[time-nuts] antennas

k6rtm at comcast.net k6rtm at comcast.net
Mon Sep 27 14:50:15 UTC 2010

Rather than put up two antennas, why not use one, and pick up a HP/Symmetricom GPS splitter? (Mini-Circuits makes a similar unit). You can find them on eBay for various prices. The Symmetricom one, the 58535A, supports 2 GPS receivers. It has a built-in amplifier and filters, so it provides high isolation between the GPS units. It's powered from the GPS units, and passes power to the antenna. 

The downsides are that it costs more than a pair of cheap antennas, it's heavy (heavier than the Thunderbolt!), and uses type N connectors. 

But it's low noise, and you only have one antenna and feedline to worry about. 

73 bob k6rtm 

Message: 3 
Date: Sun, 26 Sep 2010 15:56:47 -0400 
From: "Heathkid" <heathkid at heathkid.com> 
Subject: Re: [time-nuts] DS1620 Variants in the Thunderbolt 
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com> 
Message-ID: <795F7AA593814ECB9AA24F0B55CAD45D at D1X25BD10> 
Content-Type: text/plain; format=flowed; charset="UTF-8"; 

Thanks for all the information on the DS1620. 

As it turns out, both of the TBolts (remember I got the from two different 
sellers and appear identical) have the Trimble OCXO, v3.00 firmware, but the 
DS1620's are marked as follows: 



Interestingly, the first one appears to have been swapped out at some point 
(flux residue all over the chip / had to clean it off to read the markings). 
I've already ordered another "D1" to swap out the "E2" but really need to 
get them both up and running (still trying to figure out how to mount the 
antennas!) and see how much difference there really is. 

73 Brice KA8MAV 

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