[time-nuts] Efratom FRS 10mhz rubidium frequency oscillator+ board

wje wje at quackers.net
Mon Jun 1 21:10:02 EDT 2009

Much to my amazement, I did find some notes on the DB-25 15Mhz board pinout:

1 +24V
2 +24V
3 Gnd
4 Gnd
6 Freq Adj (this goes directly to the FRS, the board does nothing with it)
7 Gnd
8 -Enable +
10 Enable - (notes are unclear on 8, 10, 11, 12. See note below)
11 To 11 on other unit
12 to Fault+ on other unit
13 External 1 (this goes to whatever the dual-osc unit plugs into, 
function unknown)
15 External 2
16 Fault +
17 Fault -
18 Ready +
19 Ready -
20 Gnd
21 Standby +
22 Standby -

Pins with no assignment are not used.

Note - as mentioned in the previous post, two units cross-monitor each 
other. One is selected as primary by a manual switch. The notes I found 
didn't cover the details, but if I remember correctly, +/- enable 
selects the primary (one unit is enabled, one disabled). Then, a fault 
assertion by the primary will cause the secondary to become primary. The 
secondary's 15Mhz output is disabled; only the primary provides an output.

The control lines are all TTL compatible, and are always provided in 
complimentary pairs.

Finally, these pinouts came from tracing a live unit and observing 
behavior. They might not be completely accurate, but they're close.

Bill Ezell
They said 'Windows or better'
so I used Linux.

GandalfG8 at aol.com wrote:
> In a message dated 01/06/2009 02:23:46 GMT Daylight Time, wje at quackers.net  
> writes:
> I did at  one time have the connector pinout info, but since the board is 
> fairly  useless, I'm not sure I kept it. It does have some nice TNC 
> connectors and  a nice crystal filter, if you happen to need a 15Mhz  
> filter.
> -----------
> Hi Bill
> I did realise, after my posted request, that what was described in the  
> auction as a 15MHz oscillator was actually a 15MHz filter with 36KHz  bandwidth.
> Not sure that I need one either:-), but if you do still have the connector  
> pinout I'd be grateful for a copy.
> regards
> Nigel

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