I too have the UNSHIELDED Noland Engineering broadband transmitter
aboard "Lionheart". Every cable on the boat's extensive system is
foil shielded twisted pair carefully bonded to a common point. But,
alas, what a noisy mess......Stupid NMEA is useless.

I'm going to put my Noland into a aluminum Budbox with each cable, and
there are many, being bonded to the box where the wire goes into it.
That should shut it up from radiating itself so bad, and it IS bad.

Our other problems with NMEA is the stupid MANUFACTURERS all drifting
off in their own directions, the idiots! NMEA was designed as a
BALANCED LINE standard.....when one wire went positive, the other went
negative, cancelling out any signal intrusion coming in and cancelling
out any radiation going out. Notice NMEA has a + and - wire, NOT + and
GROUND. If everyone used balanced isolators in and out, this would be
fantastic. But, we're BOAT electronics manufacturers trying to outdo
TV manufacturers trying to see who can make the cheapest piece of crap
that floats. Isolators and balanced lines costs pennies per unit more
to produce....what a waste of company profits. Let's just hook the B
(-) lead to CHASSIS GROUND making a hundred ground loops and ground
antennas feeding the SSB RF energy INSIDE the shielded wire. We're a
GPS company. Who cares about RF intrusion, anyways?! We're after
PROFITS with minimal parts counts. Single ended is always cheaper.

So, what happens aboard "Lionheart" is the idiots at Icom used a BNC
connector....AN UNBALANCED BNC ANTENNA JACK to hook coax cable
to....for its GMDSS "GPS Input" from my NMEA system. Right at the
TRANSMITTER I have a huge ground loop attached to the antenna tuner!
Stupid, stupid, stupid.

Then, the idiots at Garmin, geniuses one and all, use all unbalanced,
DC-grounded NMEA single wire I/O grounding the NMEA B (-) points to
ANOTHER DC ground point on the boat with lots of unshielded wire so it
radiates like hell into the HF rig and the HF transmitters 150 Watt
beast just scrambles any data on those wires.

Then, the idiots at Noland Engineering, not the brightest bulbs in the
box, tell me if I want output from the NMEA multiplexer to use WITHOUT
using the computer, I'm gonna have to hook the NMEA A (+) to the
COMPUTER'S RS-232C TX terminal.....not the NMEA TLK balanced output
leads which only run from the computer's RX terminal when the computer
(and The Cap'n) are running. Again, another UNbalanced output feeding
every NMEA input jack on every instrument on the boat....with another
DC ground antenna feeding RF into the shielding by the back door.

The list goes on and on. NOONE ever takes into account this crap will
be working in an RF HOT ENVIRONMENT out there! Every time you key the
transmitter, data ceases to exist and it will all go berserk until you
unkey that transmitter.....

How stupid.....Seatalk - Unbalanced, unshielded.....FastNet -
unbalanced, mostly unshielded.....

They all need to get together and have ONE STANDARD THAT'S BALANCED
AND TOTALLY SHIELDED and ridgidly enforced throughout the stupid
industry!

Don't hold your breath, every boat I work on has the same
troubles.......idiots.



On Sat, 20 Sep 2003 10:11:16 -0500, "Keith"
wrote:

I have a problem that's got me stumped. I am getting NMEA string noise in my
SSB on various channels, starting with 2162.

I have a Garmin GPS that feeds into a Noland Engineering NMEA Expander. The
SSB and three other devices come out. When I turn the power off to the
expander, I lose my GPS signal to all of the devices. When I power it up, I
get the noise in the SSB.

I even hooked the SSB NMEA cable to the input side of the expander, directly
to the GPS signal, and I still get the noise when the expander is turned on.
Thinking the expander was bad, I contacted them, and they sent a new one.
Same problem. I even get the noise in the SSB when the NMEA data cable is
unplugged from it. It has to be coming in either radiated or through the
power supply.

I'm lost... any suggestions?




Larry W4CSC

3600 planes with transponders are burning 8-10 million
gallons of kerosene per hour over the USA. R-12 car air
conditioners are responsible for the ozone hole, right?