Tom, we've made these for years under sanction from Walt, W2DU and in
some later configurations by Jack, VE2CV, who did much research after
Walt had pioneered the system. The 73 bead on RG141was first, and now
RG303, since the teflon stands the heat under excessive load much better
than the low temp PVC jackets. There hasn't been a need for the 43 type
on the 3-30 MHz models, since they never had a problem up to 6KW at low
SWR at 1:1 ratio. At 160, 5 - 43's improved the units made to include 160
meters, and 5 - 43's on the output leg of the 4:1 configuration cut down
heating as well. W2DU strongly recommends that the 4:1 model should be
avoided for power greater than 100 watts. We have not received reports of
failure on the 4:1 run under 200 watts. Recently, a number of 160 meter
designs have employed the principle using 100 73's - double the standard
- with excellent success in the 1:1 ratio configuration. Using the larger
beads on RG213 for the same effect is more costly in addition to the
greater thermal risk.
In the last 15-20 years these "baluns" have become more popular than the
voltage types for both dipole and beam configurations.
Press Jones, N8UG
The Wireman, Inc., Landrum, SC 29356
use n8ug@juno.com or (864) 895-4195 for tech help
orders only use 800-727-WIRE(9473) or cqwire@juno.com
http://www.thewireman.com
On Mon, 03 Nov 1997 08:56:50 -0800 "C.T. Morton" <k6ct@earthlink.net>
writes:
>Have question about material for bead balun for 160 and 80m antennas.
>
>I understand that Material 43 is for 30MHZ and up and 77/73 is for
>1.5
>to 30MHZ, I remember reading that some of you use the 43 on the lower
>freq because
>it has better heat dissipation. Now, what do you guys think about a
>bead
>balun with the first 6? beads being 43 and the remainder being 77?
>I have always used type 77 beads, usually 12inches of them on RG213.
>What R ur suggestions?
>73 Tom
>
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