[time-nuts] Re: Looking for interconnection information for Spectracom 8171A clock

Carl Walker wa1raj at arrl.net
Wed Apr 6 18:44:05 EDT 2005

Sorry for the bandwidth, but I thought this information might be useful to archive for the next person that goes searching for information on the Spectracom 8171A clock without luck.

I spent a bit of time looking at the circuit and old data books list night, and got my unit up and running with the 8164.

As it turns out, the 15 pin Molex interconnect _IS_ a straight through connection to an 8164 type receiver. There are some oddities that throw off the casual observer - like only connecting to the inverting side of an RS-422 driver, but otherwise it's fairly straight forward.

For those interested in trying to connect one of these to some other type of receiver, I'll give a brief signal description;

Pin 	Function
4	Phase Lock - TTL active high indication the receiver is locked to WWVB
7	Time Code - TTL high when WWVB is at full power, low when WWVB is -10 db
9	Major Alarm - half an RS-422 signal - logic 1 when there's a fault
12	10 MHz standard - inverting half of RS-422 buffered 10 MHz from the xtal standard
13	10 MHz phased locked to WWVB - this is the noisy 10 MHz that's locked to the 60 KHz broadcast
4,6,10,14 and 15 are all grounds.

It's unknown how the phase locked WWVB 10 MHz is used relative to the xtal standard 10 MHz, but there's a family of counter/timer devices in there for the CPUs; they may do something algorithmically with the differing clock sources. There's external 1 MHz clock backup input on the back panel as well as an internal PCB footprint for a TCXO. Must have been a bunch of options for this beast.

Hope that's a help to the next poor soul that needs some data on this device, and again sorry for the list bandwidth.


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