[TowerTalk] Remote RF coax switch utilizing DC on coax

[Jim Lux]

Another approach (which might be useful for remote bandswitching using the
stepped voltage output of radios like the FT-817) is to use a LED bargraph
chips  (LM3914?) to measure the voltage, rather than a stack of comparators.
Tie the relay control to one or more of the LED outputs of the chip.

----- Original Message -----
From: "Rick Karlquist" <richard at karlquist.com>
To: <towertalk at contesting.com>
Sent: Friday, January 21, 2005 5:58 PM
Subject: [TowerTalk] Remote RF coax switch utilizing DC on coax


> Several people have asked about my beverage switching scheme.
> I send a different DC voltage down the coax for each antenna
> and have a circuit at the end that detects the different
> voltages with comparators and activates an RF relay to select
> an antenna.  I have posted an article about it at:
>
> http://www.n6rk.com/Comparator_RF_switch.pdf
>
> Rick N6RK
>
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