On 5/8/2014 6:51 PM, Stuart Rohre wrote:
These types of problems usually indicate that there is RF leaking
> back to any any transceiver he might try, because his antenna is too
> close to the shack ...
An interesting thought, but can we always blame the "antenna being too
close to the shack"?
I bought my Omni VI new in 1994 and have never been able to operate SSB
or PSK31, SSTV or any other mode that required the use of the mic jack.
(Good thing I am 99% a CW and RTTY guy. <grin> ) Anything over about 10
(ten) watts of power seems to cause the problem, utter and complete
distortion of the radiated signal.
The shack is in the basement, the antenna is a 132' long dipole about 25
feet high and fed with ladder (window) line to a Johnson KW Matchbox
tuner. The length of the window line between the Matchbox and the hole
in the wall where it exits the basement is no more than five feet. Yes,
when I measure the RF current in each leg of the window line they are
different -- to be expected as this is not a perfect world and the
dipole is not in free space. The coax cable to the Centurion / Omni VI
has a multiple ferrite bead balun.
After years of unsuccessfully chasing around with ferrite beads and
chokes, I was finally told [by ******] that my dipole was "too close to
the house". Unfortunately, because of the shape of the lot, the location
of trees and zoning/deed restrictions, the antenna HAS to be where it is.
So...problem occurs at around 10 watts of output, the antenna can't be
moved and I don't think I am the only ham in the world using a dipole
close to the house fed with window line.
This leads me to do the unthinkable and to ask about the elephant in the
room. Rather than everyone saying the antenna "is too close to the
house", is it possible that this particular vintage of Omni VI option 3
is just particularly sensitive to RF getting into the mic jack (or other
ports)??? Is this unique to my radio? Do Yaecomwoods suffer from the
same issue?
The reason I ask is that I am getting into PSK31, JT9 and JT65-HF (and
yes, I realize these are "low power" modes), but I wouldn't mind going
up to 20 or 25 watts -- or SSTV at (gasp!)100 watts.
I would appreciate any thoughts or suggestions. New /different radio or
fixing this radio (how?) is OK, but a 100' tower 300' away is just not
an option.
73,
Carter K8VT
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