I recently installed one of the 58532A GPS antennas (this same part
number is applied to both units marked Symmetricom and marked HP and the
data sheets are very similar, though not identical). I'm confident it is
the same antenna as the dimensions and appearance are identical.
I'm using this with a HP Z3801A and GPSCon software. Previously, I had a
simple GPS puck antenna fed with RG-174 and RG-58A. The new HP (that's
how mine was supplied new and boxed) antenna uses Andrew 1/2-inch Heliax
50 feet long. Both antennas are in the same rooftop location and have
clear field of view.
Terminating Andrew Heliax was a learning experience! You *really* want
the simple, inexpensive Andrew tool to cut the shield; else, it's
hacksaw time...
GPSCon reported satellite signal strengths of about 25-80 units with the
old antenna and feedline; I did not realize how low was that signal
strength until I put up the new antenna. GPSCon now reports signal
strengths of about 80-230 units.
The new antenna resulted in a marked increase in the average number of
satellites tracked. Previously, the plot was a heavy line showing many
changes from six to two. With the new antenna, the plot line is
typically fixed at six with an occasional drop to 5.
HP SmartClock in the Z3801A is slow to react to changes--long "filter"
time constants. But, after about a week, there was significant
improvement in the Predicted Uncertainty and in the TI noise average
shown in GPSCon.
Granted, mine was a big change in antenna and feedline. But, antennas
matter!
Larry
On 4/29/2012 9:51 AM, [email protected] wrote:
Hi Ken,
Hi, Time-Nuts guys I just baught a Trimble Thunderbolt on ebay. I am in
need of an antenna, there are so many on ebay I am not sure which one to
get. Maybe someone could point me in the right direction?
Thankyou
Ken Kubick
How long antenna cable do you need in your location?
How low-loss antenna cable will you use?
The orginal antenna to the Tbolt is the Trimble Bullet antenna.
http://trl.trimble.com/docushare/dsweb/Get/Document-8420/Bullet-III_DS.pdf
Ebay #220997989191
Here is a former HP/Agilent antenna that has worked fine for me.
http://www.symmetricom.com/products/gps-solutions/gps-timing-products-and-accessories/58532A-GPS-L1-Reference-Antenna/
Generally most GPS antennas will work. (Searching for "GPS timing antenna"
will give you some choice)
Here is a very nice antenna. Rather good gain at 33dB, LNA power from
2.5VDC to 24VDC - which means it can take the oldtimer GPS receivers
giving 12V or 15V and new giving 3.3V or lower. (Like Antcom antennas, no
dealings with that particular seller.)
Ebay #150753929036
Datasheet
http://antcom.com/productsheets/2G15A-XTB-1-N_D.pdf
--
Best wishes,
Larry McDavid W6FUB
Anaheim, CA (20 miles southeast of Los Angeles, near Disneyland)
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