[time-nuts] Thunderbolt question
paulswedb at gmail.com
Fri Aug 4 18:10:55 EDT 2017
Looked at the pix and yes the ant power are the caps and traces on the left.
Hard to get lightning through most saw filters. There is an inductor to the
right of the am50002 preamp and that would also be a great check. Open
shorted the V should be 1-3V approx. 0 or 5 is bad.
I looked to see if am50002 were available a quick search didn't show
On Fri, Aug 4, 2017 at 5:13 PM, Arthur Dent <golgarfrincham at gmail.com>
> 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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