Re: Topband: Common Mode currents via Antenna Switch(Ungrounded)
On 8/6/2014 2:50 PM, Hugh Valentine wrote: I have some RF in shack/house/computer which usually manifests when use the OCF dipole at High Power. No surprise, an OCF dipole is a common mode current generator, and it's very difficult to choke it, especially for high power, because the high common mode voltage/current will fry a choke. I've written extensively on applications like yours, it's on my website. Study the RFI tutorial and the Coaxial Chokes power point. Chokes are generally ineffective except at the feedpoint. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ferrite Cores
On 8/6/2014 12:47 PM, Carl wrote: You should start selling them on here along with those balun cores. I'm retired, and in giving back mode. :) 73, Jim _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ferrite Cores
On 8/6/2014 8:31 AM, Carl wrote: 31 and 43 mix are the popular ones in the 2-30 MHz range for common mode suppression; 31 wins at 160 and 80, but 43 is better in the 7-30 range. I would amend that only to say that #31 and #43 are roughly equivalent in the 5-15 MHz, range, #43 is slightly better above 15 MHz. #43 is a bit less expensive than #31, but the cost difference disappears if you buy #31 in quantity. My last group purchase of #31 2.4-in cores was for 1,100 pieces, about two years ago. We paid about $4. Because #31 is so much better on 80 and 160, because it is more broadband below 15 MHz, and because it remains effective through the HF range, I long ago made the engineering decision to buy #31 in quantity for ham HF applications. If I were ONLY working above 80M, I would look at pricing on #43 in the quantities I needed. 73, Jim K9YC Im just basing it on some personal experience but havent run any lab tests. On a 40M inverted V with apex at 55' Id been using a pigtail with 43 for years, switching to 31, and no ferrite I couldnt hear any difference, both worked well. I mentioned the 43 since it is much cheaper. For 20M I used a 3 el HB monobander at 60' on another tower and the 43 seemed a hair better. Not exactly scientific and with a wide range of mix tolerances Im not going to worry about it, a few extra turns of coax would have sufficed. Both antennas are part of the AM station and were easy to get to. Since I dont run enough power to cause non linearities that isnt a concern on TX. Carl KM1H _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Common Mode currents via Antenna Switch(Ungrounded)
I have the following Transmit antenna questions, relative to Common Mode. Please let me describe what I have. Linear>30'RG213>W0MLY 5 position Coax Switch in shack.(Does not Ground unused centers) with 3 antenna ports used:Then at the W0MLY Inputs:Antennas:(1)160M Inv. "L"(Infamous Bird Feeder)using 80' LMR400 to feed point..6 radials into Marsh, 2 Ground rods all connected to Shield, no balun. Ant 33' Vert, 90+ ft horiz.Feedline buried.(2) 50' of RG-213 to OCF Dipole 80-6 Balun Designs 4114 balun. No other "Current Balun" in line. (3) 50' LMR400 to Steppir Big IR w/ numerous radials/ground screen,Ground rod in marsh. Feedline buried under screen.** All 3 Antennas in close proximity of course due to short coax feeds. My objective is to do whatever I need to minimize noise but still use the W0MLY Box to switch antennas if possible. I have some 2.4" cores, Mix 31 on the way to build chokes per K9YC.I have some RF in shack/house/computer which usually manifests when use the OCF dipole at High Power. Questions: Is it OK to connect the grounds and radials in common at the Feedpoint I nv L? Should I just connect Radials but ground coax shield when it comes in shack?Do I need a choke Balun there(feed point)? A 5,000 Ohm described by K9YC. Do I need to ground the W0MLY Box? There is one about 5' away on the other side of the wall. Should I have separate Chokes for each feed at their inputs at the box? Should I replace the W0MLY with a Grounding-Unused coaxes type? Is the Box re-radiating noise by having all shields connected at the box? Should I put a K9YC Common Mode Choke at the output side of the Linear? I know this is a lot to ask. Any comments would be appreciated and may apply to many other amateur's situation and help others. There are some real knowledgeable guys here who really know this stuff I cannot comprehend. I have been trial-and-erroring for so long I am praying some positive results come from this inquiry. I am hoping to clean up the station a little and be more prepared for some new ones even though I am using the smallest antenna for Top Band probably on the East Coast. Fortunately, the feed is about one foot from Salt Water. I'm gunning for the FT5. and VK9s. and, JT1 for my last Zone. If this is too much for the reflector, please reply direct and I will later condense the suggestions. Thanks in advance. 73Val The #1 Worst Carb Ever? Click to Learn #1 Carb that Kills Your Blood Sugar (Don't Eat This!) http://thirdpartyoffers.juno.com/TGL3141/53e2a37d53bf5237d6a77st03vuc _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ferrite Cores
Well, I don't think there is a "one-size" or "one--mix" "fits all" preferred solution. I've wanted to try some 31 mix cores for common-mode isolation at 80 and 160. On the other hand, some of the Fair-Rite 71 (73?) material toroids and binocular cores provide really good performance, even at lower frequencies, because of the lower losses and better frequency response. I also suspect that for power handling applications ( including common-mode suppression), the 31 mix might have some heating issues, because of the higher losses. BTW, I do know from experience that the Fair-Rite 71/73 etc. mix higher frequency cores seem to be impervious to weather! I have used the tubular cores and large binocular cores out of doors for years as common mode chokes on RG-213 for my 5-band quad feed-line and to make quick home-brew W2DU 1:1 current baluns for vertical dipoles for. 30 and 40 meters. I've never seen any evidence of corrosion nor have I noted any performance degradation. I've used the binocular transformer cores to construct matching transformers for "KAZ" terminated receiving loops for 160.80.40 and 30 m and use a larger binocular core to match 50 ohms up to the cathode impedance of my home-brew 3-500ZG amp, to avoid having to install a much more complex band-switch. Works quite well 160-10m and comfortably handles everything that my FT-1000MP delivers. Fortunately I had a good selection of cores in my Fair-Rite developer kits from my engineering days! 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Tom W8JI Sent: Wednesday, August 06, 2014 3:09 PM To: Ron Stordahl, AE5E; topband@contesting.com Subject: Re: Topband: Ferrite Cores In this discussion two different ferrite mixes are mentioned: #31 and #61. >From the descriptions of these on the Fair-Rite web page, it appears that 31 would be more suitable for lower frequency applications. Core selection can be fairly complex in transmitting systems. I've yet to see a case where one core mix is the be all end all for the range of things you run into in the field. Especially at high common mode impedances. Receiving is a completely different story, because core stresses are always low. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband --- 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: Ferrite Cores
You should start selling them on here along with those balun cores. Carl KM1H - Original Message - From: "Jim Brown" To: "'TopBand'" Sent: Wednesday, August 06, 2014 1:10 PM Subject: Re: Topband: Ferrite Cores On 8/6/2014 8:31 AM, Carl wrote: 31 and 43 mix are the popular ones in the 2-30 MHz range for common mode suppression; 31 wins at 160 and 80, but 43 is better in the 7-30 range. I would amend that only to say that #31 and #43 are roughly equivalent in the 5-15 MHz, range, #43 is slightly better above 15 MHz. #43 is a bit less expensive than #31, but the cost difference disappears if you buy #31 in quantity. My last group purchase of #31 2.4-in cores was for 1,100 pieces, about two years ago. We paid about $4. Because #31 is so much better on 80 and 160, because it is more broadband below 15 MHz, and because it remains effective through the HF range, I long ago made the engineering decision to buy #31 in quantity for ham HF applications. If I were ONLY working above 80M, I would look at pricing on #43 in the quantities I needed. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4716 / Virus Database: 3986/7988 - Release Date: 08/05/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ferrite Cores
In this discussion two different ferrite mixes are mentioned: #31 and #61. From the descriptions of these on the Fair-Rite web page, it appears that 31 would be more suitable for lower frequency applications. Core selection can be fairly complex in transmitting systems. I've yet to see a case where one core mix is the be all end all for the range of things you run into in the field. Especially at high common mode impedances. Receiving is a completely different story, because core stresses are always low. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ferrite Cores
On 8/6/2014 8:31 AM, Carl wrote: 31 and 43 mix are the popular ones in the 2-30 MHz range for common mode suppression; 31 wins at 160 and 80, but 43 is better in the 7-30 range. I would amend that only to say that #31 and #43 are roughly equivalent in the 5-15 MHz, range, #43 is slightly better above 15 MHz. #43 is a bit less expensive than #31, but the cost difference disappears if you buy #31 in quantity. My last group purchase of #31 2.4-in cores was for 1,100 pieces, about two years ago. We paid about $4. Because #31 is so much better on 80 and 160, because it is more broadband below 15 MHz, and because it remains effective through the HF range, I long ago made the engineering decision to buy #31 in quantity for ham HF applications. If I were ONLY working above 80M, I would look at pricing on #43 in the quantities I needed. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ferrite Cores
#31 is a very nice mix for winding chokes especially at topband and lower HF and for EMI suppression. #61 is very common for HF transformers up to medium power levels. #43 is also useful at HF transformers and chokes especially at upper HF. #73 is a very nice mix for low band transformers but some of the testing done shows typical transformers to be good 5kHz-50MHz: http://www.cliftonlaboratories.com/imd_in_broadband_transformers.htm I have been using #73 binocular cores for all sorts of things lately. A little Fair-Rite 2873000202 core works excellently in isolated DC-to-DC power converters at the several watt power level. On Wed, Aug 6, 2014 at 11:15 AM, Ron Stordahl, AE5E via Topband < topband@contesting.com> wrote: > In this discussion two different ferrite mixes are mentioned: #31 and > #61. > > > From the descriptions of these on the Fair-Rite web page, it appears that > 31 would be more suitable for lower frequency applications. > > > Is this the case? > > Ron, AE5E > > > > On Wednesday, August 6, 2014 4:02 AM, Charlie < > charlie-cunning...@nc.rr.com> wrote: > > > > I agree with all those points, Jim! Over the years, professionally, we > designed many Fair-Rite, cores into most of our electricity, gas and water > meter and electricity load-management products and shipped millions of > Fair-Rite products in our devices. Fair-Rite and Kreger are excellent > suppliers, and I still have many of their development kits around here. > Their products are excellent and very consistent > > Lynne Frye, of Kreger, is a very helpful contact person, that I have worked > with over the years! > > Have a good day! > > 73, > Charlie Cunningham, K4OTV > > > > -Original Message- > From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Jim > Brown > Sent: Tuesday, August 05, 2014 3:00 PM > To: topband@contesting.com > Subject: Re: Topband: Ferrite Cores > > On 8/5/2014 11:36 AM, Mike Waters wrote: > > FT-240-61 cores. Amidon was $9/ea, Mouser (for the Fair Rite > > equivalent) > > >was $14/ea. > > The actual manufacturer of a 2.4-in o.d. #61 toroid IS Fair-Rite. It is > not > an "equivalent," #61 material is Fair-Rite's mix. Other companies may make > a > "knock-off," but the REAL part is made by Fair-Rite. > > 73, Jim K9YC > > > _ > Topband Reflector Archives - http://www.contesting.com/_topband > > > --- > 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 Reflector Archives - http://www.contesting.com/_topband > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ferrite Cores
31 and 43 mix are the popular ones in the 2-30 MHz range for common mode suppression; 31 wins at 160 and 80, but 43 is better in the 7-30 range. Before 31 came along I used 43 even at 160 and observed problems went away since they werent as bad as others experienced. Carl KM1H - Original Message - From: "Ron Stordahl, AE5E via Topband" To: ; Sent: Wednesday, August 06, 2014 11:15 AM Subject: Re: Topband: Ferrite Cores In this discussion two different ferrite mixes are mentioned: #31 and #61. From the descriptions of these on the Fair-Rite web page, it appears that 31 would be more suitable for lower frequency applications. Is this the case? Ron, AE5E On Wednesday, August 6, 2014 4:02 AM, Charlie wrote: I agree with all those points, Jim! Over the years, professionally, we designed many Fair-Rite, cores into most of our electricity, gas and water meter and electricity load-management products and shipped millions of Fair-Rite products in our devices. Fair-Rite and Kreger are excellent suppliers, and I still have many of their development kits around here. Their products are excellent and very consistent Lynne Frye, of Kreger, is a very helpful contact person, that I have worked with over the years! Have a good day! 73, Charlie Cunningham, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Jim Brown Sent: Tuesday, August 05, 2014 3:00 PM To: topband@contesting.com Subject: Re: Topband: Ferrite Cores On 8/5/2014 11:36 AM, Mike Waters wrote: FT-240-61 cores. Amidon was $9/ea, Mouser (for the Fair Rite equivalent) >was $14/ea. The actual manufacturer of a 2.4-in o.d. #61 toroid IS Fair-Rite. It is not an "equivalent," #61 material is Fair-Rite's mix. Other companies may make a "knock-off," but the REAL part is made by Fair-Rite. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband --- 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 Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4716 / Virus Database: 3986/7988 - Release Date: 08/05/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ferrite Cores
In this discussion two different ferrite mixes are mentioned: #31 and #61. >From the descriptions of these on the Fair-Rite web page, it appears that 31 >would be more suitable for lower frequency applications. Is this the case? Ron, AE5E On Wednesday, August 6, 2014 4:02 AM, Charlie wrote: I agree with all those points, Jim! Over the years, professionally, we designed many Fair-Rite, cores into most of our electricity, gas and water meter and electricity load-management products and shipped millions of Fair-Rite products in our devices. Fair-Rite and Kreger are excellent suppliers, and I still have many of their development kits around here. Their products are excellent and very consistent Lynne Frye, of Kreger, is a very helpful contact person, that I have worked with over the years! Have a good day! 73, Charlie Cunningham, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Jim Brown Sent: Tuesday, August 05, 2014 3:00 PM To: topband@contesting.com Subject: Re: Topband: Ferrite Cores On 8/5/2014 11:36 AM, Mike Waters wrote: > FT-240-61 cores. Amidon was $9/ea, Mouser (for the Fair Rite > equivalent) > >was $14/ea. The actual manufacturer of a 2.4-in o.d. #61 toroid IS Fair-Rite. It is not an "equivalent," #61 material is Fair-Rite's mix. Other companies may make a "knock-off," but the REAL part is made by Fair-Rite. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband --- 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 Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Owner of 4-square antenna near Hammerfest ?
It might be for an AM broadcast station. You should be able to tune it in when driving by as it will be very loud. Another possibility is for the new 600M ham band and the elements are loaded for 475 KHz. Carl KM1H North of Hammerfest, near Farsol up on top of a flat rock, there is a professional build (remotely controled ?) LowBand 4-square antenna. Look like (high) half wave elements for 160m. Each element has its own smal building at the feed point. And there is a greater building for controls. The most perfect installed 4-square I have seen yet. Anyone knows, who the owner is of that antenna ? 73 de Thomas, DL1AMQ --- Diese E-Mail ist frei von Viren und Malware, denn der avast! Antivirus Schutz ist aktiv. http://www.avast.com _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4716 / Virus Database: 3986/7988 - Release Date: 08/05/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Owner of 4-square antenna near Hammerfest ?
North of Hammerfest, near Farsol up on top of a flat rock, there is a professional build (remotely controled ?) LowBand 4-square antenna. Look like (high) half wave elements for 160m. Each element has its own smal building at the feed point. And there is a greater building for controls. The most perfect installed 4-square I have seen yet. Anyone knows, who the owner is of that antenna ? 73 de Thomas, DL1AMQ --- Diese E-Mail ist frei von Viren und Malware, denn der avast! Antivirus Schutz ist aktiv. http://www.avast.com _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Ferrite Cores
I agree with all those points, Jim! Over the years, professionally, we designed many Fair-Rite, cores into most of our electricity, gas and water meter and electricity load-management products and shipped millions of Fair-Rite products in our devices. Fair-Rite and Kreger are excellent suppliers, and I still have many of their development kits around here. Their products are excellent and very consistent Lynne Frye, of Kreger, is a very helpful contact person, that I have worked with over the years! Have a good day! 73, Charlie Cunningham, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Jim Brown Sent: Tuesday, August 05, 2014 3:00 PM To: topband@contesting.com Subject: Re: Topband: Ferrite Cores On 8/5/2014 11:36 AM, Mike Waters wrote: > FT-240-61 cores. Amidon was $9/ea, Mouser (for the Fair Rite > equivalent) > >was $14/ea. The actual manufacturer of a 2.4-in o.d. #61 toroid IS Fair-Rite. It is not an "equivalent," #61 material is Fair-Rite's mix. Other companies may make a "knock-off," but the REAL part is made by Fair-Rite. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband --- 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
