Re: Topband: Wellbrook receive loop performance
I made some signal to noise measurements last night between my short BOG and LOOP. Local (100-300 miles away) cw signals. The Loop, which is still living in my basement, is within 3DB of the BOG. I will move it outside soon and see what happens to SNR. I still need to try it out on some weaker DX stations. The LOOP has also proved to be promising on hearing multiple AM broadcast stations on the same frequency due to its good nulling capability. I could never do this with the BOG or L. On Tue, 2012-04-10 at 11:04 -0400, joe wrote: I built it in one evening using two pieces of scrap 1x3 lumber for spreaders. I pounded in four large wire staples to hold the wire to the spreaders and threaded both loops through them. The five wire and one wire pickup loop are not separated. I used a variable cap of roughly 150-200PF to resonate the 5 wire loop. I fed the pickup loop directly with RG-58 coax. No matching transformer. The loop is roughly 32 inches square. I tune the cap for maximum noise for the desired frequency. The loop is tunable from about 1600 - 1850 KHZ. I modeled my loop after the following designs for unshielded loops. http://www.i1wqrlinkradio.com/antype/ch9/chiave1183.htm http://members.verizon.net/~vze24qhw/loop.html On Tue, 2012-04-10 at 08:49 -0400, joe wrote: I am experimenting with a small one meter square loop. It is 5 turns of #14 wire with a one turn pickup loop. Feeding the pickup loop directly with 50 ohm coax. Using air variable cap to resonate the 5 turn loop. I have it setup in my basement on a tripod with small TV rotator and it works amazingly well. I can null stations about 3-4 S units with it and it is about 4 S units (24 DB) quieter than my inverted L. I also have a short 140 foot BOG and the loop performs nearly the same with the added ability null out noise sources. I plan to move it outside and take some more measurements. I'm pretty impressed so far. -Joe KB3KJS On Mon, 2012-04-09 at 17:17 -0700, Jim WA9YSD wrote: How well does this antenna perform in a City environment like mine on top of a 50 foot tower? Stay on course, fight a good fight, and keep the faith. Jim K9TF/WA9YSD ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Wellbrook receive loop performance
Dave, This is a great topic as there are a lot of us on small lots active on topband needing what ever edge we can find... Do you have this loop you've designed published where we can see it? I know as a low power backyard set up with a MA160V, it would be interesting to look into.we have an East/West oriented K9AY that has got back on 160M with an awesome receive. It would be fun to play around with a loop but not sure which one to decide on- We still need 24 for DXCC on topband and we need every bit of help we can get! 73! Paul N0AH Anna W0ANT Peggy KD0ISN ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Wellbrook receive loop performance
A comparison of the Wellbrook product which is a magnetic loop is not a good one to a AY loop or other low angle directive receive antenna. Mag loops are not directive in the same way they only have a very sharp null to two opposite directions and omni directional vertically. Nice for nulling strong local point source noise but that's it. It will enable qsos not possible otherwise and some DX I suppose but Wellbrook is not a good choice for any serious DX work. No mag antenna is. Sent from my iPad On Apr 11, 2012, at 11:43, BP Veal bryonv...@msn.com wrote: Dave, This is a great topic as there are a lot of us on small lots active on topband needing what ever edge we can find... Do you have this loop you've designed published where we can see it? I know as a low power backyard set up with a MA160V, it would be interesting to look into.we have an East/West oriented K9AY that has got back on 160M with an awesome receive. It would be fun to play around with a loop but not sure which one to decide on- We still need 24 for DXCC on topband and we need every bit of help we can get! 73! Paul N0AH Anna W0ANT Peggy KD0ISN ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Wellbrook receive loop performance
From what Ive read elsewhere their target market is often the cave dweller surrounded by 100+ other units making electronic noise and the poor owner is trying to hear something on his $59 allband Chinese toy. Carl KM1H - Original Message - From: W2PM w...@aol.com To: gali...@comcast.net Cc: Top Band topband@contesting.com Sent: Wednesday, April 11, 2012 3:24 PM Subject: Re: Topband: Wellbrook receive loop performance BCB work would be good for the Wellbrook and I suspect that is their target market. Sent from my iPad On Apr 11, 2012, at 9:14, joe gali...@comcast.net wrote: I made some signal to noise measurements last night between my short BOG and LOOP. Local (100-300 miles away) cw signals. The Loop, which is still living in my basement, is within 3DB of the BOG. I will move it outside soon and see what happens to SNR. I still need to try it out on some weaker DX stations. The LOOP has also proved to be promising on hearing multiple AM broadcast stations on the same frequency due to its good nulling capability. I could never do this with the BOG or L. On Tue, 2012-04-10 at 11:04 -0400, joe wrote: I built it in one evening using two pieces of scrap 1x3 lumber for spreaders. I pounded in four large wire staples to hold the wire to the spreaders and threaded both loops through them. The five wire and one wire pickup loop are not separated. I used a variable cap of roughly 150-200PF to resonate the 5 wire loop. I fed the pickup loop directly with RG-58 coax. No matching transformer. The loop is roughly 32 inches square. I tune the cap for maximum noise for the desired frequency. The loop is tunable from about 1600 - 1850 KHZ. I modeled my loop after the following designs for unshielded loops. http://www.i1wqrlinkradio.com/antype/ch9/chiave1183.htm http://members.verizon.net/~vze24qhw/loop.html On Tue, 2012-04-10 at 08:49 -0400, joe wrote: I am experimenting with a small one meter square loop. It is 5 turns of #14 wire with a one turn pickup loop. Feeding the pickup loop directly with 50 ohm coax. Using air variable cap to resonate the 5 turn loop. I have it setup in my basement on a tripod with small TV rotator and it works amazingly well. I can null stations about 3-4 S units with it and it is about 4 S units (24 DB) quieter than my inverted L. I also have a short 140 foot BOG and the loop performs nearly the same with the added ability null out noise sources. I plan to move it outside and take some more measurements. I'm pretty impressed so far. -Joe KB3KJS On Mon, 2012-04-09 at 17:17 -0700, Jim WA9YSD wrote: How well does this antenna perform in a City environment like mine on top of a 50 foot tower? Stay on course, fight a good fight, and keep the faith. Jim K9TF/WA9YSD ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1424 / Virus Database: 2411/4928 - Release Date: 04/11/12 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Wellbrook receive loop performance
W2PM said, A comparison of the Wellbrook product which is a magnetic loop is not a good one to a AY loop or other low angle directive receive antenna. Mag loops are not directive in the same way they only have a very sharp null to two opposite directions and omni directional vertically. Nice for nulling strong local point source noise but that's it. It will enable qsos not possible otherwise and some DX I suppose but Wellbrook is not a good choice for any serious DX work. No mag antenna is. -- And so far my testing fully supports the above comments by W2PM, and calculated RDF values along with takeoff angle really appears to help predict the S/N performance of one antenna system versus another when dealing with normal atmospheric noise that's coming in from all directions or at least say multiple directions (with a higher RDF value and lower takeoff angle generally being desired for DX which is not a strong point of Mag loops compared with AY loops, Flags/Pennants, etc.). For local point source generated noise such as a Plasma TV, the Mag loop really helps if the offending signal is 90 degrees (or 270 deg) to the desired signal. Whereas the Pennant/Flag really helps when the offending signal is 180 degrees to the desired signal. I have a gut feeling through preliminary testing I've done that a shielded mag loop has less interaction (less distortion of its pattern) due to nearby objects when compared with a small rotatable flag, possibly making a well balanced mag loop usable where the Pennant/Flag might not be (very small lot size, indoor operation, etc.). Detailed pattern measurements need to be done in order to quantify this casual observation. I should also mention that I only obtain an approximate 2 db improvement (on average) in S/N performance using my half size pennants compared with my 68 foot tall base loaded TX vertical (but in reality I believe this is close to what I should expect based on calculated RDF values). I also notice that the S/N difference is much greater between my pennants and TX vertical for stations close in versus DX which is likely due to differences in elevation patterns between my pennants and my TX vertical. Contrary to most folks opinion, I set my preamp gain on my pennants to provide a noise floor identical to that of my TX vertical for S/N comparison measurements (I find it impossible to quantify S/N performance between two antenna systems any other way under real life operating conditions, and I continuously switch rapidly between the two different antenna systems in order to evaluate the average S/N improvement). I am by no means an expert on this topic, but I wanted to share my comments/experiences since I've been doing a lot of testing of shielded mag loops and small pennants and flags during the past 3 years. 73's Don (wd8dsb) ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: Fwd: Wellbrook receive loop performance
I've had a Wellbrook 1530 loop up for a few years on a rotator at about 20' It excels on a small city lot in nulling local noise sources off its sides. Far better than the MFJ and ANC noise nuller boxes and sense antennas I have used on 80 and 160. Legal limit 75' away on 160 hasn't killed it yet. I do have the rotator control cable and coax common-mode suppressed with ferrite cores at both ends. I get no RF feed back in the shack via the device. If the desired signal and noise sources coincide (for example there's a powerline 60' away between me and EU), it still provides a better S/N than my Inv-L in that direction. 73, Gary NL7Y ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: LED Light Redux
I do not use LED lights so far at my home as they are much more expensive than the CFL's but I have found a good use for solar powered LED strings. After the outside Christmas decorations were taken down I had a bunch of solar powered DC LED strings wanting to find some usage. So after stumbling through the grasses weeds and bushes at night, generally during a contest, to find out if my two wire beverage was knocked of by a deer, or a 600 ohm termination was measured open from the feed end, I decided to use the end support termination pole and ground rod to support a string of the LED Christmas light that are power by the sun. they cause no interference and I get even with the sun (the enemy of 160 meters for sure) by sapping away a miniscule amount of its power. Now i can drive down the road at the end of my several Beverages and see at night exactly where they are planted. it saves time and energy especially during a contest or DX--pedition in making quick repairs. There are all sorts of LED solar powered yard light at Home Depot (yes we them in the VI) but the Christmas solar powered string are dirt cheap after the season and cost nothing to operate. In fact they are really impressive to drive by at night and some nocturnal creatures may even shy away from them whether two legged or otherwise. Herb Schoenbohm, KV4FZ St. Croix, US Virgin Islands ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Small loop Performance
A lot of us are of course interested in the results of these experiments because the loop is small enough to fit into a typical suburban or urban lot. In evaluating the performance of these antennas it is interesting to hear about one's ability to null out a local Am broadcast station. However that doesn't tell the whole story. How well does it hear pitifully weak DX stations? I've worked with a couple of loops based on N6RK's designs, and while they have deep nulls and work as expectred they also don't seem to produce any usable RF from DX stations. I can hear stateside signals with it but rarely anything weaker. A practical receiving antenna, at least for those of us living in the depths of the Black Hole, has to capture enough RF to produce some audio in the headphones. 73 Steve K0SR ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
