Thanks to everyone who responded. Lee's answer seems representative of
the bulk of the mail I received. Back to coax switching!
73, Pete N4ZR
The World Contest Station Database, updated daily at www.conteststations.com
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On 2/1/2011 9:42 PM, Lee K7TJR wrote:
> 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
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
>
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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