Re: Fisher 500C-how hot is too hot?

[ Tubes Forum ] [ Help ]

Posted by hurdy_gurdyman [ 4.229.195.209 ] on September 06, 2005 at 22:03:42:

In Reply to: Re: Fisher 500C-how hot is too hot? posted by hurdy_gurdyman on September 05, 2005 at 16:32:13:

>That's good advice. If this were my receiver, I would assume even worse, and modify the output stage to insert a cathode standoff resistor on the cathode of all 4 tubes, to further decrease plate current. I suggest a big 100 ohm wirewound resistor bypassed with a 1000 uF, 25v capacitor.<

OK, I'm working on this. I'm not sure if you mean a 100 ohm resistor on each cathode or a single 100 ohm resistor to work for all four cathodes wired together.

I tried a single resistor for all the cathodes. I now have:

Plates = 450 V
Screens = 350 V
Grids = -27 V
Cathode resistor = 25 V

I'm not sure if this is an improvement...

Dave




Replies:



[ Tubes Forum ] [ Help ]