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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