[Amps] Yaesu FT-2000 "TX-INH" Spec?

[Bill Putney]

Has anyone cracked this nut yet? I'm doing a mod to my Henry 2KD-4 to 
replace the open frame T-R relay with Gigavac relays. I'm using the 
SEQ-QSK sequencer to drive the relays. I want to use the "TX-INH" 
(transmit inhibit) line into my FT-2000 to keep it from sending power to 
the Henry while the relays are in motion.

The "TX-INH" line is on pin 8 of the "Band Data" plug on the FT-2000 and 
is intended for use with Yaesu's amps. Trouble is there isn't a spec for 
that line I can find. So I looked in the VL-1000 service manual to see 
what Yaesu does with it. Now I'm even more confused. The lead starts out 
life as an open collector pulled up to +13.8V with a 10K resistor on the 
"Main" board. It then goes on to a connector board where it is diode 
clamped to between +5 and 0 after a 1K resistor. I've seen other 
references online to it being +13V to inhibit transmit and 0 enable 
transmit. That seems at odds with it being clamped to the +5 and gnd 
rails in Yaesu's amp.

Any thoughts?

Thanks, Bill - WB6RFW