[Elecraft] KAT100 woes... Time to 'fess up...

[Tom Hammond]

Hi Folks:

Man, I just HATE it when I have to come clean... but here goes... mainly 
for the benefit of anyone else out there who runs into the same problem...

About three weeks ago, the day before left on a trip, we had a pretty 
'healthy' thunder storm track right over the top of N0SS Central.

When I heard the first thunder clap, I legged it out to the shack In the 
garage) and started disconnecting coaxes like a mad man...

I had just(!) managed to get the last coax connector DISconnected and moved 
away from the rig(s) when an all too close bolt of lightning struck. 
Fortunately I wasn't touching anything (by about 1/2 second!) when it hit 
and I heard/saw a nice arc between the shell of one coax connector and the 
nearby ground.

I finished up my work and got the heck out of the shack, vowing to return a 
bit later.

Well, things conspired to keep me out of the shack until the next week when 
I'd returned from my trip.

I reconnected the coaxes, AND the K2 and all appendages. Turned on the rig, 
hit TUNE and listened as the KAT100 went through its paces, tuning up on 20M.

Everything SOUNDED just as it should have sounded. The ATU took the right 
amount of time, to tune, and the ratta-tat-tat of the relays made the right 
rhythm. The K2/100 put out 100W into the beam, and all the other (external) 
meters indicated perfect operation.

The one thing which WASN'T right was that the K2's LCD display indicated an 
SWR of 9.9:1 while the ATU tuned, and NOT ONE of the LEDs on the front of 
the KAT100 illuminated while it tuned up. Something was obviously wrong!

I set the K2 to 5W, the KAT100 to CAL mode and pressed TUNE in an effort to 
see what things looked like there. THIS time the K2 LCD display indicated 
2W output and an indicated SWR of EITHER 1:1 or 9.9:1, kinda randomly 
changing between the two SWRs with each successive press of TUNE. And, this 
time, the LEDs on the front of the KAT100 were ALL LIT!!!

I then inserted a second ATU in-line, so I could create a varying SWR of 
known quantity, so I could monitor what the KAT100 showed. With an 
'inserted' of 1:1, the KAT100 generally indicated NO LEDS (or 1:1, I 
guess). With virtually ANY other inserted SWR from the 2nd ATU, ALL of the 
KAT100 LEDs illuminated.

I checked the 1N5711's in the KAT100 bridge. They were good and working as 
expected. In fact, everything SEEMED to be working properly... other than 
the weird LCD and LED indications.

I asked the experts... they'd never seen anything such as this, but several 
were certain the nearby lightning strike had 'farkled' something somewhere.

I obtained a new PIC for the KAT100 and also a number of TPICs (LED 
drivers, etc.) as a precaution that some of them had been 'taken out' as well.

Replaced the PIC in the KAT100 and nothing changed.

Did a hard RESET of both the K2 and the KAT100, but to no avail.

Then... as I was about the disconnect the K2/100 from everything in 
preparation to taking it out back and using is as target practice... there 
it was... the culprit...

It seems that, during my haste to get everything reconnected (remember, 
somewhere about 30 lines above in this treatise)... I'm managed to connect 
the RF OUT from the KPA100 to the ANT1 jack on the KAT100 and the coax from 
the external antenna switch to the RF IN jack on the KAT100... in short, I 
had the RF IN and ANT1 connections reversed!!!!!

Swapped these two connections on the back of the KAT100 and EVERYTHING 
WORKED PROPERLY!!!

So now my conscience is clear... I've confessed to my transgressions... and 
done all sorts of penance to the RF gods. And I'm sitting here baring my 
soul to you so you might not make the same mistake!!!

ALWAYS DOUBLE-, no... TRIPLE-CHECK YOUR EXTERNAL CONNECTIONS!

And, if your KAT100 seems to tune properly but INDICATED weirdly, don't 
jump to conclusions... the problem may be man-made rather than the fault of 
Mother Nature.

73,

Tom Hammond   N0SS

p.s.

I find it very interesting that the KAT100, regardless of the fact that the 
I/O lines had been crossed, CONTINUED to PROPERLY TUNE TO A (verified) 1:1 
SWR, even though everything else was seeing 9.9:1 by virtue of the reversed 
connections. That's some ATU there!