Ron Lawrence KC4YOY wrote:
Anyone got a HF Plate Modulated AM transmitter for sale in North
Carolina. Hopefully the coastal area?
Grab a good ol' Johnson Viking II. They're floating around pretty
much everywhere,
Saturday night we put the Viking II on the bench at w4zo's for a
little check out,
and got it working after finding about half the tubes had shook out of
their sockets.
100 watts out with 300ma on the plate. It's loaded with AM crystals.
Ron,
Typically, a pair of 6146's should probably only be loaded to around
220mA ~ 230mA *max*.
The manuals for the Viking Ranger, and Viking II's, and Viking Valiants
(all use 6146's in the final) say to load the final to 110mA, 220mA and
330mA, respectively.
They -more strongly- state that grid drive should not exceed 2.5mA, 5mA
and 7.5mA, for the Ranger, Viking II and Valiant.
Just something to keep in mind, when you're loading the final.
A tip I learned a -long- time ago, from Fred/W5JKD in Priddy, TX (high
school chum of W5PYT) was to load the rigs 10 to 20mA -less- than what
the book says. 20mA is pretty significant as far as the impedance of
the final is concerned, and a difference of about 5 watts output (not
that anyone could tell), but -more room- for the audio to expand in the
plate of the final.
Best of luck with your find!
--
73 = Best Regards,
-Geoff/W5OMR
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