Re: {Collins} 75s1 PS Hum



George,
     The 6U8's are famous for causing your exact problem due to filament to cathode shorts. Try replacing them one at a time. It could be more then one. The 6EA8 is a better substitute if you don't have any 6U8's. 

73
Tony - W9JXN

 

Sent from my iPad

> On Oct 12, 2017, at 10:23 AM, Glen Zook via Collins <collins@xxxxxxxxxxxxx> wrote:
> 
> In fact, many of the machine screws may just be loose.  Those fasteners work loose, or become corroded, over the years, for any number of reasons.  I "fix" a lot of "screwy" problems in "boat anchor" equipment just by tightening and / or loosening and then tightening, all of the machine screws and nuts that go through the chassis.  Remember, all of the grounds are made through these fasteners.
> 
> 
>  Glen, K9STH 
> Website: http://k9sth.net
> 
>      From: kc9cdt--- via Collins <collins@xxxxxxxxxxxxx>
> To: bridkarl@xxxxxxx; ne2i@xxxxxxxxx 
> Cc: collins@xxxxxxxxxxxxx
> Sent: Thursday, October 12, 2017 10:10 AM
> Subject: Re: {Collins} 75s1 PS Hum
> 
> Go through and loosen(slightly) ...re-tighten every ground...including tube socket mountings.
> In some cases you may have to find a way to hold the nut as u tighten the screw.
> 73,
> Lee
> 
> 
> 
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