[Elecraft] [K3] Test Mode TX and TX Monitor?

[Dan Atchison]

To answer a few questions, I'll try to be as definitive as possible.

I see, according to both the P3 TX Mon AND the LP-100A up to about 0.4 
watts output from the K3S on CW mode in TEST.  The sensors for both the 
TX Mon and the LP-100A are in series, the TX Mon immediately after the 
K3S and the LP-100A through a short piece of RG-400.  If I substitute 
the K3 for the K3S, there is no indication on either "wattmeter."  So 
methinks that this proves an issue with the K3S.

Also what is interesting is if I monitor the K3S signal (while in TEST 
mode) on the K3, the signal level pins the meter on the K3. Reverse (the 
K3 transmitting in TEST MODE to the K3S), it's about S7.  Not a great 
test, but significant I think. It's almost like a short spike of power 
is output (as indicated on the P3 TX Mon and LP-100A).  I contacted a 
local ham but he cannot hear any transmitted signal (he's about 7 air 
miles away), but methinks it's a spike of such short duration or 
generation that he wouldn't.

I am also seeing an anomaly with the K3S that I have yet to fully 
understand and as far as I can tell happens only on 80M.

I run SO2R and have bandpass filters between the K3S and K3 and their 
respective amplifiers.  On 80M, and according to the internal K3S 
wattmeter, I have a 1:1 swr going into the bandpass filter but as soon 
as the rig output is set to above 12 watts, i.e. the KPA3A kicks in, the 
SWR immediately rises to 5:1.  The SWR remains high until I increase the 
power up to about an indicated 45 W output (by virtue of the power 
control on the K3S), then the SWR immediately reduces back to 1:1 and 
remains there to max power output.  Of course the "real" power output is 
cut back until the SWR goes down.  So, you say, it's the bandpass 
filter.  Perhaps, but I have swapped bandpass filters and the problem 
remains with the K3S.  I have also eliminated the amplifiers by 
installing a dummy load in their place.  I did this to make sure the 
KPA3A was not transmitting a dirty signal on some other frequency 
against a resonant 80M antenna.  Same issue.  There are no issues with 
the K3 in line - it's only the K3S.

I realize, because the K3S has the new KAT3A with a bypass relay as well 
as the upgraded KPA3A, that things are different than the K3, but 
still???  Some kind of matching anomaly?

I plan on sending the K3S back to Elecraft to witness this (and yes, I 
will include the bandpass filter), but rumor has it that their repair 
center is backlogged and it's too close to contest season to risk being 
without.  My K3S works fine except for these problems.

73,
Dan