On Thu, 22 Jan 2004 06:00:09 -0600, "Keith"
wrote:

Well, now that my SSB is up and running, I have one more minor problem ( I
think). Whenever I key up the mike to talk, some of the electronics go nuts,
like the Link 20 (near the grounding foil), the VHF goes blank and one of
those "touch" 110 lamps goes on and off. The radio tech that got me up and
running said these were symptoms of reflected power.

You need a new radio tech who WASN'T a CBer. These are symptoms of
RADIATING RF ENERGY out a tuned antenna.....in an RF transparent,
unshielded, plastic boat! The RF energy from the backstay or whatever
you're tuning for an antenna, passes THROUGH everything on the boat
and will wreak havoc with everything that is A) solid state
electronics and B) unshielded, like marine electronics crap with bare
wires marked NMEA + to ground in an unshielded plastic box,
themselves. Damned digital circuitry goes CRAZY...BERSERK when a
good, strong RF field just overruns the data stream, gets rectified by
a zillion tiny transistor junctions into DC bias that screws
everything. My ham station (1500W PEP) nearly blew the neighbor's big
stereo speakers clean out of the cabinet when my RF induced serious
signals into his speaker wires and fed it into the 800 watt power
amplifiers.

Hams know better than to buy touch lamps......

The VHF makes me think its antenna coaxial cable may have a broken
shield connection or, worse yet, has a resonant ground connection to
it. 1/4 of a wavelength back from your ground plate, and every odd
multiple of 1/4 wavelength back from your ground plate is a HIGH
VOLTAGE RF lobe caused by the ground wire acting like an antenna. If
you're so lucky as to have just the right length, 1/4 wavelength from
the groundplate where the RADIO is attached, the RF on the "ground" of
the VHF radio will drive it nuts. RF is blasting away on the OUTSIDE
of the VHF coax cable, every time the HF keys up. If the radio is
near just the right 1/4 wave point from its ground plate (or the DC
power wiring is near 1/4 wavelength to the HF frequency, the whole
thing will be RF "hot" and may do anything. Try disconnecting any
grounds (except battery - of course) you may have attached to it and
see how it does. Pull on those PL-259 coax connectors to see if the
shield braid is firmly attached to them, too.

The link is easy to fix. Run FOIL SHIELDED, multiconductor cable
between the Link and its big shunt and battery connections to keep the
unshielded wires you probably have now from acting like a big HF
antenna to receive the SSB transmitter and feed it to the Link's
damned computer chips. EVERYTHING on the boat needs foil shielded
signal/data wiring. Connect the foil shield to the ground or battery
negative post on the Link. Leave the other end foil and drain wire,
where it comes up to the battery connections, UNCONNECTED. This makes
a Faraday Shield, named after Michael Faraday (discoverer of
capacitance). This unconnected shield encasing the control wiring
keeps the RF OUTSIDE the cable from coupling to the wires INSIDE the
shield feeding the computer circuits.

I'm using a 23' digital
antenna, and seem to be transmitting well. Is there anything I can do about
this, or should I even be worried about it?


Digital antenna? It transmits DATA instead of RF??!....????????

What does this antenna look like and how far is it located from the
scrambled electronics. Lionheart's AT-140 antenna tuner sits on top
of the aft cabin right behind the cockpit-mounted mizzen mast. The
insulated backstay's tension screwjack bolts to the fiberglass next to
it and the tuner has a 8" stainless steel wire connecting to a
hoseclamp around the jack. The whole cockpit is RF hot because it's a
couple of feet from the main antenna.....(sigh).


Larry W4CSC

Is it just me or did the US and UK just capture 1/3
of the world's sweetest oil supply? What idiot wants to
GIVE IT BACK?!!
Let's do what Europeans have been doing for centuries.
DIVIDE UP THE SPOILS OF OUR CONQUEST! Gas will be
$US0.50/US gallon again, STUPIDS!