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From: dbm
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
Date: 25 Oct 92 04:49:08 GMT

References:<1992Oct24.082655.7322
Sender: news
Distribution:usa

Organization: New Jersey Institute of Technology, Newark, N.J.

Lines:25

Nntp-Posting-Host: cats.njit.edu







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 very very tight in this





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




From: dbm
Newsgroups: rec.radio.amateur.misc

#Subject: Re:Standard 800 Portable

Message-ID: <1992Dec10.084258.10918
Date: 10 Dec 92 08:42:58 GMT

References:<1992Dec9.004644.9797
Sender: news
Organization: New Jersey Institute of Technology, Newark, N.J.

Lines:71

Nntp-Posting-Host: cats.njit.edu





                   Maxtrax 900 Ham Conversion        5/30/92

    

    

    

    

    Confirm that your radio had firmware FVN4019A. If not order this

    from Motorola (510291S04). Using Motorola MAXTRAC (conventional)

    software program ham freqs into radio. Software will warn that

    freqs are not authorized, press F2 to continue entering ham freqs.

    

    

    Once this is done perform VCO mods on next page.

    

    

    After radio is programmed and VCO mods made radio should have rated

    TX power but poor RX sens. This is due to the two 932 Mhz filters

    in front end. Replace FL1 and FL2 with Murata DCF3R915P025BTD

    filters. This will correct the condition.

    

    

    Note:You will be working with CMOS!!!!! Use Caution!!!!!

          VCO and Filter MODS are made on RF board.

          Firmware chip is U804 on Logic board.

          Maxtrac software can be bought from Motorola or a local shop  

          with software can program radio.

    

    

                    Motorola Maxtrac 900 VCO

    

    

    

    

           .......................................................

           :                                                    :

           :                                                    :

           :--//--                                      --//--  :

           : (RX)                                        (TX)   :

           :                                                    :

           :                                                    :

           :                                                    :

           :                                                    :

           :                                                    :

           :                                                    :

           :                                                    :

           :                                                    :

           :                                                    :

           :                                                    :

           .......................................................

    

    

    

    RX VCO Mod

    

     Remove RX cap, Remove TX cap, Place TX cap in location of original

    RX cap. (Note- You may be able to leave orig RX cap in place and

    add a large amount of solder to right side of cap while metering

    Steering Line voltage. Add solder until S/L voltage is in the area

    of 7 volts when radio is on your highest receive ham freq).

    

    

    TX VCO Mod

    

     After removing TX cap place a 1.7 pf cap in it's place. If this

    value is not available you may place a high stability variable cap

    of .5 to 4 or 5 pf in this place. If a variable cap is used you may

    have to use metal tape to make a cover with a hole for the cap to

    fit. Use as little solder as possable on the TX side. You should

    have a S/L voltage of no less then 2 volts while transmitting on

    your lowest freq.

    






SOURCE: The QRZ Windows Ham Radio CDROM



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