I found an old note from 9/16/2020, made when I was testing my new -1899 multiband whip antenna.? With the jumper set for 80 meters, and a counterpoise wire of roughly 10 feet connected, I could get an SWR of 1.0 at 3.685 MHz.? (Unfortunately, I didn't write down the whip length setting.)? I also noted that 40 meters was also good with a 10 foot (and less) counterpoise wire.? 20 meters, with about 6 feet of counterpoise wire.
And I've found a fairly convenient way to connect a counterpoise wire.? I had a spare coaxial DC power connector, and soldered a piece of thin, limp counterpoise wire to the negative contact of the plug.? Before using it, I did verify with an ohmmeter that the negative power jack connection does go to radio chassis ground.? So the counterpoise wire just plugs in - even handier than using a big (wide jaw) alligator-type clip on the BNC connector.?
My X5105 power connector is 5.5 mm x 2.5 mm (larger center pin than the much more common 5.5 x 2.1 connector).
--
Doug, K8RFT
