I have a C4SXL mounted on a TriEx LM470D so I don't have to climb, also I have a
"hanging hinge plate" that keeps the antenna level as the tower tilts over, so I
have tried lots of trial and error tuning adjustments on the 40m elements of the
C4SXL.
When the antenna is about shoulder height and elements kept off the ground with
a wooden chair or other similar item,
I tuned the driven element for about 6900 KHz (with the hairpin removed and the
reflector jumper removed).
I tuned the reflector for 6800 KHz.
Tuning for X=0 and R=??? using an MFJ Antenna Analyzer (269B), ??? being in the
25 ohm vicinity.
I have since replaced the hairpin with a 1:2 balun (25 ohms balanced to 50 ohms
unbalanced) and tuning is easier.
when at 70 feet, SWR is 1:1 at about 7170 and less than 2:1 from 7.0 to 7.25.
QUESTION:
I don't see a lot of front-to-back or front-to-side compared to the 20-15-10
section of the beam...
Do I have the frequency difference between driven element and reflector at the
correct value? Or could something else be wrong?
Maybe it needs to be at 140 feet high to see a good pattern?
Terry / W1TR
------------------------------
Message: 9
Date: Mon, 13 Jun 2011 10:00:43 -0400
From: "John Santillo" <u1004467@warwick.net>
Subject: Re: [TowerTalk] C4S-XL assembly/tuning tips
To: "'krishna kanakasapapathi'" <kkanakas@cisco.com>,
<towertalk@contesting.com>
Message-ID: <20110613140046.04D58FC40EE@dayton.contesting.com>
Content-Type: text/plain; charset="us-ascii"
Krish,
I have the same antenna. I found if I tune it on the ground for 6.9MHz, as
the antenna is raised the tuned frequency increases to 7.1MHz depending on
height above the ground. Your mileage may vary but it's a good place to
start.
73,
John
N2HMM
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of krishna
kanakasapapathi
Sent: Saturday, June 11, 2011 12:37 PM
To: towertalk@contesting.com
Subject: [TowerTalk] C4S-XL assembly/tuning tips
Hello all,
My primary day-to-day use antenna is a 20-6m 3Ele steppir @ 50ft.
I am contemplating on a second antenna at 72 feet for the telescoping tower.
Main goal is for a 2ele 40m. However, having coverage on other
bands is a plus(backup to the primary antenna).
I have a C4S-XL (23ft boom,C3S + 2 linear loaded 40m elements) and
am thinking of installing it perhaps.
The tower is in a tight spot due to the presence of trees around. Hence
cannot
raise the tower with the yagi installed on the ground. Tuning of the 40m
will
need to happen while on the roof. So, any sage advice on how to go about
getting the antenna tuned will help a lot. Tnx for reading.
73s
krish
w4vku
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