43 Foot Vertical and Coax Switches

Furthering the discussion of the 43 foot vertical antenna I wanted to report a concern I have with this antenna and the use of any relay based coax switch.

If you install a 43 foot vertical in your back yard, route the coax through a switch and handle the tuning inside your ham shack, you need to ensure you do not exceed the voltage or current limits of the relays in the switch.

This issue comes from the expected high SWR on the coax. When there is high SWR on any transmission line you will have points along the line that may be high current or high voltage. Either could exceed the limit of the relay.

The good folks at DX Engineering confirmed my 8 port switch I purchased from them can handle an SWR of about 2:1 at full power. Everything else being the same this limit will climb as power is reduced.

The point is if you are using the tuner in your shack to load up the 43 foot vertical along with its transmission line, that transmission line has high standing waves on it which will cause trouble for anything in its path… like a switch box.

If you insist on tuning the 43 foot antenna in your shack you are well advised to connect it straight to your matcher.

If you are using a switch, as I am, that is in the RF path for the 43 foot vertical, you should seriously consider placing a tuner at the base of the antenna to avoid the high SWR issues on the coax.

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