Topband: Half slopers ???
Hi, I am trying to work on 160m (also on 80m) from a city lot. I have been reading about half slopers in the ARRL Wire antenna classics B (chapter 7). I have a 50 ft grounded tower available and can run an sloping wire 60 ft (1/4 wl on 80m) then add an 80m trap and more wire to work 160m. Any thoughts about this kind of antenna?... Thanks, Doug, CO8DM _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: FT4JA easy copy tonite
Well that was amazing. FT4JA super-easy copy in W3 for several hours before his sunrise. My RX antenna pointed toward EU. Working well into USA midwest with a very occasional European. I didn't get through but I heard many regulars that did!!! Now about 10 minutes after his sunrise I can still hear him but copy way down. Time to get ready for LZ Open 40M sprint :-). Tim N3QE _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Receive loop observations
Tnx, Jim...yes, see now where 43 material works almost as well...will find #43 core...Jim R. From: Topband on behalf of Jim Brown Sent: Friday, April 1, 2016 2:55 PM To: topband@contesting.com Subject: Re: Topband: Receive loop observations On Fri,4/1/2016 1:36 PM, James Rodenkirch wrote: > need to find a Fair-rite 61 core N6RK notes that Fair-Rite #43 will work fine, with slightly increased loss. Mu is higher, so you will likely need fewer turns to get 100 uH. #43 is much easier to find. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Receive loop observations
On 4/1/2016 1:25 PM, donov...@starpower.net wrote: Hi Jim, A properly constructed loop antenna absolutely requires a preamp. Yes, but usually the preamp function built into the radio is sufficient. If your loop is operating correctly it will be omni-directional for skywave signals and it will have an extremely deep null for an unwanted signal propagated to your antenna from one local vertically polarized interference source. A well constructed loop should have a null depth of 60-80 dB and a null beamwidth of just a few degrees. A very rigid mechanical mount is required to keep the deep null pointed directly at your interference source. It is easy to model a loop on NEC, and the results I have seen do not predict anything like 60 to 80 dB nulling. With a circumference of 20 to 40 feet on 160 meters, the null is only 10 or 15 dB deep. A properly constructed loop should be transformer matched to keep the loop balanced and both the coaxial cable and power cable must be exceptionally well isolated from the loop. Exactly right A low noise figure high gain preamp is essential. I've tried that on my loops, and all it does is make the S-meter move more. No audible difference. Frank W3LPL 73 Rick N6RK _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Receive loop observations
On Fri,4/1/2016 1:36 PM, James Rodenkirch wrote: need to find a Fair-rite 61 core N6RK notes that Fair-Rite #43 will work fine, with slightly increased loss. Mu is higher, so you will likely need fewer turns to get 100 uH. #43 is much easier to find. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Receive loop observations
You are the 2nd fella, Frank, to remind me about a matching/coupling xfmr.muchas gracias!!! 71.5/72 de Jim R. K9JWV From: donov...@starpower.net Sent: Friday, April 1, 2016 2:25 PM To: Top Band Contesting Subject: Re: Topband: Receive loop observations Hi Jim, A properly constructed loop antenna absolutely requires a preamp. If signals are so strong that you don't require a preamp then its likely that the signals you're hearing are not actually coming from the very inefficient loop but from other sources such common mode from your coax feed line if its not very well isolated from the loop. If your loop is operating correctly it will be omni-directional for skywave signals and it will have an extremely deep null for an unwanted signal propagated to your antenna from one local vertically polarized interference source.A well constructed loop should have a null depth of 60-80 dB and a null beamwidth of just a few degrees. A very rigid mechanical mount is required to keep the deep null pointed directly at your interference source. A properly constructed loop should be transformer matched to keep the loop balanced and both the coaxial cable and power cable must be exceptionally well isolated from the loop. A low noise figure high gain preamp is essential. 73 Frank W3LPL From: "James Rodenkirch" To: "Top Band Contesting" Sent: Friday, April 1, 2016 7:04:25 PM Subject: Topband: Receive loop observations I have installed a receive loop ( http://www.qsl.net/kc2tx/ ) and finished measuring and observing... Measurements: VSWR --- 1.7 @ 1.830 ZO - 77 at 1.830 Observation: Following ON4UN's comments regarding needing a preamp or not, measured S1 to 2 noise level with antenna connected during mid-day, S0 with dummy load connected. During evening hours, notice some improvement - S2 drop in noise level when switching from xmt antenna (inverted U) to the loop - but not hearing much in the way of receive signals (e.g., hear a fairly strong signal from the west coast on the xmt antenna, nothing on the loop and I have it oriented east/west). I'm uncertain if a low noise amp will help my cause (thoughts??) I do not have a common mode choke installed, yet...will one make that much difference? The loop is located about 60' away from the Inverted U and radials. Comments/suggestions appreciated. Thank you, in advance, for constructive, relative to what I have now, repliesnon-"constructive" means I can't erect a BOG, Beveridge or Waller Flag so don't ask why I didn't go that route. 71.5/72 de Jim Rodenkirch K9JWV _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Receive loop observations
Doggone it, Don...I'd seen that presentation before - simply forgot about using a xfmr to couple unbalanced coax to balanced rcv antennagood on ya for sending that on -- need to find a Fair-rite 61 core.hihi From: Don Kirk Sent: Friday, April 1, 2016 2:02 PM To: James Rodenkirch Cc: Top Band Contesting Subject: Re: Topband: Receive loop observations Hi Jim, I know my following info does not directly answer your question, but I do think it's important regarding feedline isolation. I suggest you take a look at the recommendations of N6RK regarding the use of a matching transformer to feed tuned shielded loops as it isolates the feedline from the antenna (shield of coax not tied directly to the loop). I use the N6RK matching transformer method on my loops of similar design and think it makes the most sense regarding feedline isolation, and maintaining proper balance of the antenna. Here is a link to his paper, and his matching transformer is shown on page 30 and 33 of his paper. http://www.n6rk.com/loopantennas/pacificon.pdf 73, Don (wd8dsb) 73, Don (wd8dsb) On Fri, Apr 1, 2016 at 3:04 PM, James Rodenkirch mailto:rodenkirch_...@msn.com>> wrote: I have installed a receive loop ( http://www.qsl.net/kc2tx/ ) and finished measuring and observing... Measurements: VSWR --- 1.7 @ 1.830 ZO - 77 at 1.830 Observation: Following ON4UN's comments regarding needing a preamp or not, measured S1 to 2 noise level with antenna connected during mid-day, S0 with dummy load connected. During evening hours, notice some improvement - S2 drop in noise level when switching from xmt antenna (inverted U) to the loop - but not hearing much in the way of receive signals (e.g., hear a fairly strong signal from the west coast on the xmt antenna, nothing on the loop and I have it oriented east/west). I'm uncertain if a low noise amp will help my cause (thoughts??) I do not have a common mode choke installed, yet...will one make that much difference? The loop is located about 60' away from the Inverted U and radials. Comments/suggestions appreciated. Thank you, in advance, for constructive, relative to what I have now, repliesnon-"constructive" means I can't erect a BOG, Beveridge or Waller Flag so don't ask why I didn't go that route. 71.5/72 de Jim Rodenkirch K9JWV _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Receive loop observations
Hi Jim, A properly constructed loop antenna absolutely requires a preamp. If signals are so strong that you don't require a preamp then its likely that the signals you're hearing are not actually coming from the very inefficient loop but from other sources such common mode from your coax feed line if its not very well isolated from the loop. If your loop is operating correctly it will be omni-directional for skywave signals and it will have an extremely deep null for an unwanted signal propagated to your antenna from one local vertically polarized interference source. A well constructed loop should have a null depth of 60-80 dB and a null beamwidth of just a few degrees. A very rigid mechanical mount is required to keep the deep null pointed directly at your interference source. A properly constructed loop should be transformer matched to keep the loop balanced and both the coaxial cable and power cable must be exceptionally well isolated from the loop. A low noise figure high gain preamp is essential. 73 Frank W3LPL - Original Message - From: "James Rodenkirch" To: "Top Band Contesting" Sent: Friday, April 1, 2016 7:04:25 PM Subject: Topband: Receive loop observations I have installed a receive loop ( http://www.qsl.net/kc2tx/ ) and finished measuring and observing... Measurements: VSWR --- 1.7 @ 1.830 ZO - 77 at 1.830 Observation: Following ON4UN's comments regarding needing a preamp or not, measured S1 to 2 noise level with antenna connected during mid-day, S0 with dummy load connected. During evening hours, notice some improvement - S2 drop in noise level when switching from xmt antenna (inverted U) to the loop - but not hearing much in the way of receive signals (e.g., hear a fairly strong signal from the west coast on the xmt antenna, nothing on the loop and I have it oriented east/west). I'm uncertain if a low noise amp will help my cause (thoughts??) I do not have a common mode choke installed, yet...will one make that much difference? The loop is located about 60' away from the Inverted U and radials. Comments/suggestions appreciated. Thank you, in advance, for constructive, relative to what I have now, repliesnon-"constructive" means I can't erect a BOG, Beveridge or Waller Flag so don't ask why I didn't go that route. 71.5/72 de Jim Rodenkirch K9JWV _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Receive loop observations
Hi Jim, I know my following info does not directly answer your question, but I do think it's important regarding feedline isolation. I suggest you take a look at the recommendations of N6RK regarding the use of a matching transformer to feed tuned shielded loops as it isolates the feedline from the antenna (shield of coax not tied directly to the loop). I use the N6RK matching transformer method on my loops of similar design and think it makes the most sense regarding feedline isolation, and maintaining proper balance of the antenna. Here is a link to his paper, and his matching transformer is shown on page 30 and 33 of his paper. http://www.n6rk.com/loopantennas/pacificon.pdf 73, Don (wd8dsb) 73, Don (wd8dsb) On Fri, Apr 1, 2016 at 3:04 PM, James Rodenkirch wrote: > I have installed a receive loop ( http://www.qsl.net/kc2tx/ ) and > finished measuring and observing... > > > Measurements: > > > VSWR --- 1.7 @ 1.830 > > ZO - 77 at 1.830 > > > Observation: > > > Following ON4UN's comments regarding needing a preamp or not, measured S1 > to 2 noise level with antenna connected during mid-day, S0 with dummy load > connected. > > > During evening hours, notice some improvement - S2 drop in noise level > when switching from xmt antenna (inverted U) to the loop - but not hearing > much in the way of receive signals (e.g., hear a fairly strong signal from > the west coast on the xmt antenna, nothing on the loop and I have it > oriented east/west). > > > I'm uncertain if a low noise amp will help my cause (thoughts??) > > > I do not have a common mode choke installed, yet...will one make that much > difference? > > > The loop is located about 60' away from the Inverted U and radials. > > > Comments/suggestions appreciated. > > > > Thank you, in advance, for constructive, relative to what I have now, > repliesnon-"constructive" means I can't erect a BOG, Beveridge or > Waller Flag so don't ask why I didn't go that route. > > > 71.5/72 de Jim Rodenkirch K9JWV > _ > Topband Reflector Archives - http://www.contesting.com/_topband > _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Receive loop observations
I have installed a receive loop ( http://www.qsl.net/kc2tx/ ) and finished measuring and observing... Measurements: VSWR --- 1.7 @ 1.830 ZO - 77 at 1.830 Observation: Following ON4UN's comments regarding needing a preamp or not, measured S1 to 2 noise level with antenna connected during mid-day, S0 with dummy load connected. During evening hours, notice some improvement - S2 drop in noise level when switching from xmt antenna (inverted U) to the loop - but not hearing much in the way of receive signals (e.g., hear a fairly strong signal from the west coast on the xmt antenna, nothing on the loop and I have it oriented east/west). I'm uncertain if a low noise amp will help my cause (thoughts??) I do not have a common mode choke installed, yet...will one make that much difference? The loop is located about 60' away from the Inverted U and radials. Comments/suggestions appreciated. Thank you, in advance, for constructive, relative to what I have now, repliesnon-"constructive" means I can't erect a BOG, Beveridge or Waller Flag so don't ask why I didn't go that route. 71.5/72 de Jim Rodenkirch K9JWV _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Wind Farming
I live in one of the areas of G-land with the highest concentration of wind farms. What I learned while looking for a new low-noise QTH: - small wind generators (50kW or less) have induction generators and therefore are essentially no-noise on HF & VHF. - mid-size (up to around 1MW) usually have an inverter (think SMPS on a 20-50m (70-170ft) tower) which is a noise generator. - large turbines most always use an inverter architecture and some of the towers are 80m/300ft or more high. Gives them the ability to spread their hash over very wide areas and be prominent in the field of view of your antennas. - I drove around several of the larger windfarms at distances from 3 miles down to 500ft or so. One particularly noisy site (with IIRC 19 x 2MW turbines) could be heard out to 3 miles or so. RX was KX3 with a 9ft whip on the roof of the SUV. No doubt would be heard at a much greater distance at a fixed QTH with towers/beams. - I set a goal of being no closer than 5 miles from a turbine of 1MW or more. Hard to achieve on this crowded small island (it's a 1000 miles long but has a population of 60 million+). - The ZL6QH experience appears to validate my experimental findings. So if that farm really is local and they want to install big wind generators, be ready for QRN. 73, David G3WGN M6O -Original Message- From: Jim Murray [mailto:adkmur...@yahoo.com] Sent: 30 March 2016 20:07 To: TopBand List Subject: Topband: Wind Farming Hello all,There is talk of local farmers bringing in windmill companies. With the low prices now on milk it is one way to boost income. Wondering if anyone has experienced any interference/noise from the generators.ThanksJimk2hn _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Wind Farming
Brian, The last paragraph is particularly interesting. Variable speed drive motor controllers are well known noise generators, primarily because they are generally very poorly installed in a manner that their wiring forms loops with a large loop area, establishing strong magnetic fields that strongly couple harmonics of the square waves used to control the motors. The fix is to reduce the size of the current loop. It would be interesting to know if any of this might be part of the problem at the wind farm near ZL6QH. I'm forwarding this email to the RFI reflector. 73, Jim K9YC On Fri,4/1/2016 5:22 AM, Brian Miller wrote: Thanks Frank I was previously the chair of the Quartz Hill User Group responsible for the ZL6QH station. We undertook measurements of the noise from the wind farm at the ZL6QH site. A report on our measurements is published at http://www.zl6qh.com/rf-noise-measurements-quartz-hill-2009-v3.pdf . The ZL6QH wind farm used Siemens 2.3 MW variable speed turbines. We believe the noise was generated by the water cooled electronic power converter technology that was used to convert the variable output of each turbine to the fixed voltage and frequency of the national grid. Our observations suggested that a HF contest station would have be located at least several km from a wind farm using these turbines to reduce the interference to an acceptable level on the low frequency bands. But not all turbines are this noisy. We also conducted some HF radio frequency noise measurements at the Meridian Energy Te Apiti wind farm (near Palmerston North) in October 2005 but found no evidence of any significant noise being radiated by the turbines, even at locations within 100 metres of the nearest turbines. Unlike the turbines at Quartz Hill, the Te Apiti turbines were a fixed speed design and did not use a separate power converter unit 73 Brian VK3MI ZL1AZE -- Message: 7 Date: Wed, 30 Mar 2016 15:59:34 -0400 (EDT) From: donov...@starpower.net To: TopBand List Subject: Re: Topband: Wind Farming Message-ID: <990159030.6273859.1459367974629.javamail.r...@starpower.net> Content-Type: text/plain; charset=utf-8 The Quartz Hill Contesters -- once very well known as ZL6QH -- were forced to shut down their spectacular contesting location by the RFI from a wind farm installed in the same location as their contest station. http://zl6qh.com/logs/Quartz%20Hill%20Pictures%20-%20%20March%202010.pdf 73 Frank W3LPL _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Wind Farming
ZL6QH is the only Long Path 160m qso I ever made. Pity it had to switch off! PE5T -- From: "Brian Miller" Sent: Friday, April 01, 2016 2:22 PM To: Subject: Re: Topband: Wind Farming Thanks Frank I was previously the chair of the Quartz Hill User Group responsible for the ZL6QH station. We undertook measurements of the noise from the wind farm at the ZL6QH site. A report on our measurements is published at http://www.zl6qh.com/rf-noise-measurements-quartz-hill-2009-v3.pdf . The ZL6QH wind farm used Siemens 2.3 MW variable speed turbines. We believe the noise was generated by the water cooled electronic power converter technology that was used to convert the variable output of each turbine to the fixed voltage and frequency of the national grid. Our observations suggested that a HF contest station would have be located at least several km from a wind farm using these turbines to reduce the interference to an acceptable level on the low frequency bands. But not all turbines are this noisy. We also conducted some HF radio frequency noise measurements at the Meridian Energy Te Apiti wind farm (near Palmerston North) in October 2005 but found no evidence of any significant noise being radiated by the turbines, even at locations within 100 metres of the nearest turbines. Unlike the turbines at Quartz Hill, the Te Apiti turbines were a fixed speed design and did not use a separate power converter unit 73 Brian VK3MI ZL1AZE -- Message: 7 Date: Wed, 30 Mar 2016 15:59:34 -0400 (EDT) From: donov...@starpower.net To: TopBand List Subject: Re: Topband: Wind Farming Message-ID: <990159030.6273859.1459367974629.javamail.r...@starpower.net> Content-Type: text/plain; charset=utf-8 The Quartz Hill Contesters -- once very well known as ZL6QH -- were forced to shut down their spectacular contesting location by the RFI from a wind farm installed in the same location as their contest station. http://zl6qh.com/logs/Quartz%20Hill%20Pictures%20-%20%20March%202010.pdf 73 Frank W3LPL _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Wind Farming
Thanks Frank I was previously the chair of the Quartz Hill User Group responsible for the ZL6QH station. We undertook measurements of the noise from the wind farm at the ZL6QH site. A report on our measurements is published at http://www.zl6qh.com/rf-noise-measurements-quartz-hill-2009-v3.pdf . The ZL6QH wind farm used Siemens 2.3 MW variable speed turbines. We believe the noise was generated by the water cooled electronic power converter technology that was used to convert the variable output of each turbine to the fixed voltage and frequency of the national grid. Our observations suggested that a HF contest station would have be located at least several km from a wind farm using these turbines to reduce the interference to an acceptable level on the low frequency bands. But not all turbines are this noisy. We also conducted some HF radio frequency noise measurements at the Meridian Energy Te Apiti wind farm (near Palmerston North) in October 2005 but found no evidence of any significant noise being radiated by the turbines, even at locations within 100 metres of the nearest turbines. Unlike the turbines at Quartz Hill, the Te Apiti turbines were a fixed speed design and did not use a separate power converter unit 73 Brian VK3MI ZL1AZE -- Message: 7 Date: Wed, 30 Mar 2016 15:59:34 -0400 (EDT) From: donov...@starpower.net To: TopBand List Subject: Re: Topband: Wind Farming Message-ID: <990159030.6273859.1459367974629.javamail.r...@starpower.net> Content-Type: text/plain; charset=utf-8 The Quartz Hill Contesters -- once very well known as ZL6QH -- were forced to shut down their spectacular contesting location by the RFI from a wind farm installed in the same location as their contest station. http://zl6qh.com/logs/Quartz%20Hill%20Pictures%20-%20%20March%202010.pdf 73 Frank W3LPL _ Topband Reflector Archives - http://www.contesting.com/_topband
