Discone Ant

[rufust]

Hello
Is there a way to run a scanner and radio off of a common discone antenna without frying the scanner ? It would probably only be a hand held for now.
Thanks

 

[ka3aaa]

nope dont even try if they are both hooked at the same time.

 

[popnokick]

There is a way: When you are listening to the scanner plug in the antenna cable from the discone to the scanner. When you are planning to transmit, UNPLUG the antenna from the scanner and connect it to the hand held transmitter. Or use an A-B switch to select the SINGLE device that is connected to the antenna. It's possible to use a diplexer to have both connected, but that would very narrowly limit the frequency range of the discone. Do not use a coaxial "T" connector... practically guaranteed to fry your scanner. Here's a related thread
Popular options for dual purposing scanner receive and VHF/UHF transmit?

 

[mrweather]

Side question: is the isolation sufficient on a A-B switch to prevent damage to the scanner?

 

[popnokick]

Depends on the switch, but most manual switches provide isolation in the 60-7dB range at 1KW. You can spend more and get more... and there are auto-sensing switches as well.

 

[vagrant]

A proper switch is a fine solution for your use case. In addition to that you could place a limiter inline between the switch and your scanner. For example, an HP 5086-7284 limiter will also work to protect your scanner/receiver. Some may say overkill. Others may say it is inexpensive insurance for a $$$ receiver. A member here with professional radio experience alerted me to these fine solutions, but I am not using a switch.

I transmit on HF, VHF and UHF. I also have RX only antennas for receivers that would not be fun to unplug each time I TX. While I space my antennas to eliminate problems, I also use these HP limiters at home as well as in my vehicle.