Re: Topband: Skimmer calibration
To have an idea of what kind of spread of SNRs one can expect from skimmer reports, I performed a test this morning I recorded two overlapping CQ messages with two different callsigns, one had the sidetone on 500 Hz (EA5RS) and the other at 900 Hz (EA5BY), and applied it to the MIC input of my SSB/USB transceiver (just like you would do in AFSK). I first equalized amplitudes to make sure both tones generated equal output. I then waited for the skimmer reports (and answered to those who called!). So it is the same power, QTH, antenna, . only selective fading can introduce a difference between data reported for both stations Some skimmers reported only one of the calls (some BY, some RS) and some reported both. I cannot guarantee the skimmers decoded both calls exactly at the same time (maybe there are some seconds difference) Here are the reports from the skimmers that decoded both calls at the same minute: 21046.6 EA5RS 19-Aug-2014 0714Z CW 12 dB 34 WPM CQ DJ9IE-# 21047.0 EA5BY 19-Aug-2014 0714Z CW 12 dB 34 WPM CQ DJ9IE-# 21041.6 EA5RS 19-Aug-2014 0711Z CW 27 dB 33 WPM CQ SK3GW-# 21042.0 EA5BY 19-Aug-2014 0711Z CW 25 dB 33 WPM CQ SK3GW-# 21046.6 EA5RS 19-Aug-2014 0708Z CW 22 dB 33 WPM CQ SK3W-# 21047.0 EA5BY 19-Aug-2014 0708Z CW 26 dB 34 WPM CQ SK3W-# 21044.6 EA5RS 19-Aug-2014 0704Z CW 29 dB 34 WPM CQ SK3W-# 21045.0 EA5BY 19-Aug-2014 0704Z CW 30 dB 33 WPM CQ SK3W-# 14047.6 EA5RS 19-Aug-2014 0655Z CW 7 dB 33 WPM CQ DK0TE-# 14048.0 EA5BY 19-Aug-2014 0655Z CW 7 dB 34 WPM CQ DK0TE-# 21044.6 EA5RS 19-Aug-2014 0652Z CW 23 dB 35 WPM CQ SK3GW-# 21045.0 EA5BY 19-Aug-2014 0652Z CW 24 dB 35 WPM CQ SK3GW-# I think this shows averaging is necessary if you want precision measurements. 73 Juan EA5RS -Mensaje original- De: Topband [mailto:topband-boun...@contesting.com] En nombre de Tom W8JI Enviado el: lunes, 18 de agosto de 2014 20:26 Para: topband@contesting.com Asunto: Re: Topband: Skimmer calibration Since no one likely knows the gain of a reference antenna within a dB or so, splitting hairs doesn't matter. Ten dB would jump right out, while 3 dB might get lost in the QSB. When I was comparing high dipoles to verticals on 160, I collected reports for about a year. It was thousands of reports. I probably could have done it in a week or two with skimmer, but then I would have had to repeat it for seasonal changes. I'm sure a good test protocol using skimmer could be worked out. - Original Message - From: Jim Brown j...@audiosystemsgroup.com To: topband@contesting.com Sent: Monday, August 18, 2014 12:47 PM Subject: Re: Topband: Skimmer calibration On Mon,8/18/2014 4:53 AM, Tom W8JI wrote: A live comparison of S/N ratio or relative level over time is with very few exceptions an excellent comparative test. It is much more accurate than S meters or absolute levels without a comparison reference. As such, the RBN is a great tool for evaluating systems. Yes. BUT -- my experience has been that I must average hundreds of data points to get meaningful data. The reasons are simple -- we must contend with QSB, and as Tom noted in another post, nulls in the patterns of antennas at both ends. A few years ago, I tried to compare two 160M antennas using JT65 and W6CQZ's JT65 RBN. On a good night, I would see reports from 3-4 stations east of the Mississippi. I alternated between the two antennas for hours, putting the reports in a spreadsheet, and studying the data. Modelling predicted differences of a few dB, and I never found that the data was good enough to confirm the models. The antennas are passive arrays of fairly tall verticals of a quarter wave or less, so there are no vertical nulls in their pattern. I can clearly hear their directivity on RX, but their gain is what I was trying to confirm. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4745 / Virus Database: 4007/8057 - Release Date: 08/18/14 _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Skimmer calibration
When I last investigated, all the skimmers and Web SDRs that were outside of North America all had terrible receive antennas for copying DX signals on 160. (And who knows how many of them are in quiet locations?) When I say terrible, I mean small magnetic loops, very short whips, low dipoles, a random end-fed wire, etc. No phased arrays or Beverages, and not even a Flag, K9AY, EWE, etc. Does anyone know if that is still the case? 73, Mike www.w0btu.com _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Skimmer calibration
Sure it is. Most skimmers are setup to receive all directions on more then one band. Anyway, Skimmers only show S/N. 73 Peter -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike Waters Sent: Dienstag, 19. August 2014 11:34 To: topband Subject: Re: Topband: Skimmer calibration When I last investigated, all the skimmers and Web SDRs that were outside of North America all had terrible receive antennas for copying DX signals on 160. (And who knows how many of them are in quiet locations?) When I say terrible, I mean small magnetic loops, very short whips, low dipoles, a random end-fed wire, etc. No phased arrays or Beverages, and not even a Flag, K9AY, EWE, etc. Does anyone know if that is still the case? 73, Mike www.w0btu.com _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: A35LT
So far no show. Lou KE1F On 8/18/2014 3:30 PM, Brian Sarkisian wrote: A35LT was on 160 during the North American morning grey line. We plan on being on the air again the next North American morning grey line. 73 de Brian, KG8CO A35CO _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Modeling the proverbial vertical on a beach
I'll just stick in a few responses to others' comments about what I wrote on the 'beach' thread and then I'll get out of the way. It is tricky to use receiving tests to gauge the effectiveness of proposed transmitting antennas for two reasons. You are probably listening on receiving type antennas rather than transmitting antennas. In that case, you have only shown that receiving antennas work better over salt water. Definitely, as I'd mentioned, less site-to-site variability would be shown with a full-size efficient transmitting type antenna, whether a vertical over a good ground system or a high (150 ft. elevation) horizontal dipole / yagi. Smaller receiving loops and active whips exhibit the greatest influence due to surrounding ground conductivity and elevation profiles. This is particularly the case on groundwave or very low angle skip. High angle skip is largely unaffected by the nature of the surrounding landscape; certainly by the time you get to Near Vertical Incidence, that can work even if you are surrounded by tall buildings or mountains. As some of the propagation paths we desire do involve things such as the ability to open the band pre-sunset on the US/Canada East Coast to incoming Europeans, skip propagation at very low angles is a matter of interest. If sunset is at 4 p.m. EST (2100 UTC) in December in MA/ME, for instance, the ability to work Europeans as much as three hours earlier than that is going to be more likely at a shore site for a given transmitter/receiver/antenna configuration. For such early QSO's inland I think a mountain top (and a heck of a lot of buried copper) would be needed. By an hour or so after sunset, the shore versus inland differences would reduce to barely perceptible as the optimum take-off angle would be considerably higher above the horizon. Still, having potentially two or more hours of useful communication at the start of an opening going east or the end of an opening going west is still not a trivial matter, especially in a contest scenario when every added QSO point matters. Extrapolating groundwave results from a proper-size broadcast vertical with radials exhibits that coverage even from a professional-grade antenna is affected greatly by surrounding ground conductivity. Keeping in mind that the following map for WOND 1400 (near Atlantic City, NJ) shows a pattern from a single-tower non-directional antenna, it's quite obvious that sea gain is for real: http://www.radio-locator.com/cgi-bin/pat?call=WONDservice=AMstatus=Lhours=U This station is easy daytime copy here on Cape Cod at over 250 miles. Going inland to the northwest of the tower, WOND has less strength at a mere 30 miles. Reciprocity would mean that the same tower used as a receiving antenna would have a similar pick-up pattern: far better sensitivity going east than west. This jibes quite well with what is observed routinely at seashore broadcast-band DXpeditions even when talking about afternoon low-angle skip from Europe, the Middle East, Africa, and Brazil. Second, are these comparisons based on S meter readings or signal to noise ratio? If the latter, then it could just as well be that it is very quiet on the shore because nothing is out there. Especially if you use directional antennas to listen. S-meter readings. Northeastern Brazil stations (Fortaleza / Natal / Recife areas) and deep Africans (e.g. the former BBC Lesotho on 1197 kHz) that could routinely hit S-9 on the Drake R8A or Perseus with car roof loop at shore sites in Rockport, MA and Orleans, MA were, at best, in the S-2 category (or more likely just non-existent) with the same mobile set-up at my former location in Billerica, MA (15 miles northwest of Boston; 15-25 miles inland on bearings of interest). Differences on western Europe (e.g. Absolute Radio UK 1215), especially after sunset, were a good deal less as the skip was at a high enough angle to be less groundwave-like. I believe that Nick Hall-Patch and others have done simultaneous inland versus coastal signal observations of Asian and Down Under signals received around dawn in BC, WA, and OR on a fairly regular basis. I think that, for them, coastal beats inland most of the time on both actual signal strength as well as signal-to-noise / signal-to-interfering stations metrics. Once in a while greyline does give you one of those high angle is best tilted-layer paths and the best location winds up being the one under the spotlight. In that case, coastal versus inland becomes largely irrelevant. BTW, what are the best California BC stations to look for? Its been decades since Ive heard one but I havent tried hard at all. Carl KM1H KNX on 1070 is about the only California station that has a ghost of a chance to make it to New England now that the former clear channels are plugged up with so many domestic and Cuban stations. Try just before dawn. A properly-aimed
Re: Topband: Skimmer calibration
the gw8izr skimmer seems pretty good to me...dr1a also...both, better than average, IMHO a belgian one also ( can't remember the call..) couple in JA also.. 73, w5xz, dan On Tuesday, August 19, 2014 4:33 AM, Mike Waters mikew...@gmail.com wrote: When I last investigated, all the skimmers and Web SDRs that were outside of North America all had terrible receive antennas for copying DX signals on 160. (And who knows how many of them are in quiet locations?) When I say terrible, I mean small magnetic loops, very short whips, low dipoles, a random end-fed wire, etc. No phased arrays or Beverages, and not even a Flag, K9AY, EWE, etc. Does anyone know if that is still the case? 73, Mike www.w0btu.com _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Skimmer calibration
I quickly noticed that some skimmers seem to have more effective antenna systems than others. More than S/N, I look at kinda the breadth and depth of where I'm spotted. On 160M, GW8IZR and DL1A are where I'm first spotted. If I'm getting spotted more broadly or deeply than that, then I know conditions are really good. Tim N3QE On Tue, Aug 19, 2014 at 5:33 AM, Mike Waters mikew...@gmail.com wrote: When I last investigated, all the skimmers and Web SDRs that were outside of North America all had terrible receive antennas for copying DX signals on 160. (And who knows how many of them are in quiet locations?) When I say terrible, I mean small magnetic loops, very short whips, low dipoles, a random end-fed wire, etc. No phased arrays or Beverages, and not even a Flag, K9AY, EWE, etc. Does anyone know if that is still the case? 73, Mike www.w0btu.com _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: New 3 el 160m yagi at 7J4AAL
From the reflector of the Northern IL DX Association. 73, Jim N7US From: ni...@yahoogroups.com [mailto:ni...@yahoogroups.com] Sent: August 19, 2014 07:49 To: ni...@yahoogroups.com Subject: [NIDXA] New 3 el 160m yagi at 7J4AAL Now that is an antenna! http://www3.ocn.ne.jp/~kan1/newmonsterantenna2.html The three SteppIR DB42s look small! 73, John K9EL Posted by: John, K9EL k...@comcast.net _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: New 3 el 160m yagi at 7J4AAL
Actually 4x DB42 are stacked and Kan applied for a 160m sideband approval 73 Peter -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Jim N7US Sent: Dienstag, 19. August 2014 18:22 To: 'Topband Reflector'; CADXA Reflector Subject: Topband: New 3 el 160m yagi at 7J4AAL From the reflector of the Northern IL DX Association. 73, Jim N7US From: ni...@yahoogroups.com [mailto:ni...@yahoogroups.com] Sent: August 19, 2014 07:49 To: ni...@yahoogroups.com Subject: [NIDXA] New 3 el 160m yagi at 7J4AAL Now that is an antenna! http://www3.ocn.ne.jp/~kan1/newmonsterantenna2.html The three SteppIR DB42s look small! 73, John K9EL Posted by: John, K9EL k...@comcast.net _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: New 3 el 160m yagi at 7J4AAL
When you have money, it's amazing what can be done. I thought the consensus now is yagi antennas on 160 don't perform well (i.e. OH8X) when compared to vertical arrays. Doug Think of all the ways you can hurt yourself laughing. -Original Message- From the reflector of the Northern IL DX Association. 73, Jim N7US --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: WTB: Hi-Z 4-8PRO
I'm thinking of getting the 8 element version to replace my existing Hi-Z triangular array. Anyone have a Hi-Z 4-8PRO system they want to let go of? Please reply direct. 73, Gary KA1J --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: New 3 el 160m yagi at 7J4AAL
The web site talks about a CL-75 Yagi, which operates as a dipole on 160 meters, and has 5 elements on 80. Is there also some different antenna that is actually 3 elements on 160 meters? My Japanese is a little rusty :-) Rick N6RK On 8/19/2014 9:22 AM, Jim N7US wrote: From the reflector of the Northern IL DX Association. 73, Jim N7US From: ni...@yahoogroups.com [mailto:ni...@yahoogroups.com] Sent: August 19, 2014 07:49 To: ni...@yahoogroups.com Subject: [NIDXA] New 3 el 160m yagi at 7J4AAL Now that is an antenna! http://www3.ocn.ne.jp/~kan1/newmonsterantenna2.html The three SteppIR DB42’s look small! 73, John K9EL Posted by: John, K9EL k...@comcast.net _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: New 3 el 160m yagi at 7J4AAL
His CL75 CX-M 5-element 80m yagi is on the other tower and still in use. The new 160m antenna was built on order by Create. 73 Peter -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Richard (Rick) Karlquist Sent: Dienstag, 19. August 2014 19:29 To: Jim N7US; 'Topband Reflector'; CADXA Reflector Subject: Re: Topband: New 3 el 160m yagi at 7J4AAL The web site talks about a CL-75 Yagi, which operates as a dipole on 160 meters, and has 5 elements on 80. Is there also some different antenna that is actually 3 elements on 160 meters? My Japanese is a little rusty :-) Rick N6RK On 8/19/2014 9:22 AM, Jim N7US wrote: From the reflector of the Northern IL DX Association. 73, Jim N7US From: ni...@yahoogroups.com [mailto:ni...@yahoogroups.com] Sent: August 19, 2014 07:49 To: ni...@yahoogroups.com Subject: [NIDXA] New 3 el 160m yagi at 7J4AAL Now that is an antenna! http://www3.ocn.ne.jp/~kan1/newmonsterantenna2.html The three SteppIR DB42's look small! 73, John K9EL Posted by: John, K9EL k...@comcast.net _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: New 3 el 160m yagi at 7J4AAL
On Tue,8/19/2014 10:03 AM, Doug Renwick wrote: I thought the consensus now is yagi antennas on 160 don't perform well (i.e. OH8X) when compared to vertical arrays. That is STRONGLY dependent on the height of the Yagi and soil conductivity around the vertical antenna. A horizontal antenna lower than about a half wave is a low antenna, so the vertical pattern is compromised. On the other hand, verticals are strongly affected by soil conductivity -- as much as 6 dB between very poor and very good -- while horizontal antennas are not. This Yagi is at almost 3/8 wavelength on 160, pretty good, but still not great. I'd guess the gain to be no better than 5 dB over a dipole at the same height. Does anyone remember this array? It's gone now, but I'd be inclined to do some sort of vertical array if I had the real estate with decent soil and the bucks. http://nidxa.org/memberWWW/k9dx_antennas.htm 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: New 3 el 160m yagi at 7J4AAL
I had the opportunity to work K9DX many times when he was using this array, he was one of the only stations who would hear me call an hour before my sunset, and when he switched the array from EU to KH6 it was nothing but amazing. To be honest I have never heard another ham array do as well, But to give credit, he also had the best ears , he had a method of switching around receive antennas that was amazing, thus the reason he could copy me so early..Other operators had the antenna switchs glued to EU at that time and never did have the intelligence to understand that the Pacific was coming through calling. I have heard so many times in so many contests Pacific stations calling USA, not just KH6 but some juicy mults out here, that operate only for fun and only one evening, calling and calling with no response, and I have heard every excuse known to man why the big guns did not answer, when in fact its plain operator error 90 percent of the time, they just do not listen this direction at that time of the day. I wish I had recorded the K9DX signal and the drastic change as he switched from EU to KH6, it made the others with switching 4 squares sound anemic. It is one of the highlights I will never forget working top band from KH6. 73 Merv K9FD/KH6 Does anyone remember this array? It's gone now, but I'd be inclined to do some sort of vertical array if I had the real estate with decent soil and the bucks. http://nidxa.org/memberWWW/k9dx_antennas.htm 73, Jim K9YC _ _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: New 3 el 160m yagi at 7J4AAL
I guess we’ll hear this 160 season from 7J4AAL. Living mid-path USA-JA affords KL7’s the opportunity to receive both as W’s and others turn their attention to JA. Why not give it a try if one has the motivation, real estate, and resources? And about which antenna is better? His 160 beam on a hill will outperform what most of us will ever have available. I wonder what his noise floor will be, and if he employs receiving arrays? Source: http://www.cd-corp.com/english/ http://www3.ocn.ne.jp/~kan1/cy163tower.html 73, Gary NL7Y _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Switching Pennants
I am wanting a simple way of switching 3 or 4 pennants. Anyone done this? Quote From K6SEE ... All four Pennants would be installed with their points all adjacent to each other. Only one feedline would be necessary and only one transformer would be necessary, with the high impedance winding of the transformer being switched to the feedpoint of the Pennant in the desired direction ... 73, de Earl, K6SE 73 Dwight NS9I _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Skimmer calibration
Do we really care that skimmers aren't hooked up to antennas with pattern and gain? One of the things in using VOACAP is knowing the pattern of the RX antenna as well as TX. Omni pattern at RX removes RX antenna bias. Why shouldn't we specifically use omni on RX, so that any enhancement is from the sender or the propagation/environment? The thing about sensitivity is that it rarely matters if the out-there-on-the-band noise is controlling. Band-noise controlling is far more common on 160 than 80 and above. Running stuff from here to W4KAZ 7+ miles away always shows an initial 3-4 dB drop in S/N when the band just starts to open. Why I generally run stuff to him in the middle of the day when I want to know the numbers. 73, Guy On Tue, Aug 19, 2014 at 12:06 PM, Tim Shoppa tsho...@gmail.com wrote: I quickly noticed that some skimmers seem to have more effective antenna systems than others. More than S/N, I look at kinda the breadth and depth of where I'm spotted. On 160M, GW8IZR and DL1A are where I'm first spotted. If I'm getting spotted more broadly or deeply than that, then I know conditions are really good. Tim N3QE On Tue, Aug 19, 2014 at 5:33 AM, Mike Waters mikew...@gmail.com wrote: When I last investigated, all the skimmers and Web SDRs that were outside of North America all had terrible receive antennas for copying DX signals on 160. (And who knows how many of them are in quiet locations?) When I say terrible, I mean small magnetic loops, very short whips, low dipoles, a random end-fed wire, etc. No phased arrays or Beverages, and not even a Flag, K9AY, EWE, etc. Does anyone know if that is still the case? 73, Mike www.w0btu.com _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Skimmer calibration
Depends what are you expecting from Skimmer-RX-ANT setup. If you want skimmer to find DX before the pack and looking for low angle signals, then setup better use antenna with proper low angle vertical pattern. Also getting true report when evaluating beach antennas with low vertical angle, skimmer should be using similar antenna to even detect the signals. High angle skimmer antenna would make TX beach vertical vs. horizontal or other antennas inland look about the same and erasing the impossible 10 -20 dB advantage. Just like say if one is driving mobile on the land, you don't hear low angle signals. Get close to the water, or better, bridge over salty water, band comes to life, 10 - 20 dB enhancement becomes reality. Skimmers and testing over longer distances is fine to get ball park idea how, or if the antenna works, but the true indicator of performance is the field strength measurement in the vicinity of antenna, eliminating finicky propagation and other undesirable variables. For unbelievers in salty beach phenomena, I recommend reading K2KW and Team Vertical exploits, tests, measurements http://www.k2kw.com/verticals/verticalinfo.htm and take to the beach with radio and see it, before posting authoritative denials. I did, I knew salt water is good, but wanted to see it with my own ears. I packed 10m setup ( 3el. vertical Omni with Stackmatch) and went to Cape Hatteras, NC. Just driving around the banks, bridges and sandy islands it was an eye and ear opener. Second time I brought 4 square and vertically polarized 2 el. Quad on a boat deck. I saw that 10 - 20 dB difference and the ability to work juicy stuff before packs got to it. (Still US 10m LP record as N2EE/4) I figured 10m would be least advantageous band to take advantage of the effect (low bands would be more enhanced), but I was sitting there unbelieving. Good enough for me, I understand the phenomena, I figured how to take advantage of it and when I get the chance to play I will pack my fishing rods and play on the beach. I don't need skimmer to tell me that. Yuri, K3BU.us www.MVmanor.com for your DXContestvention or ham radio weddings On Tue, Aug 19, 2014 at 05:01 PM, Guy Olinger K2AV wrote: Do we really care that skimmers aren't hooked up to antennas with pattern and gain? One of the things in using VOACAP is knowing the pattern of the RX antenna as well as TX. Omni pattern at RX removes RX antenna bias. Why shouldn't we specifically use omni on RX, so that any enhancement is from the sender or the propagation/environment? The thing about sensitivity is that it rarely matters if the out-there-on-the-band noise is controlling. Band-noise controlling is far more common on 160 than 80 and above. Running stuff from here to W4KAZ 7+ miles away always shows an initial 3-4 dB drop in S/N when the band just starts to open. Why I generally run stuff to him in the middle of the day when I want to know the numbers. 73, Guy On Tue, Aug 19, 2014 at 12:06 PM, Tim Shoppa wrote: I quickly noticed that some skimmers seem to have more effective antenna systems than others. More than S/N, I look at kinda the breadth and depth of where I'm spotted. On 160M, GW8IZR and DL1A are where I'm first spotted. If I'm getting spotted more broadly or deeply than that, then I know conditions are really good. Tim N3QE On Tue, Aug 19, 2014 at 5:33 AM, Mike Waters wrote: When I last investigated, all the skimmers and Web SDRs that were outside of North America all had terrible receive antennas for copying DX signals on 160. (And who knows how many of them are in quiet locations?) When I say terrible, I mean small magnetic loops, very short whips, low dipoles, a random end-fed wire, etc. No phased arrays or Beverages, and not even a Flag, K9AY, EWE, etc. Does anyone know if that is still the case? 73, Mike www.w0btu.com _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Skimmer calibration
Do we really care that skimmers aren't hooked up to antennas with pattern and gain? One of the things in using VOACAP is knowing the pattern of the RX antenna as well as TX. Omni pattern at RX removes RX antenna bias. Why shouldn't we specifically use omni on RX, so that any enhancement is from the sender or the propagation/environment? If I wanted to know what antenna was better, I would use a short vertical or vertically polarized antenna for most applications. Ideally, you want a broad elevation pattern with no nulls. A 2 foot vertical has about the same pattern as a 130 ft vert for elevation on 160, so the only issue is sensitivity falling into RX internal noise. I think people live on the false notion that verticals have a null at near zero, which patterns on Ham models will show, but that is a program display shortfall causing that error. If they really were zero, all broadcast stations would be dark for groundwave. :) _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Switching Pennants
I would not switch high impedance lines without very special precautions. I really do not think it is worth the small parts savings. - Original Message - From: DGB ns9i2...@bayland.net To: topband@contesting.com Sent: Tuesday, August 19, 2014 4:38 PM Subject: Topband: Switching Pennants I am wanting a simple way of switching 3 or 4 pennants. Anyone done this? Quote From K6SEE ... All four Pennants would be installed with their points all adjacent to each other. Only one feedline would be necessary and only one transformer would be necessary, with the high impedance winding of the transformer being switched to the feedpoint of the Pennant in the desired direction ... 73, de Earl, K6SE 73 Dwight NS9I _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4745 / Virus Database: 4007/8063 - Release Date: 08/19/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Modeling the proverbial vertical on a beach
On Tue, Aug 19, 2014 at 11:24 AM, Tom W8JI w...@w8ji.com wrote: Why would it matter? The receiving antenna does not matter, provided it responds to the wave angle at the receive site. It doesn't matter if it is loop, a 10 foot vertical, or a 200 foot vertical so long as the antenna does not null the primary wave angle for the incoming signal. It does not matter if it is a large receiving array or a whip, provided each are not nulling the primary signal arrival. Or giving advantage to one or the other incoming angle in effect setting the primary signal arrival Not using a small omni RX antenna for this experiment introduces some serious calculation issues. E.g. if the RX setup has pattern and gain, we first have to know what incoming angle and direction a signal is arriving at and then divide the pattern out BEFORE any comparisons are made. So how do we know that? VOACAP has that built in where you are supposed to supply the RX pattern, which otherwise defaults to omni. No pattern is required to eliminate direction and elevation arrival adjustments to reported readings if the antenna is truly omni. If the RX antenna is omni and low enough then any enhancements are due to the propagation or environment or the TX station's antennas, which is what you WANT to see. FURTHER, since nearly all ham TX antennas are NOT at water's edge, then any tests looking for water's edge enhancement must do so by placing RX at water's edge and placing another identical RX/antenna back on the beach a few hundred feet off and another identical RX/antenna at typical shore site antenna-distance-from-actual-water's edge as in 1500 feet for W2GD and K3ZM. Putting up and maintaining TX antennas right at water's edge and feedline back to safe location for transceivers, etc, is something that likely unworkable or will not be tolerated by those controlling public beach fronts, would be a maintenance nightmare to begin with. These include such things as guy anchors under water on the beach, that will not come loose under typical random sand rearrangement underwater. Or continuous corrosive/shorting salt spray on metal and insulators. Or exposure to vandalism. RX skimmers with a short antenna can be made very small, battery charged by solar power, completely enclosed in smallish sealed box and communicating with the internet via wifi back off the beach. They can be put on top of pier poles, etc, and completely controlled remotely. 73, Guy _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Skimmer calibration
Do we really care that skimmers aren't hooked up to antennas with pattern and gain? One of the things in using VOACAP is knowing the pattern of the RX antenna as well as TX. Omni pattern at RX removes RX antenna bias. Why shouldn't we specifically use omni on RX, so that any enhancement is from the sender or the propagation/environment? If I wanted to know what antenna was better, I would use a short vertical or vertically polarized antenna for most applications. Ideally, you want a broad elevation pattern with no nulls. A 2 foot vertical has about the same pattern as a 130 ft vert for elevation on 160, so the only issue is sensitivity falling into RX internal noise. I think people live on the false notion that verticals have a null at near zero, which patterns on Ham models will show, but that is a program display shortfall causing that error. If they really were zero, all broadcast stations would be dark for groundwave. :) BC antennas have the elaborate radial system in order to get that groundwave while the typical on ground ham vertical loses a lot of the 0-10 degree (or more) radiation. Go to the beach to get it back.or go with elevated radials. Carl KM1H _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Skimmer calibration
BC antennas have the elaborate radial system in order to get that groundwave while the typical on ground ham vertical loses a lot of the 0-10 degree (or more) radiation. Go to the beach to get it back.or go with elevated radials. That just isn't factual at all. Radials under the vertical antenna have virtually no effect on wave angle unless they are sparse and grossly unbalanced, allowing them to radiate like a low horizontal antenna. Radials change the efficiency, not the pattern, unless the radials radiate like a dipole. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband
