[Elecraft] k2: KPA 100 capacitor Specs. etc.

[Ron D'Eau Claire]

That's a real mystery John. Don should know if others have experienced it.
It sure sounds like something in that environment. It's an even greater
mystery since it's happened more than once, and now with a good solid d-c
path to ground on that antenna. 

I used to handle the annual SOLAS inspections for a lot of vessels around
the San Francisco bay, demonstrating all the ship's gear to the FCC
engineer. Often the SGC 230 ATU at the base of a 22 foot whip for the 2182
kHz SSB rig would be dead. Opening it up would reveal signs of arcing. 

If the Radio Officer was handy, he'd often say, "Yeah, it's been
intermittent ever since we took a lightening hit a few months ago but it
usually works..." Hi! 

So I have no trouble believing that something can be 'killed' - sort of -
and work -sort of - afterwards - especially something hooked to an antenna
on a ship.  

Y'know, the 1-mH choke to ground will keep draining the accumulating static,
but how about a pulse from a sudden discharge somewhere (lightning or
something else)? That may be a very fast-rise-time (high-frequency) pulse
that the inductance of the choke may actually prevent shunting to ground,
just as the inductance isolates the RF from ground. 

Is the transmit RF voltage low enough to allow you to add something like an
NE-51 neon bulb that would ignite quickly if the voltage spike exceeds about
40 or 50 volts? 

I think I'd go for the larger caps too, if you can squeeze them in! 

Ron AC7AC

P.S. Gentlemen, after the MFJ thing, I don't want to start an SGC-bashing
thread ;-! Anything that survives out in the weather bolted to a ship's
funnel has got to be good. 



-----Original Message-----

Ron,
your experience is similar to mine. Your snaps are identical to the ones i
heard before I did what I describe next.  There is a lot of history to the
ESD problems on Arcadian
?and yes, in  some conditions, you could hear the zaps all over the boat.
The precautions are much more recent.  I wound a 240 torroid to produce 1
milliHenry inductance and shunted the antenna lead-in to "ground/salt water"
where it came into the cabin .  No apparent ESD problems since then.

No more fried 1N5711's.  I feel, though, that the failing capacitors may be
residual from some of the more exciting failures associated with no output
power control
due to SWR sniffing circuits having been fried by a Zap.  I ususally feel
that if a component doesn't fail when it is abused, it won't fail later
either, but????
Radio is working fb right now.  

I'm thinking about doing what Bill recommends and I discussed with Don,
upping the caps to 100 volt size.  But if problem continues, even this might
not be enough.  It may also be good to see if I'm getting ESD into the radio
via some other 
route than the obvious.  This would be a real aggravation if I didn't enjoy
working on the K2 so much.

NO, I don't either have masochistic tendencies.

73   john