parnass@ihuxz.ATT.COM (Bob Parnass, AJ9S) (02/21/89)
Put aside the 60 Hz filter idea for the moment. Rather than
poor power supply filtering, it sounds like your hum problem
may be due to:
1. a ground loop or
2. an open shield in the patch cables connecting the
recorder to the receiver.
I assume the receiver is powered by 120 VAC, although your
article didn't specify.
If it is indeed a ground loop problem, it could be solved by
breaking the ground connection at one end of each patch
cable.
Since I have to do this when connecting my monophonic
Panasonic recorder to some scanner radios, but not others, I
constructed 2 different patch cables. One cable has shield
connections at both ends, and the other cable is a shield
connection at only one end.
If, instead, the problem is an open shield, then repair or
replace the cable(s).
In article <2313@rayssdb.ray.com>, iws@rayssdb.ray.com (Ihor W. Slabicky) writes:
>I use a portable stereo cassette recorder to record music off my
>receiver. When the recorder is powered from the AC line, I can hear
>lots of 60 Hz being recorded on the tape. Moving the recorder, cables,
>or power cord around tends to lessen the hum. When I record using the
>batteries, no hum. Also, when I playback, if I put the INPUT switch
>on the recorder to the MIC position, no or very little 60 Hz hum is
>heard, but when the INPUT switch is set to LINE, lots of hum. Ideas?
--
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Bob Parnass AJ9S, AT&T Bell Laboratories - att!ihuxz!parnass - (312)979-5414