GWS charger question(s)

Just bought a GWS MC 2002 field charger and would like some advice please. I've fitted 2 leads to it, one with a normal battery plug and
another with the transmitter plug on - both Futaba. When I plug a rx battery in it works fine. Do you set the dial so that it sits on the upper edge of the green area to charge the battery?
When I use the Tx plug, having changed from the cell switch, nothing seems to happen except the indicator needle swing back and forth. If I disconnect the Tx then it still does the same. Remove the Tx battery and plug it in the normal Futaba battery plug and it appears to charge it fine, again setting the dial to sit at the top end of the green area.
With both Tx and Rx batteries, after it's charged it drops to trickle as expected. Are Futaba Tx sockets wired differently such that this thing can't charge without removing the battery?
Hope all this makes sense to someone and I would really appreciate advice as to where to set the charge needle.
TIA
cheers, Len
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Len Cuff wrote:

Some transmitters have diodes between the plug and the battery to prevent shorting out the plug with a bad charger. If the GWS is the kind of peak-detect charger that turns off the charge current to check the battery charge level the diode will confuse the snot out of the poor charger.
That's all I know...
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Tim Wescott
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