Topband: (2wire) Beverage transformers

[Mike Waters]

Ah! Very helpful, thanks!

73 Mike
W0BTU

On Sat, Jan 2, 2021, 2:21 PM Lee STRAHAN <k7tjr at 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 <mikewate at gmail.com>
> *Sent:* Saturday, January 2, 2021 11:44 AM
> *To:* Lee K7TJR <k7tjr at msn.com>
> *Cc:* HA3LN <list at ha3ln.hu>; topband <topband at 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 <k7tjr at 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. ...
>
>