On Sun, Feb 12, 2017 at 8:39 AM, Dan Rae <danrae@verizon.net> 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

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 <alan.melia@btinternet.com> > 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" <danrae@verizon.net> >> 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. >

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

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

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.

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

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. >

Hi > On Feb 13, 2017, at 10:35 AM, Scott Stobbe <scott.j.stobbe@gmail.com> 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 <aa8k@comcast.net> 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 thermometer >> mounted to the front panel. It is custom-marked with a correction factor >> for that specific unit. I left the Lampkin turned on from October, but the >> temperature soon stabilized. The metal 6J7 tube has the Bakelite cap >> removed, to eliminate changes due to moisture absorption in the Bakelite. >> >> Striking features of the Lampkin are: The very smooth tuning with almost >> zero backlash. Turning the dial clockwise lowers the frequency, but that >> is because the micrometer screw is a right-hand thread and moves the rotor >> into the stator, increasing capacitance and lowering frequency. Increasing >> frequency moves the micrometer post outwards through the center of the >> dial, like Pinocchio's nose growing. The outboard transformer looks clunky >> at first, until you realize why he did it. >> >> Modifications. I replaced the 1 ampere line fuse with a 0.5 ampere for >> additional protection. (I have been wary of unattended equipment ever >> since an un-fused Radio Manufacturing Engineers receiver monitoring RTTY >> autostart almost burned our house down in the 1960s.) Measuring frequency >> requires table look-ups and correction math. Since I did not have the >> original manual with calibration data, and the end-stop was nowhere near >> 000 on the counter dial, I decided to calibrate it myself. At the same >> time, I added ferrite inside the coil to drop the oscillator frequency down >> into the 160 meter band. Using my OpenHPSDR, I calibrated by noting the >> Lampkin dial reading for every 100 Hertz on the HPSDR. During the FMT, I >> used a Collins 75A-4 receiver in AM mode and adjusted the Lampkin 105-B to >> zero-beat the signal. Using the Lampkin dial reading and looking it up in >> the table, I could interpolate for the frequency between the two >> calibration values. >> >> During the test, I noticed that the Lampkin was varying because the line >> voltage was changing. The next time I will build the recommended line >> voltage regulator using two 0C3 (VR-105) tubes and a 60 Watt ballast lamp. >> >> I uploaded my mods, photos of the inside, and a scan of the manual to >> mods.dk. I tried to ftp and email the manual to BAMA/eDebris without >> success. >> >> See attachments >> >> _______________________________________________ >> 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. >> > <Lampkin105_SwitchOn.png>_______________________________________________ > 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.

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 <john@miles.io> 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.

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-bounces@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