[TowerTalk] Testing C-3 near ground

[Robert Harmon]

Al,

I have tried what Tom suggests with a 10 meter yagi and it worked pretty well.  

I have a Force 12 C3 also and I mounted mine 12 feet above the ground for testing as you described.  Tom Schiller 
suggests this method in his C3 manual.   If you try this method for testing the resonant frequency will be about 25Khz lower in frequency 
than when it is raised up and mounted on the tower.  Keep the wire length from the balun to the attachment point at 2 1/2" or less.  If you don't
the resonant frequency on the 20M driver will be lower than it should be and you will be thinking of shortening the driver tips.  I made this mistake and 
fiddled with changing the driver tip lengths and everything was off.   Finally was reading the manual about the do not exceed 2 1/2" length and discovered 
mine were about 5" long  :-(    so I shortened them to 2 1/2" and put the driver tips back where they were originally and then everything fell into place.  
I am planning on lowering my C3 down and doing a complete cleaning and overhaul myself.   Great antenna.  Good luck on your install !

73,
Bob
K6UJ






> On Sep 1, 2020, at 8:10 PM, Tom Osborne Sr. <w7why1 at gmail.com> wrote:
> 
> Hi Al
> 
> What I have done is mount the beam so that the reflector is close to the
> ground and pointing upwards if possible.  Can get pretty good readings that
> way.  73
> Tom W7WHY
> 
> 
> 
> On Tue, Sep 1, 2020 at 7:57 PM Al Kozakiewicz <akozak at hourglass.com> wrote:
> 
>> I'm refurbishing an old F12 C-3 that is currently disassembled, and looks
>> like it has been for at least a decade.  The tower it is going on isn't
>> here yet and won't be for a few weeks.
>> 
>> I'd like to assemble and do some testing before I put it up sufficient to
>> make sure I don't have any bad joints or assembly mistakes. Having both an
>> analyzer and a VNA, what, if anything, can I do while it is in the
>> proximity of the ground?  I'll be doing the assembly work on sawhorses, but
>> I could mount it on a 10' mast supported by a ladder after it is together
>> for testing. I don't expect to make meaningful VSWR or bandwidth
>> measurements, but since the 15 and 10 meter elements are fed parasitically,
>> it would be comforting to know that there aren't any major issues before I
>> put it up for real.
>> 
>> Al
>> AB2ZY
>> 
>> 
> _______________________________________________
> 
> 
> 
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk