Ah! Very helpful, thanks! 73 Mike W0BTU
On Sat, Jan 2, 2021, 2:21 PM Lee STRAHAN <k7...@msn.com> wrote: > Hi Mike, > > Assuming that you did not miss that this was a tapped winding and not > separate windings as Csaba mentioned. I see on reflection that he measured > 1:1.16 on one of his tests. In reality it wont likely get much better than > that. That test was likely the 3:12 he mentioned using. The high impedance > side of these transformers are a little unpredictable using simple formulas > with winding capacitance and magnetizing inductance added in the mix. > > Sometimes I use wire wrap wire if it is not going to be used outside > otherwise I use #27 high temp motor winding class insulation wire which > helps keep from shorting the wires to the core. I have the benefit of many > part spools of motor winding wire scraps from a best friend and Ham in the > Motor rewinding business. By the way, Norton amplifiers require 1:11:4 > which is the same problem to solve as they are separate windings in the > ones I use. I also fit shrink tubing in the Norton amp cores for insulation > first. I don’t use Teflon because it has a dielectric constant around 5 > which increases the capacitance from the wire to the core. Its tedious but > can be done easily. And in the case of the Norton amp it leaves room for a > larger wire on the 1 turn winding. Yes 4 AND16 for 20 total can be done but > yes it takes time and lots of patience. For those turns counts I go to # 75 > material toroid cores which have slightly more winding room but require > more turns usually for 160 meter stuff. All this probably more than you > wanted to know. HNY > > Lee K7TJR OR > > > > *From:* Mike Waters <mikew...@gmail.com> > *Sent:* Saturday, January 2, 2021 11:44 AM > *To:* Lee K7TJR <k7...@msn.com> > *Cc:* HA3LN <l...@ha3ln.hu>; topband <topband@contesting.com> > *Subject:* Re: Topband: (2wire) Beverage transformers > > Lee, > > What kind of wire do you use that allows that many turns (4t and 16t)? > > 73 Mike W0BTU > > On Sat, Jan 2, 2021, 1:37 PM Lee STRAHAN <k7...@msn.com> wrote: > > Hello Csaba, > I approach this problem this way your impedance ratio is 745/50 ohms or > 14.9 . To get turns ratio use the square root of that which is 3.86 . So > round that up to 4 as a good turns ratio. > On a BN73-202 core I usually use a minimum of 4 turns on the 50 ohm side > for 160 meters, so the secondary would need 4 turns ratio times that for 16 > turns. Therefore 16 turns tapped at 4 turns should work for you. ... > > _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector