Hello technicians,
I was adding a power meter to a new homemade linear. I used the directional
coupler of the "Digital PEP Wattmeter and SWR calculator" from an old ARRL
handbook (1987). I did not get a too deep null on calibrating, so the
directivity was only 20 dB. As I only wanted to monitor the output of a linear
with that coupler, the directivity was sufficient.
The problem: The output voltage for a given power is the same from 40-10m, but
nearly null on 80m and different on 160m.
Then I tried the design from the linears in the W6SAI handbook. They use Amidon
50-6 toroids. The output voltage ón 160 is about 1/2 of the voltage on 10m.
Has anyone successfully built a directional coupler with constant frequency
behaviour from 160-10m?
I would like to have proven designs.
Thanks!
Tom, DJ5RE
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