Hi Charlie
I have a new, probably never used, BC-442-A Relay unit.
I measure 5 mA FS meter deflection with an internal meter resistance of 0.033 ohms.
These were measured by the usual means of a series resistance to give FS deflection then a shunt to give half-scale deflection.
Across the meter leads of the thermocouple, I measure 1 ohm (meter disconnected).
Across the other leads I measure about 0.7 ohms (wires also disconnected).
There lead resistances were subtracted out to give the above two measurements.
Remember, the meter face reads Antenna Current Indicator -- there are no units given.
As mentioned in other posts, at home I go through a 4:1 UNUN then through an air variable series capacitor (an old HT-37 cap with some rotors removed...) to get to 50 ohms to feed my home antennas.
Sometimes I see my BC-442 hit '2", other times it just budges a little, yet my wattmeter shows 40 to 50 W out. I think the current distribution depends upon what antenna you are using and the matching network.
LIke others have said, one can ignore the relay meter reading when you have a wattmeter in line further downstream.
As posted a few weeks ago, I experimented with a 45 foot random wire antenna as that is what the B-24 used, but I did not have a counterpoise (I didn't think about the fuselage being the counterpoise.....).
I plan to recreate that later this month with an insulated counterpoise and see if that has any impact on the relay meter movement.
I hope this helps.
73 Mark K3MSB