Topband: FERRITE BEADS

[Milt Jensen, N5IA]

----- Original Message ----- 
From: "Tom Rauch" <w8ji at contesting.com>
To: <w0vd at sofnet.com>; <Topband at contesting.com>; "Earl W Cunningham"
<k6se at juno.com>
Sent: Friday, December 19, 2003 2:46 PM
Subject: Re: Topband: FERRITE BEADS

SNIP

> The cheapest way to make a good balun is still an air core winding of
coax,
> assuming you have the room and weight isn't a problem. If you want to save
> space or weight, something like a 65 material with multiple turns is the
> next choice.

SNIP

> 73 Tom

My solution, relatively inexpensive but quite time consuming at the lower
frequency bands, is to use 1/4 WL open sleeve baluns.  I use these on 70 CM
and 2 M directionals in quantity on our VHF and UHF mountaintop systems.  I
have constructed them to use on 10 M and 6 M vertical wire dipoles used by
our mountaintop remote controlled base stations.  I use one on the 20 Meter
monobander as well as the 40 Meter monobander and the 80 Meter dipole her at
the home QTH.  AND I have one constructed for use with a portable 160 Meter
dipole that I carry around to temporarily string from tall towers.

I strip the 95% braid from older RG-8 or RG-11 and sleeve it over the
feedline for a 1/4 WL and solder it to the braid of the coax at that point.
The sleeve is open at the feedpoint end of the coax.  I typically cover the
entire length of the braid with black tape after sealing the two ends with
silicone.

I must admit that the 160 M model was quite a chore.  Sleeving 125' of braid
over the feedline and then taping it all down is NOT a single night project.
However, the results are superb.  No additional losses from extra length of
coiled coax or a heavy coil to hang somewhere.  No beads to heat or worry
about.  I certainly don't own the patent for the design but I suppose I have
constructed a hundred or so of these over the past 25 years.  Never a
failure and 100% performance.

Happy holidays de Milt, N5IA