Hi Julien,
Earlier replies that discussed removing the DC supply from the 8140 outputs gave me the impression your requirement was to connect directly the outputs of the 8140 without line tap modules, which is what I was addressing with my recent suggestion of a series capacitor, but can see now that's not the case. If you were to build your own termination the same principle would still apply of course but perhaps another option for a reasonably compact solution, aside from a coaxial DC block followed by a 50 ohm termination, might be a DC blocking attenuator followed by a BNC shorting dust cap, as the latter are generally quite small. For example, current Ebay item 332461304064 is a DC blocked 20dB attenuator, they are also available in pairs at a slight discount, and that fitted with a shorting cap would give you a return loss of 40dB, which is probably as good as you'd get from most 50 ohm terminations anyway and would save having to build your own. The VersaTaps phase lock an internal crystal, any frequency between 4 and 20MHz, to the 10MHz input and then provide an output at the crystal frequency or the crystal frequency divided by a fixed integer between 1 and 8,192, so in that sense yes they're a synthesiser but the few I've seen were still supplied preset for a specific frequency. However, "versatile" does not necessarilly mean quick or convenient to reprogram. Aside from perhaps needing to change the crystal the division ratio needs to be set by adding or removing links across pairs of holes in the circuit board. Those holes are on a standard 0.1inch pitch so fitting headers that would take shorting links should be straightfoward enough, and I suspect what was originally intended, but the units I have were supplied preprogrammed using resistor style wire ended zero ohm links mounted above the circuit board and soldered from below. Reprogramming one of these would involve unsoldering and perhaps removing all the connectors etc in order to remove the circuit board, so I'd certainly make darn sure they had headers fitted before being returned to the box! Nigel, GM8PZR -----Original Message----- From: Julien Goodwin <time-n...@studio442.com.au> To: gandalfg8 <gandal...@aol.com>; Discussion of precise time and frequency measurement <time-nuts@febo.com> Sent: Thu, 14 Jun 2018 11:36 Subject: Re: [time-nuts] Spectracom 8140T Line Tap Schematic I'm somewhat tempted to take the schematic and see if I can fit it in the comparatively tiny Pomona boxes, although I have far too many side projects already, enough 10MHz taps, and I still need to do the terminators. The VersaTaps are supposed to be an actual synthesizer IIRC. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
