[SixClub] db 212

[Chris Boone]

A DB212 is a single dipole on lowband...the DB224 is a 4 dipole VHF Highband
version...the DB212 uses a -x to denote the number of dipoles...so a
DB212-2,-3,-4, etc means how many dipoles in the array......on 2mtrs a 224
is 20ft tall on its mast no matter how they are mounted (they are spaced
1/2wl tip to tip); a DB212-4 on lowband is 60-80ft tall depending on
frequency and must be side mounted on a tower because of their size, etc.

The conventional 4 dipole array you find in Handbooks, etc usually uses
75ohm coax in the harness BUT you can use 50ohm coax if cut right BUT the DB
folded monopole dipoles are cut shorter than 1/2wl to allow them to resonate
lower in freq (the 468/length will give you a freq 10MHz higher than it
actually is cut for) and the VB83 coax they use is not 75 or 50ohm coax
(can't recall off the top of my head what impedance it IS). The DB design is
not the same as the conventional model you see in books.

Chris
WB5ITT
ARRL TS/Lifer as well :)

-----Original Message-----
From: sixclub-bounces at mailman.qth.net
[mailto:sixclub-bounces at mailman.qth.net] On Behalf Of Roger (K8RI)
Sent: Tuesday, August 05, 2008 8:37 PM
To: World Wide Six Meter Club
Subject: Re: [SixClub] db 212


Is that an array of 4, or a single folded dipole?  4 of those on 
2-meters makes for a big antenna unless they are mounted in pairs with 
each pair 90 degrees to the other.   4 take a phasing/matching harness 
of 90 ohm coax (believe it's 90).

These are easy to make out of copper pipe, or were until it became so 
valuable.

Roger (K8RI - ARRL Life Member)
www.rogerhalstead.com
N833R (World's oldest Debonair)