From the May
2002 edition of QST Magazine (Matt Kastigar NØXEU)- see the pictures below
It took only
a few minutes into the project to discover that the author described the
procedures using an AT power supply and MY units were both XT power supplies.
I found a
pot on the supply board that would permit an adjustment of the 12 volt output.
Full clockwise however would only adjust the 12 volt output to 13.03 volts.
When testing the power supply with a Radio Shack HTX-10 25 watt rig, the
voltage would drop to 12.87 on FM transmit . The voltage drop was only a
“flicker” when transmitting SSB. The
same drop to 12.87 was indicated using KDK 15 Watt FM rig.
The only
“minus” I’ve found was attempting to use the Yaesu PA-6 DC/DC
supply/charger and the Yaesu FT- 411 Handie.
The PA-6 has an internal regulator to control vehicle voltage down to 7.2
volts. I connected a cigarette lighter receptacle to the “switcher” power
supply and plugged in the PA-6 unit. The battery charging side worked but as
soon as I keyed the rig, the “switcher” power supply “shut down.”
I’m assuming that there is a high frequency component on the DC output and it
is sensed by the PA-6 which causes a high current draw to ground within it’s
regulator. Doesn’t seem to damage anything ... after a minute or so and
an “ON/OFF” the “switcher” again puts out 13.03 volts.
All in all,
it was a very satisfying weekend project. I’m
planning on using the “switcher” on my ten meter beacon.