Hi Elecraft list & Bob,
Sigh. Sometimes it don't pay to get up in the morning.
First, I was having a CW QSO on 40M with a station in the East Coast...
My K2/10 was driving the Tiny Linear - we were seeing 150W on the meter.
Suddenly, the screen of the linear flashed bright white, and the RF went
away, leaving me with the barefoot K2.
Seems that 150W was Just Too Much for the little fan-driven heat sink,
and the PA transistor shorted out. My fault, of course. I have a few
more of those transistors, but I'll have to hold the power down,
instrument the heat sink temperature, and put in some sort of
protection.
In the meantime...
I installed the recently acquired KPA100 in my K2. Actually, that
KPA100 came from ANOTHER K2, acquired on Ebay. I swapped it into my
first K2, because that one has the V2 mods, including the upgraded
crystals.
So here I am, ready to continue hamming. My K2 ( now /100 ) is doing
strange rf-in-the-shack'y things. If I send a bit of CW, my sent CW
starts breaking up, and strange pops and clicks (like relays ) come out
of the radio. Then when I stop sending, the radio is completely silent
- no audio. I can see band noise and signals on the S-meter(bargraph)
but no audio WHATSOEVER. Hitting a band button or the display button
fixes it, and audio is back.
Sometimes OTOH, when I stop transmitting, the audio comes back much
LOUDER than it was before I transmitted.
This all happens at any power level where the final is engaged. If I
turn the power down to 8W or so, all is good. If otoh, I turn the power
knob anywhere past that *click* where the PA comes on line, the bad
things happen. Even at, say, 12W.
I made up a short length of RG8/U with 4 Palomar 31-mix giant ferrite
beads - a common mode choke. No difference.
With a dummy load, all is good. No fuss no muss, it just transmits
nice.
The antenna is very low SWR. It is a 6BTV vertical about 100 feet up
the hill from the house. There is an MFJ998RT remote autotuner up at
the base of the antenna. It is grounded with an Ufer ground - 80 feet
of #6 copper wire
buried in the concrete pad, which is 70 feet long by 10 feet wide.
If I turn the PA off, the K2 behaves well, even at the full 15W. Tune
mode shows SWR 1.2 to 1. My K2 btw has the KDSP2 audio filter.
- Jerry KF6VB
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
