[time-nuts] Antenna for T-bolt

[Chris Albertson]

On Mon, Apr 2, 2012 at 3:28 PM, Bob Martin <k6rtm at comcast.net> wrote:
> Bill--
>
> The Thunderbolt wants a higher gain antenna than most standard GPS receivers.  I tried standard Garmin active antennas, and while they worked (I have a good view of the sky), signal levels could be better.
>
> Best match probably is something like the HP/Symmetricom 58532A antenna, which has gain > 30dB -- most "active" GPS antennas are in the 24 - 26 dB range.

I have a 26dB timing antenna the kind that is easy to find on eBay.
It works well with my T-bolt.   I have the antenna on a short mast
made of galvanized iron plumbing pipe with the feed line coming down
the center of the iron pipe.

Yes it is true the t-bolt can use more gain but it is not so clear I'd
get better timing.  I can lock satellites from horizon to horizon.   I
think what IS clear is that location maters MUCH more than any other
factor.  First you need to find a way for the antenna to get a full
360 degree view of the sky down to the horizon, all the way around.
This may mean you have to move the t-bolt too.   By that I mean,
rather then saying you can't run antenna feed down from the roof,
place the t-bolt new the roof then use cat-5 wire ro whatever to bring
the 10MHZ and PPS and Serial data down.  Details are site dependent
but getting the antenna to a good location should drive all yu other
trade offs.

Lastly you can replace the antenna with a "real" timing antenna.   I
had a patch type mag mount on the roof, it worked but the pointed
radome but keeps birds off and if it snowed here would keep that off
too.
Chris Albertson
Redondo Beach, California