[R-390] What's with the 5.3V filament

[David Wise]

It's to reduce noise and hum.  That tube is not called on to conduct more than about a hundred microamps, so it is feasible to run the cathode below normal temperature.

Dave Wise
SWL in Oregon

-----Original Message-----
From: R-390 [mailto:r-390-bounces at mailman.qth.net] On Behalf Of Grayson Evans
Sent: Wednesday, June 17, 2015 10:18 AM
To: R-390 Forum
Subject: [R-390] What's with the 5.3V filament

Can anyone tell me why the R390A IF deck 5314 limiter tube is run with a 5.3V filament?
while all the other tubes on the module run at 6.3?
Was there some reason to drastically lower the gain of this tube?  This is an odd way to do it. 
I read through the manual on the limiter section, but it makes no mention of the odd filament voltage.

Grayson
TA2ZGE - Ankara, Turkey
KJ7UM









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