Topband: best core material?
I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector
Re: Topband: best core material?
Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector
Re: Topband: best core material?
If receive only, you will do just fine using the 2873000202 binocular 73 material core that Tom mentions. I think this corresponds to Amidon part number BN-202-73. Newark stocks the part under the original Fair-Rite 2873000202 number. Tom shows 2:5 ratio but I've done other ratios just fine. I am very very impressed with the 2873000202 core, in fact I also use it in some DC-DC converters and the core just barely gets warm at the 10 watt level. Whenever I've accidentally transmitted into my receive antenna, the transformer survives just fine, it's the terminating resistor that goes up in smoke. I try not to make a habit of it :-) Tim N3QE -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
Hi, Jim Yes, I gathered that it was a receiving loop. I built one a few years ago and used 73 mat'l for the transformer because it's what I had. Worked quite well. It was also a delta-shaped Kaz antenna like what John, ON4UN, did for F00AAA. My turns ratio was not quite as high as yours. 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
I wasn't going to use a binocular core, Tim - I was going to use the Amidon FT-140-43 OR the FT-140-77 IF it made any noticeable differenceis there some magical reason to use binocular vice standard round? From: tsho...@wmata.com To: rodenkirch_...@msn.com; ma...@isp.ca; topband@contesting.com Subject: RE: Topband: best core material? Date: Mon, 5 Aug 2013 18:12:48 + If receive only, you will do just fine using the 2873000202 binocular 73 material core that Tom mentions. I think this corresponds to Amidon part number BN-202-73. Newark stocks the part under the original Fair-Rite 2873000202 number. Tom shows 2:5 ratio but I've done other ratios just fine. I am very very impressed with the 2873000202 core, in fact I also use it in some DC-DC converters and the core just barely gets warm at the 10 watt level. Whenever I've accidentally transmitted into my receive antenna, the transformer survives just fine, it's the terminating resistor that goes up in smoke. I try not to make a habit of it :-) Tim N3QE -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
BTW, Jim I assume that 18:1 is the impedance ratio, and the turns ratio is of the order of 4:1 or so Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
When I did mine, I had used up all my binocular cores that were large enough, so I taped two tubular cores together side-by-side to make a binocular core. A little more room to wind, and maybe a little less inter-winding capacitance? 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:20 PM To: Shoppa, Tim; BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? I wasn't going to use a binocular core, Tim - I was going to use the Amidon FT-140-43 OR the FT-140-77 IF it made any noticeable differenceis there some magical reason to use binocular vice standard round? From: tsho...@wmata.com To: rodenkirch_...@msn.com; ma...@isp.ca; topband@contesting.com Subject: RE: Topband: best core material? Date: Mon, 5 Aug 2013 18:12:48 + If receive only, you will do just fine using the 2873000202 binocular 73 material core that Tom mentions. I think this corresponds to Amidon part number BN-202-73. Newark stocks the part under the original Fair-Rite 2873000202 number. Tom shows 2:5 ratio but I've done other ratios just fine. I am very very impressed with the 2873000202 core, in fact I also use it in some DC-DC converters and the core just barely gets warm at the 10 watt level. Whenever I've accidentally transmitted into my receive antenna, the transformer survives just fine, it's the terminating resistor that goes up in smoke. I try not to make a habit of it :-) Tim N3QE -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
Yes to both, Charlie - a friend of mine has a calculator to figure the exact turns ratio BUT, at a web site I found for this antenna (used during an FO0 dxpedition) the ratio was defined as 8 turns in the primary, 28 turns in the secondary (for 75 ohm cable so for 50 ohms it'll be something else but still fairly close to your mentioned 4:1 ratio) From: charlie-cunning...@nc.rr.com To: rodenkirch_...@msn.com; ma...@isp.ca; topband@contesting.com Date: Mon, 5 Aug 2013 14:24:05 -0400 Subject: Re: Topband: best core material? BTW, Jim I assume that 18:1 is the impedance ratio, and the turns ratio is of the order of 4:1 or so Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
You'll notice in my original response I was trying to determine if this is only for receiving or if you were planning on transmitting with this transformer too :). FT-140 is pretty huge for a receive antenna transformer and winding just a few turns of skinny wire through it would look particularly odd. Binocular cores will have better coupling and less leakage than toroidal cores. Toroidal cores might be preferable if you had to wind so many turns that it wouldn't be possible to fit through the binocular holes (admittedly the hole in a toroid is much bigger than the holes in a binocular core :)!) Tim N3QE From: James Rodenkirch [mailto:rodenkirch_...@msn.com] Sent: Monday, August 05, 2013 2:20 PM To: Shoppa, Tim; BY THE LAKE; topband@contesting.com Subject: RE: Topband: best core material? I wasn't going to use a binocular core, Tim - I was going to use the Amidon FT-140-43 OR the FT-140-77 IF it made any noticeable differenceis there some magical reason to use binocular vice standard round? From: tsho...@wmata.commailto:tsho...@wmata.com To: rodenkirch_...@msn.commailto:rodenkirch_...@msn.com; ma...@isp.camailto:ma...@isp.ca; topband@contesting.commailto:topband@contesting.com Subject: RE: Topband: best core material? Date: Mon, 5 Aug 2013 18:12:48 + If receive only, you will do just fine using the 2873000202 binocular 73 material core that Tom mentions. I think this corresponds to Amidon part number BN-202-73. Newark stocks the part under the original Fair-Rite 2873000202 number. Tom shows 2:5 ratio but I've done other ratios just fine. I am very very impressed with the 2873000202 core, in fact I also use it in some DC-DC converters and the core just barely gets warm at the 10 watt level. Whenever I've accidentally transmitted into my receive antenna, the transformer survives just fine, it's the terminating resistor that goes up in smoke. I try not to make a habit of it :-) Tim N3QE -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.commailto:topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.camailto:ma...@isp.ca To: rodenkirch_...@msn.commailto:rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.commailto:rodenkirch_...@msn.com To: topband@contesting.commailto:topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.comhttp://www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.comhttp://www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
Thanks to all that replied - VERY informative information as well as anecdotal evidence the small delta loop receive antenna works well AND at a lower height, which I was thinking of doing but not sure if that mod would alter the antenna's efficacy all that much! Suggestion that I use a binocular core understood and I will go that route - a friend of mine will wind the binoc core for me (have severe neuropathy and can't handle small stuff like that at all!). Great group of participants here - thank you for the advice/suggestions! 72, Jim Rodenkirch K9JWV --- Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
Hi, Jim Well, seems that I may have borrowed the 40X10 dimensions from somewhere. Interesting thing, is, if you are into modeling things with EZNEC, as I am, you can play with the dimensions quite a bit. The gain goes down as the loop area is reduced, placing more demand on the preamp. My 40X10 loop did really well with an old AMECO tunable tube preamp. No, my loop was not as tall as Johns but worked really well. I had Dacron ropes on the ends, so I could re-orient it like leading a cow ! Would like to have built one rotatable, but dont think Im going to have that opportunity. Sure you can use a larger core, especially if you use 73 material. The two tubular cores that I used were almost ¼ in ID X 0.45 OD. I just taped them together to make a binocular core. They were what I had available -73 matl. I understand about neuropathy! I have it pretty bad in my right hand and some in my right leg. We recently found some lesions on my cervical spinal cord. Really scary bad news!! Enjoy the loop! 73, Charlie, K4OTV From: James Rodenkirch [mailto:rodenkirch_...@msn.com] Sent: Monday, August 05, 2013 2:53 PM To: Charlie Cunningham Subject: RE: Topband: best core material? Importance: High I was going with the standard dimensions mentioned in the ON4UN book, Charlie - 18' high, 28' wide at the baseBUT I really wanted to reduce the height so your dimensions work far more better for me. OK - I'm convinced on using binocular but that BN-73-202 core sure looks small! Is there a slightly larger one I could use (I have a sever case of neuropathy so handling small thing is next to impossible! The XYL won't even let me wash dishes 'cuz she's afraid I'll mishandle that stuff!) If I'm winding a 4:1 turns ratio for a toroid I assume I do the same for a binocular, just use less turnsi.e., instead of 28 to 8 for a toroid, 8 to 2 for a binocular??? From: charlie-cunning...@nc.rr.com To: rodenkirch_...@msn.com; ma...@isp.ca; topband@contesting.com Subject: RE: Topband: best core material? Date: Mon, 5 Aug 2013 14:45:12 -0400 BTW, Jim I think you will be pleased with that loop! Mine was 40' long X 10' high and it was an excellent receive antenna for 160, 80, 40 and 30 m. If you model it in EZNEC, you will find that the impedances and cardioid patterns stay fairly constant as you go higher in frequency, but the gain goes up with increasing frequency. It helped me to hear and work Kazakhstan on 80m, when I couldn't copy on the 80m GP. It opened lots of additional paths on 160 as well. 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:29 PM To: Charlie Cunningham; 'BY THE LAKE'; topband@contesting.com Subject: Re: Topband: best core material? Yes to both, Charlie - a friend of mine has a calculator to figure the exact turns ratio BUT, at a web site I found for this antenna (used during an FO0 dxpedition) the ratio was defined as 8 turns in the primary, 28 turns in the secondary (for 75 ohm cable so for 50 ohms it'll be something else but still fairly close to your mentioned 4:1 ratio) From: charlie-cunning...@nc.rr.com To: rodenkirch_...@msn.com; ma...@isp.ca; topband@contesting.com Date: Mon, 5 Aug 2013 14:24:05 -0400 Subject: Re: Topband: best core material? BTW, Jim I assume that 18:1 is the impedance ratio, and the turns ratio is of the order of 4:1 or so Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT
Re: Topband: best core material?
By the way, Jim. My loop was only about 3' high on the bottom 40' run and about 13' at the apex. Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 3:23 PM To: topband@contesting.com Subject: Re: Topband: best core material? Thanks to all that replied - VERY informative information as well as anecdotal evidence the small delta loop receive antenna works well AND at a lower height, which I was thinking of doing but not sure if that mod would alter the antenna's efficacy all that much! Suggestion that I use a binocular core understood and I will go that route - a friend of mine will wind the binoc core for me (have severe neuropathy and can't handle small stuff like that at all!). Great group of participants here - thank you for the advice/suggestions! 72, Jim Rodenkirch K9JWV --- Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
If you plan to use the antenna on 160m you'll need 73 material. 43 works 3.8 up. Regards JC N4IS -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:20 PM To: Shoppa, Tim; BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? I wasn't going to use a binocular core, Tim - I was going to use the Amidon FT-140-43 OR the FT-140-77 IF it made any noticeable differenceis there some magical reason to use binocular vice standard round? From: tsho...@wmata.com To: rodenkirch_...@msn.com; ma...@isp.ca; topband@contesting.com Subject: RE: Topband: best core material? Date: Mon, 5 Aug 2013 18:12:48 + If receive only, you will do just fine using the 2873000202 binocular 73 material core that Tom mentions. I think this corresponds to Amidon part number BN-202-73. Newark stocks the part under the original Fair-Rite 2873000202 number. Tom shows 2:5 ratio but I've done other ratios just fine. I am very very impressed with the 2873000202 core, in fact I also use it in some DC-DC converters and the core just barely gets warm at the 10 watt level. Whenever I've accidentally transmitted into my receive antenna, the transformer survives just fine, it's the terminating resistor that goes up in smoke. I try not to make a habit of it :-) Tim N3QE -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector _ Topband Reflector
Re: Topband: best core material?
Yes, JC - ordering 73 material binocular cores today! From: n...@comcast.net To: rodenkirch_...@msn.com; tsho...@wmata.com; ma...@isp.ca; topband@contesting.com Date: Mon, 5 Aug 2013 15:49:37 -0400 Subject: Re: Topband: best core material? If you plan to use the antenna on 160m you'll need 73 material. 43 works 3.8 up. Regards JC N4IS -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:20 PM To: Shoppa, Tim; BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? I wasn't going to use a binocular core, Tim - I was going to use the Amidon FT-140-43 OR the FT-140-77 IF it made any noticeable differenceis there some magical reason to use binocular vice standard round? From: tsho...@wmata.com To: rodenkirch_...@msn.com; ma...@isp.ca; topband@contesting.com Subject: RE: Topband: best core material? Date: Mon, 5 Aug 2013 18:12:48 + If receive only, you will do just fine using the 2873000202 binocular 73 material core that Tom mentions. I think this corresponds to Amidon part number BN-202-73. Newark stocks the part under the original Fair-Rite 2873000202 number. Tom shows 2:5 ratio but I've done other ratios just fine. I am very very impressed with the 2873000202 core, in fact I also use it in some DC-DC converters and the core just barely gets warm at the 10 watt level. Whenever I've accidentally transmitted into my receive antenna, the transformer survives just fine, it's the terminating resistor that goes up in smoke. I try not to make a habit of it :-) Tim N3QE -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Monday, August 05, 2013 2:04 PM To: BY THE LAKE; topband@contesting.com Subject: Re: Topband: best core material? Sorry - didn't make it crystal clear that this is a Delta shaped variant of a EWE antenna My bad for not utilizing all of the necessary verbiage to make that clearyou see it in ON4UN's latest book on page 7-104. From: ma...@isp.ca To: rodenkirch_...@msn.com Subject: Re: Topband: best core material? Date: Mon, 5 Aug 2013 14:00:48 -0400 A full-wave delta loop would have the transformation done with a 1/4 wave line of 75 ohm cable. This must be something other than a full-wave loop? Bill VE3NH - Original Message - From: James Rodenkirch rodenkirch_...@msn.com To: topband@contesting.com Sent: Monday, August 05, 2013 1:33 PM Subject: Topband: best core material? I have a schematic for a delta shaped loop that shows I'll need an 18:1 transformer to transform the 950 ohms of the antenna to 50 ohms (feeding it with 50 ohm coax). One transformer diagram shows an FT-140-43 core being used. BUT, looking over some of Tom's, W8JI, write-ups, I see where he uses 73 material instead. I see where 77 material replaced 73 material so -- is an FT-140-77 the mo betta way to go? Thanks, in advance, for any advice/info. Jim Rodenkirch K9JWV _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 - No virus found in this message. Checked by AVG - www.avg.com Version: 2013.0.3392 / Virus Database: 3209/6552 - Release Date: 08/05/13 _ Topband Reflector _ Topband Reflector _ Topband Reflector _ Topband Reflector
