I installed a C4-XL a few weeks ago, same basic design as your C4-SXL.
Tuning the 40 meter elements is an interesting affair.
With advice from Natan and Pete Smith N4ZR, I got the linear loading
assemblies constructed and put the antenna in the air. The assembly
manual needs a lot of help in the 40 meter section, to be blunt, it
stinks. The C-3 manual is excellent.
Make sure you have the linear loading wires in the correct
configuration, the manual refers to as "staggered". Initially, I didn't
see what they meant by "staggered" and did it wrong.
At my location I found the 40 meter portion of the antenna to be "very"
sensitive to the ground. Trying to tune it at 10 - 12 feet above the ground
was a waste of time.
You didn't say if you found a dip in the SWR near any band segment on
40. I found the specs given in the manual are approximations. Setting
them to the 7190 suggested point gave me a dip at 7.000 Mhz. Trying to
find the dip at 12 feet above the ground never resulted in anything better
than 3.0 to 1 that you're seeing, it had to go up higher.
Natan suggested that I set the reflector and driver to the measurements in
the manual (as a starting point) and further adjust the driver only. I did
change the suggested reflector setting slightly, but made all subsequent
adjustments on the driver.
At 25 feet the SWR was 2.0 to 1 at 7190. Raising the antenna to 75 feet
dropped the SWR to 1.5 to 1.
Finding the dip was important because it indicated the antenna did load,
but it was being affected by the ground. I made a few adjustments of the
tuning jumpers and the hairpin and got the SWR to 1.5 to 1 at 7190 when
the antenna is at 75 feet, it does stay low across the suggested 130KC
range. The hairpin is spread about 3/4" between the turns.
SWR on the other bands is virtually flat, the front to back is
excellent. The performance on 10 - 15 - 20 is noticeably better than my
25 year old KT-34.
It does work, but the manual is weak when addressing the linear loading
wires and their assembly. A couple of "good" pictures would have saved me
many hours of hunting an pecking..
73,
Gene K5GS
>I am having hard time to lower SWR on 40 mtr band on C4-SXL. I have
>just finished the assembly and found this problem. all ok on 10 - 20
>meter band SWR.
>I used RF choke ( 10 inch dia.) and connected hair-pin coil...SWR shows
>10.
>I removed hair-pin coil....SWR shows 3.
>I did spreading or pushing the coil, but it didn't change at all.
>I rechecked LL assembly, but I couldn't find anything .
>
>I must have made some thing wrong, but I couldn't figure out.
>
>de VE3JOY, Isao Endo
>
|