Hi, Roy,
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On 10-Feb-08 at 09:52 Roy Phillips wrote:
<snippety>
>It was switched on (and no antenna was connected), I don't have one. It
>came to life and scrolling its menu it shows a date in 1998 and a set of
>co-ordinates which suggests it was probably a ship installation. I found
>my way to your site through searching for info on this item, and I gather
>that some of you have this item of equipment - can you help - I gather
>that it requires an active antenna - what can be found or built to meet
>this need?
I have a 325 myself, though it was upgraded to a 425 by the previous
owners. I'm particularly pleased to have it because its former home was the
south pole. It was originally part of the AST/RO (Astronomical Submillimeter
Telescope Remote Observatory) project.
Anyway... IF, and only if, your unit has been retrofitted with a
Magellan GPS receiver module, it uses a standard industrial-class GPS active
antenna. Otherwise, I'm pretty sure it will require a proprietary Odetics
antenna and separate down- converter. I don't have my manual here at the
moment, or I would double-check.
If it has been retrofitted, you have another issue. The DC bias
supplied on the antenna's center conductor is normally 12V, a level which not
many modern antennas support. You can either use an antenna that supports 12V
bias (Trimble made a couple of dome antennas that do this), or you can do as I
did and install a DC injector between the unit and a 5V antenna, and feed in 5V
that way. In my case, I'm using an HP/Symmetricom 58532A antenna. It works
great, but it does not tolerate bias voltages above 5.
The way to tell if it has been retrofitted is, quite simply, open it up
and remove the clock board (the one closest to the front). The GPS receiver
assembly will be directly under it. If it says 'Magellan OEM5000' on its label,
you're good to go.
The DC injector I used (also called a 'Bias T') is made by AR-Squared
products. Its spec sheet claims that it's only good up to 1GHz, but I've not
noticed any problems using it at GPS frequencies. Here's a link to the unit.
It'll run you about $40.
http://www.advancedreceiver.com/page26.html
>Also the system is "Locked" - what do I do to clear this problem ( the
>menu display suggests I refer to the manual !!) Is it possible to obtain a
??? What's the exact wording on that message? Usually, once the unit is
settled in normal operation, it will display 'Time Locked' and that's the only
time I've seen that word in my unit's display.
In any case, I have a large amount of information on the 325 and 425 on
my FTP site. You can access it by pointing your FTP client to
ftp.bluefeathertech.com, but make sure you configure said client to use port
50021 instead of the default port 21. This is a change I found it necessary to
make after experiencing widespread abuse attempts by automated scripts, looking
for places to dump "warez."
Once you connect, sign on with the user name ftp and the password can
be anything you want (though I prefer an E-mail address for logging purposes).
The path to the material is: electronics/radio/GPS/clocks/Odetics
Happy tweaking.
-=-=-=-=-=-=-=-=-=-=-=-
Bruce Lane, Owner & Head Hardware Heavy,
Blue Feather Technologies -- http://www.bluefeathertech.com
kyrrin (at) bluefeathertech do/t c=o=m
"If Salvador Dali had owned a computer, would it have been equipped with
surreal ports?"
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