Hi Mike,
In my opinion, the best material for sleeve baluns is type 73 material, the
same as recommended buy W2DU. The 77 material is like a resistor!
BTW, the balun that WX0B sells I believe is a copy of the W1JR broad band
toroid balun design as originally described in my Ham Radio Magazine,
September 1978 article! Changing the core material to type 43 ferrite will
probably extend it down to 160 meters.
BTW #2, it is the balun used in the Cushcraft R5, R& etc. verticals so it's
had lots of use!
73,
Joe W1JR
At 06:30 PM 7/11/2003 -0700, Michael Tope wrote:
>The type 77 material is notorious for having a poor loss
>tangent, hence the 60 deg phase angle. Type 61 material
>is much better, but the mu is much lower so you need
>bocque beads to get the same series impedance as with
>type 77. One design worth looking at is WX0B's 1:1 balun.
>He winds RG-142 on a large torroid and puts it in a plastic
>box. With this method you get a lot more inductance per
>pound of ferrite as compared to the beads, so you can use
>a lower mu material with better loss characteristics than
>type 77. It would be interesting to measure the choking Z
>of Jay's balun and compare it with one of those type 77
>bead baluns.
>
>73 de Mike, W4EF............................
>
>----- Original Message -----
>From: "Jim Lux" <jimlux@earthlink.net>
>To: "Pete Smith" <n4zr@contesting.com>; <towertalk@contesting.com>
>Sent: Friday, July 11, 2003 3:06 PM
>Subject: Re: [TowerTalk] Balun filler
>
>
> >
> > The beads show a phase angle of 60 odd degrees, implying that the XL is
> > about 1.7 times the R.. .. from that you could calculate the heat
> > dissipated, for a given amount of power incident in the choke. I wonder
> > why the Z is so high below 14 MHz.. Do you happen to know what material it
> > is? Maybe the mu starts to drop off above 14 MHz, so the inductance
>starts
> > to drop, making the resistive losses more significant?
> >
> >
>
>
>
>_______________________________________________
>
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>
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