Thankyou Johan, Rik, Stewart, Alan, Dave, Alex and others, for giving me
your thoughts.

I like Dave's "quick and dirty" way, which is basically what started out by
doing, except that I relied on the rig's power meter to give me 50W which,
using I squared R, gives 1 Amp.

I'm using a pair of ferrites from a TV scan coil yoke, so I can clamp them
round any conductor that needs measuring. I compared the readings on the
160m and 80m bands, but found that I got different readings on the two
bands. The reading was less on 80m - indicating some loss. A coil wound on a
nice RF ferrite toroid gave the same readings at both frequencies. I expect
the scan coil ferrites would be ok at 136kHz, but it didn't inspire
confidence in my calibration technique.

It is really a case of pulling myself up by the bootstraps, because the TX
is an unknown quantity at the moment, so it looks like I need to press on
with that to get a good source of current, to test the meter, that I wanted
to test the TX amp with !

You're right, Alan, I'll just be looking for changes (increases) to start
with - so I can worry about fine tuning it later. Think I'll borrow a scope
from work and then I can do the job properly.

Thanks once again.
73
Hugh M0WYE.