[R-390] 3tf7 replacement proceedure

[Mark Huss]

Lankford did some data collection on replacement options for the 3TF7.  
Turns out the most stable option is a simple 40-50 ohm, 10 watt 
wirewound resistor.  Not only is it a bit more stable than the tube sub, 
but you get less rush current on turn-on.  After doing a bunch of design 
work trying to come up with a solid state replacement, i just put the 
resistor in my R-390A with pins soldered to the leads.  works fine for me.

Norman J McSweyn wrote:

> Hi all.
> I've been doing some reading on the 3tf7 replacment schemes. For the 
> time being I think I'll use a 12bh7 in place of the 3tf7.
> All I have to do is move the wire on pin two to pin four and the wire 
> on pin seven to pin five, right?
> de n3ykf
>
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