[Elecraft] KPA1500 Enhancement

[Jim Brown]

I have one of these switches, and put it on the bench with my VNWA 
vector network analyzer before installing it. Isolation is greater than 
100 dB between radios for any combination of selected antennas, WITH ALL 
OUTPUTS UNTERMINATED, and only the two radio ports terminated by the 50 
ohm source and 50 ohm load of the VNWA.  This is a worst case condition. 
Return loss is also quite low up to 6M.

The switch offers many control options, from pulls to ground or to V+ or 
BCD to the far more sophisticated Antenna Genius controller, so it's 
sufficiently versatile that it can be used in almost any station. I'm 
controlling mine with the "pull to ground" control output of a 5B4AGN 
TXBPF filter set, which gets its input from the K3 AUX out band data. 
Which control logic for the 8x2 is selected by a DIP switch, and wiring 
is to a 15-pin DB connector.

This is an excellent switch, and by far the best I've measured. As a 
point of reference, isolation for the Array Solutions 6x2 is about -55 
dB, and return loss gets unpleasantly high above 15M. The 403A 6x2 is in 
the range of 75 dB isolation.

I haven't measured any other switches.

73, Jim K9YC

On Fri,4/28/2017 12:05 PM, Barry Baines wrote:
> I currently have the ability to remotely select my antennas for the K3 and Flex using 403A’s Antenna Genius 8x2 antenna switch (it has a LAN connection) that I can control through my network connection to the shack.  The Antenna Genius allows only one active RF input per antenna port, which provides some degree of protection to both transceivers.  Thus, I will eventually have two radios both connected to the same amplifier operating as needed and then use the Antenna Genius to determine which radio is connected to which antenna (Dummy load/KT-36/End Fed Half Wave).