[Elecraft] Icom 7100 and KAT500/KPA500 PTT issues

[kb2m at comcast.net]

The 4-wire AH4 connection doesn't PTT key the amp. It has 12v, ground, Start, which is a signal from the Icom to the tuner that is asserted when you press the Icom tune button, and ah4 key, which is asserted by the tuner when it needs a tune level signal from the Icom.  The amp needs a separate PTT key line from the Icom RCA connector to the kat500, and another RCA cable from kat500 to amp.  The AH4 Key line is distinct from exciter to amp PTT and although both have key in their names, they have different purposes.

One of our diagrams in the owners manual may have omitted the RCA keying cables. A manual revision is in the works. 

73 de Dick, K6KR


 Thanks for the info Dick. The  use of the word KEY in the Icom description of pin 1 was confusing me. Your explanation makes this much clearer now. I also got a reply on this offlist and was told they got their 7100 KAP500/KAT500 setup working with the interface explained in the IC-7100 advanced instruction manual page 2-11. In addition to wiring the PTT OUT circuit, you also must configure H-SEND in the SET CONNECTIONS menu (page 17-26). Also found on page 19-11 is a simple mod to output the band information. I'm not sure how this would be used with the Elecraft pair without building another cable. We will look into this later, unless someone has tried already. 
 So I think we can say the Icom transcerivers with AH-4 ATU interface description on page 8, and figure 3 in the the KAT500 tuner manual would be in error if all Icom AH-4 interfaces are the same ?     

73 Jeff kb2m