NC-270

[Fred Wittman]

You might want to check for a leaking bypass cap on any of the cathode bias
resistors.  Just a guess, but I seem to remember a similar problem years ago
with an old Zenith table radio.

73,

Fred W.  --  KG6NYK
----- Original Message -----
From: "Brian Wood" <brianmwood at DIRECWAY.COM>
To: <HEATH at LISTSERV.TEMPE.GOV>
Sent: Saturday, November 30, 2002 8:41 PM
Subject: NC-270


> Thanks to everyone who helped me figure out what the problem was with the
> DX-100 grid current flicker. Turned out to be the 47 pf loading cap on the
> final grids. Bob, W3CD gets the prize for that one.
>
> I'm now working on my National NC-270. The receiver has a lot of hum in
the
> audio. I don't know if this is normal for a boatanchor receiver, since hum
> was something we just lived with when using ac filament power, if I
recall.
> But I thought I'd ask if anyone on the list has an NC-270 and could tell
me
> if they have noticeable hum when the audio gain is turned down. I also
have
> a fair amount of microphonics from the two audio stages (6T8 and 6CW5). A
> three-prong cord helped a little, but not enough. I also added 3 big
filter
> caps to the supply, and that had no effect. Would appreciate any ideas. AS
> this is off-topic, please reply off-list.
>
> 73,
>
> Brian, W0DZ
>
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