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CDM750 Lowband 29-36 60W 4Ch


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#1 Sasquatch

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Posted 17 November 2016 - 09:07 PM

I ran across this refurbished (CDM750 Lowband 29-36 60W 4Ch) radio that operates on the 29-36 MHz band. I have searched the internet but still can't get a clear understanding on who uses these frequencies or how one might get a licence to leagally operate this type of low band radio. Does anyone have any information?

 

Thanks!

 

https://www.used-rad...36-60w-4ch.aspx


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#2 SteveC7010

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Posted 17 November 2016 - 09:33 PM

I ran across this refurbished (CDM750 Lowband 29-36 60W 4Ch) radio that operates on the 29-36 MHz band. I have searched the internet but still can't get a clear understanding on who uses these frequencies or how one might get a licence to leagally operate this type of low band radio. Does anyone have any information?

 

Thanks!

 

https://www.used-rad...36-60w-4ch.aspx

For the most part, those would be all Part 90 licensed frequencies. Mostly business and public safety. PS is drifting away from low band at this point.


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#3 Sasquatch

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Posted 17 November 2016 - 09:45 PM

For the most part, those would be all Part 90 licensed frequencies. Mostly business and public safety. PS is drifting away from low band at this point.

Thanks!  So some where on the FCC web page a private individual could get a Part 90 licence for the 29-36 MHz band...or do you have to be a business?


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#4 SteveC7010

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Posted 17 November 2016 - 11:00 PM

Thanks! So some where on the FCC web page a private individual could get a Part 90 licence for the 29-36 MHz band...or do you have to be a business?

An individual could get a Part 90 station license, but if you look over Part 90, you'd need to justify the application to something that meets their rules. Business, government, transportation, etc. all qualify with a minimum of detail. Look through Part 90, you'll see what I mean.

All of my experience is government and related emergency services so I've never had much need prove a need for a Part 90 license. "Applicant is a government entity providing public safety services." Is plenty.

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#5 PastorGary

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Posted 18 November 2016 - 06:34 PM

I was licensed for operations on two of the Part 90 frequencies using AM - just above 'CB' and just below 31 MHZ for many years.  It was OK, but during the peak of the 11 year sunspot cycle, the frequencies were a bit noisy with other stations from all over the US "skipping" to my location.  That is the primary reason that most Public Safety agencies that were on low band in the 50's, 60's and early 70's, went to VHF.  I still have the commercial EF Johnson Messenger radios and even though they are tube type, they are still type certified and still operate as designed (into a dummy load for testing only).

 

These days, with very few stations using low band - it might be a good place to go for Part 90 licensing if you want to be under the radar for some reason. My equipment was AM and worked better than some, because the AM system did not demodulate skip FM signals very well, so the interference to my system was minimal.  Mobiles with a 5/8 wave base loaded antenna would net roughly 20 to 30 miles mobile to mobile and 40 + miles mobile to a simplex base. Never needed a repeater with that type of local coverage.


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#6 quarterwave

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Posted 23 November 2016 - 10:02 AM

There are commercial industrial operations in that area, like power companies, contractors that move around and don't use repeaters. They use low band for longer range simplex. 

 

There is at least one itinerant in there...it may be 33.04, but need to look it up. Low band radios fall in 3 bands, 29-36, 36-42, and 42-50. Back when I worked in radio professionally, we have business customers and public safety/services in all 3 bands.

 

Upside - long range...especially to a base. Downside - radios draw more power, larger antenna on vehicle, and harder to match the antenna given mounting choices on newer vehicles and their materials. 



#7 cdesigns

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Posted 25 November 2016 - 08:05 AM

Low band means big antennas, not my thing lol



#8 mainehazmt

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Posted 25 November 2016 - 05:40 PM

In my early days here in Maine the fire dept ran 33.9. You would never guess how many times I was awakened by the exact same tones as we used. Only they were from several hundred miles away...I was very glad when we moved to VHF

#9 Jones

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Posted 27 November 2016 - 09:46 PM

The 29MHz band is part of (top half of) the 10 Meter Ham band.

 

29.000-29.200 is the AM window, with 29.000 being the calling frequency for 10AM. 

29.300-29.510 is used for Ham Satellite down-links, and should not be used by ground services. 

29.520-29.590 are FM repeater inputs. Usually 10Kc spacing, +-3Kc deviation

29.600 is the FM Simplex calling frequency.

29.620-29.690 are FM repeater outputs, and FM simplex talk-around.

 

A General class or higher Amateur license is required to use frequencies higher than 28.500 in the 10 Meter band.



#10 Sasquatch

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Posted 01 December 2016 - 11:38 PM

Thanks to all who replied to my questions!  Always an education on here.


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#11 eubank282

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Posted 25 March 2019 - 04:41 AM

There are commercial industrial operations in that area, like power companies, contractors that move around and don't use repeaters. They use low band for longer range simplex. 
 
There is at least one itinerant in there...it may be 33.04, but need to look it up. Low band radios fall in 3 bands, 29-36, 36-42, and 42-50. Back when I worked in radio professionally, we have business customers and public safety/services in all 3 bands.
 
Upside - long range...especially to a base. Downside - radios draw more power, larger antenna on vehicle, and harder to match the antenna given mounting choices on newer vehicles and their materials.


The itinerant freqs are 35.02 (restricted to 2w and itinerant use only) and 35.04 ( itinerant use only) in that range.

#12 taco6513

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Posted 25 March 2019 - 07:32 AM

Who operates the largest VHF low band system in the USA?



#13 Jones

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Posted 25 March 2019 - 10:05 AM

Who operates the largest VHF low band system in the USA?

 

Without looking it up, I would take an educated guess, and say either oil well drilling companies in Oklahoma and Texas, or the US military.  Just look for the trucks with 6-7.5 foot-tall whip antennas. (8 foot whip is a quarter wave on the 27 MHz CB band)



#14 taco6513

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Posted 25 March 2019 - 12:59 PM

The California Highway Patrol. The largest low band system in USA.

 

The Oklahoma still run simplex operations on 44.7 and 44.9Mhz. They are migrating to VHF. Oklahoma is trying to set up a state wide trunking system.

Can't seem to get the state funding to get of the ground in rural Oklahoma.

 

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