Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Cushcraft 17B2 Uni-match "black box"  (Read 736 times)
W4GRW
Member

Posts: 11




Ignore
« on: July 25, 2002, 06:54:46 PM »

I have a Cushcraft 17B2 2 meter boomer, that fell because of high winds during a hard storm.
There is a "black box" balun/match that was damaged.
Has anyone had any experience with replacing these with regular baluns? Cushcraft wants $65 for the replacement & I hate to pay that if not necessary.
any suggestions, ideas or comment are appreciated.
73 de W4GRW
wvfisher@earthlink.net  
Logged
WB2WIK
Member

Posts: 20543




Ignore
« Reply #1 on: July 26, 2002, 06:56:02 AM »

How damaged was it?  Unless it was completely shattered, I'd think it should still work, as the box contains a 1/2-wave balun and connectors, and nothing else.

The 17B2 uses a conventional "T" match.  The balun's 1/2-wave of coaxial cable, which for 144 MHz is 27" long assuming cable with solid dielectric having a Vf = 0.66.  The center conductor of each end of the 27" long coaxial balun goes to each side of the "T" match.  The main transmission line (to the station) center conductor goes to either side of the "T" match, where it joins the center conductor of one end of the balun.  All three shields (the braids of each end of the balun, and the braid of the main feedline) are tied together and grounded to the boom, directly under the "T" match.

The "black box" is merely a convenient place to mount this stuff and provide connectors, rather than exposed wires, to make the connections.  If you make your own balun, keep connections short and secure, and weatherproof with good outdoor sealant, you'll have the same thing.

WB2WIK/6
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!