Batboard

Has anyone upgrade the wide band Motorola GR500 repeater with GM120 radios and a Zetron ZR320 tone panel to use the Motorola CDM750 narrow band-able series radios?
Likes / Dislikes / unforeseen problems?

Or should we look at another repeater to replace this unit all together?

Thanks in advance.

Though never having actually done this, I see no unforeseen consequences with using CDM's in place of the M120's.

You can now order a "CDR500" with CDM750's with a housing almost identical to the GR500, and you can order a CDR700 with a housing like a GR300. I have put together a new CDR700 with an old i20R controller, and that worked without a hitch (though the repeater took a lightning hit a short while after it was installed, which is a great example of the benefits of R56 compliance, but that is a topic for another thread).

I have switched the GM300's with a RICK to CDM750's and the RICK.
Works fine. Basically the same as a GR300.
While the CDM is still a mobile, and so not as good as a purpose built repeater, they are a good low cost alternative in the right application.

PETNRDX wrote:I have switched the GM300's with a RICK to CDM750's and the RICK.
Works fine. Basically the same as a GR300.

Ditto

Hello
Or assuming you can find them and wanted to.
Replace the M120 wide band mobiles with M120 narrow band mobiles.
The GM300 was also made in narrow band if you wanted those or couldnt find the M120.
Leaves you repair parts for the narrow band as wide band does use most of the same parts other than the filters being diferent from wb to nb .
Check the model number for 00 or 09 ect to make sure its12.5 narrow band and have at it.
Umm flea bay comes to mind if you can trust the seller ect.
I did not say that but did type it .
satelite

Thanks everyone.
Going to upgrade the radios with CDM750's

Depending on what service, Business, Public Safety or GMRS, your repeater is in you may have to have a CDM radio that has the Base Station frequency stability option to meet the FCC rules.

This would apply to the TX radio.

Will wrote:Depending on what service, Business, Public Safety or GMRS, your repeater is in you may have to have a CDM radio that has the Base Station frequency stability option to meet the FCC rules.

This would apply to the TX radio.

The CDR700 manual specifically states that CDM radios do not meet the TX frequency stability requirements for narrowband UHF service. For any other band or for Part 95/97 service you're fine. In the real world it doesn't make much difference, but if you want to stay in compliance for Part 90 UHF I believe the recommended upgrade is a XPR repeater.

Hello :
Wow now im wondering this qestion.
Is the GM300 in the narrow band model from the factory FCC compliant as the transmit unit for a repeater such as the GR500 ect ?
GM300 model number M44GMC09C3A is the model im refering to here.
My license states radio service is IG=Industrial/Business Pool Conventional .
Im possibly going to use it as the transmitter turned down to 20 watts with a astron fan cooled enclosed power supply to drive a PA amp.
Im aware of the long tx times heating up the pa troubles ect and believe i can overcome that potential problem .
Also it was my understanding here on batlabs that GMRS was exempt from having to go 12.5 narrow band and that GMRS could remain 25 wide band after 2013.
True or false on the GMRS n/b or w/b ?
Thank you
Satelite

GMRS is remaining wideband.

Pat

Hello all. Looking for some additional info on this post. Have same repeater with one m120 for tx and gm300 for rx in vhf high band. Could a pair of m1225 be substituted in place of the two wide band radios ? I have heard that the 1225 is not type accepted for repeater use as the tx deck . true or false. If true does that only apply to uhf repeaters ?
Thanks
73 de Jeff/N0SIH

Old thread bump: if anyone needs it, the part # for the retrofit kit to upgrade a GR500 to CDR500 is HKLN4117A and it lists for $93.45 on MOL.

Out of curiosity, what does that kit get you?

- Jeff

Just a guess, but probably new sheet metal bracket for the radios/duplexer. The Motorola description is as follows:

Radio/Duplexer Mounting Bracket Retrofit Kit


When we've done the change, we made a couple of spaces for the sides of the CDM's as the're narrower than the GM300's

Yes, I saw that on MOL. Thanks. I was curious what, if anything, other than a big square bracket you might get for the just-under-$100 pricetag. The kit name hinted at the bracket part, but I just wondered if M had another part or two in mind for the conversion. Power cables, interface cables, etc. should all be the same between the GMs and the CDMs, but you just never know. I'll go with the bracket-only assumption for now, but we're using the cylindrical white nylon spacers leftover from new Troy faceplates to make up the width differential in ours. -J

JeffFireRadio wrote:I'll go with the bracket-only assumption for now, but we're using the cylindrical white nylon spacers leftover from new Troy faceplates to make up the width differential in ours. -J

Those white nylon spacers are readily available at most any hardware store or home improvement center. I picked up a bunch last year for some challenging mount issues. And I am using them on CDM's in several different applications.