Hi Dave,
> For the past few years, I have been using the BBR 7731 cores for
SNIP
> brand, part number, core material type, etc. Anyone have suggestions?
The core Misek suggests (dc ui~10000) is actually not the correct core for
160 anyway. Ui values should be picked at the lowest operating frequency,
never at dc! The dc ui 10, 000 core has less permeability on 160 meters
than the following core materials:
77 ui 1800, 73 ui 800, 43 ui 900.
All of these materials are suitable for broadband transformers. They have
better RF performance and are more common. If you select a 73 or 43
material, you can use about 40% less turns on the transformer (even fewer
with the 77 core) for the same stack length. Fewer turns reduces unwanted
coupling from primary to secondary, and they saturate at high signal
levels. They also work much better at higher frequencies, making the
Beverage very useful on 7 MHz and higher.
Ameritron has a binocular core 412-5250 (73 mix) for $.60 each. A two turn
primary is more than enough for 50 ohms at 160 meters, and the core
saturates at about 30 watts. Alternately, a stack of FB73-601 beads can be
substituted. I did use beads, but now switched to the free (eerrr $.60)
412-5250 cores. I use #24 wire, and have yet to lose a core during
lightning despite losing dozens of two watt resistors on my 11 Beverages.
Alan Bond (770) 973-6251 (before 9 pm eastern time) e-mail mgs@avana.net
has a large 43 material core (about 1" OD by 1" tall) that would make a
killer transformer or feedline choke core.
73 Tom
--
FAQ on WWW: http://www.contesting.com/topband.html
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Problems: owner-topband@contesting.com
|