• Effective immediately we will be deleting, without notice, any negative threads or posts that deal with the use of encryption and streaming of scanner audio.

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    https://forums.radioreference.com/rants/224104-official-thread-live-audio-feeds-scanners-wait-encryption.html

RF protection for scanner

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LTW

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Hope someone here has a suggestion for this potential problem.
Looking for a way to protect my receivers from RF overload. My transmit antennas are only about 2-3 feet from my scanner receiver antenna. I’m concerned that transmitting 50watts of power so close to my scanner antenna that I may overload the front end of the scanners and damage them. Some way to automatically ground or short out the scanner antenna when going to transmit would be the best vs. having to remember to manually operate a switch would be best I think.
Thanks
 

jim202

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Mar 7, 2002
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2,550
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New Orleans region
Hope someone here has a suggestion for this potential problem.
Looking for a way to protect my receivers from RF overload. My transmit antennas are only about 2-3 feet from my scanner receiver antenna. I’m concerned that transmitting 50watts of power so close to my scanner antenna that I may overload the front end of the scanners and damage them. Some way to automatically ground or short out the scanner antenna when going to transmit would be the best vs. having to remember to manually operate a switch would be best I think.
Thanks

When faced with this kind of situation, I always add a pair of hot carrier diodes back to back to ground from the input through a 47, 56 or 62 ohm resistor for current limiting. Find the circuit land coming from the input. Cut it and add the resistor. On the radio side of the resistor, put the hot carrier diodes back to back to ground. Make sure that your not on a line with a DC voltage on it. generally there will be a coupling cap going to the first RF amp.

When I say back to back, you hook the diodes with the cathode of one going to the anode of the other. This way it doesn't matter if it's a positive or negative voltage. Either way, it will be shunted to ground.

Have had to do this to a number of commercial public safety radios that have had damage to the front end pre amps.
 
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wa1nic

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Westfield, Ma
I blew out what I believe is a T/R switching diode on an Alinco DR130 last night.

It's a new installation in my new pickup... 5 feet away from the 2 meter antenna is a VHF High band antenna connected to a 50 watt commercial ICOM radio. I tuned the Commercial radio antenna last night and then I noticed that I could no longer transmit on the Alinco 2 meter radio.

Live and learn.

One probably wants to be careful who you park next to for that matter. If there is a transmitting sort of antenna on a car/truck in a parking lot, find a safe place a few spots away to park.

Rick
 
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