[Elecraft] Interesting observations after installing antenna switch

[Jim Brown]

On 8/29/2023 11:58 AM, ken.kj9b at gmail.com wrote:
> The designer of the switch says that each band data channel only draws
> around 4 mA, with each channel buffered by a transistor switch in an attempt
> to isolate the band data voltage from the radio.  In my working days in the
> entertainment industry, I would use a distribution amp to give me multiple
> audio outputs when needed.  Is there such a "distribution amp" available for
> the band data signals?  Would the Elecraft KRC2 accomplish this?

There are multiple formats for band data. I suspect that the one used by 
your switch is one that is not compatible with Elecraft's. It's been a 
while since I worked with the KRC2 that's in W6GJB's contesting trailer, 
but I think I remember that it can be set for all of the common band 
data formats. I suggest studying the manual for the KRC2 -- most if not 
all Elecraft manuals are on their website.

Your KPA500 is probably throwing an alarm because it's not being 
band-switched. However -- I've never sent band data to my Elecraft amps 
or tuners -- all it takes is a single dit or tap on the mic for them to 
detect frequency and switch on their own.

I don't see mention of a tuner, so I suspect all of your antennas are 
reasonably matched to coax. If not, remember that any transmission line 
transforms any mismatched load to some different complex impedance (that 
is, resistance and reactance), depending on its length. So if line 
lengths changed as a result of the switch, it could change that 
impedance, and some impedances with the same VSWR look different to the 
transmitter than others.

73, Jim K9YC