Hi all there has been discussion about Aerial Current measurement on many
occassions in the past, and many have built versions of the "Clothes Peg"
clip on ammeter.
Dave Powis G4HUP announced a kit for an HF clip-on current meter in the
December Radcom. After some prodding by me he has had a sample tested at 136
and 475kHz and as expected the instuments works well and sensitivity is flat
from here up to 30MHz or more. The instructions include a simple calibration
proceedure. Sensitivity down to 100mA FSD allows it to be used with low
power systems where the use of a thermocouple RF meter is not posssible.
Dave also produces a board intended to break out the IF signal from many
standard tranceivers for input to an SDR dongle. These were intended to work
in the IF frequency range and use SMD parts to give an add-in pcb little
larger than a postage stamp. A look at the circuit shows that this is very
similar to the circuit used by Roelof (mini-whip) and others for use in
E-field antennas. I believe the coupling capacitors will need to be
increased in size, but I believe Dave can produce these for LF to order,
either as a kit or completed board. He has not yet had a chance to try this
out at LF but it's a chance to experiment at little cost. Getting the
receive antenna away from habitation and power wiring is a good move at VLF
!.
I have no pecunary interest but I admit that Dave is a good friend and ex
work collegue, and an excellent engineer. Look at his web pages
http://g4hup.com email [email protected]
Alan
G3NYK
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