[Elecraft] Woe is me.....

[William M. Spaulding, Sr.]

Folks,

The joy was real, but short.  I installed the 160 Meter option.  I turned
the K2 on after installing the K160RX board without the top cover, which
includes the antenna tuner.

Power levels dropped WAY down.  I tried adjusting the transmit BPF's again -
no difference.  Then, all of a sudden, smoke started coming out from the
area between the control board and the front panel board 2 to 3 seconds.  I
immediately shut if off.  I took the radio apart and searched for two hours
for a component that looked like it had been hot enough to smoke.  I never
did find anything.  I re-assembled the radio and it "worked" albeit with
transmitter troubles on the poor bands.  I have been through the BPF filter
tweaks four times.  I can't get the radio to put out the normal power levels
except on 10, 15 and 17 meters.  Everything else is in the 4 to 5 watt area.

On 80 and 40 , I can get the two watts, and that's it.

I am stumped.  This problem was there when I first fired up the kit.  During
the process of troubleshooting the open pop-through, it was "fixed".  Now
it's back and here to stay.

One observation - the two bands that work best - 10 and 15 Meters - have
filters with far lower insertion loss than the others.

I think I'm gonna have to start looking for gain problems from the output
mixer.  I've gone over everything from the BPF inputs on out to the antenna
spigot without results.

Anyone else who has seen a radio that functions on three bands in the middle
(10, 15, 18 M), but not the low and high bands, please drop me a note.  I'm
stumped and could use some ideas from those with a lot of experience with
this rig.

It's so frustrating.  It worked so well up until I added the 160 option.
That shouldn't have hurt a thing on just some bands.  The 160 BPF is a
little over-coupled, but works fine with good insertion loss.

The receiver works VERY well still with the 160 option and the two antenna
spigots.

There's one other concern I have.  The 2N5109 transistors are loaded down to
the board.  If solder should wick up through the base and/or emitter holes,
or the solder mask had a hole in it, the transistors will short out, because
the case is also the collector.  This applies to all the 5109's.  If they
are down on the board for heat sink reasons, then there should be some
little thermally conductive electrically insulating pad under the
transistors.  Could that be part of the Q22 mystery written about on the
reflector not long ago?

Something tells me this is gonna be a tough one.  Maybe there's another pop
through?  Where did the smoke come from????  Help?

Bill
NA7Y