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? on sharing an antenna between a low-power xmiter and receiver

Am just realizing that this is something I need to figure out, and have never thought about it before. Would a simple SPDT relay do the trick (switching the current path from one side to the other...)? Where could I find info on this topic. Not even sure what to type into Google. Guess I'll check my ARRL handbook, and see if it offers anything. Any advice would be appreciated.

Thanks,

Dave

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Dave
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That's commonly done in transceivers, even some that are in the hundreds of watts. There may also be a set of relay contacts that grounds the receiver input when the transmitter is on and/or there may be some protective device(s) on the receiver input..

  1. How much power is "low power"?

  1. Is the receiver solid state or tubes? (Tubes can take a lot more abuse than solid state devices.)

Reply to
news

I'm thinking "low power" along the order of 10mW or so. Maybe less than that.

Receiver is solid state.

Seems like I should be able to switch the antenna from RX to TX and back by turning transistors on and off. Just never put my mind to it before...

Thanks.

Dave

Reply to
Dave

Here's how to use a relay to switch your antenna between the transmitter and receiver. Please view in a fixed-width font such as Courier.

# # # Antenna # # # # ###|### | | o----------------Rcvr | / | / -----------------/ |

| o----------------Xmtr

| | | +--+ | |-----------+V | | Relay | | | | | |----------PTT +--|

Use this configuration if your PTT provides a switched ground. If PTT provides a + voltage, then change the +V on the relay to ground.

--
Dave M
A woman has the last word in any argument. Anything a man says after
that is the beginning of a new argument.
Reply to
Dave M

Thanks for this, but I have to ask, what is PTT, and what is a switched ground? And how will I know if PTT provides a + voltage? Sorry to be so ignorant, but I just don't savvy even this much about radios and RF. My currant project is to build an in-house intercom using simple low-power FM transmitters to communicate from one end of the house to the other, cutting down on the need for shouting. They will be battery powered, backed up by AC adapters to give the batteries a rest when the hand-held unit is in its cradle. No switch-mode power supplies, if that matters.

Thanks for the help.

Dave

Reply to
Dave

PTT is the Push-To-Talk button.

"Switched ground" means that the PTT switch is connected between Ground and the thing being controlled.

--
Peter Bennett, VE7CEI  
peterbb (at) telus.net
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca
Reply to
Peter Bennett

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