You will need a 1:1 choke balun between the tuner and the balanced feedline
to the antenna.

Obtain an HF-quality ferrite ring, about 1.75 inches in diameter.
Permittivity around 200-400.

Wind on 8 or 10 turns of 18 or 20 gauge, stranded, flexible,
figure-of-eight, twin speaker cable.

This should cover the range 1.8 to 30 MHz.
----
Reg, G4FGQ

Reg,
I'm afraid your "figure-of-eight" lost me. What's
that?
'Doc

Here in the states we would call it lamp or Zip cord.


--
John Passaneau, W3JXP
Penn State University



"'Doc" wrote in message ...


Reg,
I'm afraid your "figure-of-eight" lost me. What's
that?
'Doc

Is lamp or zip cord twisted with a fairly short lay?

The stuff I have in mind for baluns lays flat. Colourless. It may be sold as
speaker cable.

It has lower copper loss then coax, easier waterproofed and constructed.
----
Reg

===========================

Here in the states we would call it lamp or Zip cord.

Reg Edwards wrote:

Is lamp or zip cord twisted with a fairly short lay?

The stuff I have in mind for baluns lays flat. Colourless. It may be sold as
speaker cable.

It has lower copper loss then coax, easier waterproofed and constructed.

Reg, is that superior to coax wound on the same toroid?
I use RG-400 teflon coax for my baluns.
--
73, Cecil http://www.qsl.net/w5dxp



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Reg, is that superior to coax wound on the same toroid?
I use RG-400 teflon coax for my baluns.
--
73, Cecil http://www.qsl.net/w5dxp

============================

Just compare the coax inner conductor diameter with the 18-gauge wire of the
zip-cord. Conductor resistance is inversely proportional to wire diameter.

Furthermore, the transition from 50-ohm to open-wire line is less abrupt.
In theory, the impedance of the line wound on the transformer should be
intermediate between coax Zo and open-wire Zo.

On the other hand, the difference in loss due to either effect is hardly
detectable. The length of line involned is too small to make much
difference. I shouldn't bother changing the design.

I can't imagine how the coax got in there in the first place.
---
Reg, G4FGQ

In a 1:1 current balun, you would want the Z of the line in balun to be the
same as the transmission line i.e. 50 ohms not some Z in the middle. If it
is different it will do an impedance transformation of the load Z based on
the Z of the line in the balun, its length and frequency. In a 4:1 current
balun the Z should be about 100 ohms. I don't know if zip cord or what ever
you call it makes a 50 ohm open wire line. I think the spacing is to large.
I know that #14 enameled wire close spaced does make a 50 ohm line. Anyway
the difference in loss between #18 wire and RG-400 due to IR drop in the
length of wire in a balun is too small to worry about.


John Passaneau, W3JXP
Penn State University



"Reg Edwards" wrote in message
...
Reg, is that superior to coax wound on the same toroid?
I use RG-400 teflon coax for my baluns.
--
73, Cecil http://www.qsl.net/w5dxp

============================

Just compare the coax inner conductor diameter with the 18-gauge wire of
the
zip-cord. Conductor resistance is inversely proportional to wire
diameter.

Furthermore, the transition from 50-ohm to open-wire line is less abrupt.
In theory, the impedance of the line wound on the transformer should be
intermediate between coax Zo and open-wire Zo.

On the other hand, the difference in loss due to either effect is hardly
detectable. The length of line involned is too small to make much
difference. I shouldn't bother changing the design.

I can't imagine how the coax got in there in the first place.
---
Reg, G4FGQ

On Thu, 22 Jan 2004 10:43:15 -0600, Cecil Moore
wrote:

I use RG-400 teflon coax for my baluns.

I've done that too, however, the other day I was made aware of
teflon's problems with cold flow. You might want to look into that.

Danny, K6MHE

Figure-of-eight . . . .

Two circles stuck together. Outline of plastic insulation surrounding a
pair of close-spaced wires.

Zip-cord ?
---
Reg



--
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........
"'Doc" wrote in message ...


Reg,
I'm afraid your "figure-of-eight" lost me. What's
that?
'Doc

Reg,
Okay, now I understand what you're talking about.
For a while there, I thought you may have been talkng
to Mr. Moebus...?
'Doc