[NJARC] Radio Repair Questions

Tue, 16 Mar 2004 10:06:10 -0600

On Mon, 15 Mar 2004 22:24:15 EST [email protected] writes:
> "matched" tubes are usually not truly matched, but  approximately equal
in 
> transconductance as measured on a tube tester. They probably never stay

> "matched" very long. For the purpose of  getting the GE to play It is
not at all 
> neccesary to match tubes. Depending on the heater voltage your "?" 
reading on the 
> one tube may be meaningless.  If your radio sounds garbled or 
> distorted you  will want to check that the tubes are ok  by
substituting them with 
> known good ones before tearing into the circiutry. 
> Marty 
> 

Grant and Marty
All of the "tube matching" (or any other device matching come to think
about it) I am aware of has to do with plate current at a specified grid
voltage.  This is done to prevent output transformer core saturation when
unequal currents are present in Class AB amplifiers.  It is near
impossible to match more then a few basic tube parameters as Marty
indicates.  Just a complicated machine, those vacuum tubes!
Regards,
Jim