Good morning, Mike.
Thanks for the opportunity to respond to your Tower Reflector comments.
Two important subjects here:
* One is the UPS situation on your boom.
* The other is the 40 mtr portion of the antenna and the process to
follow should be useful for anyone putting up various antennas where strange
The boom was replaced as quickly as possible, after a very difficult time
with UPS. As we told you on the day it was shipped, we sent it to you
without any authorization from UPS of replacement value, nor UPS covering
the next day air shipping expense. To date, we have received nothing from
them, not even a promise, so the entire expense is out of this company.
The pictures you sent via e-mail were viewed, after checking for viruses.
This took some time, as this system is not set up to do that. The photos are
from such a distance that there is nothing useful that can be seen. They are
apparently scanned photos and are also very grainy. I used some graphics
software to enhance them, but met with little success.
The comment about the 40 mtr being properly resonant on the ground and then
moving to 4.26 MHz in the air indicates there is something dramatic
happening that is out of the ordinary. This is the first you have mentioned
this to us, so let's go through a logical process.
Most important to know is that the 40 mtr elements are not possible to
resonate at 4.26 MHz. The bottom of their tuning range is about 6.850
MHz. So, when you see the antenna "resonance" moving down to 4.26 MHz,
it indicates something major (external to the antenna) is coming into play.
Also, common sense will tell us initially that even if the 40 mtr driver
location is off by yards, it will not cause such a situation as this.
To trouble shoot this problem, let's go through this process:
A) Helpful to understand what "on the ground" means. Does this mean the
tower is down, or the antenna is a few feet off the ground?
A1) If it means the tower is cranked down, then the most the 40
mtr will shift is 10-20 kHz to its final height. This is an
upward shift, not downward.
A2) If it means a few feet off the ground, this is not an
acceptable height for tuning a 40 mtr antenna and is covered
in the manual. However, even in this case, the 40 mtr will
not shift downward to 4 MHz, even if this is the case,
without something else being involved.
B) Since we know the issue is a dramatic downward shift, out of the
possible tuning range of the 40 mtr elements, something else is
happening. We know this because of two reasons:
1) The apparent resonant frequency when the tower is up is
so far removed from the possible range of the 40 mtr
elements as to not be possible without an external
2) The shift is downward, whereas an antenna will normally
shift upwards as the tower is raised.
From several years of working through "strange occurances", things
that I have seen more than once before are (not in any particular
B1) Does the feedline possibly have a worn jacket and coming
into contact with the tower when it is up?
B2) Is the antenna selector on the right antenna?
B3) Is the antenna (40 mtr) coming into contact with anything
when it is up?
B4) Is the antenna (40 mtr) coming into close proximity with
something conductive when it is up?
B5) Does the apparent resonant frequency (and VSWR) vary as the
antenna is rotated?
B6) Is there another antenna on the tower, such as a wire
antenna, that is not up unless the tower is up?
OK, that should do it. My apology for being out of the office a couple days
this week. Some kind of cold/flu bug has been going around and got to me. I
have been coming in anyway for short periods in the morning to not get too
far behind on all the e-mail.
Hope you have an enjoyable Holiday Season and a terrific New Year!
Have a good day and 73,
Force 12 Antennas and Systems
(Home Page http://www.QTH.com/force12 )
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