[Elecraft] Good experiance using the K3-100 on battery power

[Kenneth A. Christiansen]

I have used my K2 and later K2-100 as my camping rig since the year 2000.
This year I wanted to try my K3-100 for field day as QRP 1B ND. I took the
K3 with me over Memorial day and ran it at 100 W CW. On Sunday morning
I did 160 meter SSB and AM. I was pleasantly surprised how well the battery
lasted and no body gave me any bad reports. The time I tried the same thing
with my IC-737 I was getting chirp reports within the first half hour 
and later
on the receiver lost mow5 its sensitivity due to the low voltage. On the 
IC-737
I had to add a dry cell to the battery bus for the lower power stages 
but it was
generally not a satisfactory situation.

The K2 was never bothered by the low voltages and in fact I never even saw
the power back down as the regulators and auto gain circuits compensated
well for the low voltages. I continued with the K2 even though I had the K3
last year as I felt any rig with all those nice features of the K3 could 
not
possibly work on my camping battery.

I ran the K3 as QRP 1B ND for field day and was pleased with how well
it worked and my battery did not run down. I had always wanted to take
a ham radio vacation to the woods of Northern Minnesota and decided this
should work with the K3-100.

I am using a three year old 105 amp hour group 24 RV battery and picked
out a camp ground with no electricity for no AC line noise. I bought a Honda
EU2000I generator and used my MFJ-4225MV switching power supply
to recharge the battery. I changed every DC connector to the same
PowerPole connector as the K3-100 uses for ease of charging and
changing 12 volt configurations.

I ran the K3-100 well over 100 hours and 25 days this summer at
100W CW using the following procedure. I would rag chew 3 to 5 hours
a day and let the XL use the camper lights. The K3 would indicate 12.0 V
on receive at the end of this time. Every afternoon I would run the
generator for two hours. I would charge the battery at 16 amps untill
the voltage reached 13.9 volts than I would continue until the charging
current dropped down to 3.5 amps. This always took almost exactly
two hours. The battery never used any water as I checked the levels
in the cells. The battery lasted as well the last day as it did the 
first. The
low background noise gave me the best ham radio experience I have
ever had. The Honda generator used about a gallon of gas every 6 days.

I operated a few times while the battery was charging and the noise from
the Honda was low if a wrapped a 50 foot extension cord into a small
coil but of course the battery by it self was another S unit or so quieter.

I hope my report is helpful to others that want to operate in remote
locations. I never thought I would replace the K2 with the K3 for
battery operation but now I plan to stick with the K3 for all my camping.

73
Ken   W0CZ