[Collins] Re: Collins digest, Vol 4 #213 - 1 msg

[ronald j deeter]

Lorin-
super glue (cyano acrylic) will work fine for the repair should you
desire to do so. I've no problem on ceramic and phenolic insulators up to
450 KV (yes KV). be careful if using epoxy that there are not any
conductive impurities (carbon fibers sometimes added for strength ) or
additives that may arc at the high voltages creating carbon tracks. also
beware of the heat problem. epoxy will not fare as well as the superglue,
but then if there is that much heat the resonance of the choke is
probally incorrect for the operating freq. best to check and if necessary
rewind/make ur own ( oh what fun!!!). good idea to check for resonances
prior operation at the operating frequencies.
Ron

On Fri, 22 Aug 2003 14:59:13 EDT LorinH@aol.com writes:
> Dear Friends,
> 
> Last night, when checking out a KWS-1 which I am restoring I tuned 
> it up at 
> full power on all bands, when I reached LOW 10 meters I suddenly 
> heard a loud 
> "Crack" which was then shortly accompanied by some smoke coming out 
> of the 
> final compartment. 
> 
> When I opened the bottom of the chassis and PA compartment I 
> discovered that 
> L 403, the Plate RF Choke had cracked in two,, It broke quite near 
> where it is 
> attached to the right side (looking down) of the compartment.  I did 
> not see 
> anything else that had burned, but will check.  This of course 
> raises several 
> questions.
> 
> Does anyone know of a source or the 90 UH ceramic RF choke?  Surplus 
> Sales 
> has one that is advertised as being for the KWS-1, but after 
> speaking with Bob 
> Grinell we concluded that it is a 45 UH choke, different in design 
> and would 
> not serve. 
> 
> If a new one cannot be purchased, repair becomes the only option.  
> Is it safe 
> to glue this ceramic core together, using some form of high 
> temperature epoxy 
> or other (super)glue?  Does anyone have experience with this, and 
> can advise 
> as to the type of substance to use?
> 
> This all begs the question of why the choke cracked in the first 
> place.  Heat 
> is the most likely answer.  (This choke was, of course, the subject 
> of the 
> service bulletin which reported its failing in the field, and 
> advised removing 
> the fiberglass insulation because it trapped moisture.)  The blower 
> seems to be 
> operating well, but things still do get quite hot around the finals 
> especially after periods of "tune" with key down.  
> 
> I am very grateful for any ideas or advice,
> 
> Also, in another domain, I am about to align my 75A-4 (I have owned 
> both rigs 
> for 48 years) and am most interested in alignment information which 
> is based 
> on the wisdom born of common shared personal experiences.  I own the 
> Electric 
> Radio compendia, and have read many of the reflector posts.  I own 
> Butch's 
> HI-RES tape, (4 hours) and would enjoy sharing ideas. 
> 
> I am also looking for a RF signal generator.  Any out there where 
> might be 
> rented or purchased for a reasonable price?  
> 
> Just wanted to share.
> 
> Thank you all.
> 
> Lorin 
> 
> WA1PGB
> Sponsored by the Collins Radio Association
> http://www.collinsra.com
> 


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