I know you can make a GR300 out of (2) UHF/VHF Maxtrac/GM300 with the 16 Pin connector on back using the R.I.C.K or a homebrew cable, but is it possible to use (2) 800 Mhz Maxtracs to make an 800 Mhz Conventional repeater and just set the tx/rx 45mhz apart? I know I couldn't get licensing to use them, but I just wanted to know if the 800/900 conventional capiable maxtracs could be used with the R.I.C.K
Thanks
Question regarding making Maxtrac repeater
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I had a project that needed a low range (repeater input sub-band) 800 receiver. I thought a Maxtrac would be perfect for this purpose (they are cheap). A Desktrac repeater is basically two Maxtracs in a box. Motorola made these for the 800 band so you know they had a low range Maxtrac receiver.
When you look in one of these 800 Desktracs you will find that the receiving Maxtrac has a different RF board than the regular mobile Maxtrac (it looks the same - it just has low range front end filters). As it turns out, there is no documentation of this different RF board in the Maxtrac or Desktrac service manuals.
If you call parts ID - they will eventually find you the part number of these filters. Unfortuanately, they show in M's computer as NLA. This in spite of the fact that you could buy this radio as recently as 3 years ago.
These filters were made by either Toyo or Murata. If you can find them from a parts supplier, the regular Maxtrac RF could be converted into a low range receiver. This is the same basic process that is used to convert a Maxtrac to the 900 ham band (i.e. changing the filters).
When I couldn't find the right filters I came up with another solution. I used a PP250 as the basis for the receive radio. These have a big heatsink on the back which contains a pair of ceramic filters that serve as a duplexer. I reconfigured the filtering to feed the receiver from what was the transmitter filter.
The filter in the duplexer also serves as the first receiver filter for the RF board in the PP250/750. I also removed the second RF filter and replaced it with a jumper. The one larger filter that was intended to be part of a duplexer seems to have as much selectivity as the two little filters in a regular Maxtrac. The resulting radio worked fine for my project.
When you look in one of these 800 Desktracs you will find that the receiving Maxtrac has a different RF board than the regular mobile Maxtrac (it looks the same - it just has low range front end filters). As it turns out, there is no documentation of this different RF board in the Maxtrac or Desktrac service manuals.
If you call parts ID - they will eventually find you the part number of these filters. Unfortuanately, they show in M's computer as NLA. This in spite of the fact that you could buy this radio as recently as 3 years ago.
These filters were made by either Toyo or Murata. If you can find them from a parts supplier, the regular Maxtrac RF could be converted into a low range receiver. This is the same basic process that is used to convert a Maxtrac to the 900 ham band (i.e. changing the filters).
When I couldn't find the right filters I came up with another solution. I used a PP250 as the basis for the receive radio. These have a big heatsink on the back which contains a pair of ceramic filters that serve as a duplexer. I reconfigured the filtering to feed the receiver from what was the transmitter filter.
The filter in the duplexer also serves as the first receiver filter for the RF board in the PP250/750. I also removed the second RF filter and replaced it with a jumper. The one larger filter that was intended to be part of a duplexer seems to have as much selectivity as the two little filters in a regular Maxtrac. The resulting radio worked fine for my project.
Last edited by Nand on Sun Jan 18, 2004 6:23 pm, edited 1 time in total.
"...The trick in getting these to receive on the low end is to program them for the image frequency..."
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That is what I did for my project. I wanted a receiving radio I could listen to the repeater input side of a multichannel system (to listen for interference, signal quality, etc.)
If you only needed a single frequency unit as a repeater receiver - use the Desktrac firmware FLN6531A. Initialize it as a Desktrac repeater receiver and you can enter the desired frequency directly.
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That is what I did for my project. I wanted a receiving radio I could listen to the repeater input side of a multichannel system (to listen for interference, signal quality, etc.)
If you only needed a single frequency unit as a repeater receiver - use the Desktrac firmware FLN6531A. Initialize it as a Desktrac repeater receiver and you can enter the desired frequency directly.
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re:
If I was to pay somebody to build me one, and I supplied the parts, how much would it be? or can someone supply me the parts with all major modifications done. I need these to be used as high powered links into nationwide 800 conventional repeaters for emergencies for use with handhelds. Somebody let me know. also, would like
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wazzzzzzzzup
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what if you were to setup several 800 maxtracs in a RICK configuration but instaed of setting them up trying to get one to recieve in the low 800 area, just set one up to RX on say 851.2375 and the other to TX on say 861.2375, then set your conventional radios to a custom split, im not 100% sure, but seems like you can custom split the jedi series of handhelds
wazz
wazz
think about how to ENCOURAGE Motorola learning safely with GRACE.....NOT condemnation.
re: maxtracs repeater
i got the conventional 800mhz maxtracs a-6 model to do the low side of the 800 band on recieve. you have to change the 2 gigafilters or short them out on the rf board. if you change them which is the best, use the toyo filters because the murata are no longer available. transistor q205 has to have a short across the base and the emitter. next hold the shift key down and type the frequency you want the radio to recieve on, but you have to add 90.2 mhz to it. for example if you wanted the radio to recieve on 811.0125, you would hold the shift key down and type in 901.2125. it will work, trust me. i got the toyo filters from avnet.com. they have plenty of the 806-824 toyo filters in stock and will sell 1 or more.
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CTAMontrose
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