Topbanders,
I didn´t make many qso´s on topband in the cq-ww, but
the single wire beverage at DL0WH has proven efficiency. I was called by
a few na-stations and called a few myself. Obviousely, the K2AV inv-L
over an FCP and the bev combo worked fine. I mostly rxed with the bev.
Just minutes after the contest i had an more than armchair copy on VE1ZZ.
I think there is room for improvement, because from what i´ve read over
the last days, the bev´s impedance should differ from what i estimated
and therefore the transformer and the terminating resistor must be
recalculated. Also, i had the impression, that stations coming in from
the rear were just too loud.
The clubstation has an antenna-analyzer with a graphic display,
smith-chart display etc.
So, how to measure the bev? Is this procedure correct:
The bev is ~8 feet above ground. The far end is open, not grounded, no
resistor.
The analyzer connects directly to the bev and the ground rod at the rx
end through its bnc-to-banana plug adaptor . Measure and note the
impedances for 160, 80, (40, 30m). Calculate the mean average.
Calculate and install a transformer to match that value to the feedline.
At the far end, find the value for the termination resulting in a flat
swr-curve over the range 1.5Mhz - 10Mhz.
Correct?
--
Ohne CW ist es nur CB..
73, Martin DM4iM
_______________________________________________
Topband reflector - topband@contesting.com
|