Thank you Nigel, I've also taken a gamble on one of these units and am keeping my fingers crossed that it has a Rb standard in it.
The service manual is most interesting, it looks like I could use one of the two 'loops' to lock a different OCXO, with a little tinkering it could be a very useful unit as there's plenty of space inside for additions and modifications. Are these the references with a rubidium oscillator ? They seem to have similar models with OCXOs etc. http://www.ebay.co.uk/itm/111862884745 Hi Adrian, The T801 first seems to have hit the UK surplus market around 2005/2006, I was told a batch of a couple of hundred, and units from that release were still trickling through until around 2011 at least. These were released by West Yorkshire Police when updating their UHF mobile network and did contain rubidium standards. The T801 contains dual nominal 12.8MHz synthesisers with very fine switched preset adjustment for base station synchronisation. These are locked to an external reference and can accept selected integer frequencies from 1 to 10Mhz and also 12.8MHz. If the internal 10MHz rubidium module is fitted and used as the reference then a short BNC link is required to couple the internal reference output to the external reference input. These were originally sold on Ebay with particular reference to the rubidium module, for most purchasers the 12.8MHz synthesiser board would probably have been of little interest, so I'm surprised to see no reference to the rubidium module with the several recent auctions. This may be due to lack of familiarity on the part of the seller but I certainly wouldn't want to take anything for granted without asking. I'm not sure either if the recent Ebay offerings are tail end leftovers from that first batch or represent a more recent release, but I have seen a number of failures with the rubidium modules in those bought between 2005 and 2011. One at least was physically faulty with others refusing to lock, either at time of purchase or subsequently, I have some of the latter still on the ever growing "to do" pile. According to the manual the rubidium module, where fitted, was originally a Quartzlock TF4010A, but all units I've seen have been fitted with FEI FE5660A modules. This required a degree of modification to the chassis and to the heatsink and the quality of that work is often poor, so quite likely a field "upgrade". The unit also contains a DC-DC convertor to derive the 24 Volt supply for the rubidium module from the 13.8 Volt input. The lock on the front panel is just an ON/OFF keyswitch, if the key is missing all those I've seen have been left in the ON position but it's easily bypassed anyway. I've tried uploading my scan of the manual to Didier's site but gave up after repeated page reset errors, it is now available here...... http://www.mediafire.com/view/0x5sa7o0s9pgc4s/Tait_T801_Frequency_Reference. pdf Regards Nigel GM8PZR _______________________________________________ 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.