Re: [time-nuts] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
On 18 July 2015 at 09:45, Ole Stender Nielsen wrote: > I had a few LM394CN left and used one for the pre-amp. > I would try to use another low-noise transistor. Furthermore, you do not > necessarily need a matched pair. The transistor on the right in the > schematic is merely used for biasing the amplifying transistor on the left. > The prices for matched pairs can get ridiculously high, so I too would try > to look for alternatives. If you still want a matched pair, there's the > SSM2212 from Analog Devices, which is priced lower than the MAT12. You may > also be able to find the earlier SSM2210, which now is obsolete. Another > alternative is the THAT300 from THAT Corporation, which has 4 low-noise > NPNs in a 14-pin DIP (great for experiments...) > Useful single NPN transistors I can think of would likely be the BC337 or > perhaps the 2SC3324 which both have low Rbb, and they are quite cheap. > Hi, I ordered the parts for this, including a MAT12. I do consider some arguments put by others - the first on the mailing list, the second privately. 1) There are cheaper low noise devices - that in itself has generated into another thread. 2) The atmospheric noise at 100 kHz is high But given * A MAT12 is not a fortune from reputable semiconductor suppliers like Farnell (I would not consider eBay, due to fakes) * I am only building one, so cost is not a huge issue. * The MAT12 is specified for low noise, without me wasting time selecting devices. * MAYBE the argument about atmospheric noise is valid - I tend to agree with it, but again due to the one-off nature of this, I am going to ignore that argument. So I bought a MAT12. I'm *not* going to change that - it is bought, paid for and here. > > The "Ca. 3 Ohm" was indeed the estimated input resistance, including the > series resistance of the input capacitor as I recall. > If the input resistance of that common-base amplifier is 3 Ohms, does it make sense to have the loop resistance 3 Ohms too? For maximum power transfer one wants the source and load to be the complex conjugate, but I know for microwave devices, you do not design the input match for maximum power transfer, but generally minimum noise. I just checked my HP 4284A precision LCR meter, which covers from 20 Hz to 1 MHz in 8000 and something discrete steps including 100 kHz. I can set the voltage as low as 5 mV, so I could measure the input impedance (R + j X) of the amplifier at 5 mV RMS. So while Ole's estimate is no doubt good, I can actually measure it with the MAT12 in place. I have 95 m of 2.5 mm^2 mains cable, with a PVC (?) jacket. The copper conductor which should have a DC resistance of about 0.7 Ohms. I'm wondering if I would be better * Having a longer piece (more resistance, higher cost, a larger thermal noise voltage, but better impedance matching) * Use thinner wire, which would be less costly, but again aim for a DC resistance of 3 Ohms - or whatever my LCR meter says in the input Z at 100 kHz. In the short term I am just going to put on the 95 m, as I have that here, but longer term I wonder if I would be better increasing the number of turns, to put the DC resistance closer to the input resistance of the amplifier. Any comments? Dave ___ 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
I had a few LM394CN left and used one for the pre-amp. I would try to use another low-noise transistor. Furthermore, you do not necessarily need a matched pair. The transistor on the right in the schematic is merely used for biasing the amplifying transistor on the left. The prices for matched pairs can get ridiculously high, so I too would try to look for alternatives. If you still want a matched pair, there's the SSM2212 from Analog Devices, which is priced lower than the MAT12. You may also be able to find the earlier SSM2210, which now is obsolete. Another alternative is the THAT300 from THAT Corporation, which has 4 low-noise NPNs in a 14-pin DIP (great for experiments...) Useful single NPN transistors I can think of would likely be the BC337 or perhaps the 2SC3324 which both have low Rbb, and they are quite cheap. The "Ca. 3 Ohm" was indeed the estimated input resistance, including the series resistance of the input capacitor as I recall. Best regards Ole Den 17-07-2015 kl. 22:49 skrev Dr. David Kirkby (Kirkby Microwave Ltd): On 16 July 2015 at 08:05, Ole Stender Nielsen wrote: I use a home-made untuned loop antenna with 4 windings of 2.5 mm2 insulated wire on a 80 x 80 cm wooden frame, and with a grounded base pre-amplifier mounted on the antenna frame. A schematic is enclosed for you to copy. The pre-amplifier is powered through the cable, and loads the FS700 input as required. I live about 290 km from the island of Sylt, and get nice noise margin figures from the FS700, normally about 40 dB, often up to 46 dB. A couple of questions 1) Do you have any suggestions for a replacement for the LM394CN, which is obsolete and unobtainable from any reputable source? There are plenty on eBay for a few $'s from China, but the probability of them being fakes is greater than 0.99. The MAT12 seems to be one possible candidate for a replacement and while not cheap, is available from reputable sources like Farnell. 2) What is the "Ca. 3 Ohm" to the left of your circuit? Is that what you estimate the input impedance is? I've got 95 m of 2.5 mm^2 wire. The resistance of that is about 7.41 mOhm/m so my 95 m would have a DC resistance of around 7 Ohms if I used it all. I have built the loop 1.0 x 1.2 m. Hopefully that will be ok to receive at least one or both of * Lessay, France, power = 250 kW, distance = 321 km, bearing = 211 degrees. * Anthorn, England, power =- 250 kW, distance = 419 km, bearing 331 degrees. I now need to work out how many turns to put on it. Dave ___ 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
MAT12 of ADI is good replacement and it is available at Mouser http://www.mouser.com/Search/Refine.aspx?Keyword=MAT12 On 7/17/2015 1:49 PM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote: On 16 July 2015 at 08:05, Ole Stender Nielsen wrote: I use a home-made untuned loop antenna with 4 windings of 2.5 mm2 insulated wire on a 80 x 80 cm wooden frame, and with a grounded base pre-amplifier mounted on the antenna frame. A schematic is enclosed for you to copy. The pre-amplifier is powered through the cable, and loads the FS700 input as required. I live about 290 km from the island of Sylt, and get nice noise margin figures from the FS700, normally about 40 dB, often up to 46 dB. A couple of questions 1) Do you have any suggestions for a replacement for the LM394CN, which is obsolete and unobtainable from any reputable source? There are plenty on eBay for a few $'s from China, but the probability of them being fakes is greater than 0.99. The MAT12 seems to be one possible candidate for a replacement and while not cheap, is available from reputable sources like Farnell. 2) What is the "Ca. 3 Ohm" to the left of your circuit? Is that what you estimate the input impedance is? I've got 95 m of 2.5 mm^2 wire. The resistance of that is about 7.41 mOhm/m so my 95 m would have a DC resistance of around 7 Ohms if I used it all. I have built the loop 1.0 x 1.2 m. Hopefully that will be ok to receive at least one or both of * Lessay, France, power = 250 kW, distance = 321 km, bearing = 211 degrees. * Anthorn, England, power =- 250 kW, distance = 419 km, bearing 331 degrees. I now need to work out how many turns to put on it. Dave ___ 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
On Fri, 17 Jul 2015 21:49:01 +0100 "Dr. David Kirkby (Kirkby Microwave Ltd)" wrote: > A couple of questions > > 1) Do you have any suggestions for a replacement for the LM394CN, which is > obsolete and unobtainable from any reputable source? There are plenty on > eBay for a few $'s from China, but the probability of them being fakes is > greater than 0.99. The MAT12 seems to be one possible candidate for a > replacement and while not cheap, is available from reputable sources like > Farnell. The SSM2212 seems to be a quite compatible replamcement, with most parameters being in the same range. Cost ~6USD/pcs But i guess, for this application, the noise performance of the transistors is not that critical and something like a BCM847 should do the job as well. (cost <0.5USD/pcs) > 2) What is the "Ca. 3 Ohm" to the left of your circuit? ca. = circa = approximately. Probably an abrevation that is only common around europe. > Is that what you > estimate the input impedance is? I've got 95 m of 2.5 mm^2 wire. The > resistance of that is about 7.41 mOhm/m so my 95 m would have a DC > resistance of around 7 Ohms if I used it all. Hmm.. I think the impedance matters more than the resistance. But the schematics does not make any reference to that. Consider me confused. Attila Kinali -- I must not become metastable. Metastability is the mind-killer. Metastability is the little-death that brings total obliteration. I will face my metastability. I will permit it to pass over me and through me. And when it has gone past I will turn the inner eye to see its path. Where the metastability has gone there will be nothing. Only I will remain. ___ 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
On 16 July 2015 at 08:05, Ole Stender Nielsen wrote: > I use a home-made untuned loop antenna with 4 windings of 2.5 mm2 > insulated wire on a 80 x 80 cm wooden frame, and with a grounded base > pre-amplifier mounted on the antenna frame. A schematic is enclosed for you > to copy. > The pre-amplifier is powered through the cable, and loads the FS700 input > as required. > I live about 290 km from the island of Sylt, and get nice noise margin > figures from the FS700, normally about 40 dB, often up to 46 dB. > A couple of questions 1) Do you have any suggestions for a replacement for the LM394CN, which is obsolete and unobtainable from any reputable source? There are plenty on eBay for a few $'s from China, but the probability of them being fakes is greater than 0.99. The MAT12 seems to be one possible candidate for a replacement and while not cheap, is available from reputable sources like Farnell. 2) What is the "Ca. 3 Ohm" to the left of your circuit? Is that what you estimate the input impedance is? I've got 95 m of 2.5 mm^2 wire. The resistance of that is about 7.41 mOhm/m so my 95 m would have a DC resistance of around 7 Ohms if I used it all. I have built the loop 1.0 x 1.2 m. Hopefully that will be ok to receive at least one or both of * Lessay, France, power = 250 kW, distance = 321 km, bearing = 211 degrees. * Anthorn, England, power =- 250 kW, distance = 419 km, bearing 331 degrees. I now need to work out how many turns to put on it. Dave ___ 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
In message , paul swed writes: >So I have been interested in building a large loop for LORAN C. You cannot use a tuned/resonance loop for LORAN-C the way you can for CW stations like WWVB. Loran-C needs +/- 15kHz flat bandwidth (85-115 kHz) otherwise you loose the pulse-shape which allows you to find the right zero-crossing. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
In message <36e5f870-b2dd-42bb-a1d5-24d241aca...@n1k.org>, Bob Camp writes: >> It's interesting that >> >> http://www.vlf.it/feletti2/idealloop.html >> >> says that sensitivity is set by the mass of copper used. To quote >> >> "A single turn square loop, 1m side, made with 1kg copper has the same >> sensitivity of a 1000 turns square loop made with 1kg copper and same >> dimensions. In this context, the sensitivity limit is represented only by >> loop thermal noise: >> > >The *power* into the loop is a function of the area. I think they're barking up another tree: The number of turns you can make is inversely proportional to cross-section of the wire, so given a fixed mass of conductor, you can trade current for voltage by the number of turns. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
On Fri, 17 Jul 2015 12:55:07 +0100 "Dr. David Kirkby (Kirkby Microwave Ltd)" wrote: > Thank you Ole. That at least gives me something to start from. I guess the > op-amp design Poul-Henning Kamp used offers more flexibility for gain > adjustment. I might look at that too. If the amplifier is in a box with a > couple of banana jacks and a BNC socket, it is fairly easy to change one > amp for another. I assume from what you say that the FS700 will report the I would probably replace the AD797 with it's younger cusin the AD8099. The noise performance is very similar, but it has a GBW-product of >3GHz (instead of 110MHz), which potentially allows you do get much higher gain in the first stage. And best is: you can run it from a +5V supply and don't need to bother with a +/-5V supply (keeping in mind that the AD797 specs are for +/-15V, so they are likely to be worse at +/-5V). Please note that neither of those opamps are rail-to-rail. You need to stay 1.3V clear of the rails for the AD8099 (both, input and output) and 2.5V and 3V for input and output respectively for the AD797. The datasheet does not specify what happens when you cross the input rails limit, but I would expect nasty stuff like gain reversal and such. Also, the absolute maximum ratings have a maximum differential input voltage of 1.8V and 0.7V respectively. Do not cross that line, lest you want to smell magic smoke (ok, not really, but it might at least detoriate the input protection diodes, if not fry them) Attila Kinali -- I must not become metastable. Metastability is the mind-killer. Metastability is the little-death that brings total obliteration. I will face my metastability. I will permit it to pass over me and through me. And when it has gone past I will turn the inner eye to see its path. Where the metastability has gone there will be nothing. Only I will remain. ___ 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
I had not been paying attention to the thread but it has evolved into an area I had a question about. Typical LORAN C systems are the vlf preamp and whip. You never see anything about larger antennas such as might be used from the US to receive Europe stations. For WWVB 60 KHz I built a large loop 10' X 10' and 800' of wire tuned with preamp. The gain was dramatic to say the least. So I have been interested in building a large loop for LORAN C. But never really found any detail. From this thread it may be actually useful. I would build the same size loop but not make it sharply tuned because of the large signal bandwidth +- 10Khz. With the whip on winter nights I do get occasional lock of the European signals. Granted this will be an over the summer project. Regards Paul WB8TSL On Fri, Jul 17, 2015 at 8:31 AM, Dr. David Kirkby (Kirkby Microwave Ltd) < drkir...@kirkbymicrowave.co.uk> wrote: > On 16 July 2015 at 23:23, Bob Camp wrote: > > > Hi > > > > Quick and simple: > > > > 1) Signal power is proportional to the area of the loop. Bigger is > better. > > 2) Inductance is proportional to the turns squared. Turns do not directly > > affect signal to noise. > > 3) Inductance may be resonated with a capacitor. This gives a bandpass > > function. > > 4) The coil shapes are very common. The many inductance calculators on > the > > web will give you an inductance estimate. > > 5) If the inductance is resonated, the system Q (and thus bandwidth) is a > > function of the coil losses and the amplifier’s input impedance. > > 6) More turns gives a power match into a higher impedance ( more > voltage). > > 7) *Practical* matching of the amplifier to the antenna will give you an > > reasonable target number of turns. > > > > Bob > > > > It's interesting that > > http://www.vlf.it/feletti2/idealloop.html > > says that sensitivity is set by the mass of copper used. To quote > > "A single turn square loop, 1m side, made with 1kg copper has the same > sensitivity of a 1000 turns square loop made with 1kg copper and same > dimensions. In this context, the sensitivity limit is represented only by > loop thermal noise: > > noise floor (nV/sqrt(Hz)) = 4 sqrt(R in kOhm)" > > It is not immediately obvious where that equation comes from, but > re-arranging the equation for thermal noise power > > P=k T B > > (P in watts, k= Boltzmann contant, B is bandwidth in Hz) > > and assuming a temperature T of 300 Kelvin, k = 1.38 x 10^-23 J/K, one > finds the constant is 4.06, so the 4 in that equation is fairly accurate at > 300 Kelvin. > > I'd much rather wind a loop with a few turns than a few hundred turns! But > obviously the voltage rises with the number of turns, so requires less > gain. > > Dave > ___ > 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
Hi > On Jul 17, 2015, at 8:31 AM, Dr. David Kirkby (Kirkby Microwave Ltd) > wrote: > > On 16 July 2015 at 23:23, Bob Camp wrote: > >> Hi >> >> Quick and simple: >> >> 1) Signal power is proportional to the area of the loop. Bigger is better. >> 2) Inductance is proportional to the turns squared. Turns do not directly >> affect signal to noise. >> 3) Inductance may be resonated with a capacitor. This gives a bandpass >> function. >> 4) The coil shapes are very common. The many inductance calculators on the >> web will give you an inductance estimate. >> 5) If the inductance is resonated, the system Q (and thus bandwidth) is a >> function of the coil losses and the amplifier’s input impedance. >> 6) More turns gives a power match into a higher impedance ( more voltage). >> 7) *Practical* matching of the amplifier to the antenna will give you an >> reasonable target number of turns. >> >> Bob >> > > It's interesting that > > http://www.vlf.it/feletti2/idealloop.html > > says that sensitivity is set by the mass of copper used. To quote > > "A single turn square loop, 1m side, made with 1kg copper has the same > sensitivity of a 1000 turns square loop made with 1kg copper and same > dimensions. In this context, the sensitivity limit is represented only by > loop thermal noise: > The *power* into the loop is a function of the area. > noise floor (nV/sqrt(Hz)) = 4 sqrt(R in kOhm) > > It is not immediately obvious where that equation comes from, but > re-arranging the equation for thermal noise power > > P=k T B simply the standard thermal noise equation for a resistor > > (P in watts, k= Boltzmann contant, B is bandwidth in Hz) > > and assuming a temperature T of 300 Kelvin, k = 1.38 x 10^-23 J/K, one > finds the constant is 4.06, so the 4 in that equation is fairly accurate at > 300 Kelvin. > > I'd much rather wind a loop with a few turns than a few hundred turns! But > obviously the voltage rises with the number of turns, so requires less > gain. *but* the load resistance (and thus the thermal noose in that load) goes up at the same time. If you have a very low impedance buffer (common base stage etc) the number of turns will be very different than if you have the input gate of a MOSFET. Bob > > Dave > ___ > 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
On Fri, 17 Jul 2015 10:03:00 +0200 Magnus Danielson wrote: > Many thanks, 2.21 Ohm sounds more reasonable than 2 ZettaOhm (or 2 ZO), > which is what 2E21 would translate into if it where 2*10^21, so I wanted > to make sure there wasn't a typo. :) xEy is some kind of semi-standard notation for resistor values in the first three decades, when people do not want to write R (as it might be confused with the part number) or a dot (which might get lost when printing). But I don't know where this notation came from, or what the E stands for. I can only say I have seen it quite a few times already. Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
On 16 July 2015 at 23:23, Bob Camp wrote: > Hi > > Quick and simple: > > 1) Signal power is proportional to the area of the loop. Bigger is better. > 2) Inductance is proportional to the turns squared. Turns do not directly > affect signal to noise. > 3) Inductance may be resonated with a capacitor. This gives a bandpass > function. > 4) The coil shapes are very common. The many inductance calculators on the > web will give you an inductance estimate. > 5) If the inductance is resonated, the system Q (and thus bandwidth) is a > function of the coil losses and the amplifier’s input impedance. > 6) More turns gives a power match into a higher impedance ( more voltage). > 7) *Practical* matching of the amplifier to the antenna will give you an > reasonable target number of turns. > > Bob > It's interesting that http://www.vlf.it/feletti2/idealloop.html says that sensitivity is set by the mass of copper used. To quote "A single turn square loop, 1m side, made with 1kg copper has the same sensitivity of a 1000 turns square loop made with 1kg copper and same dimensions. In this context, the sensitivity limit is represented only by loop thermal noise: noise floor (nV/sqrt(Hz)) = 4 sqrt(R in kOhm)" It is not immediately obvious where that equation comes from, but re-arranging the equation for thermal noise power P=k T B (P in watts, k= Boltzmann contant, B is bandwidth in Hz) and assuming a temperature T of 300 Kelvin, k = 1.38 x 10^-23 J/K, one finds the constant is 4.06, so the 4 in that equation is fairly accurate at 300 Kelvin. I'd much rather wind a loop with a few turns than a few hundred turns! But obviously the voltage rises with the number of turns, so requires less gain. Dave ___ 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
On 16 July 2015 at 08:05, Ole Stender Nielsen wrote: > I use a home-made untuned loop antenna with 4 windings of 2.5 mm2 > insulated wire on a 80 x 80 cm wooden frame, and with a grounded base > pre-amplifier mounted on the antenna frame. A schematic is enclosed for you > to copy. > Thank you. I will build one of those. I have most of the parts here, but not the transistors. > The pre-amplifier is powered through the cable, and loads the FS700 input > as required. > I live about 290 km from the island of Sylt, and get nice noise margin > figures from the FS700, normally about 40 dB, often up to 46 dB. > It's odd that http://www.loran-history.info/sylt/sylt.htm shows Sylt as closing in 2006. Did Sylt ever close and then re-open, and that web site just out of date? I'm a little further than you (321 km vs your 290 km) from my nearest transmitter. I'm located in Althorne, Chelmsford, Essex, UK (51.6517913 N, 0.7752657 E) and I *believe* my nearest Loran-C transmitters are 1) Lessay, France, power = 250 kW, distance = 321 km, bearing = 211 degrees. 2) Anthorn, England, power =- 250 kW, distance = 419 km, bearing 331 degrees. 3) Sylt, Germany, power = 250 kW, distance = 611 km, bearing = 52 degrees. 4) Soustons, France, power = 250 kW, distance = 896 km, bearing 191 degrees 5) Edja, Fraoe islands, power = 400 kW, distance = 1274 km, bearing = 341 degrees. > For larger distances to the transmitter site, you may need to insert > additional amplification between the grounded base pre-amplifier and the > FS700, and that requires that you provide power to the pre-amplifier > through a bias Tee, and that you load the FS700 input to keep it happy. A > while after I installed the antenna in the attic, I added additional > amplification, not due to a low signal level, but because I wanted to use > the loop antenna for other longwave services too, and that required that I > had to split out the signal. > > Best regards > Ole > Thank you Ole. That at least gives me something to start from. I guess the op-amp design Poul-Henning Kamp used offers more flexibility for gain adjustment. I might look at that too. If the amplifier is in a box with a couple of banana jacks and a BNC socket, it is fairly easy to change one amp for another. I assume from what you say that the FS700 will report the Dave ___ 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
Hi Ole, Many thanks, 2.21 Ohm sounds more reasonable than 2 ZettaOhm (or 2 ZO), which is what 2E21 would translate into if it where 2*10^21, so I wanted to make sure there wasn't a typo. :) Then I know that my values may vary for that part of the design. Cheers, Magnus On 07/16/2015 09:21 PM, Ole Stender Nielsen wrote: Hi Magnus, The 2E21 is a 2.21 Ohms resistor. The RC network was found useful to ensure loading at higher frequencies. Best regards Ole Den 16-07-2015 kl. 18:27 skrev Magnus Danielson: Ole, What is the value of the "2E21" resistor? Looks like a typo. 2k? Feel inspired to rig up something for my FS700. Will wooden frame my TP-cable wired to form a 8 turns times the cable-turns. Cheers, Magnus On 07/16/2015 09:05 AM, Ole Stender Nielsen wrote: I use a home-made untuned loop antenna with 4 windings of 2.5 mm2 insulated wire on a 80 x 80 cm wooden frame, and with a grounded base pre-amplifier mounted on the antenna frame. A schematic is enclosed for you to copy. The pre-amplifier is powered through the cable, and loads the FS700 input as required. I live about 290 km from the island of Sylt, and get nice noise margin figures from the FS700, normally about 40 dB, often up to 46 dB. For larger distances to the transmitter site, you may need to insert additional amplification between the grounded base pre-amplifier and the FS700, and that requires that you provide power to the pre-amplifier through a bias Tee, and that you load the FS700 input to keep it happy. A while after I installed the antenna in the attic, I added additional amplification, not due to a low signal level, but because I wanted to use the loop antenna for other longwave services too, and that required that I had to split out the signal. Best regards Ole Den 15-07-2015 kl. 18:02 skrev Dr. David Kirkby - Kirkby Microwave Ltd : Does anyone know of the latest firmware for the Stanford Research FS700 Loran-C frequency standard? I know someone who has one with firmware 1.20, but I don't know if there's any later firmware. I recall asking Stanford Research about firmware for the SR620 but got no response, so I don't know if I will have any better luck with the FS700. What's the best sort of antenna for these? I know Stanford sell one, and by the cost of new professional equipment, the $250 is not abnormally high, but I'd rather look at building something if I purchase one of these standards. I did think of using a half-wave dipole, but my garden is just a wee bit too small.:-) Dave ___ 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 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 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
Hi Quick and simple: 1) Signal power is proportional to the area of the loop. Bigger is better. 2) Inductance is proportional to the turns squared. Turns do not directly affect signal to noise. 3) Inductance may be resonated with a capacitor. This gives a bandpass function. 4) The coil shapes are very common. The many inductance calculators on the web will give you an inductance estimate. 5) If the inductance is resonated, the system Q (and thus bandwidth) is a function of the coil losses and the amplifier’s input impedance. 6) More turns gives a power match into a higher impedance ( more voltage). 7) *Practical* matching of the amplifier to the antenna will give you an reasonable target number of turns. Bob > On Jul 16, 2015, at 9:57 AM, Dr. David Kirkby (Kirkby Microwave Ltd) > wrote: > > ZOn 15 Jul 2015 22:18, "Poul-Henning Kamp" wrote: >> >> >> David Kirkby - Kirkby >> Microwave Ltd " writes: >> >>> What's the best sort of antenna for these? >> >> I use a $20 loop antenna I have rigged up myself, it lives in my attic: >> >>http://phk.freebsd.dk/loran-c/Antenna/ > > Hi, > Thank you for that. But it is a bit short of information. I appreciate > your use of "the nearest bent nail" principles, but roughly how many turns > were there on the coil? Do you have a circuit for the amplifier? The AD797 > data sheet you link to is broken, but the error message is quite funny. I > found the data sheet on the AD797 and see it is a very low noise op-amp. > > I must admit to knowing next to nothing about antennas at the Loran 100 kHz > (+/- a lot) frequency. How does one go about testing the antennas? I'm > about to place an order for an FS700, but will not have an antenna when it > arrives. I have a short period of right of return, and I'd like to get > something in place so I can quickly test this. > > I have an HP 4284A precision LCR meter which works at more than 8000 > discrete frequencies between 20 Hz & 1 MHz. Those frequencies include 60, > 80, 100, 120 and 150 kHz. That's the only thing I have got that measures > impedance as low as 100 kHz. > > There's a description of the active antenna for the FS700 in the manual, > but with no circuit diagram, it is a bit tricky to understand. I assume > that the FS700 has some sort of bias-T to pass DC up the cable to power the > amplifier - is that so? If so, do you know the voltage? > > No doubt all these things will be revealed when I get the FS700, but I'd > like to be ready to test it when it arrives. > ___ > 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
Hi Magnus, The 2E21 is a 2.21 Ohms resistor. The RC network was found useful to ensure loading at higher frequencies. Best regards Ole Den 16-07-2015 kl. 18:27 skrev Magnus Danielson: Ole, What is the value of the "2E21" resistor? Looks like a typo. 2k? Feel inspired to rig up something for my FS700. Will wooden frame my TP-cable wired to form a 8 turns times the cable-turns. Cheers, Magnus On 07/16/2015 09:05 AM, Ole Stender Nielsen wrote: I use a home-made untuned loop antenna with 4 windings of 2.5 mm2 insulated wire on a 80 x 80 cm wooden frame, and with a grounded base pre-amplifier mounted on the antenna frame. A schematic is enclosed for you to copy. The pre-amplifier is powered through the cable, and loads the FS700 input as required. I live about 290 km from the island of Sylt, and get nice noise margin figures from the FS700, normally about 40 dB, often up to 46 dB. For larger distances to the transmitter site, you may need to insert additional amplification between the grounded base pre-amplifier and the FS700, and that requires that you provide power to the pre-amplifier through a bias Tee, and that you load the FS700 input to keep it happy. A while after I installed the antenna in the attic, I added additional amplification, not due to a low signal level, but because I wanted to use the loop antenna for other longwave services too, and that required that I had to split out the signal. Best regards Ole Den 15-07-2015 kl. 18:02 skrev Dr. David Kirkby - Kirkby Microwave Ltd : Does anyone know of the latest firmware for the Stanford Research FS700 Loran-C frequency standard? I know someone who has one with firmware 1.20, but I don't know if there's any later firmware. I recall asking Stanford Research about firmware for the SR620 but got no response, so I don't know if I will have any better luck with the FS700. What's the best sort of antenna for these? I know Stanford sell one, and by the cost of new professional equipment, the $250 is not abnormally high, but I'd rather look at building something if I purchase one of these standards. I did think of using a half-wave dipole, but my garden is just a wee bit too small.:-) Dave ___ 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 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
Ole, What is the value of the "2E21" resistor? Looks like a typo. 2k? Feel inspired to rig up something for my FS700. Will wooden frame my TP-cable wired to form a 8 turns times the cable-turns. Cheers, Magnus On 07/16/2015 09:05 AM, Ole Stender Nielsen wrote: I use a home-made untuned loop antenna with 4 windings of 2.5 mm2 insulated wire on a 80 x 80 cm wooden frame, and with a grounded base pre-amplifier mounted on the antenna frame. A schematic is enclosed for you to copy. The pre-amplifier is powered through the cable, and loads the FS700 input as required. I live about 290 km from the island of Sylt, and get nice noise margin figures from the FS700, normally about 40 dB, often up to 46 dB. For larger distances to the transmitter site, you may need to insert additional amplification between the grounded base pre-amplifier and the FS700, and that requires that you provide power to the pre-amplifier through a bias Tee, and that you load the FS700 input to keep it happy. A while after I installed the antenna in the attic, I added additional amplification, not due to a low signal level, but because I wanted to use the loop antenna for other longwave services too, and that required that I had to split out the signal. Best regards Ole Den 15-07-2015 kl. 18:02 skrev Dr. David Kirkby - Kirkby Microwave Ltd : Does anyone know of the latest firmware for the Stanford Research FS700 Loran-C frequency standard? I know someone who has one with firmware 1.20, but I don't know if there's any later firmware. I recall asking Stanford Research about firmware for the SR620 but got no response, so I don't know if I will have any better luck with the FS700. What's the best sort of antenna for these? I know Stanford sell one, and by the cost of new professional equipment, the $250 is not abnormally high, but I'd rather look at building something if I purchase one of these standards. I did think of using a half-wave dipole, but my garden is just a wee bit too small.:-) Dave ___ 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 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
In message , "Dr. David Kirkby (Kirkby Microwave Ltd)" writes: >but roughly how many turns were there on the coil? Probably too many, all things considered, but I have *no* idea. >Do you have a circuit for the amplifier? It was based on/inspired by a schematic I found on vlf.it >I must admit to knowing next to nothing about antennas at the Loran 100 kHz >(+/- a lot) frequency. How does one go about testing the antennas? Plug it into a spectrum analyzer or oscilloscope. Use average mode. Trigger with a pulse generator with a period of: 6731 * 2 * 10µs) = 0.13462 Hz and you should see the pulses. If you have a good spectrum analyzer, you can probably do this with a few meters of wire as antenna. The result should look something like: http://phk.freebsd.dk/misc/dscf0275.jpg >That's the only thing I have got that measures impedance as low as 100 kHz. 100 kHz is practically audio, impedances hardly matter: The reflections have wavelengths measured in km. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
In message <55a757d3.9050...@mail.tele.dk>, Ole Stender Nielsen writes: >I use a home-made untuned loop antenna [...] A note about Loran-C and loop-antennas: The loop-antennas are sensitive to magnetic fields and therefore sensitive to direction. Depending on side of the loop you point at the Loran-C transmitter you will get a "true" or inverted signal. If you get an inverted signal, a Loran-C receiver will lock onto the wrong zero-crossing, which will increase your phase noise because only the 3rd positive crossing is truly steered. If you want to receive more than one Loran-C transmitter, the directivity of the loop-antenna is a disadvantage and you are better of with a monopole (electric) antenna. I can recommend Chris Trasks designs: http://www.home.earthlink.net/~christrask/ I built one from the "Complementary Push-Pull Active Antenna Amplifiers" document and it drags in signals from 4kHz to well north of 150Mhz. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
ZOn 15 Jul 2015 22:18, "Poul-Henning Kamp" wrote: > > > David Kirkby - Kirkby > Microwave Ltd " writes: > > >What's the best sort of antenna for these? > > I use a $20 loop antenna I have rigged up myself, it lives in my attic: > > http://phk.freebsd.dk/loran-c/Antenna/ Hi, Thank you for that. But it is a bit short of information. I appreciate your use of "the nearest bent nail" principles, but roughly how many turns were there on the coil? Do you have a circuit for the amplifier? The AD797 data sheet you link to is broken, but the error message is quite funny. I found the data sheet on the AD797 and see it is a very low noise op-amp. I must admit to knowing next to nothing about antennas at the Loran 100 kHz (+/- a lot) frequency. How does one go about testing the antennas? I'm about to place an order for an FS700, but will not have an antenna when it arrives. I have a short period of right of return, and I'd like to get something in place so I can quickly test this. I have an HP 4284A precision LCR meter which works at more than 8000 discrete frequencies between 20 Hz & 1 MHz. Those frequencies include 60, 80, 100, 120 and 150 kHz. That's the only thing I have got that measures impedance as low as 100 kHz. There's a description of the active antenna for the FS700 in the manual, but with no circuit diagram, it is a bit tricky to understand. I assume that the FS700 has some sort of bias-T to pass DC up the cable to power the amplifier - is that so? If so, do you know the voltage? No doubt all these things will be revealed when I get the FS700, but I'd like to be ready to test it when it arrives. ___ 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
In message <55a68425.6020...@kirkbymicrowave.co.uk>, "Dr. David Kirkby - Kirkby Microwave Ltd " writes: >What's the best sort of antenna for these? I use a $20 loop antenna I have rigged up myself, it lives in my attic: http://phk.freebsd.dk/loran-c/Antenna/ -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
Hi Dave: I've used both an active short whip antennas and what may be better a long wire (100 feet) resonated with a series inductor (Miller adjustable 3 mH). http://www.prc68.com/I/LF-Ant.shtml http://www.prc68.com/I/Spec_0002.shtml Mail_Attachment -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html Dr. David Kirkby - Kirkby Microwave Ltd wrote: Does anyone know of the latest firmware for the Stanford Research FS700 Loran-C frequency standard? I know someone who has one with firmware 1.20, but I don't know if there's any later firmware. I recall asking Stanford Research about firmware for the SR620 but got no response, so I don't know if I will have any better luck with the FS700. What's the best sort of antenna for these? I know Stanford sell one, and by the cost of new professional equipment, the $250 is not abnormally high, but I'd rather look at building something if I purchase one of these standards. I did think of using a half-wave dipole, but my garden is just a wee bit too small.:-) Dave ___ 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] Firmware and antenna for Stanford Research FS700 Loran C frequency standard
David Any LORAN C boat antenna will work fine. I do know that if you have a distribution system then to make the SRS happy you need to add a 420 ohm R to ground to act as a antenna preamp current load. It checks. Equally a fet/transistor VLF preamp will work well. Even a long length of wire if the signals strong. Regards Paul WB8TSL On Wed, Jul 15, 2015 at 12:02 PM, Dr. David Kirkby - Kirkby Microwave Ltd < drkir...@kirkbymicrowave.co.uk> wrote: > Does anyone know of the latest firmware for the Stanford Research FS700 > Loran-C frequency standard? I know someone who has one with firmware 1.20, > but I don't know if there's any later firmware. I recall asking Stanford > Research about firmware for the SR620 but got no response, so I don't know > if I will have any better luck with the FS700. > > What's the best sort of antenna for these? I know Stanford sell one, and > by the cost of new professional equipment, the $250 is not abnormally high, > but I'd rather look at building something if I purchase one of these > standards. I did think of using a half-wave dipole, but my garden is just a > wee bit too small.:-) > > Dave > > -- > Dr. David Kirkby Ph.D CEng MIET > Kirkby Microwave Ltd > Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 > 6DT, UK. > Registered in England and Wales, company number 08914892. > http://www.kirkbymicrowave.co.uk/ > Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please) > > > ___ > 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.
