[R-390] My 'new' '67 EAC is now "on line" 8^) Ballast Tube question.

[rbethman]

Phil,

    Experience has shown that the filament of the ballast tube SHOULD 
only partly glow when all is well.  The symptoms you describe SHOULD 
mean that the circuit that it regulates is drawing too much current.  
Either one of the tubes has some form of a short, or something else is 
causing excessive current draw.

    It's probably going to be painful to track down, but will be worth 
it in the long run.  As mentioned in an earlier post, if the PTO tube 
came from the same lot, it could be a bad lot.

    Try swapping the two tubes that R510 regulates from another R-390A.  
If the ballast tube goes down in brightness, then one or both of them 
are problem children.  IF NOT, then something else is awry.  Perhaps a 
bad or flaky ground.  These radios are notorious for this with the MFP 
coating

Phil Atchley wrote:

>BALLAST TUBE QUESTION:  In all the R-390A's that I've had previously (that
>still had the ballast tube) I seem to recall the filament having just a dull
>glow in only a small part of the filament.  This one glows fairly brightly
>over nearly the entire length of the filament and makes me feel uneasy in
>that I'm afraid it's nearing the end of its lifespan (seems I recall reading
>that was an indicator).  No, my line Voltage is under 120 VAC, especially
>this time of day with everybodies A/C running.  Do I have cause for concern?
>Perhaps I should start looking for a 12BH7 tube (I did the 	12BH7 mod
>while recapping the IF strip).
>
>73 de Phil, KO6BB
>
>  
>
Bob Bethman

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|        2 BC-610s w/BC-614s, 2 R-390As - 1 Collins 1 Eac          |
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