CDM 1550 Low band Programming

[HappilyRetired]

I will admit right up front that I am relatively new to radios. I've been using amateur equipment and learning of antennas and cable and things like that. But I've decided I'd like to pick up a Motorola CDM to listen to the California Highway Patrol for better performance. The model they have though covers 42 - 50 MHz but the frequencies I need actually start at 39 MHz and go to about 46 MHz..

I have been told that I can use a hex editor and move the frequency range down. Can anyone point to a document that can tell me how to do that?

Thank you in advance.

 

[mmckenna]

I have been told that I can use a hex editor and move the frequency range down. Can anyone point to a document that can tell me how to do that?

Thank you in advance.

Batlabs is your friend:

HT750/1250/1550/PRO5150/7150/9150/GP320/340/360/380/ GP318/338/GP640/680/1280/CDM750/CDM1250/CDM1550,etc.

 

[K2NEC]

Very simple process, takes only about 5 minutes to do

 

[HappilyRetired]

Thank you to both of you! We all have to start somewhere.

I'm not sure my wife is completely happy with me at this point but I bought a Child's low band VHF antenna and it rocks! But on a scanner it's not as good as it could be. I think the scanner is picking up computer network noise. The signal bars are full strength a lot of the time. So I figured I would get a decent radio since everybody else is encrypted around me and I can at least listen to Chippies. They talk car-to-car are quite often.

Antennas seem to be a lot like rabbits. They multiply quickly. 🤣

 

[K2NEC]

Antennas seem to be a lot like rabbits. They multiply quickly. 🤣

I could say the same about my radios

 

[HappilyRetired]

Absolutely. After decades as a cop I never thought I would be interested in listening to the fire department or the highway patrol. I started out with a handheld scanner and before you know it I have to 996P2's and I'm looking to buy a cdm1550 for low band. I started off with a TV antenna turned vertical following advice from a ham I know and it works fairly well for the forest service. Kind of so so I guess for San Bernardino County Fire Department. So then I was on the internet and I found a scanner beam the cover is 100-200 MHz and I pick that up and that thing works pretty darn good! Where I point it goes. I think I might be too far away though to pick up helicopters if there's a fire. Not over here in the Cleveland though. I hear a lot over here. And then of course Riverside County uses Cal Fire and I'm not too far from the Batista area that goes up every year!

Going on for radios now and 4 antennas. It's not counting my ham radio stuff. I think my wife is going to divorce me. LOL. Irreconcilable differences. I'm trying to convince her to go take the ham test with me.

 

[n3obl]

For listening to CHP you might be better off using a Kenwood 690 vs a CDM where you would need to hex edit the band limits.

The TK-690 can do 39-50 which is what they were using.

 

[HappilyRetired]

I hadn't heard that one before. I must confess that I've been leaning towards all Motorola only because my ham radio Elmer is a Motorola fan. He had a Vertex and the Motorola and one of the things he pointed out to me is that when you plug an external speaker and as I do you can hear the PL tone on the Vertex but not the Motorola. The hum is annoying. You're right that having a radio that natively covers it might be easier. Thank you for another option.

I live in a rather frequent vegetation fire area and so I'll be streaming over Cal Fire from the Belly of the Beast so to speak as well as the hot zone for the Cleveland National Forest. CHP has a lot of car to car that you don't hear over the repeater that I think others would appreciate as well.

 

[mancow]

Thank you to both of you! We all have to start somewhere.

I'm not sure my wife is completely happy with me at this point but I bought a Child's low band VHF antenna and it rocks! But on a scanner it's not as good as it could be. I think the scanner is picking up computer network noise. The signal bars are full strength a lot of the time. So I figured I would get a decent radio since everybody else is encrypted around me and I can at least listen to Chippies. They talk car-to-car are quite often.

Antennas seem to be a lot like rabbits. They multiply quickly. 🤣

I have to know what a child's low band antenna is.

 

[ff026]

Try this page for info on Hex editing your CDM. It has a lot of great info and tools. It takes a little reading but it’s very informative.

Waris - W9CR

wiki.w9cr.net

 

[mmckenna]

I must confess that I've been leaning towards all Motorola only because my ham radio Elmer is a Motorola fan.

Yeah, good to get a second opinion. Motorola makes mostly good stuff, but there are better options. Even CHP uses Kenwood for their mobile radios.

"Motorola fans" can be a bit funny sometimes….

He had a Vertex and the Motorola and one of the things he pointed out to me is that when you plug an external speaker and as I do you can hear the PL tone on the Vertex but not the Motorola. The hum is annoying.

Not sure if the Vertex has it, but usually there is a 'low cut' audio filter that either permanently in place, or selectable (it was on the Icoms) that will roll off all the audio below 300Hz. I used to have access to a GMRS repeater and the PL I was assigned was 254.1Hz. That's high enough that it comes across as a low rumble on the audio. Turning the low cut filter on in software removed it.

 

[mmckenna]

The TK-690 can do 39-50 which is what they were using.

TK-6110K2 will also do 35-50MHz. Not as fancy as a TK-690 or NX-5600, but you might be able to find some on the used market. Just make sure you get the K2 model.

 

[n3obl]

TK-6110K2 will also do 35-50MHz. Not as fancy as a TK-690 or NX-5600, but you might be able to find some on the used market. Just make sure you get the K2 model.

I thought about recommending that but I wasn't sure how many channels and PL combos they use whether it would require more than 32 channels.

 

[Anderegg]

The built in speaker of the 6110 is weaker and much more high toned than the Maxtrac or CDM's...just FYI...it exagerates the static on weak low band reception.

Paul

 

[Anderegg]

BTW, here is the new CHP all band (including low band) radio setup they are switching to.

 

[k9wkj]

I have to know what a child's low band antenna is.

https://childsantennas.com/

 

[mancow]

https://childsantennas.com/

Thanks

 

[Outerbanks4wd]

BTW, here is the new CHP all band (including low band) radio setup they are switching to.

View attachment 101254

What is radio manufacturing and model number?

 

[K2NEC]

What is radio manufacturing and model number?

Kenwood NX5000 series

 

[mmckenna]

What is radio manufacturing and model number?

K2NEC is close. It is a variant of the Kenwood NX-5000 series.
They are using the EF Johnson VM-7000. Essentially the same radio with some firmware changes that allows them to run 4 RF decks instead of the 3 that Kenwood version allows.

Viking VM7000 Mobile | JVCKENWOOD

Simultaneously receive and display up to four bands with the Viking VM7000 all-band mobile so you never miss a call. The “select” and “unselect” speakers give you the option for audio control similar to a dispatch console. KENWOOD Viking is the industry’s only mobile platform providing...

www.efjohnson.com

Oh, and the Pyramid SVR-p752 mobile repeater for their extender.