Switching Transmit/Receive Antennas

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by VE7PJR, Jan 13, 2018.

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  1. VE7PJR

    VE7PJR Ham Member QRZ Page

    I need somebody to tell me what I'm looking for! I have an IC-7200. Great rig; love it. But it only has one antenna port.

    What I want to know is: is there some automatic antenna switch or T/R switch that can switch between transmit and receive antennas? I'd like to experiment with LoG receive antennas for MF, but that means I'll have to add some box that can do the switching outside the rig and just use the one port on the rig.

    I need to know what it's called so I have keywords to search with. If there are several options, that'd be good to know. Even names of manufacturers who make one is useful.

    I imagine it would connect the receive antenna by default, then switch when it sensed TX RF coming up the line. (or could be over-ridden if the receive antenna wasn't needed on a higher band.) I operate CW only, and appreciate full break-in.

    Thanks for any and all help!

    73,

    Chuck VE7PJR
     
  2. K7TRF

    K7TRF Premium Subscriber QRZ Page

    NH7RO likes this.
  3. WA7ARK

    WA7ARK Ham Member QRZ Page

    I just built my own. An automotive sugar-cube relay (C0m, No, Nc contacts, 12Vdc coil) with a 1n4007 snubber diode wired across the relay coil, keyed by the rig. My IC7300 has an internal keying circuit which pulls to ground on Tx, with sufficient rating to switch the relay directly.

    One end of the relay coil and the cathode of the snubber diode go to a source of +12V. The anode and other end of the coil go to the RCA keying jack on the back of the rig.

    The Com terminal goes to the rig's SO239 (thru a short piece of RG-58). The Nc contact goes to the receive antenna (thru RG-58) and the No contact to the transmit antenna... The relay just switches the center-conductor of the RG58. The coax shields are soldered together close to the relay.

    Relay like this. Solder direct to the tabs; do not use a socket.
     
    Last edited: Jan 14, 2018
  4. VE7PJR

    VE7PJR Ham Member QRZ Page

    Thank you! I had been all through the Antenna Book 18th ed. and didn't see anything like it.

    I also found this one after I looked around a little:

    https://www.mfjenterprises.com/Product.php?productid=MFJ-1707

    Now that I know WHAT I need, I can think about which one...

    I'm likin' the simplicity of that homebrew design! I just knew there had to be something that did what I want.

    73,

    Chuck VE7PJR
     

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