[TowerTalk] OCF Dipole

Jim Jarvis jimjarvis at optonline.net
Wed Oct 31 11:33:10 EST 2007


Scott (wu2x) wrote:

It is not necessarily true that a tuner will be required, except for
on the 15 meter band. I am personally running the Buckmaster OCF
dipole, which they claim uses a 6:1 balun of a non-descript type. I
believe it is of the voltage type. You can read my detailed review on
eham about it. I am happy with it.

-0-

Scott:

6:1 is what Belgrave (ve2cv) specified.

It is true that there are solutions which won't require a tuner, you are
Absolutely right.  An 80m OCF dipole will work on 80, 40, 20, 10, and
provide some reasonable VSWR bandwidth, if fed with coax which is a half
wave multiple at 80m.

As you say, it's a bad match on 15.  But it's also not great on 17, or 12 or
30m.

A 160M OCF dipole gives you resonances every 1.8MHz, and does better on 15
and the WARC bands.  Unfortunately, I don't have room for one here.

However, if you want a 'go everywhere, do everything' antenna...you'll want
a tuner with an OCF.

The minute you get out on the edges of the vswr curve, or use a non-resonant
length (including VF) of coax, you have no idea what you'll see in the
shack.  And trust me, feeding 1500w into one, if you haven't taken great
pains to tame the common mode current on the outside of the coax, will prove
an exciting experience.

Been there, done that, and wore out the Tee Shirt!

Jim/N2EA




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