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General Radio Discussion / Re: 49 MHz Range Testing Part 15 Experimentation
« on: September 29, 2019, 2213 UTC »
An old trick that was done in the past was to monitor your "special" unlicensed frequency with PL turned on while you waited for a call. Then when you received a call you'd turn off the receive PL so you can hear all channel activity to make sure you weren't interfering with a legit user. Most older portables had this feature right on the top of the radio.
Actually FCC rules requires you monitor a freq before transmitting to avoid just that. When you picked up a mobile microphone in the old days it would no longer be grounded to the metal car dashboard where your mic hang up clip was mounted. More recently, most land mobile radios had mic hang up clips with a wire attached to sense the mic off hook since vehicle interiors are plastic now. This would open the receiver so that you no longer had receive PL. This made sure you weren't interfering with a co-channel user. Base stations had a monitor key on the mic that you pressed first to listen to channel activity before calling. This was necessary when many licensees shared one freq but had different PL tones.
I have rarely seen this in the last decade or two. Frequencies are coordinated now and fewer are shared with nearby co-channel users.
The MT1000 can be made into a nice little base station with a vehicular Converta-Com that will bring the antenna out to a UHF connector as well as power the radio off 12 volts. Might be good to have the base station connected to a big antenna to increase its range if needed. Handy if the 49 MHz portables get out of range of each other.
Actually FCC rules requires you monitor a freq before transmitting to avoid just that. When you picked up a mobile microphone in the old days it would no longer be grounded to the metal car dashboard where your mic hang up clip was mounted. More recently, most land mobile radios had mic hang up clips with a wire attached to sense the mic off hook since vehicle interiors are plastic now. This would open the receiver so that you no longer had receive PL. This made sure you weren't interfering with a co-channel user. Base stations had a monitor key on the mic that you pressed first to listen to channel activity before calling. This was necessary when many licensees shared one freq but had different PL tones.
I have rarely seen this in the last decade or two. Frequencies are coordinated now and fewer are shared with nearby co-channel users.
The MT1000 can be made into a nice little base station with a vehicular Converta-Com that will bring the antenna out to a UHF connector as well as power the radio off 12 volts. Might be good to have the base station connected to a big antenna to increase its range if needed. Handy if the 49 MHz portables get out of range of each other.
