[time-nuts] Spectracom 8140T Line Tap Schematic

gandalfg8 at aol.com gandalfg8 at aol.com
Tue Jun 12 18:05:09 EDT 2018

This is probably now well past its sell by date but over the years there have been a number of requests here for schematics of the Spectracom 8140T Line Taps as used with the 8140 Frequency Distribution Amp.

 The standard reply has always been that no schematics were available from Spectracom, which is true, and that tracing one out wasn't a viable option either as the 8140T modules were potted in some kind of foam, but a few years ago I made an interesting discovery about the 8140T that enabled me to quickly produce a sketched schematic followed by the intention of posting it here just as soon as I'd turned it into something a bit more legible.

Unfortunately those good intentions got left behind as other projects came along and it was only the recent posts regarding removal of the DC feed from the outputs of the 8140 that reminded me this was still a work in progress, or more to the point, remarkably little progress:-(

BTW, with reference to removing the DC supply on the 8140 outputs, although it is possible to effect this by removing internal components  by far the most straightforward arrangement, and most easily reversible, would be to use an inline DC blocking capacitor of between say 100 and 470 nF, just as is already very commonly used with  remotely powered HF active receiving antennas.

Anyways back to the 8140T schematic, I have now posted on mediafire the schematic of an 8140T10, the basic 10MHz in 10MHz out version, complete with far too many assorted internal photos plus details of said interesting discovery, with extra brownie points to anyone who might already be thinking foam and cardboard sandwiches:-)


Nigel, GM8PZR


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