Wednesday 4 April 2018

Feeder losses - Worse problems to have. HF. Part 1.

Feeder losses - Worse problems to have. HF. Part 1.

In the past feeder losses at HF have not been a concern for me.
The antennas used were nearly always resonant and due to amount of space available, a normal run would have been 45 - 50 metres. [17m from antenna to tower base and 25 - 30m run around the garden borders neatly to the shack].
To squeeze every extra db out the system I would still run W103 or Ecoflex15, but loss as such was never a main concern.

Since moving QTH I began planning how and where the antenna systems could go. Initial idea were put the whole lot in the bottom field out the way, less qrm noise etc, however the bottom field is actually 200 plus metres away... A problem, maybe.

Sites were choosen for the antennas and using a feed loss calculater I worked out how and what the losses may be.
First up was the main HF antenna position. This will be a main run to remote switch.
There were to two routes. (1) Directly to it, or (2) around the permeter.

(1) Direct - 150 metre run. 



 Results show the losses with LDF4-50, RG-213U and RG-58 on a 150m run.
-
1.8MHz.

3.5MHz.

7.0MHz.

14MHz.

21MHz.

28MHz.

Next-
(2) around the permeter. - 250m run!


 Results show the losses with LDF4-50, RG-213U and RG-58 on a 250m run.
-
1.8MHz.
3.5MHz.

7.0MHz.

14MHz.

21MHz.

28MHz.

Some of the losses are incredible and totally unacceptable.
10m and 15m certainly could do with with a seperate closer system.

The neater option is certainly out the question.

Part 2 to follow.

Tim M0BEW.

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