Hi Jim,
thanks for the thoughts on the the puzzle.
The coil is between antenna and earth and the input simply tapped to where I
get the best balance of max antenna current with optimum amplifier output
current, voltage (and phase), which are constantly monitored and things
adjusted (including resonance) to try and match the three last to what they
are when a 4.7Ohm resistive load is substituted
The antenna current is now 2A plus or minus the accuracy of the system.
Ground system consists of a fan of heavy bare copper earth wires of
25sq.mm.at least and length about 30 ft laid on the bare earth under the
concrete foundations and subfloor of
the extension which houses the shack, joined at the apex to the original
station earth which consists of three fourfoot earth rods under the floor of
the original shack at the other end (diagonally) of the bungalow and which
are in turn bonded to all the plumbing in the house, which is all copper and
continues in copper right out to the street main (spuncast iron) and to a
disused electricity earth. Connection is made by two 10mm cables from an
outside coldwater tap to the apex of the fan, and an additional 25mm cable
runs underground from this point into the shack where it is in turn bonded
to the plumbing system and a brass plate as station earth connectiion point.
All radio equipment is earthed to this point (and also to mains earth via
the two analogue PSUs), using braiding recovered from bits of damaged co-ax.
As mentioned, the TX is grounded via various interconnections when not
actually directly connected to the station earth, and the coil is fed with
30 ft of RG213 which is taken (via current sensor and TX/RXrelay) directly
from the amplifier output. As recommended by LDO and others the input to the
amp is loaded with a 2 K of resistance.
All sounds horribly complicated and I hope not too confusing.
73
Ian
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