[Drake] R4C T10

[Garey Barrell]

Cecil -

I've not had that specific problem, but a couple of ideas.. 

1.  Mica capacitors are known to grow "whiskers" that can sometimes 
short between "plates" of the capacitor.  This is less common in the 
DurMica style used by Drake than in the older "postage stamp" style, but 
it DOES happen.  This often shows up only under high voltage, and so 
might not be caught by a typical "capacitor checker" that only measures 
capacitance.

2.  Another problem that I have seen in Drake low frequency transformers 
is that some use an "external" ferrite "pot" core style.  This core is 
pressed down against the terminal headers inside the can, usually with a 
thin rubber washer to insulate it.  I have seen a few of these 
transformers where the person who built the transformer cut off the top 
of the header wire with side-cutters, leaving a pinched, sharp edge 
pointing up into that rubber insulator.  After 30-40 years of pressure 
...   Most seem to have the terminal header bent over inside before 
cutting, eliminating the problem.

Be sure and let us know what you find.

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
<www.k4oah.com>



Cecil Acuff wrote:
> Good evening folks,
>  
> Anyone ever had problems with T10 in their R4C.  I'm restoring one for 
> use here and it's started generating random static and poping noises.  
> Chased it around all evening and it appears to be T10...the winding on 
> the plate of the tube it's associated with (primary).  I'm guessing it 
> is arcing between turns in the winding or something.  I have checked 
> the caps that bypass it and that is in parallel with the primary of 
> T10 and it's not the caps. 
>  
> Any ideas on how to check the thing.  I put it on my Sencore inductor 
> tester and it says it fails the ring test with 8 rings.  The secondary 
> passes with 11 rings...not sure this is an accurate test.
>  
> Any help would be appreciated....
>  
> Cecil Acuff
> K5DL
>  
>