I think you meant to say shorter instead of longer in the second
sentence and then to say you can use one capacitor if the electrical
length of the structure is a quarter wavelength or more?
Kelly - How tall is the tower, what antenna is installed on top and
are the guy wires insulated from the tower?
Sent from Stan's IPhone
On Dec 11, 2010, at 7:49 PM, "Gene Smar" <email@example.com> wrote:
> The two-capacitor matching system is probably the Omega match.
> matching system is typically used on towers that are longer than 1/4
> (electrical) WL. Most of us mere mortals are confined to feeding
> If that is the case, you can most likely use a single capacitor of
> appropriate voltage rating as part of a Gamma matching system. This
> is a
> single large gauge wire (think CATV coax sheath) or a wire cage of
> parallel wires supported off the tower by a couple of feet or even
> more and
> tapped onto the tower somewhere near the top. The capacitor
> (usually a
> transmitting variable but can also be a fixed value, once the proper
> has been obtained) is connected at the bottom of the tower between
> the end
> of the shunt wire/cage and the center of the coax cable. The coax
> shield is
> connected to the tower itself and to the radial system emanating
> from the
> Once you have the wire tapped and capacitor connected, you start
> game of adjusting the cap for minimum SWR, then changing the tap
> point on
> the tower if you can't get the match low enough. This may take a
> few trips
> up and down the tower before you get a decent match.
> You can check out KB9CRY's tower and shunt feed at
> http://nidxa.org/kb9cry_shunt_fed_tower.htm . Mine is pretty
> including the wire cage on PVC supports off the tower.
> 73 de
> Gene Smar AD3F
> ----- Original Message -----
> From: "Kelley" <firstname.lastname@example.org>
> To: <email@example.com>
> Sent: Saturday, December 11, 2010 6:57 PM
> Subject: [TowerTalk] 160m Shunt Feed
>> Multitudes of web pages show, well, multitudes of setups for shunt
>> a tower. Many appear to use a couple of variable capacitors in
>> order to
>> adjust for lowest SWR. Having a limited junk box, what kind of parts
>> should I be looking for to build a generic matching network?
>> TowerTalk mailing list
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