[AMRadio] Valiant Problems

Bill Pancake bpancake at mindspring.com
Thu Jun 10 20:41:23 EDT 2004

Could really use some help here from those of you who have had experience with the Johnson Valiant xmtr. Three questions...

1) Why does the 1.6 amp slo-blo low voltage transformer primary fuse blow after an hour or so of just sitting there with the filament switch on with no plate voltage applied? The 300 vdc and -250 vdc bias circuits are reading as they should when measured. Transformer and filter choke case temperature are warm to the touch but not "HOT". Line voltage is @ 110vac thru a Variac.

2) What is the correct setting for the voltage at the modulator grids (pin 5)? Page 9 of the ops manual says "-55 volts", page 31, socket voltage chart says "-46 volts", and the assembly manual eratta sheet says "-35 volts".

3) What is the correct voltage for the RF amp bias? Page 8 of the ops manual & the socket voltage chart says "-70 volts", service bulletin #1 says "-52 volts" and the assembly manual errata sheet says "-85 volts".

Any help here would be greatly appreciated. Thanks, Bill, ab0zz at arrl.net

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