From allegra!ulysses!dptg!att!att!linac!pacific.mps.ohio-state.edu!cis.ohio-state.edu!rutgers!njitgw.njit.edu!cats.njit.edu!dbm Mon Oct 26 14:39:11 EST 1992
Article: 26894 of rec.radio.amateur.misc
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From: dbm@cats.njit.edu (Dean McDermott - WB2CMN)
Newsgroups: rec.radio.amateur.misc
Subject: Re: Any info on Moto gear for 902mhz FM?
Keywords: Motorola FM 900 902
Message-ID: <1992Oct25.044908.24872@njitgw.njit.edu>
Date: 25 Oct 92 04:49:08 GMT
References: <1992Oct24.082655.7322@grian.cps.altadena.ca.us>
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Yes the Maxtrac will work on the 900 ham band. However the Spectra is much harder. I have one Maxtrac converted and while getting to work took quite some time the final mod is not that bad. 

Conversion:

Start with a 900 Mhz Maxtrac. If is is conventional then fine, if not then order FVN4019A conventional firmware. You will also need to order two Murata filters (# DFC3R915PO25BTD) from a Murata Erie dist in your area. Locate two chip caps with a value of 1.1 pf.


Install firmware if not already conventional. Remove the two Murata filters in the front end and replace with the above so that the radio will pass 915 +- 12.5 freqs. Locate the VCO and using a LARGE solder iron heat the top cover and pry it off. Now looking into VCO you will see that the small board has components on left and right halfs and they are a mirror of each other (the left and right). Looking in two corners you will see chips with chip diode directly under it. It is ver very tight in this area. 







Remove these two chip caps that are next to the chip diodes. Replace with the 1.1 pf caps *** NOTE: The value of these caps might vary -- you may have to put anything from 1.1 to 1.9 pf in -- DO NOT use too much solder when installing caps. It is very easy to damage the VCO!!!!

Now put everything back together. I have mine operating with a RX area of 920 to 921 and TX of 907 - 909. Programming of the radio will require Maxtrac conventional software and when the program tells you the frq you entered is out of band disreguard it and continue.




I am working on Spectra but not sure if this radio will make it. Anyone that has info on the Spectra please contact me.


Dean


dbm@cats.njit.edu