - 12:48:35 EDT

>Allen, K9DZE wrote:
>>This must not be a universal problem as my SW-40 does not exhibit the trait.
>>I'm using a gel cell for power.
>My SW-40 does it regardless of the power source. I've sorta gotten used to it,
>though. After I finish operating, the squeal is kinda like the "dit dit" at
>the end of a QSO (or Chuck's email). :-)
>73, Craig WB3GCK

I don't have an SW-40 so don't know what it uses for audio amp(s). However,
I had a similar problem with a DSP filter and cured it by replacing an
op-amp -- can't recall the actual op-amp part munber, but I replaced it with
a different type with similar characteristics (gain, bandwidth, etc.) and
the power-down squeal went away. Guess the original op-amp went into
oscillation when the supply voltage dropped below a certain point. Maybe a
similar thing is going on in this case... just a thought.

72, Larry W1HUE/7

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