Re: [time-nuts] HP 10811 stabilizing time
C12 and C15 on the support board are for peaking the multiplier/amplifier for the external standard input. The unit accepts 1MHz, 5MHz or 10MHz for the external reference frequency. The capacitors tune the external input to 10MHz for the counter to use as the reference. Cheers, Dave M Alberto di Bene wrote: On 2019-07-23 13:01, Charles Steinmetz wrote: The later HP5328 "oscillator helper" boards have EFC pots for fine tuning the timebase frequency. This includes the US military versions that are so prevalent in the US. I have schematics showing this with both the 10544 (support board 05328-60027) and 10811 (support board 05328-60038) oscillators (production shifted from the 10544 to the 10811 during the 5328's run). I found on the surplus market a board with a 10811-60111 OCXO. The board is marked 5328-20027. I suppose it is for the HP5328 counter. There is a trimmer marked "Fine Adjust" and two capacitor trimmers marked C12 and C15. I suppose the "Fine Adjust" trimmer is for the EFC, but don't quite understand what those C12 and C12 trimmers are for... Anybody knows ? Is there any schematics of this board lying around ? Thanks. 73 Alberto I2PHD ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] AN/URQ-10A standard docs
Walter Shawlee 2 wrote: Does anybody have the manual for this old standard? mine works, but is a bit high, and needs internal adjustment, and a new battery pack. pretty good condition for this old unit, and the 5MHz output is only 4.8Hz off after heaven only knows how many years in a dark corner. it's only been running for 12 hours, so it might drift in after 30 days at the oven temperature, but my offset adjustment is maxed out. I have had good luck converting the older 5Mhz standards to 10Mhz using a cheap chinese doubler board off ebay and a 10Mhz bandpass filter. the results were great (although about 6dB down from the original level), and made them a bit more useful around the shop as an external reference. Any PDF would be appreciated. All my web searches were total dead ends so far. all the best, walter Download Navships 0967-170-3010 for the URQ-10A at http://www.navy-radio.com/manuals/urq10a-man-0967-170-3010-6609.pdf Seems to be pretty complete, with schematics, maintenance and calibration. Wish I had a URQ-10A; they were pretty good instruments in their day. Cheers, Dave M ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Building new pods for the Spectracom 8140 using modern components
Good work on the project, Julien. I have a couple of the 8140 distribution amps, one of which I use in my shop. Instead of buying the line taps that are supposed to be used with the 8140, I just disabled the 12V riding on the output signal coming out of the amp. I have another unit as a spart, but not modified (yet). Your pods seem to be good replacements for the line taps... Do you plan to publish the details of your pods (schematics & PCB design)? I might be tempted to build a few for my own use. Thanks for posting your project. Nice work. Dave M Julien Goodwin wrote: Slightly edited down from my blog, if you want the full thing with photos see: https://laptop006.livejournal.com/60862.html I've mentioned a bunch of times on the time-nuts list that I'm quite fond of the Spectracom 8140 system for frequency distribution. For those not familiar with it, it's simply running a 10MHz signal against a 12v DC power feed so that line-powered pods can tap off the reference frequency and use it as an input to either a buffer (10MHz output pods), decimation logic (1MHz, 100kHz etc.), or a full synthesizer (Versa-pods). It was only in October last year that I got a house frequency standard going using an old Efratom FRK-LN which now provides the reference; I'd use a GPSDO, but I live in a ground floor apartment without a usable sky view, this of course makes it hard to test some of the GPS projects I'm doing. Despite living in a tiny apartment I have test equipment in two main places, so the 8140 is a great solution to allow me to lock all of them to the house standard. Another benefit of the 8140 is that many modern pieces of equipment (such as my [HP/Agilent/]Keysight oscilloscope) have a single connector for reference frequency in/out, and should the external frequency ever go away it will switch back to its internal reference, but also send that back out the connector, which could lead to other devices sharing the same signal switching to it. The easy way to avoid that is to use a dedicated port from a distribution amplifier for each device like this, which works well enough until you have this situation in multiple locations. As previously mentioned the 8140 system uses pods to add outputs, while these pods are still available quite cheaply used on eBay (as of this writing, for as low as US$8, but ~US$25/pod has been common for a while), recently the cost of shipping to Australia has gone up to the point I started to plan making my own. By making my own pods I also get to add features that the original pods didn't have[1], I started with a quad-output pod with optional internal line termination. This allows me to have feeds for multiple devices with the annoying behaviour I mentioned earlier. The enclosure is a Pomona model 4656, with the board designed to slot in, and offer pads for the BNC pins to solder to for easy assembly. This pod uses a Linear Technologies (now Analog Devices) LTC6957 buffer for the input stage replacing a discrete transistor & logic gate combined input stage in the original devices. The most notable change is that this stage works reliably down to -30dBm input (possibly further, couldn't test beyond that), whereas the original pods stop working right around -20dBm. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 4.19 MHz xtal
Neville Michie wrote: Hi, I have a Philips quartz clock that runs on 4.19 MHz. In spite of the high frequency it still runs for years on a C cell. Can any of the quartz crystal gurus explain why this frequency was chosen? I believe that this clock was supposed to have better than usual accuracy. Philips always had a high level of engineering excellence. cheers, Neville Michie Your clock's crystal is more likely 4,194304 Mhz, which can be divided down to 1Hz, which is used by your clock to keep time to the second. Dave M ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
