Topband: Re: [TowerTalk] Winding Beverage RX Balun de K0FF

[Maurizio Panicara]

After some bad experiences, to prevent damages from (indirect) lightning
strikes I stopped with using small cores and thin wires turning in favour of
medium-large toroidal ferrite cores (AL = 4000, or more),  and also thicker
winding wires.
This produces a transformer that's more symilar to a transmitting than to
receiving device, but finally it's not a disadvantage.
With a convenient (for a practical winding on a board) primary of 2-3/4
turns and  8-3/4 turns in the secondary, the transformer perfectly covers 5
octaves, obviously including the 160m band.

73,
Mauri I4JMY


----- Original Message -----
From: "Tom Rauch" <w8ji@contesting.com>
To: "Tower Talk (mail list)" <towertalk@contesting.com>;
<topband@contesting.com>; "K0FF" <K0FF@ARRL.NET>
Sent: Saturday, September 16, 2000 2:31 AM
Subject: Topband: Re: [TowerTalk] Winding Beverage RX Balun de K0FF


>
>  Hi George,
>
> > Anyway this one is four windings of 16 turns each to make both the
primary
> > (3 windings) and secondary (1 winding....the impeadance ratio is the
> > SQUARE of the windings ratio), and the little paper tags you see are to
> > help me remember which phase is which. The core is an FT50-75 and I've
had
> > good results here with similar layouts. There are two schools of thought
>
> If you use the correct core, two turns are enough for the primary
> and five for the secondary for 75 ohm. I hate winding a bunch of
> turns, plus the winding is more prone to failure.
>
> For 50 ohm cable, make it a two turn primary and 6 turn secondary.



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