[SOC] Antenna matching

[Paul Bartlett]

Hi All,

Here's a proper radio question.

I'm still learning about this so apologies for any gaffs.

I have an Elecraft K2 (with which I'm extremely happy) running into a full
size G5RV.

The G5RV consists of a horizontal dipole with an impedance matching ladder
line dropped from the centre.

It currently terminates in a BNC connector and thence to a length of 50 ohm
co-ax to the transceiver.

It works tolerably well on 40 but is hopeless on other bands.

I'm uncomfortable about going from the unbalanced co-ax straight into the
ladder line without a balun though it's more intuition than having done the
sums.

I'm mean and impecunious so I want to use what I have to hand. I have an
ex-military ATU built by Redifon. This takes a 50 ohm unbalanced co-ax feed
and matches to an arbitrary dipole. BNC connector on the front, two
terminals on the back for the antennae and a further terminal for a ground
stake.

Of course the best place for the ATU would be at the base of the antenna but
this is impracticable so the ATU must reside in the shack.

I'm only using 10W so I want as much of the transmitter power to be coupled
to the antenna and waste as little as possible in the feeds.

My guess at the moment is that what I need to do is to connect the 50 ohm
output of theK2 into the ATU, take the ATU outputs and feed into a balun to
drive the coax feed and then have a further balun at the base of the G5RV to
match to the antenna.

Does this sound sensible or am I completely barmy?

Paul M3CRQ