(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


Search QRP-L Archives

[ QRP-L Archive | ]
[ 1993 | 1994 | 1995 | 1996 | 1997 | 1998 | 1999 | 2000 ]

---------

This archive was generated by hypermail 2b29 on Fri Jun 02 2000 - 11:28:25 EDT

kd4ab@kd4ab.org