[Elecraft] Transmit Inhibit

[Clay Autery]

I'm going to use ACC Pin #7 as Transmit Inhibit (High), and the manual 
says this:

"TX INH (Transmit Inhibit Signal)
Pin 7 of the ACC connector can be configured as a
transmit inhibit input by setting CONFIG:TX INH
to LO=Inh (or HI=Inh). Holding pin 7 low (or
high) will then prevent transmit. An external 2.2 to
10 K pull-up resistor (to 5 VDC) is required.
If TX INH is set to OFF, pin 7 reverts to its
default output function, K3S ON (see above)."

This has confused me a bit...  I'm not an electronic expert. The input 
signal is 12 vdc, present all the time EXCEPT when the K3s keys up... 
the amp gets that message and drops the signal to ) vdc...  Not sure how 
to pull off reducing the input from 12 to 5vdc with a single external 
resistor.
I DO know how to do it with a voltage divider....  Vout = Vin x 
R2/(R1+R2)  Calculate resistor values, tie them together at one end and 
that end connects to Pin #7 at K3s end.  R1's other end ties to the (+) 
signal in from amp, and R2's other end ties to the ground (conductor on 
Pin #5).

Is there a simpler way to do this with a single resistor?  Am I missing 
something?

And am I in fact reading the manual correctly?  The K3 expects a TTL 
logic level + 5 vdc on Pin #7 to activate inhibit with TX Inh set to 
"high"?  A straight 12vdc exceeds the spec for that pin as an input?  
(When it's used as the K3s ON output to XVERTER, it OUTPUTS +5 VDC)

I'm trying to get this custom cable built for this amp this weekend....  
I'd appreciate a little help here.  I don't want to let the smoke out of 
anything....

73,

-- 
______________________
Clay Autery, KY5G
(318) 518-1389