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KX1 hi current on 80 and power mod.

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Frederick Dwight

KX1 hi current on 80 and power mod.

Hello BART,
RE: High current on 80. I had a similar problem when I built my KX1. Do a search on KL7CW and see my post of April 19th
on the Elecraft site. IMPORTANT...while troubleshooting with kx1 out of case..use a low voltage (7 volts ?) and short transmission
times.
RE: Power modification. Do the mod after you find the 80 meter problem. I was very happy for over a year with only just over
1 watt output. However when you operate under marginal conditions and/or with compromise antennas you want all the power you
can generate. You can always turn down the power if you really want a 1 watt transceiver. 6 internal Lithium cells have a very long
life, even with the power modification. I have not tracked the life, but suspect it is at LEAST 20 or 30 hours of operation, possibly
much more if you listen most of the time like I do. I operated the Field Day contest and needed all the signal I could get. Hiking for an
hour up a mountain probably gained me a few db. Hauling a 1.5 Kg 9 meter mast up the mountain probably gained me another few
db. When I got to the site and found out that conditions in Alaska were only fair I changed out my well used Lithium cells to a fresh
pair and gained perhaps another db. Also I carried RG58 instead of RG174 which may have gained me another db or so. Any of these
individual actions may not have made much difference, together they enabled me to actually squeeze some qso's out of my set up.
Rick KL7CW Palmer, Akaska Kx1 # 798

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Don Wilhelm-3

RE: KX1 hi current on 80 and power mod.

> -----Original Message-----
IMPORTANT...while troubleshooting with kx1
> out of case..use a low voltage (7 volts ?) and short transmission
> times.
>

Folks,

I would go a bit further and say NEVER operate the KX1 out of the case
without a suitable heat sink on the output transistor - no matter what the
supply voltage.

I have a 2 inch square of 1/8 inch aluminum that I have drilled and
countersunk a hole in for the mounting screw. A spare thermal pad provides
the needed insulation from 12 volts (if you don't use an insulator and a
metal screw is used, a short to the 12 volt supply line will result). If
the nylon screw is used, the thermal pad insulator should still be in place
because the heat sink will be 'hot' with the supply voltage.

With this simple little device on my workbench, I can operate the KX1 in
TUNE (with a 13.8 volt supply) long enough to make any measurements I need
and/or do extensive troubleshooting. Check this heat sink occasionally, and
if it gets warm, give it a time to rest before continuing.

73,
Don W3FPR

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