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

Rex rexa at sonic.net
Tue Jun 16 06:24:46 EDT 2009


I posted this in reply to the original question in the Microwave list...

What you are describing is not an FRS-C but a box that contains an 
FRS-C. I think it was some kind of Telco package. The box produces 
versions of the 10 MHz from the FRS-C on two of the TNC's and a 15 MHz 
sine generated from the 10 MHz on the third.

I bought one of these in 2004 and did some digging to try to figure out 
what is inside. The results of this are in a document I created, here:
ftp://ftp.sonic.net/pub/users/rexa/FRSrubidium/rubid_notes.pdf

There's a version of the FRS-C manual in that same FTP directory.

My recollection is that the FRS-C is not very clean in phase noise. The 
document should have all you need to get it working. If you learn any 
more about what the mystery pins (11 - 25 on the DB-25) might have been 
for, I'd be interested to hear about it.

-Rex, kk6mk

I see from the pin-out below, that some of the unknown pin signals have been given names. Good to know.


GandalfG8 at aol.com wrote:

> 
>Bill's connection info for Lucent FRS module, forwarded as agreed.
>Nigel GM8PZR
> 
>In a message dated 02/06/2009 02:11:10 GMT Daylight Time, wje at quackers.net  
>writes:
>
>Much to  my amazement, I did find some notes on the DB-25 15Mhz board 
>pinout:
>
>1  +24V
>2 +24V
>3 Gnd
>4 Gnd
>5
>6 Freq Adj (this goes directly to the  FRS, the board does nothing with it)
>7 Gnd
>8 -Enable +
>9
>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)
>14
>15 External 2
>16  Fault +
>17 Fault -
>18 Ready +
>19 Ready -
>20 Gnd
>21 Standby  +
>22 Standby -
>23
>24
>25
>
>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
>> GM8PZR
>>
>>  
>>    
>>
>
>
>
>
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