[Drake] AC Hum in TR-4C speaker`

[Tony Sokol]

Hi Gang,]

     Thanks for all the reply's.  I think Bill has got me going in the 
right direction on this one.  Using highly technical methodology,  I 
smacked it on the top once and the hum has all but disappeared.  That 
says "Mechanical" so I think there is a ground lug somewhere not doing 
it's job after 40 years or so.  I did try the plug but it did not effect 
the hum so it is most likely a floating lug.
     That ACR-4 kit is really a nice way to go.  For those that haven't 
installed one yet I highly recommend it.  I had a ball yesterday 
afternoon and into the evening being reminded of the many Heathkit rigs 
and accessories that I have built over the years. Have a great 2011!

73
Tony - W9JXN



On 1/2/2011 12:38 AM, William Houghton wrote:
> Tony,
> I had an hum in my TR-4C even after installing the AC-4R kit. Turned 
> out to be a bad ground connection on the tube socket for the 6AQ5 
> audio amp. Loosen and retighten the screws and the hum was reduced to 
> barely perceptible. A lot of the tube sockets have tie points on the 
> socket mounting frame that are used for a ground connection. Can't say 
> this will be your problem but it was in my case. I've been told that 
> after 30 or 40 years these connections can oxidize. It was recommended 
> to me to loosen and retighten all of the ground lugs that I can find 
> in one of these old radios. I ignored this advice at first until I had 
> the hum problem. I tried the 6AQ5 first and it solved my problem. Then 
> I went back through the radio and did all of the ground lug screws.
> Bill
>
> ------------------------------------------------------------------------
> *From:* Tony Sokol <tonysokol at sbcglobal.net>
> *To:* Drake Listserver ( QTH.NET ) <drake at mailman.qth.net>
> *Sent:* Sat, January 1, 2011 9:44:34 PM
> *Subject:* [Drake] AC Hum in TR-4C speaker`
>
> Happy New Year!
>
>     Before I spend a bunch of time chasing my tail trying to solve an
> AC hum issue in my newly acquired TR-4C, I thought I would try the
> reflector.  I found a pretty nice AC-4 to go with the TR-4C on Ebay.  I
> also found an AC-3.  I just installed the AC-4R kit in the '4 which is
> really nice!  The problem is that there is a noticeable AC hum in the
> speaker all the time.  I hear it when I key the mic. or turn the RCVR
> gain down.  It's always there and fairly loud.  BOTH supplies exhibit
> the same problem even after installing the new AC-4R upgrade.  Now I am
> thinking maybe a tube with a filament to cathode short.  Anybody run
> into this before?
>
> Thanks and have a great 2011!
>
> 73
> Tony - W9JXN
>
>
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