Topband: Switching Beverages

[Lee K7TJR]

   Pete, here is my take on switching Beverages, It is a lot harder to make
 a switch with very good isolation at 500 ohms than it is at 50 or 75 ohms.
 You need very good isolation between connections so that your 20 to 30
 dB notches are not destroyed by leakage from another antenna. What you
 save on transformers will surely be spent on doubling up relays to get
 decent isolation.
    If you consider a relay with a few pf of feedthru capacitance, it will have
 a certain reactance at the operating frequency. This reactance will form a
 voltage divider with the switched impedance. If it is 500 ohms there will be
 a lot more feed through than if it was 50 or 75 ohms. 
   What ever you do for switching, think it through and make sure you
 consider the isolation between antennas. Keep looking as there are some
 that have solved this problem before.
My 2 cents worth.
Lee  K7TJR