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, iw2...@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 _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
