[time-nuts] What outdoor antenna for Tbolt?

Didier Juges didier at cox.net
Sun Sep 14 10:01:59 EDT 2008


I have tried three models the original Trimble Bullet, the HP 58532A and
several pucks, including a nice Trimble mag-mount unit. Two of the pucks are
designed for marine use, with a decent waterproof case and mounting, but
they are in an all plastic case. There have no part number that I could see,
I need to look closer to see if there is a manufacturer's mark. They were
obtained on eBay from a long forgotten vendor...

I am not sure how Trimble rates the mag-mount antenna, but it probably was
not designed for permanent outdoor installation, even though it is heavy and
looks very well made.

They were compared by plugging them into my main Thunderbolt receiver and
checking the time to complete self-survey. Because of the constantly
changing constellation, it is difficult to compare antennas otherwise over a
short time. I felt the self-survey was a useful indicator even though I am
perfectly aware it is just that. Self survey takes several hours (2 to 8 in
my experience, depending on the combination of antenna and receiver).

It seems my main Thunderbolt receiver (original OEM design with built-in
supply) is more sensitive than the two Group-buy Thunderbolts I also have,
as it does complete self-survey faster and seems to report more satellites,
even though I have not yet attempted to log that information over a period
of time to give an objective result. Another project for the winter.... That
could also be due to a different internal configuration of the receivers,
even though I have not seen any difference in look-up angle settings and
such.

All antennas were compared while inside the house, in the upstairs ham
shack/office/lab, so pretty close under the shingles covered roof and facing
south.

The Bullet I have is less sensitive than the others. I receive fewer
satellites with it and it takes much longer for the self-survey to complete,
I do not use it. I got it with my main Thunderbolt receiver and it was not
new when I got it. All other antennas were bought new.

The HP and the pucks seems to give about the same signal strength and take
about as long to complete the self survey. The HP will go outside when I
have a chance to install it, it's still way too hot over here to do anything
outside that you don't HAVE to do...

I bought the HP on eBay, new, for $50 with shipping, compared to about $25
each for the pucks, including shipping costs. Unless you are satisfied with
an indoor antenna (in which case I would say: "What are you doing on
time-nuts?"), I can't justify saving $25 by using a puck compared to the
wonderful piece of design and technology that the HP 58532A is. By the
pound, you get much more with the HP :-)

Didier KO4BB

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of David Medin
> Sent: Saturday, September 13, 2008 3:28 PM
> To: time-nuts at febo.com
> Subject: [time-nuts] What outdoor antenna for Tbolt?
> 
>    What outdoor bullet antenna are people using for their Tbolts
>    (manufacturer and model number), where did you find it, 
>    and how much did you pay for it? I'm looking at several eBay 
>    antennas and the like crossing my fingers that the bias 
>    voltage and current will work, but I'd rather get some 
>    advice from those of you that have actually done
>    the deed. I'm only really interested in antennas designed 
>    for permanent outdoor or marine installation.
> 
>    Thanks!
> 
>    Dave Medin





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