Re: Topband: Amplitude Modulation
Try http://amfone.net. Lots of good, knowledgeable people there, and some are on 160. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: EIRP Measurement
In thinking about the measurement of EIRP for the new band it occurred to me that this might be the time for a few folks to think about how we could fabricate a commonly calibrated field strength meter. Such a device might well be used on both 160m and the 600 kHz band. By commonly calibrated in mean a device that has an agreed upon standard way to calibrate it that can be done with simple methods. One thing that always intrigued me about the HeathKit products was the fact that they used very simple methods to allow the builder to adjust the device without expensive equipment. Sometimes that meant a special circuit built into the product which was only used for adjusting the device. The important thing is to have a way to assure that when someone measured the same field at the same point with the same type of measurement device they would get the same measurement result. That would allow us to compare measurements between different people even if we did not know the absolute field strength value. An interesting idea might be to make such a field strength meter have an interface to Wi-Fi so that it could be positioned at a remote point and send its readings to one's local network. There are a lot of ways to do that of course, but planning to have it part the device initially would simplify taking measurements. I am sure that there are others who could contribute ideas that eventually could be used to formulate design objectives for such a device. If there was enough interest I can imagine that a single PCB could created and a lot of such devices built to allow us to add to our collection of measurement devices that help us fabricate better antennas and stations. I wonder if I am the only one who thinks this might be a useful TopBand subject. Tod, K0TO ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: EIRP Measurement
You can get an absolute calibration by the reciprocity method, using two identical antennas. An extension of this technique is the 3 antenna method which gets rid of the assumption that the antennas are identical, by doing 3 pairs of measurements. In the reciprocity method, you transmit on one short vertical and receive on the other. The gains can then be determined by the usual path loss equation. Rick N6RK On 2/20/2012 6:04 PM, Tod - ID wrote: The important thing is to have a way to assure that when someone measured the same field at the same point with the same type of measurement device they would get the same measurement result. subject. Tod, K0TO ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: EIRP Measurement
On Mon, 2012-02-20 at 19:04 -0700, Tod - ID wrote: In thinking about the measurement of EIRP for the new band it occurred to me that this might be the time for a few folks to think about how we could fabricate a commonly calibrated field strength meter. Such a device might well be used on both 160m and the 600 kHz band. By commonly calibrated in mean a device that has an agreed upon standard way to calibrate it that can be done with simple methods. One thing that always intrigued me about the HeathKit products was the fact that they used very simple methods to allow the builder to adjust the device without expensive equipment. Sometimes that meant a special circuit built into the product which was only used for adjusting the device. The important thing is to have a way to assure that when someone measured the same field at the same point with the same type of measurement device they would get the same measurement result. That would allow us to compare measurements between different people even if we did not know the absolute field strength value. An interesting idea might be to make such a field strength meter have an interface to Wi-Fi so that it could be positioned at a remote point and send its readings to one's local network. There are a lot of ways to do that of course, but planning to have it part the device initially would simplify taking measurements. I am sure that there are others who could contribute ideas that eventually could be used to formulate design objectives for such a device. If there was enough interest I can imagine that a single PCB could created and a lot of such devices built to allow us to add to our collection of measurement devices that help us fabricate better antennas and stations. I wonder if I am the only one who thinks this might be a useful TopBand subject. Tod, K0TO ___ UR RST IS ... ... ..9 QSB QSB - hw? BK I think this thread will quickly get of hand even though it may be applicable on Top Band (and every other band). I took a quick look at the QTH.net lists and I didn't see anything resembling instrument(ation) or measurement. Are there lists or web groups for amateur instrumentation? I will expand my own search and report back here if I find anything useful but maybe some list member(s) already know where to look. The whole point of having standards is so that we can get the same results under the same conditions as other people. It should not be any more difficult to 'calibrate' to an existing, published standard than 'calibrating' to a new 'nonstandard'. There are a lot of different approaches to accomplishing that and we should look for them. If there is interest we might start a new list to explore the possibilities. 73, Bill KU8H ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: EIRP Measurement
On 2/21/2012 8:26 AM, Joe Subich, W4TV wrote: On Mon, 2012-02-20 at 19:04 -0700, Tod - ID wrote: The important thing is to have a way to assure that when someone measured the same field at the same point with the same type of measurement device they would get the same measurement result. That would allow us to compare measurements between different people even if we did not know the absolute field strength value. I think simple, repeatable and accurate are a difficult triad. What you are talking about is an accurate Field Intensity Meter (FIM) and getting stable calibrations with home constructed equipment is not going to be easy - let along easy to duplicate. The closest solution is to use standard antennas (not simple whips) and calibrate them against broadcast signals at known locations and known field strengths. This will still require separate antennas for 160 and 630 meters and separate calibration sources on the appropriate ends of the standard broadcast band (due to the antennas). 73, ... Joe, W4TV ___ UR RST IS ... ... ..9 QSB QSB - hw? BK It's been many years since I have had to make any AM broadcast field measurements. I don't recall if the Potomac Instruments, or other, FIMs go much below 550kHz. 73, -- Jack, W6NF Silver Springs, NV DM09ji ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: EIRP Measurement
The link provided below shows how to calculate EIRP. I think each administration will spell out the requirements of how to legally calculate EIRP. To me it is fairly straight forward. 60M in the US is an example. While there is an EIRP limitation, the FCC simplified the determination by assuming a dipole and the amount of power fed to it. On 600M, one could easily put up as much tower as reasonable and then measure the tower's impedance. Once the impedance is known it is easy to calculate the input power to the radiator and therefore the current. This method is virtually universal for MW power measurement. There are calibrated RF ammeters available since they are required at each AM broadcast station (directional stations may use as many as a dozen depending on the array). Alternatively the voltage can be measured. In either case it is relatively easy to build and calibrate a voltage or current sampling device. That will establish the actual power input to the antenna. An 80 foot tower on 600M has around .6 ohms impedance therefore 1 amp will produce about 600 milliwatts into the antenna. 1.3 amps would be 1 watt in this example. The antenna has 4.78 db gain over an isotropic radiator so this needs to be reduced to .75 amps which is 340 milliwatts into the antenna (or 1.7 watts if a 5 W EIRP limit , slightly more than 1.5 Amps). This method eliminates having to calculate matching network losses as the ammeter is at the antenna feed point. I also think that actual field measurement is a bad idea and probably not allowed by most administrations. The reason is that the losses near the ground will be higher than the skywave component which is where there will be the possibility of interference. We will all have to wait and see how the rules are written. On 2/21/12 12:09 PM, Brad Rehm wrote: I also think this topic is worth addressing, but Bill is probably right in saying it could gobble all the bandwidth on this reflector. Maybe someone would be willing to be the moderator of a new reflector. In the mean time, we should acknowledge that a lot of the work has already been done by the hams who've been experimenting on 136 kHz. See http://www.strobbe.eu/on7yd/136ant/#Loops for example. BTW, the three-antenna method is not considered the best way to make field strength measurements at these frequencies. Since the field is magnetic, loops, monopoles, helmholz coils, and other kinds of probes are normally used. I wonder how many 160 ops are considering trying the new band. I wouldn't be surprised if the answer were very few. Although the new band is just below AM broadcast frequencies, instead of just above them, this is the region in which transmitters and antennas begin to look very different from conventional HF setups. After we've made substantial investments in time and resources in decent 160m stations, moving down will present new challenges which may only interest experimenters. Brad KV5V On Tue, Feb 21, 2012 at 8:49 AM, Bill Cromwellwrcromw...@gmail.com wrote: On Mon, 2012-02-20 at 19:04 -0700, Tod - ID wrote: In thinking about the measurement of EIRP for the new band it occurred to me that this might be the time for a few folks to think about how we could fabricate a commonly calibrated field strength meter. Such a device might well be used on both 160m and the 600 kHz band. By commonly calibrated in mean a device that has an agreed upon standard way to calibrate it that can be done with simple methods. One thing that always intrigued me about the HeathKit products was the fact that they used very simple methods to allow the builder to adjust the device without expensive equipment. Sometimes that meant a special circuit built into the product which was only used for adjusting the device. The important thing is to have a way to assure that when someone measured the same field at the same point with the same type of measurement device they would get the same measurement result. That would allow us to compare measurements between different people even if we did not know the absolute field strength value. An interesting idea might be to make such a field strength meter have an interface to Wi-Fi so that it could be positioned at a remote point and send its readings to one's local network. There are a lot of ways to do that of course, but planning to have it part the device initially would simplify taking measurements. I am sure that there are others who could contribute ideas that eventually could be used to formulate design objectives for such a device. If there was enough interest I can imagine that a single PCB could created and a lot of such devices built to allow us to add to our collection of measurement devices that help us fabricate better antennas and stations. I wonder if I am the only one who thinks this might be a useful TopBand subject. Tod, K0TO
Re: Topband: EIRP Measurement
The Potomac Analog FIM is no longer available, nor are the parts to repair them and calibration service is no longer available. The new meters are expensive digital units. But in broadcast we do not use them to determine power but rather coverage usually when directional systems are tuned. On 2/21/12 1:05 PM, Jack/W6NF wrote: On 2/21/2012 8:26 AM, Joe Subich, W4TV wrote: On Mon, 2012-02-20 at 19:04 -0700, Tod - ID wrote: The important thing is to have a way to assure that when someone measured the same field at the same point with the same type of measurement device they would get the same measurement result. That would allow us to compare measurements between different people even if we did not know the absolute field strength value. I think simple, repeatable and accurate are a difficult triad. What you are talking about is an accurate Field Intensity Meter (FIM) and getting stable calibrations with home constructed equipment is not going to be easy - let along easy to duplicate. The closest solution is to use standard antennas (not simple whips) and calibrate them against broadcast signals at known locations and known field strengths. This will still require separate antennas for 160 and 630 meters and separate calibration sources on the appropriate ends of the standard broadcast band (due to the antennas). 73, ... Joe, W4TV ___ UR RST IS ... ... ..9 QSB QSB - hw? BK It's been many years since I have had to make any AM broadcast field measurements. I don't recall if the Potomac Instruments, or other, FIMs go much below 550kHz. 73, ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: EIRP Measurement
Joe, et. al I am quite certain that there will need to be different sense antennas for 160m and 630m. I would not be surprised if we did not also need bandpass filters for each of the bands as well. As I recall there were several circuits in QST using a single analog Devices unit to measure RF input levels. I think that it have several decades of measurement and the output was on a log scale. Since the input of those circuits was broadband something would need to be altered to make it usable on 160m and/or 630m for measuring rf at those specific frequencies. There is a device called a Helmholtz pair that might be used on low frequencies to help with calibration. See → www.ets-lindgren.com/page/?i=6402M I have been advised by Dave Bowker, K1FK, that such a device might be constructed for quite low cost. Thanks for the suggestions Joe. Tree, if this is going over the edge let me know. It was not my intention to subvert the TopBand reflector. Tod, K0TO On 2/21/12 10:26 AM, Joe Subich, W4TV li...@subich.com wrote: On Mon, 2012-02-20 at 19:04 -0700, Tod - ID wrote: The important thing is to have a way to assure that when someone measured the same field at the same point with the same type of measurement device they would get the same measurement result. That would allow us to compare measurements between different people even if we did not know the absolute field strength value. I think simple, repeatable and accurate are a difficult triad. What you are talking about is an accurate Field Intensity Meter (FIM) and getting stable calibrations with home constructed equipment is not going to be easy - let along easy to duplicate. The closest solution is to use standard antennas (not simple whips) and calibrate them against broadcast signals at known locations and known field strengths. This will still require separate antennas for 160 and 630 meters and separate calibration sources on the appropriate ends of the standard broadcast band (due to the antennas). 73, ... Joe, W4TV ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: EIRP Measurement
As I posted earlier field measurement is not an accurate method of determining power. I seriously doubt an administration permit such a technique unless it was very dumbed down and produced very 'safe' results or in other words less power than could otherwise be achieved. On 2/21/12 2:54 PM, Tod Olson wrote: Joe, et. al I am quite certain that there will need to be different sense antennas for 160m and 630m. I would not be surprised if we did not also need bandpass filters for each of the bands as well. As I recall there were several circuits in QST using a single analog Devices unit to measure RF input levels. I think that it have several decades of measurement and the output was on a log scale. Since the input of those circuits was broadband something would need to be altered to make it usable on 160m and/or 630m for measuring rf at those specific frequencies. There is a device called a Helmholtz pair that might be used on low frequencies to help with calibration. See → www.ets-lindgren.com/page/?i=6402M I have been advised by Dave Bowker, K1FK, that such a device might be constructed for quite low cost. Thanks for the suggestions Joe. Tree, if this is going over the edge let me know. It was not my intention to subvert the TopBand reflector. Tod, K0TO On 2/21/12 10:26 AM, Joe Subich, W4TV li...@subich.com wrote: On Mon, 2012-02-20 at 19:04 -0700, Tod - ID wrote: The important thing is to have a way to assure that when someone measured the same field at the same point with the same type of measurement device they would get the same measurement result. That would allow us to compare measurements between different people even if we did not know the absolute field strength value. I think simple, repeatable and accurate are a difficult triad. What you are talking about is an accurate Field Intensity Meter (FIM) and getting stable calibrations with home constructed equipment is not going to be easy - let along easy to duplicate. The closest solution is to use standard antennas (not simple whips) and calibrate them against broadcast signals at known locations and known field strengths. This will still require separate antennas for 160 and 630 meters and separate calibration sources on the appropriate ends of the standard broadcast band (due to the antennas). 73, ... Joe, W4TV ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: EIRP Measurement
If you can find a used FIM 22 it goes from 200 KHz to 550 KHz. That said I can not see determining EIRP by field measurement. There are just two many variables and a degree of engineering skill not posessed by the average amateur. The various national authorities must have a means of measurement accessible to the average operator and is easy to enforce. Then as I stated previously there is the interference problem. The signal measured along the ground will be less than at higher angles. Skywave interference will be greater because the real EIRP will be exceeded and by a large amount in some cases. I could see where if there were a sufficient market a device that was sort of a combination of a vector impedance meter and an ammeter could calculate EIRP on the fly. It would have to be located remotely at the antenna feed. On 2/21/12 5:22 PM, Jack/W6NF wrote: On 2/21/2012 11:51 AM, W2XJ wrote: The Potomac Analog FIM is no longer available, nor are the parts to repair them and calibration service is no longer available. The new meters are expensive digital units. But in broadcast we do not use them to determine power but rather coverage usually when directional systems are tuned. On 2/21/12 1:05 PM, Jack/W6NF wrote: On 2/21/2012 8:26 AM, Joe Subich, W4TV wrote: On Mon, 2012-02-20 at 19:04 -0700, Tod - ID wrote: The important thing is to have a way to assure that when someone measured the same field at the same point with the same type of measurement device they would get the same measurement result. That would allow us to compare measurements between different people even if we did not know the absolute field strength value. I think simple, repeatable and accurate are a difficult triad. What you are talking about is an accurate Field Intensity Meter (FIM) and getting stable calibrations with home constructed equipment is not going to be easy - let along easy to duplicate. The closest solution is to use standard antennas (not simple whips) and calibrate them against broadcast signals at known locations and known field strengths. This will still require separate antennas for 160 and 630 meters and separate calibration sources on the appropriate ends of the standard broadcast band (due to the antennas). 73, ... Joe, W4TV ___ UR RST IS ... ... ..9 QSB QSB - hw? BK It's been many years since I have had to make any AM broadcast field measurements. I don't recall if the Potomac Instruments, or other, FIMs go much below 550kHz. 73, ___ UR RST IS ... ... ..9 QSB QSB - hw? BK Yes, I am aware of that, having been CE at several DAs, including one critical night-time array. I was thinking that, if the FIMs covered the necessary frequencies, EIRP could be inferred by measuring field strength. I'd still be curious if any of the new FIMs have extended coverage that would make them useful. Oops, I guess this is now OT, right? ;) ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: EIRP Measurement
If it is true that the skywave is stronger than the ground wave, then the power would need to be backed off, Fortunately, it is not true with short ground mounted monopole antennas. In order for the skywave to exceed the groundwave, the monopole needs to be longer than half wave (somewhere in the area exceeding 0.64 wave). 73, ... Joe, W4TV On 2/21/2012 8:58 PM, Rick Karlquist wrote: W2XJ wrote: If you can find a used FIM 22 it goes from 200 KHz to 550 KHz. That said I can not see determining EIRP by field measurement. There are just two many variables and a degree of engineering skill not posessed by the average amateur. The various national authorities must have a means of measurement accessible to the average operator and is easy to enforce. Then as I stated previously there is the interference problem. The signal measured along the ground will be less than at higher angles. Skywave interference will be greater because the real EIRP will be exceeded and by a large amount in some cases. The RF ammeter test merely measures the total radiated power. It does not account for the effective signal strength at some skywave angle. If it is true that the skywave is stronger than the ground wave, then the power would need to be backed off, but there is no way to determine how much to backoff without a helicopter field measurement. It would depend on ground conductivity, so there would be no way to calculate it or model it accurately. Rick N6RK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Topband list and 630 Meters - the decision
On Tue, Feb 21, 2012 at 7:58 PM, ZR z...@jeremy.mv.com wrote: I recently talked to Ken Gordon, W7EKB, who owns 600...@w7ekb.com, the 600M experimental group forum about opening it up to hams Do you have a link to the forum, Carl? It doesn't appear to be on w7ekb.com. 73, Mike www.w0btu.com ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: 600 Meters live
Here is a chance to see, if not hear, signals on 600 meters. http://w5jgv.com/Spectrum/index.htm There are a lot of guys who participated in the experimental effort - check out http://www.500kc.com/USA_600_M_Station_ID.htm - - - probably some of those guys we have worked on TopBand. Guess this thread may be at the end since there is a place to go for more info on 600 meters and there does not seem to be an identified need for EIRP measurement on 160 meters [ yet ]. Tod, K0TO ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Topband list and 630 Meters - the decision
Thanks. That must be it. http://www.500kc.com/Maillists.htm On Tue, Feb 21, 2012 at 9:59 PM, Tod Olson t...@k0to.us wrote: http://www.500kc.com/ ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
