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 difference....is 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 +0000 > > 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 clear....you 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