I was the project manager of the 5334B, which was a reduced factory cost replacement for the 5334A. Of course I thoroughly evaluated the 5334A before deciding what changes to make. I will apologize on behalf of the company for that oscillator in the 34A. It is a really poor design. Giving the 5334A project team the benefit of the doubt, I guess the philosophy was that the built in oscillator is for very non-critical applications and they didn't want to increase the cost to those users but putting a decent oscillator in the standard counter. Many users were like us and had a house frequency standard, so we never used a built in oscillator in a counter. Due to time and cost pressures, we unfortunately inherited the same oscillator in the 5334B.
So in both products, please plan on getting a 10811 or using an external frequency reference. Rick Karlquist N6RK Project manager, 5334B, circa 1986 Colin Bradley wrote: > I recently took one of my 5334As off of the house standard to lend to a > friend. I thought it a good idea to check the onboard oscillator before > lending it out. Both of my 5334As lack Opt 10 oscillators. This > particular unit was almost 40Hz high in frequency. I tried to set it to > frequency and had trouble getting it closer than 2Hz. The set-ability was > very poor. I checked the service manual and found that HP only specified a > final frequency within 8Hz. I can now see why. I then turned the > instrument off for 12 hours. The next day I powered the unit back up. The > oscillator was 20Hz higher than where I had measured it at shutdown the > night before. It took well over an hour for it to re-stabilize and > overshot the previous set point by 2Hz. At this point I decided to lend a > Heathkit IM-2420 to the friend and continued experiments with the 5334A. > > I now took the second 5334A down and ran the same tests on it. This > instrument was somewhat better but still shared many of the problems the > first unit. > 1) 60+ minutes to stabilize after power-up. Oscillators > would start out 9 19Hz high and settle in at +- 1Hz. > 2) Poor retrace at turn on. Final settling frequency can > vary by 1Hz. > 3) Poor set-ability due to the ceramic trimmer. > 4) Oscillator pulling of 2 3Hz when I connected another > counter to the rear panel oscillator jack. The oscillator buffer is on the > same ECL chip as the oscillator. > After looking at the circuit I decided that a new TCXO would be a better > solution than trying to modify the existing circuit for better > performance. Since these units are used at room temp most of the time, I > need not worry about a wide temp range specification. > > I set the following goals for the replacement oscillator. > 1) Improvement of stability by an order of magnitude and > set-ability of two orders of magnitude. > 2) Replacement to be built on a circuit board that would > mount in the oven oscillator connector on the main circuit board. > 3) Use of the full time 24vdc at this connector to power > the oscillator at all times. Use of an on-card battery supply for > oscillator backup. > 4) Cheap > 5) Use of readily available TCXO oscillator module. After > checking Mouser and Digi-Key I settled on a Mouser supplied FOX801BE 10mHz > unit @ $13.46. to start my experiments. This oscillator draws only 2ma. > and frequency is set by an external trim pot. > > I would be interested in the experiences of others with respect to the > performance of their non-oven 5334s (or 5328s) and ideas that support > the design goals. Thanks > Colin > > > > ____________________________________________________________________________________ > Do you Yahoo!? > Everyone is raving about the all-new Yahoo! Mail beta. > http://new.mail.yahoo.com > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts