[time-nuts] Thunderbolt not seeing satellites
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...
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.
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