Batboard

Hello
I apologize if this has been covered before, but I have a UHF Maratrac that I'd like to use as the TX unit in a UHF-amateur repeater. Considering the steps involved to make the Maratrac ham-band-friendly, I'd appreciate any input advice or hints involving the Maratrac accessory connector compared to the GM300 accessory connector - my direct question is, other than COS, is there anything else I need to consider cabling/connection-wise when swapping a GM300 TX unit for a Maratrac TX unit?
Thanks again, the help here has always been great,
Mike

The MaraTrac is built around a MaxTrac. The GM300 is just slightly newer than the MaxTrac and is internally quite similar.

The MaraTrac was meant to be put into the trunk of a vehicle. It has NO spare pins or wires in the control cable. The Option jack is inside the radio and was meant for internal options only. On the GM300, the accessory jack is easily accessible at the back of the radio, as very few accessories got mounted inside the radio itself. You'd need to drill a hole in the MaraTrac or leave the top cover off to access anything other than what already comes out to the control head.

The MaraTrac logic board is a 5-pin, EPROM-based unit. It didn't have any of the programmable output pins that most of the 16-pin boards had. The MaraTrac programming software doesn't have the capability to access those pins. The MaxTrac and GM300 radios do.

Since you want to use the MaraTrac as a transmitter, you won't need COS, so why concern yourself with that. You'll need PTT and an audio input. You can use the MIC HI input on the control head or control jack at the front of the radio. Ditto with PTT. You can cause the radio to power up by grounding one lead on the control jack, so you shouldn't need the control head. You'll have to go digging inside the radio for Flat TX audio, if that's what you're using now with the GM300.

Most high-power mobile radios aren't made for continuous repeater-duty operation. You would probably have to set the radio for about 40 watts output and still provide a lot of cooling air, to let it survive some one-hour transmit sessions.

Bob M.

This may be a late reply, but I use Maratrac's as repeater transmitters all the time. I just turn down the 110 watts to about 40 watts. Also depending on the type of head you are using, there are lots of spare wires in the control cable. I use the basic A-3 rotary head. If you are going to use only one channel you can lock it on that channel. That gives you 4 spare wires, also there is still another spare for the extender (low band) that's not used in VHF and UHF.

I 'm looking to replace the logic and rf board in a Maratrac with those of a narrow banded GM300 to use as a Base satation. Has anyone done this?

From memory, I know the GM300 and MARATRAC Logic boards are a bit different.
And looking at the two manuals, there are some pins that go between the logic and RF boards that ARE different.
The trouble would be that the MARATRAC has "extended" pins on the logic board that go to other boards in the radio that the GM300 doesn't have. The MARATRAC and M400 have an "interconnect" board, an "audio squelch" board, and RF control board.
Those boards are connected to the logic board thru those extended pins and just a quick look tells me that the GM and MARATRAC connections are not 100 per cent compatible.
If you wanted to spend a lot of time, you could probably swap wires around and make it work, but why?
Either NB the MARATRAC RF board, or just use the GM300 as is would be my suggestion.
I am pretty sure the HLN9575 NB kit for the GM has the same parts as those needed to NB a Maxtrac, Radius, and Maratrac.
Now whether or not that is a type accepted radio after the conversion is another matter.
I know for certain that FL51, FL52, and Y51 A & B ARE the same part number for Maxtracs, Radius ( Radmbl ) Maratrac, M400 and the GM300 line. The other parts are just SMD resistors. I can verify those if anyone needs it.
And, as far as I can tell there was not a 12.5 khz spaced Maratrac, but there were Maxtracs and Radius models.

Thanks !
JB Young

You're into new territory on that one. I'd recommend dropping into The Repeater Builder's list and asking about doing so. There are a few Motoheads there who have gotten pretty far into the GM300/Maratrac series.

http://www.repeater-builder.com/rbtip/

http://groups.yahoo.com/group/Repeater-Builder/

There are many radio manuals up there now:

http://www.repeater-builder.com/rbtip/mojoindex.html
http://www.repeater-builder.com/maxtrac ... index.html
http://www.repeater-builder.com/motorol ... index.html

The M400 is the same as the Maratrac, just a different name to fill a sales-created niche. The M400 manual documents the radio, but the Lowband Maratrac manual documents the Clamshell head.

My Maratrac/M400's have 20 kHz filters in them. That knocks out the stuff 12.5 khz spaced.

The M400 is a Radius radio different paint job (on some) although they are the same.

The Maxtrac, Radius and GM boards will not work in the Maratrac. The Maratrac has a different ROM chip to work with the control heads.