[time-nuts] strange hp 5345A option C19

GandalfG8 at aol.com GandalfG8 at aol.com
Wed Aug 21 17:15:53 UTC 2013


Hi Luca
 
There are other items of HP equipment fitted with Ref Out  and Ref In 
terminals joined by an external link, with the intention that  the link is 
removed to connect an external standard to the Ref In terminal,  but in a "normal" 
5345A the external reference is used to phase  lock the internal oscillator 
which means that the unit can't work from an  external reference if the 
internal 10MHz oscillator has been  removed.
 
However, I found some time ago that it is possible, just by fitting a  
single link internally, to drive the counter via an external reference even if  
the internal standard has been removed so I'm guessing that the internal  
standard on this one might have been removed at some time and a previous  
owner has fitted a non original internal standard with a similar provision  to 
bypass the normal arrangement.
 
It should be fairly easy to check just by looking to see if the  original 
HP oscillator is still fitted or whether a different one has been  added.
 
Whether or not this relates to the Option C19 I don't know.
 
Regards
 
Nigel
GM8PZR
 
 
In a message dated 21/08/2013 17:00:21 GMT Daylight Time, iw2lje at gmail.com  
writes:

Dear  all,

I have bought an HP 5345A. It’s ok and I’m  very glad. On the rear
panel it is wrote "OPTION C19" (a little bit  strange!) and there are
two additional BNC installed on the little panel  normally used to
place the HPIB connector when present.

These 2 BNCs  are named REF OUT and REF IN and there is a jumper cable
that connects the  output to the input.

It seems to be a modification made by some user  (very strange: I can’t
understand why to place an extra auxiliary bypass  for the 10 MHz
reference).

Do you have an idea about this strange  modification and about the
strange option C19? Could it be a custom option?  Could the option C19
and the 2 BNC for the reference be  related?

Thanks

Bye

Luca – IW2LJE – Milano –  Italy
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