CDM1250+keypad mic vs CDM1550

[g8tzl2004]

If I use a keypad mic with a CDM1250 (so I get the extra function keys), do I get the same functionality as using a CDM1550?

I know the CDM1250 is 64 channels vs 128 for the CDM1550...but apart from channel numbers, both radios looks very similar.

I can see the logic in having a "cheaper" non display 4 channel mobile as well as a 128 display version...but why manufacture an almost identical display radio with just fewer channels?

[SteveC0625]

If I use a keypad mic with a CDM1250 (so I get the extra function keys), do I get the same functionality as using a CDM1550?

Basically yes, but the functions have to be selected and enabled in the the CPS for both radios. Looking into the CPS, I see a slight difference between the 1250 and the 1550 for choice of functions.

Is there a specific function or functions that you want/need?

[Bill_G]

I can see the logic in having a "cheaper" non display 4 channel mobile as well as a 128 display version...but why manufacture an almost identical display radio with just fewer channels?

For the same reason there is more than one kind of cereal on the grocery shelf - To have a range of product for sale. One guy wants single channel conventional operation, and another guy wants eleventy hundred channels with every signaling option ever conceived. Manufacturing has to keep costs down with the fewest form factors and board changes possible while feeding the pipeline with product. Sales wants a simplified book to work from without having to select or unselect a bazillion options. You end up with a few tiers in the product line, some standard features in each tier, some value added options that are enabled in software, and a range of prices to satisfy buyers.

[RadioSouth]

If I use a keypad mic with a CDM1250 (so I get the extra function keys), do I get the same functionality as using a CDM1550?

I know the CDM1250 is 64 channels vs 128 for the CDM1550...but apart from channel numbers, both radios looks very similar.

I can see the logic in having a "cheaper" non display 4 channel mobile as well as a 128 display version...but why manufacture an almost identical display radio with just fewer channels?

Many of Motorola's radios which have identical platforms have a different options with different prices even though cost was likely identical.
One that shakes my head was the HT1000's. Originally offered in 2,8 and 16 channels and these early 'A' rev. radios all had the antenna RF switch
so only real hardware difference was channel knob and escutcheon along with price. In 'B' rev. the 8 channel radio was cancelled but they came out with a kit to alter a 16 ch. radio to 8ch. with a price on the kit which was strictly a 8 channel knob and escutcheon. Talk about marketing !

[g8tzl2004]

Thanks for all the interesting feedback.

Is a CDM1250 identical "inside" to a CDM1550? I searched the archives and got conflicting answers.

Can you flash a CDM1250 with CDM1550 firmware so you get 128 channels?

Some say that you cannot swap heads..other comments suggested that you can although a CDM1550 head on a CDM1250 body results in the "missing front keys" not working on a CDM1550 head. However, I guess if you can flash CDM1550 firmware into a CDM1250 then a CDM 1550 head will work on a CDM1250 body??

[N6LAU]

Can you flash a CDM1250 with CDM1550 firmware so you get 128 channels?

If by firmware you mean codeplug then it might be possible so long as the radio memory will accommodate it. Not sure if the radio will be unhappy though and error out if it doesn't see the extra buttons on the head or doesn't like the fact that it's a 1250 head.

[escomm]

Is a CDM1250 identical "inside" to a CDM1550? I searched the archives and got conflicting answers.

Yes. Same guts. CDM750, 1250 and 1550LS+ all have the same guts. Only difference is the 1550LS+ has an option board for PassPort option. And the control head is different.

[g8tzl2004]

So if the guts are the same, I guess you can flash a CDM1250 into a CDM1550?..so you get extra channels etc

Has anybody ever done this? I can't see any comments in the archives...you would think there would have been lots of discussion over the years about getting more channels!! I don't want to be the 1st to do the flash and end up with a brick!!!!

[arnu]

Yes - the basic unit is the same with CDM 750 , 1250 and 1550.
You can reflash a CDM1250 into a CDM1550 no problem.
I have done that several times.
BUT ...
The CDM750/1250/1550 software checks for the correct CDM750/1250/1550 control head.
If you have a CDM1250 control head connected with a CDM1550 software it will only show an error message - no function.
So you will need the proper control head for the software to work.

[g8tzl2004]

Thanks Arnu

I wonder if it would be possible to hex edit the CDM1550 CPS so that it accepts a CDM1250 head on a "flashed" CDM1550 firmware body? You would then just need to remember not to try and prog the "missing" front keys....although you could use a DTMF mic to provide additional function keys.

[arnu]

You can actually make the 1250 control head appear to the radio as a CDM1550 head.
There are several Ohm resistors on the control head board which set the head id.
I don't have the schematics in front of me - but each type 750/1250/1550 has a unique combination.
The radio reads it on power up when it initializes the head.
There might be some problems with the menus since the 1550 uses the cursor keys in the middle which the 1250 doesn't have.
But really the easiest is to get a 1550 control head.

Alfred.

[g8tzl2004]

Thanks for the info Alfred - its good to know that the head mod just involves resisters. But as you say, getting a real CDM1550 is really the best way forward!!