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160m Receive Loop. |
This photo shows the interior of the tuning box.
The RG-59/U 75 ohm coaxial cable outer shield is connected with the feedline through the metal box.
There is a break in the coax outer jacket at the top of the loop of about 1" (25mm).
The inner conductor is joined in series with a 560pF silver mica capacitor.
The loop is tuned via a variable capacitor across the 560pF. The connection to
the feed line inner, is taken from one side of the capacitor. With a bit of further
experimentation, the inner conductor could be capacitively coupled to reduce the loading
effect on the tank circuit and possible increase the matching. I was able to obtain
a vswr of around 1.6:1 on 1.850MHz with a spread of about +/- 9kHz to 2:1 points. It certainly
knocked out the intermods produced by broadcast stations and allowed me to hear cleanly
and allowed the use of a pre-amplifier, which I wasn't able to, before. Further testing and
adjusting may yield further improvements.
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