[AMPS] controlling power with anode voltage

[nospam4me@juno.com]

re: 5894 plate voltage.

Both Motorola and GE controlled the Amplifier input 
by changing taps on the HV Supply transformers. The 
GE Master Pro had a rather novel method of stacking 
two lower ~300 volt supplies to obtain the anode 
supply. When one of the supplies blew a fuse or 
burned up, the other would operate the final at much 
reduced output. 

Something was better than nothing...

Hopefully, someone noticed the lower power output and 
repaired the EP-38 chassis supplies.  The filament 
voltage was regulated and set by a simple GE pnp 
pass transistor circuit.  This is the place I learned the 
value of the proper heater voltage.  A tube at the mfgs 
recommended voltage would last years. The same tube 
type in a sister chassis at the same location running 
excessive heater voltage would last about 3 months in 
IMTS continual service.  If you were lucky...   More than 
one cold rainy night at the mountain top replacing tubes 
was source to excessively high heater voltages. 

cheers
skipp

:From: "Jim" <jdc@ieway.com>
:The 5894 is a 90 watt output at VHF (150 MHz).
:It is run with about 250 volts of screen and 800 or so volts 
:of plate voltage...
:Used in both Motorola and GE VHF radios....Mobile and 
:base station...


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