[Elecraft] KX1, ATU, and output power

[Peter N. Spotts]

Hi folks,

Should the ATU affect output power from the KX1? If not, here's my 
conundrum:

After finishing the 80-30 mod, the power output seemed a bit low. As per 
the instructions, I adjusted turn spacing on one of the two toroids on 
the new filter board and achieved 4 watts out on 80m and 30m, and 3 
watts out on 40 and 20 at 14 vdc.

I reinstalled the ATU, buttoned up the case. With the radio running into 
a 50-ohm dummy load, and with ATU engaged, I got about 1.5 watts on 80m, 
around 3 watts on 40m, 4 watts on 30m, and about 2.5 on 20m. These 
readings came from the internal watt meter, as well as an outboard 
NorCal wattmeter.

I opened the case again, pulled the ATU, tweaked winding spacing, left 
the ATU out of the package, and the power levels returned to the 
original 4/3/4/3. I plugged the ATU back in and the same reduction in 
power out resulted.

On inspecting the boards, it didn't look as though the ATU was 
physically impinging on the new filter board. And with the ATU attached, 
but with both boards out of the case, I was able to tweak windings to 
get the 4/3/4/3 output again...until the boards went back into the case. 
Then it was back to 1.5/3/4/2.5ish.

What could be altering the output? The only thing I could think of was 
that the toroids might be wound a bit tight, so that when tweaking the 
spacing between windings, the windings basically slide back into more or 
less the original positions in about the time it takes to close the 
case. Yeah, it's a reach, but it's all I've got at the moment.

Any thoughts/suggestions? I can try operating without the ATU and use my 
outboard tuner. But I figured as long as I've got the tuner, I'd like to 
use it.

With best regards,

Pete

-- 
Peter N. Spotts -- W1PNS
http://www.w1pns.net
Email: w1pns at arrl.net | Skype: pspotts
QCWA #34679 | SKCC #4853T | QRP-ARCI #4174
NEQRP #714 | NAQCC #2446 | GQRP #13202

"Amateur radio is a contact sport.
Get on the air and make a contact!"
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