Hello Steve;
There is a pretty large group of builders assembled in one place,
and hopefully the list owner here will not mind the link post as O.T., but
the group is 900 centric and focused with some 700 list members... it is
here at yahoogroups and it is called AR902MHZ. It is dedicated to
building/re-building/modifying and utilizing gear for 900 mhz amateur
voice and data. The archives cover almost any radio you can find on the
used market in one way or another. Some special sw has been developed by
folks like Pete N2MCI to work with certain Kenwood and EF Johnson 900
radios, as well as Processor and sub-processor add on's for some of these
models.
To answer the question, just about any 900 commercial radio can
be moved to 900 amateur, although some are very limited in capability. Some
of the easiest are Motorola just about everything, and Kenwood TK 481/981
series. Others can be moved with varying degree's of skill required. Most
are RSS ( software/firmware) modifications with a hex editor, others
require hardware mods. Much Motorola centric documentation can be found at
Batlabs and the 900 conversion docs there are growing.
There is documentation, written By Gene Colson W7UVH, on my web
site and I think it is now also posted at repeater builder on modifying
Mastr II 800 crystal controlled stations to 900. This is my preferred
setup, ( Mastr II ) but others use Spectra, Maxtrac and GTX combinations
for stations. Many 800 conventional receivers ( like Maxtrac) can be moved
to 900 for RX purposes and are still pretty cheap. Some 900 prices are
going up as users figure out that the market is getting leaner on gear.
Many Paging Stations have been moved for repeater TX purposes,
again it takes a little more intimate knowledge of those box's to do this.
Quintron and others like Glenayre work very well as well as Motorola Purc
900 MHz stations and their other variants. I beleive both Nucleus and
Quantar have also been moved.
Most 800 gear transmits poorly if at all at 900, even if you can
move it there as it is about 50-100 mhz away from it's designed primary
operations. They can work as RX by strapping the vco for Talkaround
frequency range and low side injection for 902.xxxx using F.O -45.0
injection scheme. This is where the sw hacking comes in as you need to
modify most of the RSS's for out of band freq changes... Most 900 filters
and duplexers work fine in the ham band, and many 800 duplexers tune up
well at 900 even though the split shrinks from 45 mhz to 25 mhz. Paging
929-931 colinear antenna's are normally well in band for our use.
It is not easy to condense all the possibilities in a single email
which could be digested easily, but suffice to say there are MANY options
to get to the band...
Unfortunately some of us, such as myself, have done many mods over
the last 10 years on 900 and never documented them as we have been more
into doing it then writing about it... But we are working on it, and there
is always new development.
The biggest problem in setting up a repeater and selecting mobiles
and portables is there are 2 distinct repeater band segments, one is easy
to get to with 900 gear, the other is much more limited.. Check your local
repeater council suggestions. 902/927 being the easy one, 909/921 mid band
being the more difficult.
Doug
KB8GVQ
At 05:52 AM 2/3/2005, you wrote:
>I found some 900 Mhz leftovers, antenna, filters, etc, and have the
>bug to put together a 900 Mhz ham repeater.
>
>Anyone else out there have some tips?
>
>Are MAXTRAC900's still plentiful and cheap? or else what are folks
>using for subscriber units?
>
>What are ya'll building the repeaters out of?
>
>Thanks,
>Steve NU5D
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