[time-nuts] Thunderbolt question

Arthur Dent golgarfrincham at gmail.com
Fri Aug 4 17:13:47 EDT 2017

Actually that isn't my photo I linked to but one I just Googled. That is
probably a board revision most people don't have but it was the first one
I saw so I used it just to show that the GPS receiver is part of the
only circuit board and not another easily replaceable board like in some
other units.

I just took a couple of photos of the later revision of the board for
anyone interested in seeing what might be fried. In the photo of the
top of the board the signal comes into a filter then to a 25db amp
marked AM50002 by Macom. Above the filter near the input is where the
decoupled +5VDC for the antenna is connected. If you are only reading
0.5VDC, if your're lucky it might only be the amp is fried and that
could be an easy fix. If the 5VDC is ok with the amp input pin lifted,
it might be the only problem. I wouldn't bet on it though. The 4031 I
believe is a 1575.42 SAW filter

The photo of the bottom of the receiver area shows a Sawtek filter and
other parts. At the bottom of the photo is C460, a feedthrough capacitor
and that might be where the receiver output is but where my Tbolts are
working I don't feel the need to look into whether you could connect
the output of a seperate GPS receiver there to make it work.

I do have one Tbolt that has no oscillator. I brought the EFC and 10Mhz
connections to SMA connectors on the back so I can test other oscillators
or GPSDOs that don't have an easy way to monitor of graph the stability
of those units and using Lady Heather gives me a good way to compare the
graphs to ones I'm used to. You might possibly be able to replace the
built-in receiver but it might be easier to buy a working Thunderbolt.



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