[time-nuts] Thunderbolt not seeing satellites

Didier Juges didier at cox.net
Fri Jun 11 00:22:35 UTC 2010

The TB has an error flag if there is no antenna connected (open) or if it is shorted. The tboltmon PC software reports these flags, and so does my GPSMon firmware in the fluke.l monitor.

It is possible but unlikely that there would be something wrong with the bias circuit that would not be reported by the TB.


------------------------ Sent from my BlackBerry Wireless thingy while I do other things... 

-----Original Message-----
From: Arthur Dent <golgarfrincham at yahoo.com>
Date: Thu, 10 Jun 2010 15:49:00 
To: <time-nuts at febo.com>
Subject: [time-nuts] Thunderbolt not seeing satellites

It may or may not tell you what's wrong but a quick check of the 
Thunderbolt would be to put a tee in series with the antenna and 
see if the unit is supplying +5 volts under load to the antenna.You 
have verified that the antenna works with a second unit so you can 
rule that out. Where you are getting some data from Lady Heather 
showing it picks up at least 1 satellite I suspect the +5 Vdc power 
supply that supplies the logic is functioning properly or you'd probably 
see no data. The +12 Vdc mainly supplies the oscillator so if that's 
working properly, the +12 is probably ok, It may well be a component 
in the receiver section on the Thunderbolt board.

The Thunderbolt receiver board I looked at had a Macom AM50002 amplifier 
( http://cs.utsource.net/goods_files/pdf/71/71500_MACOM_AM500002.pdf ) 
located on the top side of the board directly behind the antenna connector.
The bottom side of the board has D1, Q1, and R1 directly behind the 1PPS 
connector and they apparently supply the +5 to power the antenna. Those 
two areas would be likely suspects.

time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

More information about the time-nuts mailing list