KX1 RX deaf after KB3080 installation

[Ron D'Eau Claire-2]

Looks like it's Q7. I pulled T2-2 and still had the short. So I pulled Q7.
The
short went away at L6 and the RX works. Q7 is shorted- only 3 ohms collector

to emitter. I don't think it's not a random failure. The original problem
with the KXB3080 was a hot Q6 but very low output power. That problem was
caused by a solder bridge between B and A on the KXB3080 so I'll bet too
much
TX RF got into Q7 and fried it. If I'd caught the problem during RX testing
I
would have avoided this.

At least I can play with the receiver while I wait for a new Q7. The
sensitivity does seem improved, at least on 20 m, by the KXB3080.

Thanks Ron, Don, and Alexandra, for all the help!

73,
Bruce
N7CEE

----------------------------------------

AHA! Good for you, Bruce!!

It's a great feeling to know what went wrong!

I observed to another friend recently that building something and seeing it
work is one level of achievement. Finding something that doesn't work and
fixing it is quite another!

Congratulations!

It is common to note some improvement in sensitivity on all bands after
doing the KXB3080 installation.

Ron AC7AC

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[Bill Allen-6]

John,

Thanks for the suggestions.  I can now report back to the list what I have
found.  Gary Surrency and Don Wilhelm have been helping me on the side and
here is what the problem is.

LIGHTNIHG.   Yep, I took a hit.  I started pulling the various module boards
one at a time until I found that pulling the SSB board made the K2 drop out
of transmit.  Then, reasoning that the most likely component on the SSB
board to suffer lightning damage would be the PIC processor.  So, I pulled
the PIC and replaced it with a previous revision chip that I had left over
after the last time I upgraded it.  Viola!  The K2 then worked fine except
for the KIO2 is mute.  It will taken control commands from me, but does not
send polling data back out.  Could be because I have a mismatch of
processors now.  Any notions for this specific KIO2 problem from anyone in
the group would be quite welcome.

Many thanks to Gary and Don and everyone who gave me feedback, it was all
quite valuable.

NOTE TO THE GOUP!  NEVER throw away old revision processor chips when you
make upgrades to your K2.  Tuck them away safely in something antistatic and
save them for a rainy day.  You may have to depend on them one day!

Best 73s,
Bill Allen - WA5PB


-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of John
Sent: Thursday, April 20, 2006 10:27 PM
To: [hidden email]
Subject: RE: [Elecraft] K2# 1068 stuck in transmit mode

Bill,

Do you think it could be the key input jack itself? I've had trouble with
the headphone jack on one of my K2's. I've had to replace it 3 times, not
fun. I think the key jack is about the same thing and maybe prone to the
same type problem. Just a thought.

John,
k7up

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[Rich Lentz]

 
John:

If you have an old K2 main MCU try it and see if it fixes your KIO2 problem
before you order parts.  My K2 was subject to lightning (not as direct hit
but in the neighbors yard) and the only symptom was that the KIO2 would not
work. After determining the input port on the PC was shot (tried other
serial device) thought it was fixed. Then spent many hours trouble shooting
and replacing the KIO2.  Once it was fixed I determined the pin the KIO2
interfaces with on the KIO2 was internally open - thus needed a new MCU.
Three things broke, two in K2 and one in the PC.  Strange that everything in
the PC worked except the serial port.  And everything in the AK2 worked
except the KIO2.

Rich



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