Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards
On 14/02/2017 12:24 AM, Chris Albertson wrote: Pretty dramatic difference between a "real" serial port and USB. Like two orders of magnitude or more. If you computer lacks a serial port, just buy a new computer. The Raspberry Pi or the like costs about $40 the serial port has a pin that is tied to an interrupt. If you read the code associated with that interrupt it is like maybe 4 or 6 lines of C and VERY simple. ... Great for picking up the PPS. Know of any with an Ethernet port, preferably two, that aren't run from a USB controller? Michael ___ 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.
Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards
Pretty dramatic difference between a "real" serial port and USB. Like two orders of magnitude or more. If you computer lacks a serial port, just buy a new computer. The Raspberry Pi or the like costs about $40. But the money you save on electric power will pay off that $40 in less than a year. Why is this? the serial port has a pin that is tied to an interrupt. If you read the code associated with that interrupt it is like maybe 4 or 6 lines of C and VERY simple. USB on the other hand is packetized. Nothing happens on till a block of data comes in and then it is quite complex so the time from the pin going active to the internal counter being sampled is quite variable I said "two orders of magnitude" it might even be three orders. On Mon, Feb 13, 2017 at 8:07 AM, Ruslan Nabioullin wrote: > Hi, generally speaking, what are the performance differences between the > following: 1. direct RS-232 (i.e., what I believe is a standard PCI card > offering RS-232---essentially UARTs interfaced more-or-less directly to the > PCI bus); 2. RS-232 via USB; 3. PPS decoding PCI cards (which might also > have an IRIG input or even an onboard GNSS receiver). > > Thanks in advance, > Ruslan > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/m > ailman/listinfo/time-nuts > and follow the instructions there. > -- Chris Albertson Redondo Beach, California ___ 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.
Re: [time-nuts] Vintage Frequency Measurement
just be careful, because if you under-heat the cathode you could kill it 73 Alex On 2/13/2017 7:11 PM, Bob Camp wrote: Hi On Feb 13, 2017, at 8:15 PM, Scott Stobbe wrote: On Mon, Feb 13, 2017 at 6:41 PM, Bob Camp wrote: I think what you would find is that it *is* a fairly normal AT cut and the data book that came with the instrument plotted out the data for the specific crystal in the device. The usable temperature range was fairly small, so the plot will be pretty linear. Attached is a plot of crystal calibrators temperature stability. Span is roughly 65 degC. Which eyeballs out to be pretty close to an AT. Without knowing the PPM scale there isn’t much way to be sure. One of the other aspects I think is intriguing is the DC PSRR of a vacuum tube crystal oscillator. In the case of a bjt based oscillator you have the C-V relation for depletion capacitance and the base-emitter dynamic capacitance as a function of collector current. I would suspect that for a one active device oscillator, tube vs bjt, a tube crystal oscillator would be less sensitive to small power supply variations (+- 10% ). Except you *do* have miller effect which pretty much messes things up for a triode. A pentode is a bit less sensitive, but you still have issues. Which is a convenient attribute for a poorly/unregulated battery supply in the vacuum tube case. Unless filament current has an appreciable impact on frequency, I wouldn't think so… Umm… e …. check it out :) Oddly enough, I remember a high school physics lab where they had us plot the effect of filament voltage on plate current and gain. Seemed like a weird thing to do to me at the time. Turns out the teacher grew up with microwave tubes that were tuned by varying the filament. Who knew ??? Pretty strange stuff if you ask me. The bigger issue is the tubes get hot. The heat varies with supply voltage. Temperature change is the result. That temperature change messes up oscillator stability. You pretty much have to wait for things to hit equilibrium before you do useful stuff ( = let it warm up for an hour or four). Bob ___ 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. - No virus found in this message. Checked by AVG - www.avg.com Version: 2016.0.7998 / Virus Database: 4756/13950 - Release Date: 02/13/17 ___ 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.
Re: [time-nuts] Vintage Frequency Measurement
Hi > On Feb 13, 2017, at 8:15 PM, Scott Stobbe wrote: > > On Mon, Feb 13, 2017 at 6:41 PM, Bob Camp wrote: > >> >> >> I think what you would find is that it *is* a fairly normal AT cut and the >> data book >> that came with the instrument plotted out the data for the specific >> crystal in >> the device. The usable temperature range was fairly small, so the plot will >> be pretty linear. >> > > Attached is a plot of crystal calibrators temperature stability. Span is > roughly 65 degC. Which eyeballs out to be pretty close to an AT. Without knowing the PPM scale there isn’t much way to be sure. > > One of the other aspects I think is intriguing is the DC PSRR of a vacuum > tube crystal oscillator. In the case of a bjt based oscillator you have the > C-V relation for depletion capacitance and the base-emitter dynamic > capacitance as a function of collector current. I would suspect that for a > one active device oscillator, tube vs bjt, a tube crystal oscillator would > be less sensitive to small power supply variations (+- 10% ). Except you *do* have miller effect which pretty much messes things up for a triode. A pentode is a bit less sensitive, but you still have issues. > Which is a > convenient attribute for a poorly/unregulated battery supply in the vacuum > tube case. Unless filament current has an appreciable impact on frequency, > I wouldn't think so… Umm… e …. check it out :) Oddly enough, I remember a high school physics lab where they had us plot the effect of filament voltage on plate current and gain. Seemed like a weird thing to do to me at the time. Turns out the teacher grew up with microwave tubes that were tuned by varying the filament. Who knew ??? Pretty strange stuff if you ask me. The bigger issue is the tubes get hot. The heat varies with supply voltage. Temperature change is the result. That temperature change messes up oscillator stability. You pretty much have to wait for things to hit equilibrium before you do useful stuff ( = let it warm up for an hour or four). Bob > ___ > 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.
Re: [time-nuts] Vintage Frequency Measurement
On Mon, Feb 13, 2017 at 6:41 PM, Bob Camp wrote: > > > I think what you would find is that it *is* a fairly normal AT cut and the > data book > that came with the instrument plotted out the data for the specific > crystal in > the device. The usable temperature range was fairly small, so the plot will > be pretty linear. > Attached is a plot of crystal calibrators temperature stability. Span is roughly 65 degC. One of the other aspects I think is intriguing is the DC PSRR of a vacuum tube crystal oscillator. In the case of a bjt based oscillator you have the C-V relation for depletion capacitance and the base-emitter dynamic capacitance as a function of collector current. I would suspect that for a one active device oscillator, tube vs bjt, a tube crystal oscillator would be less sensitive to small power supply variations (+- 10% ). Which is a convenient attribute for a poorly/unregulated battery supply in the vacuum tube case. Unless filament current has an appreciable impact on frequency, I wouldn't think so... ___ 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.
Re: [time-nuts] Vintage Frequency Measurement
Agreed, it's probably reasonable to say that a real absorption wavemeter would (a) have to have a meter or some other visual indicator; and (b) likely be powered exclusively by the energy its tank circuit "absorbs." The BC221/LM boxes fall a little short of both requirements. -- john, KE5FX Miles Design LLC > -Original Message- > From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob > Camp > Sent: Monday, February 13, 2017 3:47 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Vintage Frequency Measurement > > Hi > > With a VFO running, you have a heterodyne frequency meter. That is (at > least to me) > a very different device than an absorption wave meter. I know way to put > power into > a BC-221 and use it as an absorption device. > > I’m not in any way saying that the LM or the 221 are less useful. They are > still > to this day > great little boxes. The just aren’t (by my understanding) wave meters. That > term describes > a different device that works a different way. > > Bob ___ 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.
Re: [time-nuts] Vintage Frequency Measurement
Hi > On Feb 13, 2017, at 10:35 AM, Scott Stobbe wrote: > > Hi Mike, > > First of all, Wow what an interesting read, thanks for sharing some of the > history and your experiences with the 105. A second thanks for uploading > the manual, which I found to be a great read, as with most old test & > measurement product manuals, they are far from just marketing fluff. > > Bare with me, I'm not well versed in early radio history, but, I also found > it neat they choose to crystal calibrate on the 3rd harmonic of the VFO to > help prevent injection lock and for increased sensitivity (but that may be > true of all frequency meters of the era, don't know). > > Based on the manual, the thermometer is thermally mounted to crystal > holder, allowing one to temperature compensate the crystal calibration > point. I didn't see a mention as to what crystal cut they used. I would > guess it is one with a flat tempCo with no turning points for the linear > thermometer scale to be used effectively. I think what you would find is that it *is* a fairly normal AT cut and the data book that came with the instrument plotted out the data for the specific crystal in the device. The usable temperature range was fairly small, so the plot will be pretty linear. Bob > > Attached is a plot taken from the manual, the VFO stability strip-chart > > On Mon, Feb 13, 2017 at 12:24 AM, Mike Naruta AA8K wrote: > >> >> On 02/12/2017 01:08 AM, Scott Stobbe wrote: >> >>> I was inspired recently coming across a Lampkin 105 frequency meter, as to >>> how frequency measurement was done before counters. >>> >>> Certainly zero-beating a dial calibrated oscillator, would be one >>> approach. >>> >>> Is there a standout methodology or instrument predating counters? >>> >>> >> Hi Scott. That Lampkin 105 is a sophisticated design. I did some >> research that you might be interested: >> >> For the 2015 November ARRL Frequency Measuring Test, I fired up my old >> Lampkin frequency meter. For their 100th Anniversary, QST was encouraging >> the use of “vintage” equipment for the FMT, and the Lampkin was designed in >> the 1930s. >> >> I (AA8K) did surprisingly well, coming within 322 Hertz on 40 meters, 202 >> Hertz on 80 meters, and 18 Hertz on 160 meters. >> >> The Lampkin 105-B was designed by Guy Forest Lampkin BSEE, who got his >> first ham license in 1924. In 1933 he was selling the model 102, that was >> checked with the Federal Radio Commission and commercial laboratories to be >> within 3 to 15 cycles at 1,712 kc. He was also selling a “foundation unit” >> of the Precision Micrometer, Band Spread condenser, Special Isolantite coil >> form, Temperature compensator, Adjustable pad condenser, and complete >> circuit details for $14.50. Lampkin Laboratories moved from 146 West >> McMillian Street, Cincinnati, Ohio to 8400 Ninth Avenue N.W., Bradenton, >> Florida 33506 in 1935. It was incorporated in 1942. Precise Power >> Corporation had acquired Lampkin Laboratories in 1971/Oct. At that time >> Lampkin Labs had 17 employees and wasn't advertising their 107B Digital >> Frequency Meter because they were selling as fast as they could make them. >> The last known address was 12297 US Highway 41 North, Palmetto, Florida >> 34221. Voluntary Dissolution 2007/April/27. >> >> The 105-B is a fascinating design, able to measure frequency to 0.0025%. >> Signals can be measured from 100 KHz to 175 MHz. It works similarly to >> the later World War II BC-221 frequency meter. It can receive, or transmit >> the internal oscillator 2330-2670 KHz. A diode generates harmonics that >> can beat against the signal to be measured. >> >> The variable condenser has a precision-machined tubular stator and a >> tapered, conical rotor. They are made from steel and brass and copper >> plated. The parts are proportioned such that, due to the differential >> thermal expansion, the temperature coefficient of capacity is a few parts >> per million per degree Celsius at all positions of the rotor. The rotor is >> moved in and out of the stator on a micrometer screw. The large dial and >> turns counter give a dial band spread of 8,000 divisions over 42 feet! The >> inductor is wound on a six-ribbed form of polystyrene. Since the thermal >> expansion of polystyrene is greater than copper, as coil temperature >> increases, the turns are pulled from circular to hexagonal, and the average >> diameter of the coil decreases. >> >> Thermal design is utmost in the Lampkin MFM. In addition to the L/C >> circuit, the vacuum tubes and circuitry are mounted on the rear, with the >> chassis cut-away to keep it from heating the front where the L/C and >> calibration crystal are mounted. Wires connecting the L/C and crystal are >> very small diameter to reduce the thermal path. Even the power transformer >> is bolted to the outside of the cabinet. The 7.5 MHz calibration crystal >> (no oven) is held against the front panel. There is a glass thermomete
Re: [time-nuts] Vintage Frequency Measurement
Hi With a VFO running, you have a heterodyne frequency meter. That is (at least to me) a very different device than an absorption wave meter. I know way to put power into a BC-221 and use it as an absorption device. I’m not in any way saying that the LM or the 221 are less useful. They are still to this day great little boxes. The just aren’t (by my understanding) wave meters. That term describes a different device that works a different way. Bob > On Feb 13, 2017, at 5:52 PM, John Miles wrote: > > You could use it as an absorption wavemeter, in its broadest sense of a > passive tuned circuit with an indicating load. The headphone jack was > normally used to calibrate the VFO against a harmonic of the internal crystal > oscillator, but it could zero beat an external source as well. It stretches > the nomenclature but the job still gets done. > > Even as late as the 1980s a BC-221 (or LM-10 in my case) was a useful piece > of gear. As Bill suggests, all the qualities needed for indulgence in > time/frequency nuttery were present. They were incredibly expensive to > build, being engineered to survive bombs that hadn't even been invented yet, > and they could perform at levels beyond any reasonable requirement. I used > one for frequency spotting on my even-older Philco console. > > Just the other day, I visited the Spark Museum in Bellingham, WA, and was > amused to see one over by the 'Titanic' exhibit. Not a curation mistake on > their part, just a consequence of having more cool stuff than exhibit space. > I had to restrain myself from reaching down and giving the dial a tweak. > > -- john, KE5FX > Miles Design LLC > >> Hi Bob: >> >> The BC-221 is usually referred to as either a Frequency Meter or a >> Heterodyne Frequency Meter. >> > > ___ > 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.
[time-nuts] TICC shipments
Hi All -- The production batch of TICCs has arrived at TAPR and the first shipments to customers are going out today. It will probably take another few days to get them all sent -- there are nearly 100 units going out the door! As previously mentioned, the TICCs have been loaded with software and tested, so they should be "plug and play" when they arrive. I've been working on the user guide, and while it's still a bit rough, I think it's fairly complete. You can download it from https://github.com/TAPR/TICC/tree/master/docs/TAPR%20TICC%20User%20Manual.pdf The installed software version is "20170108.1" Since then, I've implemented a couple of new features, including semi-tested code for slaving multiple TICCs into a 4 or more channel counter (semi-tested because I still only have one unit!), and a polling capability in addition to the normal "talker" mode. The updated source code is available at https://github.com/TAPR/TICC/tree/master/TICC If you don't want to install the Arduino IDE and build/upload the code yourself, https://github.com/TAPR/TICC/tree/master/binaries contains a compiled version, as well as a simple Windows tool to upload it into the Arduino. The User Manual has instructions on how to do the upload. Enjoy! John ___ 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.
Re: [time-nuts] Vintage Frequency Measurement
You could use it as an absorption wavemeter, in its broadest sense of a passive tuned circuit with an indicating load. The headphone jack was normally used to calibrate the VFO against a harmonic of the internal crystal oscillator, but it could zero beat an external source as well. It stretches the nomenclature but the job still gets done. Even as late as the 1980s a BC-221 (or LM-10 in my case) was a useful piece of gear. As Bill suggests, all the qualities needed for indulgence in time/frequency nuttery were present. They were incredibly expensive to build, being engineered to survive bombs that hadn't even been invented yet, and they could perform at levels beyond any reasonable requirement. I used one for frequency spotting on my even-older Philco console. Just the other day, I visited the Spark Museum in Bellingham, WA, and was amused to see one over by the 'Titanic' exhibit. Not a curation mistake on their part, just a consequence of having more cool stuff than exhibit space. I had to restrain myself from reaching down and giving the dial a tweak. -- john, KE5FX Miles Design LLC > Hi Bob: > > The BC-221 is usually referred to as either a Frequency Meter or a > Heterodyne Frequency Meter. > ___ 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.
Re: [time-nuts] Vintage Frequency Measurement
On 2/13/2017 12:56 PM, Brooke Clarke wrote: Wes: Is this the patent for the IMPATT diode power amplifier? https://patents.google.com/patent/US3931587 No. As I recall the designer (or at least a prime mover) was a guy named Eisenhart. The Hughes organization at the time had engineering done at Conoga Park and production here in Tucson. I was in an auxiliary wing of the Conoga Park division located in Tucson to support production. Engineering didn't think we were smart enough to build the stuff here and thought it should be built at Hughes Electron Dynamics Division in Torrance. We of course thought otherwise so I was tasked to live at Conoga Park for six months to learn the system. When I came back we broke I don't know how many rules to build two prototype transmitters on the factory floor using hourly assembly workers. Lotsa fun. BTW, you and I have met. It was 27 years ago almost to the day! (February 15, 1990) I know because I still have the trip report I wrote after visiting FEI to review your design for an automatic test position for testing detector diodes. In a serious amount of understatement, I described you as "a very capable individual" but one who is spread too thin. Wes ___ 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.
Re: [time-nuts] Vintage Frequency Measurement
On 02/13/2017 10:35 AM, Scott Stobbe wrote: Hi Mike, First of all, Wow what an interesting read, thanks for sharing some of the history and your experiences with the 105. A second thanks for uploading the manual, which I found to be a great read, as with most old test & measurement product manuals, they are far from just marketing fluff. Bare with me, I'm not well versed in early radio history, but, I also found it neat they choose to crystal calibrate on the 3rd harmonic of the VFO to help prevent injection lock and for increased sensitivity (but that may be true of all frequency meters of the era, don't know). Based on the manual, the thermometer is thermally mounted to crystal holder, allowing one to temperature compensate the crystal calibration point. I didn't see a mention as to what crystal cut they used. I would guess it is one with a flat tempCo with no turning points for the linear thermometer scale to be used effectively. Attached is a plot taken from the manual, the VFO stability strip-chart Hi Scott, I don't know what crystal cut they used. It took me weeks of searching just to find what you read. It would be interesting to learn how Lampkin calibrated the Lampkin 105. Line voltage is critical. I was breezing along with 18 Hertz on 160 meters, then the line voltage here moved around for the 80 and 40 meters tests. I heard the drift and knew that my calibration chart was not very useful at that point. I like the portion of the manual that tells about building a box out of Celotex with a plastic front to avoid drafts. Celotex was an insulated ceiling tile that used to contain asbestos. It sure looked nice on the ceilings in our house. We used to spray our rooms with DDT too. It explains a lot. Did you see the photos that I uploaded to Mods.DK? I like that variable capacitor used for calibration. Simple, but effective. ___ 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.
Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards
Yo Ruslan! On Mon, 13 Feb 2017 11:07:49 -0500 Ruslan Nabioullin wrote: > Hi, generally speaking, what are the performance differences between > the following: 1. direct RS-232 (i.e., what I believe is a standard > PCI card offering RS-232---essentially UARTs interfaced more-or-less > directly to the PCI bus); 2. RS-232 via USB; 3. PPS decoding PCI > cards (which might also have an IRIG input or even an onboard GNSS > receiver). #2 will have a lot higher jitter than #1. On a #2 you can expect 500 micro second best timing. On a #1 you can get to 1 micro second. On a RasPi using GPIO you can get to 500 nano second. Data available on request, but better on the de...@ntpsec.org list. RGDS GARY --- Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703 g...@rellim.com Tel:+1 541 382 8588 Veritas liberabit vos. -- Quid est veritas? "If you can’t measure it, you can’t improve it." - Lord Kelvin ___ 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.
Re: [time-nuts] Vintage Frequency Measurement
The BC-221 was the backbone of WW2 communications. How else were all those sloppy BC-348's and AR-13's set to the called-for frequencies? Same for shipboard. Don On 2017-02-13 13:05, Brooke Clarke wrote: Hi Bob: The BC-221 is usually referred to as either a Frequency Meter or a Heterodyne Frequency Meter. -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Original Message Hi Ok, so how does that make a BC-221 a wave meter? Bob ___ 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. -- Dr. Don Latham PO Box 404, Frenchtown, MT, 59834 VOX: 406-626-4304 ___ 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.
Re: [time-nuts] Vintage Frequency Measurement
Hi Bob: The BC-221 is usually referred to as either a Frequency Meter or a Heterodyne Frequency Meter. -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Original Message Hi Ok, so how does that make a BC-221 a wave meter? Bob ___ 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] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards
Hi, generally speaking, what are the performance differences between the following: 1. direct RS-232 (i.e., what I believe is a standard PCI card offering RS-232---essentially UARTs interfaced more-or-less directly to the PCI bus); 2. RS-232 via USB; 3. PPS decoding PCI cards (which might also have an IRIG input or even an onboard GNSS receiver). Thanks in advance, Ruslan ___ 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.
Re: [time-nuts] Vintage Frequency Measurement
Hi: Here's a GR 358 wavemeter from the 1920s. Someone noticed the GR logo after I made the web page that led to it's identification. Hence the generic page URL. http://www.prc68.com/I/Wavemeter.html Covers 14 to 220 Meters (21 to 1 MHz) in four bands selected by which inductor you connect to the variable capacitor. Resonance indicated by pilot light bulb. The peak indication depends on the system Q and so at higher frequencies is not very good. The microwave cavity wavemeters attached to the message from Wes have a much narrower peak and so are more accurate. Wes: Is this the patent for the IMPATT diode power amplifier? https://patents.google.com/patent/US3931587 -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Original Message I have a General Radio Type CAG-60098-A Precision Wave Meter made for Navy Department - Bureau of Ships according to the nameplate. According to Wikipedia that would date it between 1940 (when bureau of ships was created) and 1966 (when abolished). It has an inductor in sort of a "hockey puck" labeled 16-50 kc that plugs into a socket on the front panel. Inside is a very nicely made variable capacitor with a vernier drive. It has been a while since I had it apart, but there is a diode in series with the meter and not much else as I recall. The meter scale is 0-200 (microamp?) and the capacitor scale is 0-75 with no other marking. I have no manual, but I assume there were other inductors for different frequency ranges with a calibration chart to interpret the 0-75 reading. It must have been made to test transmitters by tuning for peak reading on the meter and determining the frequency from the dial reading. a different Alan (KE7AXC) On Sun, Feb 12, 2017 at 5:47 PM, Alan Melia wrote: Hi Dan yes that is 5e-6 about all an unstabilised (temp) AT could hold for any period. I guess there were no WWV or MSF signals around then. When a good source was available off-air it was possible to do better than that. In service it was probably "dont waste time trying to better the minimum requirement. The transmitter you are looking for wont be that accurate or stable" In 1960s I saw several BC-221s in the racks at the Rugby LF and HF stations acting as standby frequency sources (VFO) for rapidly running up a transmitter on an unusual frequency (not a normal route) for which they did not have a crystal available. Alan G3NYK - Original Message - From: "Dan Rae" To: "Discussion of precise time and frequency measurement" < time-nuts@febo.com> Sent: Sunday, February 12, 2017 11:11 PM Subject: Re: [time-nuts] Vintage Frequency Measurement To put BC-221 things in perspective, the 1 Mc/s reference crystal was adjusted, according to the manual, to within 5 c/s... Things have come a ways since! Dan ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/m ailman/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/m ailman/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. ___ 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.
Re: [time-nuts] Vintage Frequency Measurement
On Sun, Feb 12, 2017 at 8:39 AM, Dan Rae wrote: > On 2/11/2017 10:08 PM, Scott Stobbe wrote: > >> I was inspired recently coming across a Lampkin 105 frequency meter, as to >> how frequency measurement was done before counters. >> >> Certainly zero-beating a dial calibrated oscillator, would be one >> approach. >> >> >> Google BC-221 and you may get some idea of how those worked. I just wish > I could find the one hidden in my garage :^) To they very long list of individuals who pointed out the BC-221, many thanks. What a endless treasure trove of great material. Double thanks, to those who have made commitments to document and share the history online, such as Alan M, Tom B, Brooke C, and others ___ 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.
Re: [time-nuts] how many seconds out does GPS discipline being to improve Rubidium stability?
Surely you just loop it through two counters using a T-piece, with those counters set to high impedance input, then only terminate the final one? Peter On 12 February 2017 at 18:16, gkk gb wrote: > That is an interesting suggestion (thanks), and would indeed work for me > if it is possible to split the DUT signal into 3 signals in a such a way > that wouldn't affect measurements for ADEV, TDEV, MTIE. But I'm thinking > anything active would introduce it's own noise into the signal and change > the data. Has this technique been used to success in the past? > > ___ 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.
