[TowerTalk] C4S-XL assembly/tuning tips

[Stan Stockton]

Terry,

I would check the Front to Back with a local from about 6850 to about 
7300 every 25 khz write it down to see where it is best.  Hopefully it 
is reasonably good somewhere.   I don't know where that reflector might 
be resonant with it installed at 70 feet - I presume higher than when it 
is at shoulder height - but you are going to perhaps want that reflector 
to be resonant just below the frequency where you want the F/R to be 
best.  I would think you might see as much as 15 dB difference between 
the best and the worst looking at a steady signal from a local.  If you 
find the F/R is best at 7.000 for example, I would lower that thing and 
shorten the reflector by whatever amount needed to make it resonant 100 
khz higher than it shows to be before the shortening and check it again, 
if you wanted the best F/R to be at 7100, for example.  All this is good 
exercise and fun.

73...Stan, K5GO

----- Original Message ----- 
From: "Terry G. Glagowski" <TGlagowski at SBCglobal.net>
To: <towertalk at contesting.com>
Sent: Thursday, June 23, 2011 9:56 AM
Subject: Re: [TowerTalk] C4S-XL assembly/tuning tips


>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 at warwick.net>
> Subject: Re: [TowerTalk] C4S-XL assembly/tuning tips
> To: "'krishna kanakasapapathi'" <kkanakas at cisco.com>,
> <towertalk at contesting.com>
> Message-ID: <20110613140046.04D58FC40EE at 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 at contesting.com
> [mailto:towertalk-bounces at contesting.com] On Behalf Of krishna
> kanakasapapathi
> Sent: Saturday, June 11, 2011 12:37 PM
> To: towertalk at 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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