[time-nuts] Racal 2201 Frequency Counter

GandalfG8 at aol.com GandalfG8 at aol.com
Thu Sep 10 16:07:26 UTC 2009

Following recent discussions about the merits, or otherwise, of the Racal  
1991/92 counters, is anybody familiar with the 225MHz two channel 2201  
which was marketed as being the 1991 replacement?
With an optional 1.3GHz third channel fitted it was  also offered as the 
replacement for the 1992.
Although a search throws up plenty of sites with the data sheet I get  the 
impression it's no longer a current model but could be wrong on that.
I'd never even heard of it until very recently but I've just bought  one 
that seems to be unused and am currently running it  alongside a 1991.
Aside from a different panel layout it does seem functionally very similar  
to the 1991, complete with the usual drifting TCXO, but one immediately  
noticeable omission compared to the 1991 is the ability to shift the  display 
one place left to up the resolution.
That, plus an inconvenient arrangement that requires setting an internal  
link to switch between internal and external frequency standards, has 
dampened  my initial enthusiasm a bit.
Another really odd quirk for something that seems to be no more  than 4 or 
5 years old is the use of a lithium battery backed memory module  for "non 
volatile" storage of user settings.
An optional D to A converter, that would provide a DC output directly  
proportional to frequency for driving chart recorders etc, seems like it could  
be useful but unfortunately it isn't just a plug in option that  can be 
added later.
The necessary components are mssing from the motherboard on this  one:-(
I've downloaded a user manual so no problems with using it but would be  
interested to hear from anyone who might be aware of any other potential 
quirks  or problems.
If anyone has a pdf copy of the service manual that would also be much  

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