Transmit-receive switches

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Posts: 55
Joined: Mon Aug 28, 2017 9:33 pm

Transmit-receive switches

Post by franko » Mon Jan 14, 2019 8:44 pm

The adjacent thread "MFJ-1708B-T/R Switch Experiences" reminded me of a question I wanted to ask, but I thought it might be clearest to post a new thread rather than tag on to that one.

Currently I have two SDRplay RSPduo units running continuously, each attached to its own magnetic loop antenna. I'd like to set up a T/R switch arrangement so that both RSPduo's are disconnected from their antennas when I transmit via my Icom IC-7300 (which has its own separate antenna).

One way to do this would be to obtain two MFJ-170B T/R switches, and connect each to one of the RSPduo's. Hopefully the IC-7300's PTT send-control signal out won't have any problem triggering both switches.

Before I proceed with this, does anyone have any suggestions for other ways to accomplish this? Are there any commercial T/R switches out there that can handle two antennas that connect to two separate receivers at the same time?

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Posts: 140
Joined: Sat Dec 29, 2018 1:07 pm

Re: Transmit-receive switches

Post by ON5HB » Tue Jan 15, 2019 3:17 pm

If it's just a 7300 and using it's own antenna, why not connect a NoElec upconverter between them?
It will give extra protection.

The switch, I ordered the B version only helps if you want to use the same RX/TX antenna.

If your TX antenna is a few meters away and the output is just 100W, nothing will happen.
I use 1KW near mine, however the TX antenna isn't in direct line with the RX antenna, they are 90 degrees angled.

But if I connect the RSP1A with NoElec to a miniwhip, 8 meters away, the waterfall is overloaded, else nothing happens.
Don't forget the level of the field drops rapidly after a few meters.

Mine work fine when making 1KW, no problem at all. As said, I added an NoElec as it has extra protection against ESD and other high levels .

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