[time-nuts] PRS10 Lamp Module Needed
Vasco, As Brooke said it is unlikely there are spare PRS10 lamp modules found outside the manufacturer. The probable reason is that when the PRS10 units are assembled certain adjustments to the firmware are necessary such as the starting level and final bias of the FET oscillator transistor. As far as I know, SRS has not revealed how to access to these factory settings. It might be possible to repair your lamp assembly. One point of failure is the Tantalum capacitor found in the lamp assembly. Another possibility is that the heater resistor may have changed value or opened. Although it looks daunting, it is possible to replace the FET power transistor; however, after replacing the transistor in one unit, I found the transistor's characteristics were a little different than the original and the operating parameters were not right. I considered adding some external resistors to shift the biasing, but finally decided to try another transistor with somewhat different characteristics. But in this second try I damaged the board. If the rubidium bulb assembly is suffering from old age, it might be possible to improve it with a heat gun as discussed on this listt several times in the past. The bulb is cemented in place, but it might be possible to remove and replace it. Bruce, KG6OJI ___ 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] FE5680 Versions
Can one determine whether a given FE5680 is of the analog or digital control type without opening it? Bruce ___ 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] FEI-5660 Rubidium Oscillator
Recently I happened across an eBay listing for an Antelope Audio Isochrome, a device that apparently packages an SRI-PRS10 rubidium oscillator and distribution amplifier in a box and sells to audiophiles for a price in the $10K range. For the fun of it I searched eBay for Audio Isochrome and found a number of listings. Clicking on the lowest priced (eBay 271432562792) for $4,500, there is a note that the SRS-10 has been replaced with a FEI-5660 which is said to be a PRS-10 equivalent. Is this the one that has been showing up from surplus cellphone equipment? Bruce ___ 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] Off-Topic Question -- German Composition Resistors
While tracing out a PC board from an instrument manufactured in Germany, I quickly discovered the color code on 1/4-watt composition resistors is not the same as that commonly used in the US For example, I would measure about 10,000-ohms across a presumably good resistor that appeared to be marked 2700-ohms. Has/does Germany used a different code for such parts? Bruce, KG6OJI ___ 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] Off-Topic Question -- German Composition Resistors
My sincere thanks to those who responded to my request for help. The link to a chart provided by Ernie allowed me to recognize I was looking at five-stripe resistors with three significant figure stripes followed by a multiplier stripe and spaced a little further away a red stripe indicating two-percent tolerance. Otherwise, they looked like conventional 1/4-watt composition resistors. I have never encountered five stripe resistors before! Bruce ___ 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] Need to measure frequencies of two sources simultaneously
If the two frequencies are reasonably separate, an EIP counter such as the 54x or 57x series could be programmed to select the desired frequency. This could be orchestrated through the counter's GPIB interface, or alternately, two counters could be used -- one for each frequency. Bruce, KG6OJI ___ 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] RB video
I believe the subject video does a nice job introducing viewers to the construction and potential of EXTRON's extensive of NTSC video equipment housed in nice, reusable cabinets. The cabinets that I am familiar with have slide-in front and back panels of 1/16-inch aluminum that can easily be replaced. Many units, including distribution amplifiers, have blank front panels. The power supplies are sometimes husky, too; apparently being designed for the largest power demand circuitry EXTRON housed in the cabinet. For example, the ADA 6 300 MX distribution amplifier has a Signal Flathead power transformer with dual 8-volt secondaries rated at 24-watts overall. These windings, in series, connect to a bridge rectifier and 6800 uFd/35-volt filter cap to deliver about 11.8-volts. There is a 7805 +5-volt regulator and a LT1054CT switched-capacitor that delivers -12-volts that is fed to a 7905 -5-volt regulator. As mentioned by others, the 300 MHz distribution amplifier, (6 outputs each for R, G, B), are a little marginal in output capability, but I have found them to work fine for 1, 10, and 100 MHz distribution. I installed one of David Partridges divider boards in the EXTRON cabinet and managed to power it and a 10 to 100 MHz multiplier unit, as well as the distribution amplifiers, from the internal EXTRON power supply. Specs say the distribution amplifier, alone, consumes 10 watts. Many of these and similar EXTRON boxes have been obseleted by HDTV and are found on eBay at low prices. Research has shown that 50 and 75-ohm BNC connectors have the same outward dimensions, although some 75-ohm versions might have internal matching by using thinner internal inner conductors. I don't think it makes a lot of sense to convert the 75-ohm outputs to 50-ohms as the internal amplifiers cannot be heavily loaded at high output. There is a little more voltage drop across the 75-ohm driving resistors, but this is useful in reducing the load on the amplifiers and provides increased isolation between outputs. The top, bottom, and sides of the cabinets are formed of 1/8-inch aluminum, with grooves for the front and rear panels. RF re-users may want to add bonding conductors to these separate parts, to improve the electrical shielding. Finally, circuit boards of the earlier distribution amplifiers I purchased, have through-hole rather than surface-mount components and are probably easier to modify. Bruce ___ 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] Distribution Amp for Thunderbolt and David Partridge's Divider Box
A year or so ago I modified an Extron ADA 6 300MX TV distribution amplifier to house one of David Partridge's divider boards along with a 1 MHz sine-wave filter and a 10 MHz to 100 MHz multiplier after Luciano Paramithiotti's design. I use the rear BNC connectors to distribute 1, 10, 100 MHz sine-waves. The synch channel was modified to distribute 1 MHz square-waves. On the front panel are BNC connectors for 1, 10, 100 MHz sine-waves; 1 MHz 5 MHz square-waves; and an output with rotary-switch-selected 1, 10, 100, 1 kHz, 10 kHz, or 100 kHz square-wave from the Partridge divider board. My ADA 6 300MX unit had conventional resistors on the board so it was relatively easy to change them to 50-ohms. I eliminated the 0.7/1.0 V switch. I found it possible to power the Partridge divider board and 10 to 100 MHz multiplier module as well as the distribution amplifier from the internal Extron power supply by adding a 12 V to 5 V inverter module (bought on eBay) and a Murata RFI filter. As modified, there is a single 10 MHz input to the assembly, and 5@ 1 MHz, 3@ 10 MHz, and 5@ 100 MHz outputs on the rear panel. There are also 5@ 1 MHz square-wave outputs from the former sync section. Connectors corresponding to the DA outputs used internally were removed and the holes fitted with plastic plugs of the correct size. To get everything to fit, I had to shift the power supply on the lid. While the Extron cases are of very fine mechanical construction, the front and rear panels are not well bonded electrically. I added bonding braids to improve the shielding and RF performance. A nice feature of these units is that the front and rear panels can be easily removed for engraving. I briefly considered trying to add miniature isolation transformers behind the connectors, but dropped the idea in view of the relatively marginal isolation between outputs, and because the amplifiers seemed to work well for my workbench application. My apology for this late comment, but I was out of town during the earlier discussion. Bruce, KG6OJI ___ 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] WWVB Clocks don't sync anymore (revisited)
Our favorite La Crosse bedroom projection clock stopped synchronizing about the time WWVB implemented phase-modulation. However, even unlocked, it keeps pretty accurate time. When Daylight time comes or goes, in the spring and fall, I have to take the clock out on the deck and remove and replace the batteries. This causes the clock to immediately try to synchronize with WWVB, rather than waiting until midnight. The clock spends the first five or ten minutes acquiring a signal from its remote, outside 450 MHz temperature/humidity sensor. When acquisition is completed, the radio symbol on the clock begins flashing indicating the clock is attempting to acquire the WWVB signal. This typically requires five to ten minutes. When WWVB is acquired, the clock displays the correct time and the wireless symbol stays on steadily. I have had to do this a number of times, and at different times of the day. Thus I am led to conclude successful locking is not related to WWVB phase-modulation being turned off, but rather to improved signal strength or signal/noise ratio out on the deck. It seems likely that computers and TVs, and even electrical appliances, generate a lot of VLF hash in the house. Many years ago, while working in the broadcast industry, we had to receive an AM radio signal deep underground in a BART tunnel. I solved this by using a three-foot diameter resonant-ring antenna (series-resonant at the desired frequency) at the underground location. Bringing portable radios within a few feet of the properly oriented resonant-ring produced loud and clear reception. Something similar can probably be done for WWVB reception. A hidden loop of wire that is series resonant for WWVB could be coupled to the radio-clock. Bruce, KG6OJI ___ 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] Repair of PRS10 Lamp Assembly
I am afraid the PRS-10 lamp starting algorithm is a little involved. I believe that once the lamp temperature is in the starting range, the microprocessor ramps up the drain and possibly gate voltage of the heating oscillator FET until the bulb strikes as evidenced by a DC signal at the detector. If the lamp overheats (as measured by thermistors imbedded in the back of the lamp block), at some point the microprocessor will reduce the drain voltage to a safe steady-state value. The starting constants for each individual PRS-10 are factory-set in the unit's programmed software, and as far as I know, access to change these settings has not been made available yet to end users. This makes it difficult to swap lamps between units. I have a PRS-10 with a lamp that is just on the edge of starting properly. Since I cannot change the factory-programmed values, I have tried adding a shunt resistor to increase the lamp current to the point where it would reliably start. But, unfortunately, other problems seem to be keeping the unit from working properly. The only luck I have had in repairing a non-working PRS-10 with certainty, was one in a Symmetricom 2500 Time Source that turned out to have a failed Mini-Circuits VCO on the synthesizer board. Replacing the VCO module restored proper operation. Perhaps someday the factory will provide end users with access to what are now factory-only settings. Bruce, KG6OJI ___ 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] Subject: Re: Don't use cheap cables -- a cautionary tale
I would like to add to Bob Camp's comment about twisted pair. In the past I used to provide one-turn resonant loop antennas for AM broadcasters who needed to monitor signals from their transmitters at studio facilities in electrically noisy urban buildings. The three-foot diameter resonant-loops were grounded at the centerpoint and provided low noise reception, but this was degraded if a coaxial lead-in was used. A workable solution turned out to be shielded audio cables. These seemed to have a characteristic impedance of about 150 ohms. At the receiving end we used ferrite 150-ohm balanced to 50-ohm unbalanced transformers. With the balanced circuit and shielded audio cable, very long runs could be employed with little noise pickup. Bruce, KG6OJI ___ 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] Thunderbolt Distribution Amplifier Needed
Chris, I was able to mount my David Partridge divider board inside an Extron ADA 6 300MX television distribution amplifier along with a 1 MHz sine wave filter and a 10 MHz to 100 MHz multiplier. On the front panel is a selector switch for selecting the division ratio, BNC jacks for this and the other board outputs, plus 1 MHz, 10 MHz, and 100 MHz sine wave output connectors. These distribution amplifiers have a very nice case with a blank front panel and are mostly empty inside. Everything inside is powered from the internal Extron power supply, although I had to add a 12/5-V switching convertor and Murata filter to obtain the 320 ma 5-V current needed for the divider board. The internal power supply generates 12 VDC at about 25 VA. a 7508 5V regulator provides +5 VDC to the DA board. An LT1054CT switching convertor develops -12 V that is passed through a 7905 regulator to provide -5 V to the DA. The power supply has vacant 12 V connection points that can be used for powering other devices. This Extron product is intended to provide six 75-ohm outputs each of RGB and sync. I used the sync DA for 1 MHz square wave and the RGB DAs for 1, 10, and 100 MHz sine wave outputs. As I recall, the internal DAs frequency response extends to about 300 MHz. I converted the 75-ohm outputs to 50-ohms by changing the buildout resistors from 75 to 50 ohms. These distribution amplifiers are available rather inexpensively on eBay as a result of the demise of NTSC. I think I paid about US$20. Bruce, KG6OJI ___ 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] Fe-5680A -vs- LPRO
Is anyone prepared to comment on the relative performance of the FE-5680A compared with the LPROs? Bruce Hunter, KG6OJI ___ 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] Fe-5680A -vs- LPRO
Bob, WOW! Thanks for the very comprehensive report. Bruce, KG6OJI ___ 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] Spectracom 8170 - SWCC clock
Jim, If your Western Union clock is similar to the type used in broadcasting, you might want a setting pulse that starts at 59:59 and ends at 00:00 . The reason is that at 59:59 the magnet pulls the second hand to the 12 o'clock position and releases it on the hour. The one-second difference might seem trivial, but it's actually about three words for an announcer beginning a network broadcast. When Western Union got out of the clock business in the late 1970s (following a technician strike where the master clocks were ignored and service deteriorated) the company I worked for purchased the clock installation from Western Union (for $75 per clock as I remember) and we installed a digital master system. The Western Union clocks were all connected in series and driven as a constant-current teletype type loop. We had wire-wrap logic panels associated with the digital master time system. Signals for the W. U. clocks, for alerting control rooms before newscasts, starting recordings, etc., were implemented by simply adding chips, DIP relays, 14/16-pin boards with components such as timing capacitors, and wire-wraping the underside pins. I/O was implemented with those 14 and 16-pin DIP connectors on one end of ribbon cables -- the other ends being terminated on barrier strips on rack wall panels. Bruce ___ 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] Symmetricom 2700 Time Source
I removed the SRS PRS-10 oscillator from my unit for examination. The 1PPS output appears on Pin #5 (See page 19 of the manual) and is not connected to the 2700. It appears the 2700 does not rely on the PRS-10 alone for timing information; it tracks and aggregates available sources. The final 1PPS is likely developed in the microcontroller chip. Is there an online source for the BTSMonitor software used to communicate with the Symmetricom 2700? I could not find it on the Symmetricom site. I am not certain it would be enough to access my unit as it is a used one and may have user names and passwords set. I bought the unit for the PRS-10 rubidium oscillator, but am becoming interested in the simplified reception capability of the unit. Bruce, KG6OJI ___ 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] Symmetricom 2700 Time Source
Following a recent posting from a group member advising that Symmetricom 2700 CDMA Primary Reference Sources contain SRS PRS-10 rubidium oscillators, I was able to buy one of these units at reasonable cost from the usual auction source. After removing the PRS-10 oscillator and while evaluating it with a laptop computer on the bench, I began to wonder if rather than trying to discipline it with a Thunderbolt GPS receiver, it would make sense to just utilize it in the Symmetricom box as intended. The Symmetricom 2700 has a 10 MHz sine-wave output. From reading the Symmetricom manual, it appears the model 2700 was designed to serve as a precision, GPS-based source for system timing. It avoids the requirement to directly receive GPS satellite transmissions by utilizing multiple CDMA cell phone service base stations as intermediaries. The cell phone transmitters are locked to GPS satellites and their 1900 MHz terrestrial transmissions are easier to receive than GPS. The manual says an indoor antenna is usually adequate. If your CDMA cellphone works in a given location, this box should too. But with the cell phone base stations serving as intermediaries, by monitoring GPS signals and using them to synchronize the cellphone base station pilot-frequency transmissions, would the performance of Symmetricom's disciplined oscillator be as good as one directly disciplined from GPS satellite transmissions? It would seem that since the system should never even slip one Hertz over the years, the long-term accuracy should be good. The remaining consideration would be intermediate-term jitter such as caused by tree branches blowing in the wind and affecting the 1900 MHz transmission phase. Short-term behavior might be fairly good as the SRS-10 has a very stable crystal oscillator and low overall phase noise. I would be interested in opinions and experience with the Symmetricom equipment or this method of disciplining an oscillator. Bruce, KG6OJI ___ 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] OT - MIT Radiation Lab Series
This discussion about the Radiation Laboratory series reminded me that in looking at a book on high vacuum techniques that I purchased in the late 1950's, I was surprised to see it was part of a series on the wartime development of nuclear energy written at the end of WW-II in a similar government effort. However, unlike the MIT Rad Lab series, the high vacuum techniques book does not include a list of other volumes in the series. Bruce ___ 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] BNC Question
An Amphenol document discussing the mating compatibility of their 50-ohm and 75-ohm BNC connectors can be found here _http://www.amphenolrf.com/products/bnc.asp?N=0sid=46B11E806D75617F_ (http://www.amphenolrf.com/products/bnc.asp?N=0sid=46B11E806D75617F) . Bruce, KG6OJI ___ 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] BNC Question
Interestingly, 50 and 75-ohm BNC connectors have the same pin/shell dimensions and properly couple together. For more information go to _http://www.cliftonlaboratories.com/august_2007.htm_ (http://www.cliftonlaboratories.com/august_2007.htm) and scroll down to the 02 August 2007 entry. There is a link to the Amphenol site for specifics about the connectors. I am planning to use an Extron video distribution amplifier for standard frequency distribution. The 75-ohm connectors will be OK. These amplifiers feed multiple 75-ohm outputs from a zero-impedance source by inserting a 75-ohm resistor in each leg. Some folks using these for standard frequency distribution change the resistors to 50-ohms. Bruce, KG6OJI ___ 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] Partridge Divider Board and 10 MHz Distribution Amplifier Enclosure -- an Idea
While admiring my newly received divider board from David Partridge and thinking about a suitable enclosure for its use on my bench, I happened to look at an Extron ADA3 80 video distribution amplifier that I acquired after suggestions from KO4BB. These enclosures are mechanically sturdy and quite empty on the inside. There is plenty of room to mount the divider board if existing (unused) threaded standoffs are relocated to match the divider board mounting holes. As the distribution amplifier's circuit board and connections are all on the back panel, the front panel is completely free and clear for mounting the division ratio switch and output connectors. The analog performance of the distribution amplifier seems very good; however, the BNC output connectors are grounded to the case and there is only one active output device for each of the R, G, B outputs. The three output connectors provided for each are simply isolated through resistors, thus isolation is limited. Nevertheless, for a single bench setup like mine, the distribution amplifier will probably serve adequately well to distribute 10 MHz from a T-bolt to the counters, divider board, and a signal generator -- all on the same bench. As the R, G, B DA inputs can be looped, the ADA3 80 can provide up to nine 10 MHz outputs via BNC connectors. The ADA3 80 is powered from an external 9-volt, 500 ma wall wart. According to KO4BB: _http://www.ko4bb.com/Timing/Distribution_Amp/_ (http://www.ko4bb.com/Timing/Distribution_Amp/) , the DA has an onboard switching converter and + and -5 volt regulators to power the distribution amplifiers. It is possible there is sufficient +5 volt current capacity to power the divider board too. I have not investigated this yet as I am not certain about the maximum current requirement for the divider board. Assuming it can be powered from the existing supply, one could wind up with a very nice and compact bench frequency reference and distribution system. Extron rates the power consumption of the ADA3 80 at 2-watts. However, it appears Extron uses the same PC board and power unit for the ADA3 180 for which the power consumption is 3-watts. Thus there may be adequate capacity to safely power the divider board. If power supply noise is a problem, there is plenty of room in the case for additional filtering. Bruce Hunter, KG6OJI ___ 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] Update -- Comparing 10 MHz Oscillators at 10 GHz
Thanks to some help from Joe Ruggieri, I finally managed to get a pair of 10.000 GHz microwave brick oscillators phase-locked to 100 MHz inputs. These require an input of about 0 dBm at 100 MHz and have an output of about + 13 dBm at 10 GHz. To gauge whether or not loop noise would interfere with using these to compare 10 MHz oscillators, I assembled the following test setup as I have not yet constructed the required 10 MHz to 100 MHz multipliers. Both 10 GHz microwave bricks were driven through a splitter from an HP signal generator locked to 100 MHz. The 10 GHz output of one brick was routed through an HP X885A phase-shifter equipped with WG/coax adapters and on to one input of an Anaren hybrid combiner. The output of the other brick was routed through a 0-10 dB SMA attenuator then on to the combiner. The reject side of the combiner was terminated. The main combiner output was routed through a 10 dB attenuator to a Systron-Donner coaxial detector. The DC output of the detector was monitored with a digital voltmeter. First the phase shifter and attenuator were adjusted to cause the two sources to arrive at the combiner with equal amplitudes and 180 degrees out of phase and produce a null at the detector output. I measured as little as 0.01 millivolt on the DVM at the null point. Then the phase-shifter was adjusted to rotate the phase 180 degrees to place the combiner inputs in phase. The detector output was about 128 millivolts. This experiment seems to confirm the earlier results by Ulrich Bangert and his friend that noise does not appear to be a problem with this method for rapid frequency comparison. However it would be convenient to have an attenuator and phase shifter to null the sources. Bruce Hunter, KG6OJI. ___ 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] Garage built Rubidium standard
The Garage-Built Rubidium Standard discussion brought to mind an experimental setup in a physics lab at U. C. Berkeley years ago. It was one of a number of elective experiments for the laboratory section of a Modern Physics course. The objective was probably to demonstrate Zeeman line splitting. I suspect much of the equipment was surplus from the nearby Radiation Laboratory. The setup was shrouded by heavy black theater curtains that hung from the ceiling to darken the experimental area. There were two, about one-inch-diameter, rubidium- filled glass spheres, each surrounded by Helmholtz coils. The first also had a toroidial resistance heater coil controlled by a Variac. It served as the light source when energized by RF from the Helmholtz coil. The temperature had to be in the correct range in order for the bulb to luminance. The second bulb was the reaction sphere. Its Helmholtz coil was fed with a trapezoidal waveform from a sweep generator along with direct current from a powers supply. The Helmholtz coil also received an RF signal of about 50 MHz from a General Radio unit oscillator (possibly through an amplifier). A rather expensive-looking, ¼-inch thick, roughly 2-inch by 2-inch filter or diffraction grating (that was normally carefully kept is in a heavy-wool envelope) was placed in a holder between the spheres. There were probably some other optical elements too, but it has been too long to remember. On the far side of the reaction sphere was some sort of photodetector that fed an old Dumont oscilloscope with the beam being swept horizontally from the sweep generator. If you managed to get the pip on the scope (not many student-pairs succeeded) the rest was calculation. One of the required calculations was the force of gravity acting on the experiment. This experiment was notable as an instructive exercise in getting old, recalcitrant test instruments to all function at the same time, more so than the theoretical physics. If one could acquire the rubidium –filled spheres and filter, a working rubidium standard could probably be constructed in the garage. Bruce, KG6OJI ___ 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] Comparing 10 MHz Oscillators at 10 GHz
Luciano Paramithiotti's January 1 post about his 10-to-100 MHz multiplier project reminded me of past musings about using two 10GHz, phase-locked oscillators to compare the 10MHz outputs of my T-bolt and LPRO so I could quickly adjust the latter by observing the mixed 10 GHz signals with a microammeter. I am talking about the California Microwave, Frequency West, etc., modules that were used as local oscillators in commercial microwave systems. I was about to ask Luciano for more information on his coil forms, amplifiers, and RF chokes when it occurred to me that loop-noise in the PLOs might force a very narrow bandwidth and correspondingly long observation time. Have members of the list been successful with this technique? While most common PLO modules require an input signal in the 100 MHz-range, I have heard of versions that lock directly to a 10 MHz input. Is anyone familiar with these and how difficult it would be to modify conventional oscillators to securely lock to 10 MHz? Bruce, KG6OJI ___ 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] Question about Russian PC-Series Circular Military Connectors
I would like to take advantage of this group's worldwide constituency and ask a slightly off-topic question about the contact numbering scheme for Russian PC-series circular connectors. I am trying to trace out the wiring of a Russian manufactured radiometer with these connectors. Surprisingly, there are no pin letters or numbers found on any of the connector parts or on new mating connectors I purchased on eBay. Searching the Internet I have found manufacturers in India and China offering knockoffs of these connectors. They have pin location drawings on their web sites, but fail to identify whether these diagrams apply to the male or female connector and whether to the wiring or interconnect side. Drawings show that the connector pins are numbered in rows from left to right, starting at the top. I have sent inquiries to these manufactures, but have only been asked how many I want to buy and how many pins. Can anyone help me identify the numbering convention for these connectors? They are well made and similar to Cannon military types. Bruce Hunter, KG6OJI ___ 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] Greyfox Surplus box
Today, while at HSC Electronics, an electronics surplus store in Rhonert park, CA, I picked up a GreyFox R1056 distribution box that looked like it had possibilities either as a distribution amplifier for 10 MHz or for GPS signals. But to my surprise, I could not find any information about the unit online. Is anyone familiar with this unit? It has 20 F-connectors. Eight marked INTERNAL and noted as DC Passing Zone 1, eight more marked EXTERNAL and DC Passing Zone 2, one marked CAMERA, one marked CATV/ANT, one marked Satellite-in DSB1, and one marked Satellite-in DSB2. Two of the eight connectors in the EXTERNAL field are highlighted and marked DSB2 OUT c1 and DSB1 OUT g1. The unit is about the size of a computer keyboard and also has a 15V, 550 ma power connector, a gain control and associated 10-segment LED level indicator, a red SURGE LED, and a green power LED. Greyfox Systems manufactures a broad line of home automation equipment. I thought this might be an interface panel to tie-in a security camera, cable and DBS systems. Bruce, KG6OJI ___ 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] Aside about Triangle Waveforms
A widely used WW-II aircraft radio altimeter used a triangular waveform to FM modulate a 400 MHz oscillator, employing a mechanical variable capacitor constructed similar to a permanent-magnet loudspeaker. To get the capacitor's diaphragm to reverse accurately, at the positive peak of the trianglular waveform, required a sharp, negative-going impulse to be added to the peak of the triangle, creating a sharp notch in the waveform about 30% deep. This makes me wonder about the limitations of speaker cones attempting to reproduce complex waveforms. If they had overall feedback for positional correction, the spectrum of the resulting driving waveform might contain some pretty complex components. Bruce Hunter ___ 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] Conducting Bench Top Material
My electronic bench is an old commercial one made with steel stampings and a steel top covered with Masonite. The Masonite is still in fair condition. Although over the years the non-conductive top has been an asset in avoiding short circuits, etc., I am concerned about static discharges when handling modern semiconductors. Would it make sense to spray the Masonite with a weak copper sulphate or similar solution so as to make the masonite slightly conductive, but not so conductive that 155 VAC connections could not safely rest upon it? Is there a better-suited material that could be used to replace the Masonite? Ironically, in the 1960's, Transite (asbestos) was sometimes used as a covering for electronic benches as as it was resistant to molten solder. The downside was that in sliding heavy equipment around, friable material could be released. Bruce Hunter ___ 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] 4 KV Power Supply Requirements
Many decades ago, before high-voltage diodes were available, I constructed 4 KV, 50 ma klystron power supplies using strings of 600-volt PIV, metal-case diodes mounted on commercial Bakelite terminal boards. After soldering, I sprayed the entire board heavily with Krylon high-voltage spray intended for television receivers. These supplies operated for many decades without any problems. Bruce Hunter, KG6OJI ___ 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] 4KV Power Supply Recommendations
Slightly off topic -- but perhaps suggestive: A couple of years ago I needed to re-train some nocturnal raccoons who were toppling our garbage can. I purchased an inexpensive and very compact fence charger at a farm supply. Opening the lightweight unit out of curiosity, I found that it contained a transformerless, voltage-multiplier that plugged into a 115 V outlet and generated about 500 VRMS. All that was inside was a small PC-board with diodes, disc capacitors, and one current-limiting resister in the feed to the HV terminal. The ground return was through the AC line neutral. Connecting the lone HV terminal to a small piece of rabbit wire placed on the lid of the plastic garbage can did the trick. I had to electrify the can once more -- about 6 months later -- but have not had to do so in the two years since. It might be possible to construct a voltage multiplier, along the same lines, that would reach 4KV. The capacitors would have to be larger to deliver 5 MA. Bruce Hunter, KG6OJI ___ 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] Question about Firmware for EIP Counters
Is anyone on the list familiar with the firmware for EIP 578 or 548 series counters? I have a favorite 578 counter, with power measuring option, that I have owned for years. All of this time I have wished it had the Frequency Extension option. Recently I bought a mechanically-damaged 578 with the desired extended frequency range feature on eBay. I removed the optional RF parts and added them to my old counter. I also transferred the associated firmware PROM (U20) to my counter's A-105 microprocessor board, and added the jumper required to activate the feature on a second board. But the option failed to work. By pressing buttons I determined the cause was a firmware rather than RF problem. While my old firmware set of 5 PROMS was Version-B, the parts counter had Version-D PROMS, even though it was not far removed in serial number and bore the same CCN code. So I transferred the remaining Version-D PROMS to my counter and presto! the frequency extension option worked great! However, before I could celebrate by closing the case, I realize the prized power measurement feature no longer worked. I tried interchanging the first then last PROMs in the programming sequence, but this just caused the microprocessor to lock-up. I am left with the feeling that the various firmware versions might correspond to the eight permutations of the three options requiring microprocessor intervention (A to D Converter, Power Meter, Frequency Extension). If this is the case, my augmentation project seems doomed unless I can obtain a copy of the appropriate firmware. Has any list member had experience adding options to the EIP counters of this family? I have already asked this question on the Microwave Reflector, but with no responses. Bruce Hunter, KG6OJI ___ 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] Multiplying 10 MHz to 100 MHz
In an earlier post I mentioned that I had been searching on-line for ideas to multiply a 10 MHz signal to 100 MHz. I would like to multiply the 10 MHz outputs of an LPRO and a Thunderbolt GPS to feed to 10 GHz phase-locked microwave sources so their outputs can be fed to a mixer for enhanced frequency comparison. F4GBC kindly provided the following link for an article in French. HI all, have a lok to : http://pagesperso-orange.fr/f5cau/ol_shf/OL9HX.pdf very interesting for those who read french. Alain F4GBC After looking at the article I searched on-line for the part number of the specified 100 MHz filter and found a link to an English language version of the article _http://g4hup.com/DFS/F9HX%20synthe%20english.pdf_ (http://g4hup.com/DFS/F9HX%20synthe%20english.pdf) , should anyone be interested. Bruce Hunter, KG6OJI ___ 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] LPRO-GPSDO
In searching on-line for ways to construct a 10 MHz to 100 MHz multiplier, I came across an interesting product offered by Silicon Forest Solutions _http://www.TenMHz.com_ (http://www.TenMHz.com) . Their LPRO-GPSDO incorporates a refurbished LPRO rubidium oscillator, disciplined by a GPS receiver, for less than $500. It looks pretty clever and compact. Perhaps this product is offered by a member of this list who could tell us more about it. Bruce Hunter, KG6OJI ___ 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] Invariance
If from relativity theory time is NOT considered invariant, would frequency (in terms of the output of a cesium standard or hydrogen maser) be considered invariant? Bruce Hunter ___ 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] GPS Antenna and Lightning (Bruce Hunter)
A 6 to 30 MHz Voice of America receiving site in North Carolina had an interesting experience when vacuum-tube antenna RF distribution amplifiers were replaced with solid-state units. At first, frequent damage occurred to the input stages of the solid-state amplifiers, whereas few problems had been experienced with the vacuum-tube amplifiers. The many, large, rhombic antennas were all equipped with spark gaps, gas tube suppressors, and 3AG fuses in the balanced, transmission lines at the antenna feedpoints. Fuses frequently opened during lightning storms. Interestingly, the manufacturer of the solid-state RF distribution amplifiers had also sold some of the units to the US Coast Guard in southern Florida. The Coast Guard found that adding 30 MHz low-pass filters at the input to the amplifiers almost completely stopped the failures. The VOA amplifiers were equipped with similar low-pass filters and the North Carolina failures also almost completely stopped. We were never sure whether the fix resulted from eliminating energy above 30 MHz or because the phase shift of the filters unstacked the harmonics making up the steep wave front, thus reducing the peak voltage. But it would seem that a suitable band-pass filter might significantly reduce the likelihood of a GPS receiver failing from energy induced by a nearby lightning strike. Bruce Hunter, KG6OJI ___ 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] GPS Antenna Voltage-Dropping
I bought a 3.6-V Trimble Bullet GPS antenna on ePay and wish to use it with my T-bolt. Rather than try to internally modify the T-bolt to provide a 3.6-V antenna feed, I decided to try to build an in-line dropping adapter. I seriesed two Si diodes inside a 100 pf tubular ceramic capacitor and installed the shrink-wrapped assembly inside a salvaged BNC-M to BNC-F coaxial assembly. Unfortunately the completed assembly exhibits about a 4-to-1 VSWR when terminated in a 50 ohm load. Has anyone else tackled this challenge? The 3.6-V Trimble antenna has less gain than the 5-V version which makes my planned antenna rcable run on the edge even without the high VSWR.. Bruce Hunter ___ 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] Connecting Wireless Adapter to a TBolt
Thanks to all for your suggestions. Bruce Hunter **It's raining cats and dogs -- Come to PawNation, a place where pets rule! (http://www.pawnation.com/?ncid=emlcntnew0008) ___ 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] Wireless Adapter for an TBolt
Has anyone coupled a wireless adapter to a TBolt so that it can be accessed from a computer in another room. This would be convenient for me if it could be made to work. Bruce Hunter **It's raining cats and dogs -- Come to PawNation, a place where pets rule! (http://www.pawnation.com/?ncid=emlcntnew0008) ___ 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] Subject: Thunderbolt Stability and Ambient Temperature
This interesting discussion of heat conduction by members of the electronics community brings to mind that in the 1870's, Joseph Fourier, while analyzing the waveform of heat propagating around a metal ring, developed the elegant method of Fourier Analysis. If you have not seen his work and can locate a copy of Fourier's: The Analytical Theory of Heat, you might find it interesting to thumb through it. Bruce Hunter **Shop Dell’s full line of Laptops now starting at $349! (http://pr.atwola.com/promoclk/100126575x1221881320x1201406166/aol?redir=http:%2F%2 Fad.doubleclick.net%2Fclk%3B215218036%3B37264217%3Bz) ___ 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] Vectron Labs OCXOs Pin-out
Steve, In my experience Vectron has not been able/willing to provide info on earlier oscillators. I acquired a 229-7730-9, 100 MHz unit and with an ohmmeter decided the pin connections seemed to match the diagram shown for the current CO-706 series. The question then was whether the supply voltage should be 12, 15 or 24 volts. The unit oscillated with 15v, but plotting the warm-up drift, I found that even after hours of operation the unit did not completely warm-up. The can was barely warm to the touch. I then tried 24v and the oscillator warmed-up in 16 minutes from a cold start -- that is the direction of frequency drift reversed in 16 minutes. The can was much warmer and reached that temperature much faster. Applying a 0 to +6 v control voltage to pin 6, I was able to shift the frequency about +/- 50 Hz. The mechanical tuning adjustment, at the top of the housing, allowed shifting the frequency over a much wider range. Initial current at 24v was 200 ma. This decreased to 105 ma after about 30 mins. Output power at 24v was +7.6 dBm. At 15v input, output power was a steep function of input voltage. Bruce Hunter **Worried about job security? Check out the 5 safest jobs in a recession. (http://jobs.aol.com/gallery/growing-job-industries?ncid=emlcntuscare0002) ___ 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] Upgrade for LPRO 10 MHz Oscillator?
Has anyone upgraded the LPRO oscillator by out-boarding a suitable OCXO unit? Bruce Hunter **Know Your Numbers: Get tips and tools to help you improve your credit score. (http://www.walletpop.com/credit/credit-reports?ncid=emlcntuswall0002) ___ 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] time-nuts Digest, Vol 52, Issue 74
In a message dated 11/26/2008 12:29:32 P.M. Pacific Standard Time, [EMAIL PROTECTED] writes: [EMAIL PROTECTED] Tom, I would be interested in one of the Thunderbolt units if you are able to do another group buy. Best regards, Bruce, KG6OJI **Finally, one site has it all: your friends, your email, your favorite sites. Try the NEW AOL.com. (http://www.aol.com/?optin=new-dpicid=aolcom40vanityncid=emlcntaolcom0006) ___ 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] Checking the Frequency of a Rubidium Oscillator
Thanks to all that explained the hopelessness of measuring GPS satellite transmission frequencies directly with a simple counter. I should have known better, but probably have been retired too long. Bruce, KG6OJI **Get movies delivered to your mailbox. One month free from blockbuster.com (http://pr.atwola.com/promoclk/10075x1212639737x1200784900/aol?redir=https://www.blockbuster.com/signup/y/reg/p.26978/r.email_footer) ___ 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] Checking the Frequency of a Rubidium Oscillator
I have an EIP Model 548 counter with a YIG-tuned front end that can be programmed to scan over narrow frequency ranges. By feeding the rubidium oscillator under test into the 10 MHz clock input of the counter, is there any reasonably simple way to directly measure the frequency of a GPS satellite transmission so as to ascertain the accuracy of the rubidium source? The counter has an input sensitivity in the order of about –25 dBm -- not sufficient to measure directly from an amplified antenna, but perhaps through an amplifier. I am not sure whether the input YIG tuner selectivity is sufficient to separate transmissions from the various satellite’s (or are they TDMS?). What do you think? Bruce, KG6OJI **AOL Search: Your one stop for directions, recipes and all other Holiday needs. Search Now. (http://pr.atwola.com/promoclk/10075x1212792382x1200798498/aol?redir=http://searchblog.aol.com/2008/11/04/happy-holidays-from -aol-search/?ncid=emlcntussear0001) ___ 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.
