[mythtv-users] OT: Addressable Antenna Switch

[Brian Wood]

On Monday 07 September 2009 15:16:12 Richard Woelk wrote:

>
> I work with RF in two-way radios. Often, the older radios had a relay to
> switch the transmitter or receiver to the antenna.
> A simple single-pole-double-throw relay will work, tie all the grounds
> together and hook the centers to the relay.
> You can then control this with an output of the parallel port.
> you'll want to make sure the project box is metal, and keep the stripped
> coax as short as possible.

Works as long as the wires are VERY short, somewhat dependant on the operating 
frequency though. Radios usually operate on a single frequency or a small 
range of frequencies, so keeping things flat over a wide range is not as 
important as it is with TV antennas, especially UHF or VHF/UHF combos.

Dow-Key makes coaxial relays that maintain shielding and the correct impedance

http://www.dowkey.com/product_search.php?pf=1#

-- 
Brian Wood
beww at beww.org