29 Mar 2012

E-field probe tests

This afternoon I built a version of the PA0RDT E-field probe. In the shack the interference was horrendous, but in the garden with the laptop PC just below it the reception of the VLF Alpha beacons and MSK signals around 18-22kHz was excellent. I need to do more noisefloor measurements and elevate the probe higher, but I think this is going to work well when mounted at the top of my neighbours tree that overhangs into my garden. This is a sycamore which I trimmed back a few months ago. The E-field probe can be mounted "in the clear" some 20m from the nearest house at a height of around 5m off the ground. I now need to rebuild it into a watertight box and think how I am going to get the output and power feed to the shack that is at the wrong side of the house some 30m away. Some have used CAT5 twisted wires for this purpose and I guess this would be a good, simple solution, although less suitable if I want to use the probe at 137 and 500kHz where a coax feed would be better.

1 comment:

Bert, PA1B said...

Hello Roger, I once built a magnetic loop with a simple feedback amplifier for the reception of VLF signals, that I published in Sprat 90. (PA3FSC)
I ordered the parts for the PA0RDT E-field probe many years ago, but still did not built it. I heard before from other HAM's that the prerfomance is very good. This probe also needs no tuning. 73, Bert