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

[Louis Mueller]

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.
>  
> that's the last problem I have with it now.
>  
> here's how it died Thursday evening,,,  the power dropped like it was  
> suppose to in the evening, but then a hissing cracking noise was coming out of  the 
> transmitter (as I was told). the owner turned the plate voltage off,  then 
> turned it back on with the same result.  he called me and I went in to  find the 
> suppressor grid cap (C 51) had blown open because when I  fired up the plate 
> voltage that's where the arcing was.
> well I got a replacement the next day, just to make sure I changed  the pa 
> tube (in case in was shorted and caused the original  problem). well the high 
> voltage came up and it started arcing  from the output of the pa tube to the 
> neutralization plate just behind  it. also found the long circuit board behind 
> the meter panel and the control  panel had burned. that killed any 3 phase meter 
> reading, but it would work with  all the rest.
> I also replaced it and all meters work fine.
>  
> and that's where I am now.
>  
> BURT in Columbia sc  told me about the continental fm rigs doing the  same 
> thing because of the plate transformer internally shorting, I needed to  isolate 
> the transformer from the rest of the transmitter. I tried that with a  board 
> between the transformer and the bottom plate of the transmitter. no  luck,,  
> same arcing..
>  
> 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...
>  
> ok all engineers what are your thoughts??
>  
> bill   wdab  wasc  wcsz  wtoy  wabv 
>  
> P. S. and PAUL WALKER, no comment from the peanut  gallery.
>
>
>
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> The 315R-1 has no DC voltage at the plate of the RF tube
>
>