Using the Elecraft KPA-500 and KAT-500 with Icom Rigs: Part I

I now have the Elecraft KAT-500 Antenna Tuner and the KPA-500 Linear Amplifier. My rigs are not Elecraft, but Icom (7600 and 7300) and Yaesu (FTDX-3000). I want to setup the Station to use the Elecraft components with my non-Elecraft transceivers. Since the KAT-500 has connections for the Icom AH-4 antenna control interface, I will use the Icom rigs, at least initially.

Reading the Elecraft documentation, they clearly state that the “power combo” (KAT/KPA-500) is made to work with any Transceivers. Unfortunately, I found that the various manuals and application notes give different views of what should be connected. I have been sorting through all of these documents, and I think I am getting close to a solution that will work. I have also received some very helpful hints from some other Hams who have used their Icom rigs with this Power suite, including K4TAX (Bob) who provided not only some hints but also the schematics for the Elecraft components. YES, schematics are available, even though Elecraft does not provide them with their manuals.

Apparently the main requirements for using these components together successfully are:

1. The KAT-500 must be connected to the PA KEY input line on the KPA-500, so the Tuner can disable the Amp when the antenna is not Tuned well enough for safe operation
2. The Transmitter must supply a KEY LINE that goes to GROUND when transmitting
3. The KAT-500 and the KPA-500 Settings must be adjusted for them to work together. Fortunately that appears to be very easy.

This all sounds very simple, but upon reading all of the relevant documents, it somehow becomes very confusing. I am confident that the Tuner will protect the Amp, so I plan to go ahead and give this a try. Here are some of the things that caused confusion for me:

1. The KPA-500 manual wiring diagrams do address using Icom radios, but they apparently apply to using ONLY the Amp and not the KAT-500 Tuner. There are some very helpful diagrams in the KAT-500 manual, that address using non-Elecraft rigs with both the KAT-500 and the KPA-500.
2. There are two phono-type (RCA) connectors on the rear panel of the KAT-500 that appear to be used for the KEY Line interface. One is Red and the other is White. The only label is below the White one and it says “PTT RLY” – not very helpful
3. There are some Elecraft App Notes for using the KAT/KPA-500 with Icom rigs, but they are not consistent in how they should be interconnected. For example, the IC-7610 document shows no connection for the AH-4 Antenna Tuner connector. The IC-7300 App note shows the use of the AH-4 connector
4. While the manuals speak about using the ACC connector (DIN) on the IC-7600 to access a PTT line, there is also a SEND connection that uses a phono-type connector on the rear of both Radios. It appears that they provide the same signal as the PTT signal on the ACC connector. It is hard to imagine anyone making a cable for a DIN connector when they could just use a cable with a phono plug on each end.

My plan for now is to use the IC-7300 or the IC-7600 with the AH-4 Tuner interface connected to the KAT-500 and using only the phono (RCA) connector for the SEND/PTT/KEY interface. I will provide an update as soon as I get a chance to try this.

Merry Christmas