But I should say that despite the bad oscillator (I think all of four or five of them I own came with the high-stability option; maybe that's why!), the 5334A/B is a really capable counter, and with eBay prices sometimes below $100, they are a great value for money. The fact that there's no fan noise is just a bonus. :-)
John ---- Rick Karlquist said the following on 12/07/2006 04:15 PM: > 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 5334A's 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 5334A's 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 5334's (or 5328's) 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 >> [email protected] >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> >> > > > > _______________________________________________ > time-nuts mailing list > [email protected] > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
