[time-nuts] Odetics 325 - 865

[Robert Atkinson]

Hi Bruce,
  DoH,
  You are correct the Magellen is the standard antenna type I was wrong in my post. The downconverter type is the big box but it says Odetics GPStar Receiver on the box.
   
  Regards,
  Robert G8RPI.
Bruce Lane <kyrrin at bluefeathertech.com> wrote:
  Hi, Roy,

*********** REPLY SEPARATOR ***********

On 10-Feb-08 at 09:52 Roy Phillips wrote:



>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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