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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Tue 06, 2018 1:26 am 
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Location: Tucson, Arizona U.S.A.
azenithnut wrote:
After all is said and done, why the hesitancy to just connect an antenna and tune around?

This is, after all, how I found out what was on different bands. This is indeed the fun part! :D

-Steve

And don't give up. These kinds of uses are intermittent and can be on the air only a few minutes a day.

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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Tue 06, 2018 3:11 am 
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Joined: Jun Sun 03, 2012 12:40 am
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Location: Cromwell, Connecticut
In the Middletown area, listen to 48.16 for county fire dispatches. Tune in 48.16 and you will have Eversource's Line dispatch channel for the East Hamton district that covers your town. It's a multicast repeater system that I setup about 7 years ago.
We still use Low Band as its called for our statewide systems. Hopefully we will soon be off the band. The noise floor is horrendous and no one makes a base station any more.

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Tony

People may not remember how fast you did a job, but they will remember how well you did it.


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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Tue 06, 2018 12:40 pm 
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Joined: Mar Sun 20, 2011 2:53 pm
Posts: 759
Location: Spain - 28110 - Algete
on each country the frecuencys are used for differents purposse.

30 to 50 MHz are a very low VHF band for private bussines, they was used also for small house´s phones, wireless microphones, remothe controls, and in-door , out-door paging systems. Also on video recorder´s RF modulators.


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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Tue 06, 2018 9:08 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3536
Location: Monterey California USA
This topic comes up aboput every 8 months, as in "What is there still on low band?"

In California the highway patrol has greatly expanded use of these frequencies and added 35 MHz and 43-45 MHz channels to their traditional line-up of 42 MHz frequencies. These are all still analog and standard 5 kHz deviation.
The officer-carried portables are 700 MHz digital P25 which talk back to a crossband repeater in the cars which runs the low band radio, a Rockwell Collins arrangement of assorted mobile radios all tied to a touch-screen display on the car dash area. Kenwood still makes low band mobiles. I am not sure what is going on with the base stations other than a lot of older stuff is still in use. When you are buying stuff in the quantity that California does you can get manufacturers to make you whatever you want.

There was no mandate to change from low band on the part of any government agency. Many police and state patrol systems moved to 700/800 MHz digital because there was grant money for that (and only for that.) Many have since regretted it.

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WB6NVH
California Highway Patrol Radio
Bell System Mobile Telephone History
http://www.wb6nvh.com


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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Wed 07, 2018 12:40 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 704
Location: Walden, NY USA
I remember during the early 1980's hearing LAPD here in NY on low band! I could only hear the dispatch side of the conversation and a beep beep beep beep as mobile units talked back. I enjoyed listening as they are extremely professional.

When I was in charge of the communications in my PD when we were on low band, we tried the uhf/ low band setup in a few cars .. The officers did not like it because it required them to throw a switch when leaving the car, to activate the cross over, something they thought they would forget in an emergency. I believe the units to accomplish this were made by a company called Pyramid.

We had difficulty copying the 100 watt mobiles from some areas even 5 miles away, due to all of the electronic noise on the band. Our frequency was 37.04 Mhz. Part of that problem was that we were simplex and our receive antenna was a 150 foot tower at headquarters.

When we left for high band repeaters in 1986, no one mourned!
Mike

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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Wed 07, 2018 12:52 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Walden, NY USA
Geoff Fors wrote:
This topic comes up aboput every 8 months, as in "What is there still on low band?"

In California the highway patrol has greatly expanded use of these frequencies and added 35 MHz and 43-45 MHz channels to their traditional line-up of 42 MHz frequencies. These are all still analog and standard 5 kHz deviation.
The officer-carried portables are 700 MHz digital P25 which talk back to a crossband repeater in the cars which runs the low band radio, a Rockwell Collins arrangement of assorted mobile radios all tied to a touch-screen display on the car dash area. Kenwood still makes low band mobiles. I am not sure what is going on with the base stations other than a lot of older stuff is still in use. When you are buying stuff in the quantity that California does you can get manufacturers to make you whatever you want.

There was no mandate to change from low band on the part of any government agency. Many police and state patrol systems moved to 700/800 MHz digital because there was grant money for that (and only for that.) Many have since regretted it.



Geoff...I absolutely enjoy you're well done website. I learned alot about the early LAPD systems and equipment history. We were all GE at my PD, and the history is fascinating.

After the war, I was told by one of the oldtimers that both GE and Motorola came out and set up High Band and Low band systems for the county to try. They went with Low Band. It replaced their original AM system made by Fred Link on 31.11 Mcs.!

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W2MDM
http://mikesradiosandstuff.weebly.com/index.html


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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Wed 07, 2018 3:35 am 
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Joined: Jun Sun 03, 2012 12:40 am
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Location: Cromwell, Connecticut
We use mostly Kenwood TK 6110 mobiles as they cover our 37-49 split. We still have some old GE matching boxes that made a 1/4 wave ball and spring work on the whole split. Pyramid makes a nice repeater too. Unfortunately some vehicles don’t lend themselves to having enough room to mount them.

Codan/Daniels made the last low band bases until they stopped making them.

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Tony

People may not remember how fast you did a job, but they will remember how well you did it.


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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Wed 07, 2018 6:11 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3536
Location: Monterey California USA
The rear of the CHP SUV's is stuffed solid with radio and emergency gear. I hear people referring to the "prisoner cage" in these vehicles. That is what it is sold as, but what it is used for here, is to keep all that junk from coming forward in a collision and killing the driver and any passengers.

The cost of implementing a 700 MHz digital system was astronomical for a state this size, hence the decision to expand low band. The 700 MHz systems are being built out gradually but low band will be here for some time. If we ever have a sunspot cycle again it will be interesting to see who is left on low band in our hemisphere.

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WB6NVH
California Highway Patrol Radio
Bell System Mobile Telephone History
http://www.wb6nvh.com


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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Wed 07, 2018 2:26 pm 
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Joined: Jun Sun 03, 2012 12:40 am
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Location: Cromwell, Connecticut
I used to listen to CHP on 42.12 and others in the late 80’s and early 90’s during that peak. Pretty cool. There were times when I could hear the mobile radios too.
We used to use GE S825/830 control heads with Ranger radios back in the90’s. If i recall, that control head was developed for CHP motorcycles.

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Tony

People may not remember how fast you did a job, but they will remember how well you did it.


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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Thu 08, 2018 10:13 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3536
Location: Monterey California USA
The CHP heads were the original prototype and were S810 (cars) and S815 (motorcycle.) Many are still in use while the touch screen system is phased in for the cars and most are still in use on the motorcycles. The S820 (motorcycle or limited features) and S825 + S830 (car, full featured) heads are the standard versions and far more useful as it turns out.

The major issue recently has been getting a loaded rooftop mobile antenna with good VSWR that can function from 39-46 MHz. That and making a motorcycle radio function when there are few steel parts to act as a ground plane anymore for an antenna. Most frames now being made of graphite composites, such as the now no-bid Kawasaki.

There used to be a plumbing contractor in my town here on the central California coast that had a simplex 31 MHz 30 Watt business radio system in his trucks. Back around 1988 when the skip was decent I noticed that his frequency was listed in an Australian scanner guide with the notation "American plumbing company, exact location unknown."

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WB6NVH
California Highway Patrol Radio
Bell System Mobile Telephone History
http://www.wb6nvh.com


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