[BC] CONTINENTAL 315R-1 5KW AM TROUBLE

[Tom]

First clue is the HV input reading - pegged meters.  Make sure 
they're really seeing that much (HV probe time!), and it's not a 
shorted multiplier resistor; then check backwards from 
that.  Possible causes - open filter cap(s) in the power supply 
allowing excessive ripple, problems with the transformer (not fully 
familiar with this PS, but many transformers can be tapped / 
connected for various secondary values allowing different 
transmitters to use same PS - and up-powering any given box easier as 
a side benefit.  If there's a lower value available, you might be 
able to connect the lower voltage to at least get the rig back on the 
air.  The cure will be, in that case, a new transformer.
Also check - three-phase? - AC incoming; a floating phase might be 
giving you more voltage in one leg than you're supposed to 
have.  Might be power pole pig, might be neutral, but if the 
incoming's not right, you can get all SORTS of problems.  Had one 
back when I was just starting out as an engineer - might have been a 
Continental, it's been a while - that the power company provided 
three-phase with  what's called a "wild phase"; the reactance of the 
transformers generate the third leg "virtually".  We kept popping 
rectifier stacks, and nothing would help - MOVs, bypass caps, you 
name it.  Finally we checked phase-to-phase and phase-to-neutral, 
both with and without the transmitter on.  BIG difference!  I left 
shortly after that; not sure who wound up paying for getting true 
three-phase service out there... or if they did, even.

HTH

Tom S.

BOYDSIRBOYD at aol.com wrote:
>to the brain trust,
>
>I have for the last 3 days racked my head literally on 
>this  transmitter (and boy does that hurt).  the trouble I have is 
>that the  high voltage on the pa tube wants to arc (and a good size 
>one too) to the  neutralization plate (C 46). I have went through 
>every power supply's in this  thing. the switch mod bias +125 V / 
>-125 V supply, the 28 V supply( I did find R  9 and R 6 both bad) 
>and the logic power supply.
>
>
>now meter information,,, as soon as I hit low power button the high voltage
>meter pegs ( max on meter is 15kw volts), the transmitter should go 
>no higher
>than 14kw volts.  the plate voltage starts to come up but arcing occurs
>before the meter reaches it's place on the scale,  the plate 
>current  comes up and arcing occurs when as the meter reaches it's point.
>I feel the plate transformer has a short causing the extreme arcing on the
>pa tube...
>