[Elecraft] KAT500 Band Data Input Question

[Randy Farmer]

Thanks to all who provided the helpful information that completely 
answers my question, both on- and off- list. The crucial information I 
needed is contained in the second paragraph of Dick's reply. It seemed 
logical that the KAT500 would switch bands based only on the information 
provided by the band code lines, but that is nowhere stated in the 
manual or in any other source I could find. It would be helpful if the 
manual stated this explicitly and even showed it as a valid setup 
configuration for using the tuner with Yaesu radios or others that can 
provide the band code directly. Dick's verbiage, with slight 
modification, would be fine.

My setup will feed the KAT500 RF input from one antenna port of my 
microHAM Double Ten antenna switch. I intend to use the tuner for two 
separate antennas. Antenna 1 will be connected to my 80 meter Inverted 
L, which also doubles as a second radio antenna that can be tuned to 
different bands if required. Antenna 2 will be connected to my 160 meter 
Inverted L, which is pretty narrowband and needs a "line flattener" to 
make it useful across the entire band. I'll set the tuner up to select 
Antenna 1 for all bands except 160m and Antenna 2 for 160 only using the 
KAT500 Utility.

I realize that the KAT500 can automatically select the correct antenna 
and tuning solution when RF at a particular frequency is applied, but my 
concern with using the RF sensing bandswitching only is the possibility 
of hot switching the antenna selector in the KPA500 when I QSY from 160 
to 80 or vice versa. I will be using the key line interrupter to the 
KPA500 on the primary station, but I'd rather have the tuner select the 
proper antenna prior to transmission so that I'm at least on the correct 
antenna before I transmit. Coming up with the tuning solution used for 
the last known frequency on each band shouldn't be a big problem. In 
order to give the tuner a "heads up" before RF shows up at the input 
I'll send it a BCD band code. I have band data available for each radio 
available at the Accessory port of my microHAM MK2R+. I'll build up a 
simple 4-bit multiplexer with simple lockout logic to steer the 
appropriate band code lines to the KAT500.

As for the KPA500, I simply misremembered my experience. I looked at my 
notes from when I first set up the amp and saw that I had at first been 
trying to use the AUXBUS alone, and that of course won't work. There's 
nothing in the KPA500 manual that says that, either. Both the KPA500 and 
KAT500 manuals would benefit from having an explanatory paragraph 
explaining exactly what information is carried on the AUXBUS and how it 
interacts with the band select lines. I also ordered a copy of the KE7X 
KPA500/KAT500 book when I bought the tuner; maybe he explains these 
nuances clearly.

Again, thanks to all who helped answer my question. Now I'm awaiting 
arrival of the KAT500 kit so I can start setting things up. See you in 
the contests and in the pileups.

73...
Randy, W8FN