Once the choke is removed from the chassis can you investigate if
its position makes any difference. I mean is the hum the result of an
induced field from something? Also, does it make any difference if the
case or frame is grounded to the chassis?
I agree about the level of hum one would expect, audible only if
you put your ear the speaker.
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On 2/18/2025 5:57 PM, thoyer via groups.io wrote:
Ok folks, I found the culprit ¨C that dog gone choke! I replaced it with
a 4hy one from an R390A AF deck and the hum is gone. I laid it in the
chassis, insulated from the circuits and wired it in with short leads.
Actually the hum is barely there, you have to put your ear up to the
speaker to get a hint of it, but this is the level I¡¯d expect from an
old radio like this.
There is a small difference in chokes in that the original is, I
believe, 220 ohms and the Collins one is 110 ohms. I¡¯ll have to try to
locate one that fits the mounting holes.
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
