Re: [time-nuts] GPS shielding by power lines?
Hi David yes indeed and the qualify of the fix imporves as we move away at right angles to the linedespite some trees and a tall hedge on one side. Dramatic and quite repeatable. Alan G3NYK - Original Message - From: David McGaw [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, August 11, 2008 5:12 AM Subject: Re: [time-nuts] GPS shielding by power lines? You didn't say if you tried the antenna under the power lines but outside the cabin. What is translucent to light may not be to microwaves. David N1HAC . ___ 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] GPS shielding by power lines?
Hi Dave, Ah I meant a 1600Mhz AM RX not a MW job the resuly is quite dramatic from seeing no usable satelites to seeing 10 to 12. The software we are running plots the tracks of the those sats seen so we can see that when seen even close to trees, foliage shielding is not a problem. I could post this plot over a number of hours it is very pretty, and shows clearly the northerly extent of the orbits very clearly. Thanks Magnus for thoughts on further tests. We are logging the NMEA sentences so most of that detail could be available. A job for a laptop I think. Alan G3NYK - Original Message - From: David Ackrill [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, August 10, 2008 8:30 AM Subject: Re: [time-nuts] GPS shielding by power lines? Alan Melia wrote: Hi all, in the process of setting up a GPS time standard for a Radio Astronomy facility (amateur) we installed a GPS receiver in a small cabin with a translucent roof, thinking that would not impede the GPS signal. After a lot of head scratching as to why we were not getting the performane we got at another site, we realised that the convenient position for the cabin was directly below a three phase 11kV power distribution line ( common UK rural electricity distribution system). Since the satellite signals are in the high UHF range, arround 1575MHz, the AM receiver test is not going to tell you alot about the noise at the frequency that the GPS receiver is using. So, even if you had detected any noise from the overhead lines, it might not have been proof that this was the cause of the problems. I find that the positioning of the antenna for a GPS receiver can be very touchy. You really need a good view to the horizon and, despite what you might see on simple presentations of the satellite positions, they do tend to be mainly in the southern sky when viewed from the UK. See http://www.guralp.com/articles/20060405-howto-gps-troubleshooting/print for details. The other effect that you may notice is that your 'good' position for the antenna isn't so good all of the time as the satellites appear to move round the sky and the signal strengths from each alters. Dave (G0DJA) ___ 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] GPS shielding by power lines?
Hi Tom Brilliant I hadnt thought of the fields actually affecting the operation of the electronics! that is certainly something that might be interesting to check. I note there lines have three phase feeds but no neutral wire so they must use ground as the return path to any unbalance currents.(?) Thanks Alan G3NYK - Original Message - From: Thomas A. Frank [EMAIL PROTECTED] To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, August 10, 2008 6:38 AM Subject: Re: [time-nuts] GPS shielding by power lines? Alan; I have no idea if this is a cause of your problem, but in some work I have done, I found that the high field strengths (electrostatic and magnetic) found under power lines can adversely effect electronic equipment that should otherwise be unaffected by the presence of power lines and their low frequency signals. there. --snip ___ 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] GPS shielding by power lines?
On Sun, 10 Aug 2008 10:27:31 +0100, Alan Melia wrote: I note there lines have three phase feeds but no neutral wire so they must use ground as the return path to any unbalance currents.(?) As long as the system is kept balanced a 3 phase energy transport system does not need a 4th wire as the sum of all the currents in the 3 wires (phase shift 120deg between the wires) is zero! regards Arnold, DK2WT ___ 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] GPS shielding by power lines?
Alan Melia wrote: Hi Tom Brilliant I hadnt thought of the fields actually affecting the operation of the electronics! that is certainly something that might be interesting to check. I note there lines have three phase feeds but no neutral wire so they must use ground as the return path to any unbalance currents.(?) On the UK 11kV overhead network the phases are all distributed without a neutral. At the 11kV/415V transformer the HV side is delta wound and the LV is star wound, so the neutral/earth for the supply is taken from that point, not from the HV side. So, you are correct, the connection to the general mass of earth at the transformers is used as the return path. Which is why there are regulations about the acceptable earthing impedances at HV/LV transformers on an overhead supply. Tales of Linesmen watering earth rods to get away without having to drive in more earth rods and connect up to the transformers, and so avoid having to drive rods into hard ground, are legion in the ESI... In fact, if you look at most of the overhead high voltage distribution systems, they are all phase only, no neutral... Dave (G0DJA) ___ 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] GPS shielding by power lines?
Arnold Tibus wrote: As long as the system is kept balanced a 3 phase energy transport system does not need a 4th wire as the sum of all the currents in the 3 wires (phase shift 120deg between the wires) is zero! regards Arnold, DK2WT That is true Arnold, but in the UK (and in some other countries) we don't always have a completely balanced load. There are cases where two phase 11kV lines are run out to farms and other rural houses and, often the equipment connected at the farm/rural supplies isn't properly balanced either. The unbalanced current is connected to earth at the HV/LV transformer, as described previously. :-) Probably getting a bit OT now... Dave (G0DJA) ___ 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] GPS shielding by power lines?
Around all high voltage lines the air is somewhat ionized and this may result in sufficient free electrons to seriously mess up the GPS signal, although I wouldn't expect much trouble from a 11kV line. The fact that the navigation message is 50Hz in the GPS signal and the power-grid in the UK is close to 50Hz is not a good thing in any case. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED] | 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] GPS shielding by power lines?
Poul-Henning Kamp wrote: The fact that the navigation message is 50Hz in the GPS signal and the power-grid in the UK is close to 50Hz is not a good thing in any case. By UK law, it must be within +/- 1% of 50Hz. :-) Dave (G0DJA) ___ 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] GPS shielding by power lines?
Hi Didier, thanks for that idea, yes they were all pucks all Garmin two intended for marine use and one was a old Garmin GPSIIplus with a mag puck. I have a Trimble Palisade that I have not got round to working on yet, but I understand that there are problems putting this version into NMEA mode...so will have to be careful. Thanks Alan G3NYK - Original Message - From: Didier Juges [EMAIL PROTECTED] To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Sunday, August 10, 2008 12:52 PM Subject: Re: [time-nuts] GPS shielding by power lines? Alan, I don't believe you have said what type of antenna you are using. If you are using a true timing antenna (Symmetricom, Trimble Bullet) I would expect little or no direct effect from the power lines, but if you are using a puck or other inexpensive commercial antenna (which have little or no filtering or shielding), you may well be affected directly by the field from the power line on the antenna itself. The Thunderbolt itself should have enough filtering to protect you from a direct effect, the Thunderbolt has been designed to be co-located with other equipment, particularly cell transmitters, so I would expect it to be fairly immune to stray fields. Didier KO4BB ___ 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] GPS shielding by power lines?
In message [EMAIL PROTECTED], David Ackrill writes: Poul-Henning Kamp wrote: The fact that the navigation message is 50Hz in the GPS signal and the power-grid in the UK is close to 50Hz is not a good thing in any case. By UK law, it must be within +/- 1% of 50Hz. :-) Yeah, but the fact that it wanders in short time would make it an excellent frustration for GPS signal locking. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED] | 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] GPS shielding by power lines?
Alan, I recommend you look for an HP 58532A. I bought a brand new one on eBay for $50 BIN, sometimes you can do better. This is a good timing-grade antenna, and intended to stay outside for a long time. They have good filtering and the LNA is shielded. Didier KO4BB -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Alan Melia Sent: Sunday, August 10, 2008 8:17 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPS shielding by power lines? Hi Didier, thanks for that idea, yes they were all pucks all Garmin two intended for marine use and one was a old Garmin GPSIIplus with a mag puck. I have a Trimble Palisade that I have not got round to working on yet, but I understand that there are problems putting this version into NMEA mode...so will have to be careful. Thanks Alan G3NYK - Original Message - From: Didier Juges [EMAIL PROTECTED] To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Sunday, August 10, 2008 12:52 PM Subject: Re: [time-nuts] GPS shielding by power lines? Alan, I don't believe you have said what type of antenna you are using. If you are using a true timing antenna (Symmetricom, Trimble Bullet) I would expect little or no direct effect from the power lines, but if you are using a puck or other inexpensive commercial antenna (which have little or no filtering or shielding), you may well be affected directly by the field from the power line on the antenna itself. The Thunderbolt itself should have enough filtering to protect you from a direct effect, the Thunderbolt has been designed to be co-located with other equipment, particularly cell transmitters, so I would expect it to be fairly immune to stray fields. Didier KO4BB ___ 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] GPS shielding by power lines?
Hi, In car radio capacitive antennas are used. The required LNA rejection for the power line frequency is in the order of 100dB. henk On Aug 10, 2008, at 15:16, Alan Melia wrote: Hi Didier, thanks for that idea, yes they were all pucks all Garmin two intended for marine use and one was a old Garmin GPSIIplus with a mag puck. I have a Trimble Palisade that I have not got round to working on yet, but I understand that there are problems putting this version into NMEA mode...so will have to be careful. Thanks Alan G3NYK - Original Message - From: Didier Juges [EMAIL PROTECTED] To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Sunday, August 10, 2008 12:52 PM Subject: Re: [time-nuts] GPS shielding by power lines? Alan, I don't believe you have said what type of antenna you are using. If you are using a true timing antenna (Symmetricom, Trimble Bullet) I would expect little or no direct effect from the power lines, but if you are using a puck or other inexpensive commercial antenna (which have little or no filtering or shielding), you may well be affected directly by the field from the power line on the antenna itself. The Thunderbolt itself should have enough filtering to protect you from a direct effect, the Thunderbolt has been designed to be co-located with other equipment, particularly cell transmitters, so I would expect it to be fairly immune to stray fields. Didier KO4BB ___ 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] GPS shielding by power lines?
Around here they place cell antennas on a monopole down the center of power transmission line towers. The GPS antennas are invariably directly below the 100-200kv lines. The GPS signal must be reliable enough or the cell sites wouldn't be there. Scott Alan Melia wrote: Hi all, in the process of setting up a GPS time standard for a Radio Astronomy facility (amateur) we installed a GPS receiver in a small cabin with a translucent roof, thinking that would not impede the GPS signal. After a lot of head scratching as to why we were not getting the performane we got at another site, we realised that the convenient position for the cabin was directly below a three phase 11kV power distribution line ( common UK rural electricity distribution system). We extended the cable and moved the antenna about 20 - 30 feet to the side of the line run, which was mounted on wooden poles at about 25 feet. In this position we immediately got a reliable fix. The fix and number of usable satellites degrades as we move nearer the lines. The thought was that there as interference arcing or corona noise from the line insulators, and a receiver (AM) was deployed to listen for what was expected to be a substantial wide band noise signalwe didnt hear one! We are now confused about what the effect is. The signal could not be screened by the wires which are about 3 feet apart, but they definite provide a cone of interference directly under the run. The experiment was later repeated with two further different GPS receivers and produced the same result. Has anyone seen this before? have you any idea of what level noise we should be looking for? I believe this is a wide signal so maybe an AM receiver is not the best choice The area is a rural, horticultural area (called market garden in the UK) We are obviouslt concerned to trace any noise sources in the vicinity of the Hydrogen line frequency at 1420MHz. Alan G3NYK ___ 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] GPS shielding by power lines?
On Sun, 10 Aug 2008 13:05:47 +0100, David Ackrill wrote: Arnold Tibus wrote: As long as the system is kept balanced a 3 phase energy transport system does not need a 4th wire as the sum of all the currents in the 3 wires (phase shift 120deg between the wires) is zero! regards Arnold, DK2WT That is true Arnold, but in the UK (and in some other countries) we don't always have a completely balanced load. There are cases where two phase 11kV lines are run out to farms and other rural houses and, often the equipment connected at the farm/rural supplies isn't properly balanced either. The unbalanced current is connected to earth at the HV/LV transformer, as described previously. :-) David, I agree with the a.m. unbalance, but the current should not be routed via the ground! As you say, there is a connection to ground on the Y circuit of the secondary side towards the load. From this point on there are then 4 wires in use (L1, L2, L3, N). I repeat, the return current shall not be run via ground! (At the entry of a building the neutral or return wire will be grounded to avoid voltage differences. At this point the PE will be connected as well for protection purposes.) Ground currents are in general very problematic because the resulting severe corrosion effects and noise. As I am informed, the connections of hundreds of loads will (statistically) appear more or less as balanced at the end. Eventual still existing unsymmetries are to be compensated at the medium (10 to 20 kV) to end voltage (eg. 230/400V) using distribution transformers via tricky Z-winding connections. To avoid overvoltage due to unbalance and the floating of the HV-lines, the star point of the Y transformer at one end may be grounded for ground reference, on the other side of the line a overvoltage protector will be used instead of direct grounding. Ground currents are not possible this way. To eliminate such unbalances on the HV-lines there are possibilities to compensate with special symmetry compensator devices (a kind of transformers). Sorry, this was in effect somewhat off topic, but I didn't want to leave this point uncomplete... Now to the main concern and question: I believe the problem with the 'blind' GPS system may have other reasons. 1. Due to very fast changing loads and pulse like loads (switcher etc.) there are indeed some rf on the lines. Driving partly the hv-transformers into saturation does as well result in higher frequencies (fourier). The long lines do act as antennas... 2. The high and very high voltage lines do create very strong fields up to several kV/m and some µT! To bring this fieldstrength significantly down one shall position the antenna at least 30 to 50m away from the center line. (35 years ago I did stop with my car directly below a 380 kV line. My feet on ground standing in the open door I put my hand on top the roof of the car - wow what a strong feeling touching that big capacitor plane 1.5 m above ground! ) I am sure, the strong fields below the power lines do create some distribution current in the soil. Perhaps specially patch antennas are very susceptable to such strong fields which may upset the amplfier shifting levels...? How strong are the rf fields from these lines being perhaps a factor of several thousands below the 50 Hz field strength? regards Arnold, DK2WT ___ 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] GPS shielding by power lines?
You didn't say if you tried the antenna under the power lines but outside the cabin. What is translucent to light may not be to microwaves. David N1HAC At 05:15 PM 8/9/2008, you wrote: Hi all, in the process of setting up a GPS time standard for a Radio Astronomy facility (amateur) we installed a GPS receiver in a small cabin with a translucent roof, thinking that would not impede the GPS signal. After a lot of head scratching as to why we were not getting the performane we got at another site, we realised that the convenient position for the cabin was directly below a three phase 11kV power distribution line ( common UK rural electricity distribution system). We extended the cable and moved the antenna about 20 - 30 feet to the side of the line run, which was mounted on wooden poles at about 25 feet. In this position we immediately got a reliable fix. The fix and number of usable satellites degrades as we move nearer the lines. The thought was that there as interference arcing or corona noise from the line insulators, and a receiver (AM) was deployed to listen for what was expected to be a substantial wide band noise signalwe didnt hear one! We are now confused about what the effect is. The signal could not be screened by the wires which are about 3 feet apart, but they definite provide a cone of interference directly under the run. The experiment was later repeated with two further different GPS receivers and produced the same result. Has anyone seen this before? have you any idea of what level noise we should be looking for? I believe this is a wide signal so maybe an AM receiver is not the best choice The area is a rural, horticultural area (called market garden in the UK) We are obviouslt concerned to trace any noise sources in the vicinity of the Hydrogen line frequency at 1420MHz. Alan G3NYK ___ 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] GPS shielding by power lines?
Hi all, in the process of setting up a GPS time standard for a Radio Astronomy facility (amateur) we installed a GPS receiver in a small cabin with a translucent roof, thinking that would not impede the GPS signal. After a lot of head scratching as to why we were not getting the performane we got at another site, we realised that the convenient position for the cabin was directly below a three phase 11kV power distribution line ( common UK rural electricity distribution system). We extended the cable and moved the antenna about 20 - 30 feet to the side of the line run, which was mounted on wooden poles at about 25 feet. In this position we immediately got a reliable fix. The fix and number of usable satellites degrades as we move nearer the lines. The thought was that there as interference arcing or corona noise from the line insulators, and a receiver (AM) was deployed to listen for what was expected to be a substantial wide band noise signalwe didnt hear one! We are now confused about what the effect is. The signal could not be screened by the wires which are about 3 feet apart, but they definite provide a cone of interference directly under the run. The experiment was later repeated with two further different GPS receivers and produced the same result. Has anyone seen this before? have you any idea of what level noise we should be looking for? I believe this is a wide signal so maybe an AM receiver is not the best choice The area is a rural, horticultural area (called market garden in the UK) We are obviouslt concerned to trace any noise sources in the vicinity of the Hydrogen line frequency at 1420MHz. Alan G3NYK ___ 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] GPS shielding by power lines?
Alan Melia wrote: Hi all, in the process of setting up a GPS time standard for a Radio Astronomy facility (amateur) we installed a GPS receiver in a small cabin with a translucent roof, thinking that would not impede the GPS signal. After a lot of head scratching as to why we were not getting the performane we got at another site, we realised that the convenient position for the cabin was directly below a three phase 11kV power distribution line ( common UK rural electricity distribution system). We extended the cable and moved the antenna about 20 - 30 feet to the side of the line run, which was mounted on wooden poles at about 25 feet. In this position we immediately got a reliable fix. The fix and number of usable satellites degrades as we move nearer the lines. The thought was that there as interference arcing or corona noise from the line insulators, and a receiver (AM) was deployed to listen for what was expected to be a substantial wide band noise signalwe didnt hear one! We are now confused about what the effect is. The signal could not be screened by the wires which are about 3 feet apart, but they definite provide a cone of interference directly under the run. The experiment was later repeated with two further different GPS receivers and produced the same result. Has anyone seen this before? have you any idea of what level noise we should be looking for? I believe this is a wide signal so maybe an AM receiver is not the best choice The area is a rural, horticultural area (called market garden in the UK) We are obviouslt concerned to trace any noise sources in the vicinity of the Hydrogen line frequency at 1420MHz. It can also be a very simple case of strong multipath causing cancelation reflections strong enought to obscure the signal. Be sure to plot signal strength and if possible delta distance from solution for each satellite along with elevation and azimuth. See if a clear pattern emerges such that certain angles is problematic. Just to make you look in another direction. Cheers, Magnus ___ 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] GPS shielding by power lines?
The thought was that there as interference arcing or corona noise from the line insulators, and a receiver (AM) was deployed to listen for what was expected to be a substantial wide band noise signalwe didnt hear one! We are now confused about what the effect is. The signal could not be screened by the wires which are about 3 feet apart, but they definite provide a cone of interference directly under the run. The experiment was later repeated with two further different GPS receivers and produced the same result. Has anyone seen this before? have you any idea of what level noise we should be looking for? I believe this is a wide signal so maybe an AM receiver is not the best choice The area is a rural, horticultural area (called market garden in the UK) We are obviouslt concerned to trace any noise sources in the vicinity of the Hydrogen line frequency at 1420MHz. Alan G3NYK Alan; I have no idea if this is a cause of your problem, but in some work I have done, I found that the high field strengths (electrostatic and magnetic) found under power lines can adversely effect electronic equipment that should otherwise be unaffected by the presence of power lines and their low frequency signals. I would imagine that the fields could desensitize receivers by overloading the front end amplifiers, and no amount of filtering is going to help because it is virtually impossible to shield against 50/60 Hz signals. A solid steel conduit several mm thick is only good for about 27 dB attenuation at power line frequencies. Fortunately, distance makes things better, so you may just have to move everything a bit away from the power lines. Our solution was to digitize our signals several hundred meters from the power lines and send the results digitally past them. Try getting a field strength meter (gaussmeter) and see what levels you have under the lines. Tom Frank, KA2CDK ___ 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.
