[time-nuts] XL-DC was Re: time-nuts Digest, Vol 127, Issue 33

[Russell Rezaian]

I can confirm there are at least two common varieties of the XL-DC GPS 
RX board.

One uses a "normal" GPS antenna (no down-converter, provides DC on the 
antenna line for an amp in the antenna, the typical antenna provided 
seems to be an AeroAntenna AT575 variety, but I suspect other antennas 
that are similar should be fine).  The specific antenna part I have is:  
AT575-142TTW-TNCF-000-RG-41-NM

It's been a while since I last decoded that part number but it's a very 
easily re-useable general use GPS antenna with an integrated RF amp.  
Works over a fairly wide range of DC supply voltages and claims a 
slightly higher gain than some other standard timing GPS ice cream cones.

There are also versions of the GPS module for the XL-DC that use a GPS 
antenna with an integrated down converter that is actually physically 
part of the antenna provided.

The down converter antenna is normally a single integrated unit. The 
part numbers I see on one I have handy are 140-614 (TrueTime) or Model 
142-6150 on the Symmetricom label.

I don't have any details for the voltages or whether there is a 
reference frequency provided for the down converter style receiver.

I have seen some suggestions that they also had a dedicated down 
converter module that could be used with "normal" GPS antennas, but I 
don't have any details on that option.

If you have a RX module that needs the converter antenna there should be 
a clearly visible little label indicating this on the module itself near 
the antenna connector.  If you don't have that label the RX should work 
with most GPS antenna systems (and also with most antenna splitter 
systems too).
--
Russell

Al Wolfe wrote:
>    I have an XL-DC and it has an internal GPS receiver in it. It 
> supplies and monitors 5 volts to a BNC antenna  jack for an external 
> amplified GPS antenna. I don't know what the internal GPS engine is 
> but doubt if it is anything special.
>
>    The manual describes the down converter system as an option.
>
> Al, k9si
>
>
>> Boy I ran out to mr google and did a search and now I am wondering if 
>> some
>> versions of the xl-dc just used a plain old GPS antenna. It sure 
>> looks like
>> that could be the case. The manual does say down converter. Maybe it
>> changed over time.
>> Regards
>> Paul
>> WB8TSL
>>
>
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