[Elecraft] K2: KPA 100 Capacitor Specification?

[Don Wilhelm]

John,

I have never found one of those caps shorted, and I believe the DC 
rating on them is 50 volts, so they should have an adequate safety 
margin since they are used in a 12 volt DC circuit.
I have trouble imagining a condition that would cause them to fail, but 
then I recall that your 'shipboard' operation is unusual and may 
introduce 'perils' that I cannot imagine.
There would be no harm in replacing those capacitors with 100 volt caps 
*if* you can get them to fit physically.  You may have to solder them 
flat against the bottom of the board.  The other problem is that 100 
volt caps may be difficult to procure with 0.1 inch lead spacing and you 
may have to get creative to substitute caps with 0.2 inch lead spacing.

73,
Don W3FPR

Jferg977 at aol.com wrote:
> Felow Elecrafters,
> I have just replaced the second-to-fail .01uF cap on the KPA/100 low band  
> filter relay circuitry of #5087.  In this case, C13.  Failure is a  partial 
> short which allows that relay pair (k3 and k4) to close even though  U2 hasn't so 
> ordered.  Symptom that this has happened is inability to  tune down SWR and 
> power runaway.  This would make sense because  in this condition - particularly 
> this one - since I don't have a 160 meter setup  - the low band filters are 
> triggered for 160 plus whatever other band I thought  I was going to work, two 
> filters for the price of one - not a bargain.
>  
> This radio has suffered some hard-knocks before I understood how to deal  
> with ESD and I feel that I owe 
> Elecraft far more than they owe me, But.........
>  
> Should I replace the relay coil caps with ones with better specs? If so,  
> what should I use?
>  
> 73   AI4TO    John Ferguson   M/V  Arcadian
>   
>