[Collins] 30L-1 cracking noise

[Dr. Gerald N. Johnson]

On Thu, 2006-06-15 at 07:20 -0400, Michael and Linda March wrote:
> Collins folks:
> 
> I recently acquired a 30L-1.  After some cleaning and painting, I put it on
> the air with my KWM-2.
> 
> It indicates about 1700 volts on the plates and my W-4 meter shows 500 watts
> out.
> 
>  
> 
> After a week or so, I began to notice a sharp cracking noise.perhaps 2-3 per
> minute.
> 
> The plate meter moves slightly with each crack.
> 
>  
> 
> Thoughts?
> 
>  
> 
> Thanks and 73,
> 
> Mike March  K4QU

 Check the insulator post under the RF choke for dust or a carbon trail. 

Check the PA coupling capacitor for the same. Check the HV wire feeding them. 

Also the bypass capacitor on the DC side of the PA plate choke.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer