All,

I don't know if I am grounding my station correctly.

The radials of my 20m vertical are connected to my trailer's electrical
system ground rod. My coax shield is connected both to the radials and
the ground rod. I plug my antenna into the Yaesu and turn it on. I
can hear stations just fine, and I have no problems touching the
chassis. However, the instant I disconnected the antenna but hang onto
the coax, I got a mild shock on both arms if I should momentarily
touch the chassis of the Yaesu. So, I understand I have a problem.

Now I noticed that the Yaesu uses a 2-prong AC cord adapter, which is
"before code" and therefore is unsafe by today's standards. If I
rewrire the AC cord to 3-prong, should that remove the hazard? If so,
what pinout do I use? The FT-101 Shop service manual does not list
where positive, negative, and neutral should be on the Yaesu power
plug.in Figure 1-2.

Thanks,

The Eternal Squire

P.S. I hope I have not long-term defibrillated myself. Should I visit
a hospital for cardiac system damage even if the shock was mild? I now
realize that I probably could have been killed. Right now I have
everything unplugged and disconnected until I can get better advice.

wrote:

All,

I don't know if I am grounding my station correctly.

You should probably connect the rig (chassis/cabinet) to your ground
system somehow. Is there a grounding lug provision on the rear of the
chassis itself?

3-wire cord should do the trick - *IF* your trailer electrical ground is
connected to its frame, etc.

-Bill

On 29 Nov 2005 21:47:59 -0800, wrote:

All,

I don't know if I am grounding my station correctly.

Years ago I had a FT101B try to kill me.

I had the system grounded, but it was a minimal ground. The
transceiver was about 50 feet to the East of the service entrance
ground. The coax tied to a 40 meter vertical out into he west yard
which was about 100 feet to the west of the service entrance. There
was a single ground round and a number of bare #10 radials tied to the
ground rod.

It was spring, the snow had melted and the ground was wet and soggy.
One of the radials had come loose and curled up around the base of the
antenna, so I picked it up, pulled it straight, bent a kink in the end
to stick in the ground. I knelt down to stick that end in the ground.
When my knees touched the wet ground that sucker didn't tickle, it
grabbed me and held on *really* tight.

I fell backwards and when I went over backwards my knees broke
contact. I threw that wire as hard as I could under the circumstances.

I brought out my Simpson 260, stuck one probe in the ground about 6
inches out from the ground rod under the vertical and stuck the other
probe in as far out as I could reach. I measured 90 volts with that
VOM across about 5 or 6 feet of wet top soil.

A close inspection turned up a liberal solder joint at the power
connector on the back of the rig (inside) which under the right
conditions could contact the chassis. The cord was one of the un
polarized type.
It passed plenty of current, but not enough to trip the breaker. (this
was before the days of GFIs)

I removed a bit of solder and never had another problem with the rig.
Actually, I'd like to find another, nice, clean, FT101B to recreate
my old station, but I'll never forget that one.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

The radials of my 20m vertical are connected to my trailer's electrical
system ground rod. My coax shield is connected both to the radials and
the ground rod. I plug my antenna into the Yaesu and turn it on. I
can hear stations just fine, and I have no problems touching the
chassis. However, the instant I disconnected the antenna but hang onto
the coax, I got a mild shock on both arms if I should momentarily
touch the chassis of the Yaesu. So, I understand I have a problem.

Now I noticed that the Yaesu uses a 2-prong AC cord adapter, which is
"before code" and therefore is unsafe by today's standards. If I
rewrire the AC cord to 3-prong, should that remove the hazard? If so,
what pinout do I use? The FT-101 Shop service manual does not list
where positive, negative, and neutral should be on the Yaesu power
plug.in Figure 1-2.

Thanks,

The Eternal Squire

P.S. I hope I have not long-term defibrillated myself. Should I visit
a hospital for cardiac system damage even if the shock was mild? I now
realize that I probably could have been killed. Right now I have
everything unplugged and disconnected until I can get better advice.

wrote:

I don't know if I am grounding my station correctly.

The radials of my 20m vertical are connected to my trailer's electrical
system ground rod. My coax shield is connected both to the radials and
the ground rod. I plug my antenna into the Yaesu and turn it on. I
can hear stations just fine, and I have no problems touching the
chassis. However, the instant I disconnected the antenna but hang onto
the coax, I got a mild shock on both arms if I should momentarily
touch the chassis of the Yaesu. So, I understand I have a problem.

So, DON'T DO THAT.

Now I noticed that the Yaesu uses a 2-prong AC cord adapter, which is
"before code" and therefore is unsafe by today's standards. If I
rewrire the AC cord to 3-prong, should that remove the hazard? If so,
what pinout do I use? The FT-101 Shop service manual does not list
where positive, negative, and neutral should be on the Yaesu power
plug.in Figure 1-2.

A three-prong plug will make the radio safe, but in fact as long as
the radio is plugged into the antenna, it's already safely grounded
by the anntena system. A three-prong plug will make it meet code,
though.

BUT, the real problem is that you have current leaking to chassis, and
your chassis has become hot. Look for an AC line filter or some
ceramic disc capacitors between the AC line and the chassis, used to
keep RF out of the power line (and out of the radio). It will be
leaky. Replace it, even if you think it's good.

P.S. I hope I have not long-term defibrillated myself. Should I visit
a hospital for cardiac system damage even if the shock was mild? I now
realize that I probably could have been killed. Right now I have
everything unplugged and disconnected until I can get better advice.

Keep your left hand in your pocket next time.

The thing about electrical injuries is that there is really nothing doctors
can do. When there is damage due to electrical power, cells become
elongated and the cell membranes break down. As this process continues,
the cell membranes break, the resistance of the tissue drops, and more
and more current flows. All the doctors can see is the surface burn,
they can't tell how bad the tissue damage is. So even in the case of
very serious electrical injury, the normal procedure is basically to wait
and see how much tissue dies. RF burns really terrify doctors, because
they look like serious electrical burns but have little or no actual
tissue damage (due to skin effect). So they look a lot worse than they
really are.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

wrote in message
ups.com...
All,

I

If the radio has bypass caps on the line to chassis, and many do, you can
develop sixty or so volts AC from chassis to ground because the two
caps form a voltage divider. Measure the DC resistance between each
of the power lugs to the chassis, you should see infinite resistance.
Don't relay on the coax shell to provide a safety ground, you're only going
to end up getting knocked on your butt repeatedly when working on the
rig. The best bet is a three wire cord with safety ground.

Pete

This is indeed the case for the FT-101E whose schematic I just
examined. What I did was remove the 2-wire cord, and then connect a
3-wire cord where plus and minus hot were in former locations, then
soldered the neutral wire of the cord to the plug's ground pin. Hope
that would work. The voltage divider effect bears out in the fact that
my original exposure to the AC was not immediately fatal.

I think from now on, I should NEVER operate a rig powered by a 2 wire
cord.... I should always replace with 3-wire on general principles.

The Eternal Squire

wrote:
This is indeed the case for the FT-101E whose schematic I just
examined. What I did was remove the 2-wire cord, and then connect a
3-wire cord where plus and minus hot were in former locations, then
soldered the neutral wire of the cord to the plug's ground pin. Hope
that would work. The voltage divider effect bears out in the fact that
my original exposure to the AC was not immediately fatal.

I think from now on, I should NEVER operate a rig powered by a 2 wire
cord.... I should always replace with 3-wire on general principles.

The Eternal Squire


NO! Don't do that! The hot goes to the + hot, and the neutral goes
to the - hot, and the green wire goes to the chassis.

Never, never, never connect the neutral and the green wire together!
(Did I mention never?)

The only place in the whole house where that is supposed to happen is
in the service panel where the power comes into the house. Everywhere
else, it must remain separate. The bond wire (green) is purely for
safety. It saves your butt when currents accidentally leak out to
the chassis. If you have the bond connected to the neutral side of the
powerline, it can energize the chassis in certain wiring failure modes.

Please don't leave it that way, save some poor soul's bacon, and go back
and fix it correctly.

Thanks,

-Chuck

I believe the important thing here is that a three wire plug be used and
that it gets wired correctly. I will never see why the neutral which is
grounded and green wire which is ground cannot be tied together. The
key here is that the plug can not get reversed like it could with the
two wire plug so getting hot AC on the chassis can never happen. If the
socket is miswired than as soon as you plug in your radio with the green
and neutral tied together your main fuse will blow. I sure would like to
know what certain wiring failure modes could energize the chassis ?
Ground is Ground period. If the original two wire plug would have been
polarized in the very beginning I expect that three wire plug would have
never happened.


Chuck Harris wrote:

wrote:

This is indeed the case for the FT-101E whose schematic I just
examined. What I did was remove the 2-wire cord, and then connect a
3-wire cord where plus and minus hot were in former locations, then
soldered the neutral wire of the cord to the plug's ground pin. Hope
that would work. The voltage divider effect bears out in the fact that
my original exposure to the AC was not immediately fatal.

I think from now on, I should NEVER operate a rig powered by a 2 wire
cord.... I should always replace with 3-wire on general principles.

The Eternal Squire


NO! Don't do that! The hot goes to the + hot, and the neutral goes
to the - hot, and the green wire goes to the chassis.

Never, never, never connect the neutral and the green wire together!
(Did I mention never?)

The only place in the whole house where that is supposed to happen is
in the service panel where the power comes into the house. Everywhere
else, it must remain separate. The bond wire (green) is purely for
safety. It saves your butt when currents accidentally leak out to
the chassis. If you have the bond connected to the neutral side of the
powerline, it can energize the chassis in certain wiring failure modes.

Please don't leave it that way, save some poor soul's bacon, and go back
and fix it correctly.

Thanks,

-Chuck

Ron wrote:


and neutral tied together your main fuse will blow. I sure would like to
know what certain wiring failure modes could energize the chassis ?
Ground is Ground period.

No, not really.
You're thinking like an electrician saying the chassis is energized.
That can happen too in a failure mode but the original poster's gist was
that he got that normal low ma bite that one gets when one creates
different ground points as opposed to a common ground.

The answer here is to tie the grounds together as short as possible. Of
course the OP is going to get a tingle when his rig is 'grounded' only
via the AC with inherent leakage of caps/yadda/yadda versus his external
antenna/trailer ground. Thats normal.

Sorry to belabour but this has been addressed in most every electronic
publication since electricity was 'invented'.

I could ground all my stuff to the hilt but you would have to pay me to
pound a separate ground rod and lick my fingers and put my hand between
the rig and the new rod. Ground ISNT ground unless they are at the same
potential.

If OP wants a no-bite situation he should visualize the ground path via
his coax versus the radio ground via the trailer AC wiring. Until the
two are essentially the same a difference in potential exists.

-Bill

Ron wrote:
I believe the important thing here is that a three wire plug be used and
that it gets wired correctly. I will never see why the neutral which is
grounded and green wire which is ground cannot be tied together. The
key here is that the plug can not get reversed like it could with the
two wire plug so getting hot AC on the chassis can never happen. If the
socket is miswired than as soon as you plug in your radio with the green
and neutral tied together your main fuse will blow. I sure would like to
know what certain wiring failure modes could energize the chassis ?
Ground is Ground period. If the original two wire plug would have been
polarized in the very beginning I expect that three wire plug would have
never happened.



Hi Ron,

You are thinking like a newbie engineer... you haven't yet discovered
multiple failures, and mistakes. If nothing fails, you are right, there
is no harm in tieing the safety ground and neutral together.

But let's first discuss the purpose of the safety ground: It
is there to make it very unlikely that the cases of appliances could ever
become elevated above earth ground. This is to protect a barefooted doofus
from getting electrocuted when he is standing on the cement floor in the
basement, and trys to operate his FT-101E. The *secondary* purpose of the
safety ground is to provide a return that will blow the circuit breaker if
the hot lead accidentally becomes shorted to the case of the FT-101E.

The way the safety ground provides these protections is by being
connected to the centertap of the pole pig (neutral), and to a grounding
rod that sticks into the earth at the house. This connection is done
at the service panel where power service enters the house. The grounding
rod is there to make sure that the safety ground, and thus the cases of
the appliances, stays at the same potential as the cement floor in your
basement.

Back in the old 2 wire days, when the neutral side of the plug wire was
connected to the chassis, and you were expected to turn the plug around
until it didn't tingle, if the cord's neutral wire broke, current would
pass through the appliance's circuitry to the chassis connection, and
as a result the chassis would become hot relative to the earth ground
(Doofus's feet on the concrete slab). Doofus would be pushing up daisies.

Let's move forward to the days of the 3 wire plug, and the safety ground...

Saint Chuck has wired Doofus's FT101E so that the hot lead goes to Hot+,
and the neutral lead goes to Hot-, and the safety ground lead goes to the
chassis:

Doofus, likes to unplug his FT101E whenever he isn't using it, and he likes to
windup the cord to look just like it did when the radio was new-in-the-box.
After doing this for a while, the hot, or neutral lead breaks. Doofus plugs
in his radio, and turns it on, and it doesn't work! So he asks Saint Chuck
to fix his radio, and life marches on. If, on the other hand, it wasn't the
hot, or neutral lead that was broken, but rather it was the safety ground lead,
Doofus wouldn't know it was broken, and would continue to operate, a little
less safe, but still safe, because the radio was wired correctly... and if
somewhere down the path, we added an additional wire to the broken safety
ground, the radio would stop working, but would still be safe.

Now, lets suppose that instead of Saint Chuck wiring Doofus's FT101E, it was
wired by some squire. This squire wired the hot lead to Hot+, and then wired
the neutral lead, safety ground lead, and chassis to Hot-.

Back to Doofus:

Doofus, likes to unplug his FT101E whenever he isn't using it, and he likes to
windup the cord to look just like it did when the radio was new-in-the-box.
After doing this for a while, the neutral lead breaks. Doofus plugs
in his radio, and trys it out, and it works just fine! Doofus continues
operating this way, and eventually, another wire in the cord breaks. If
that wire happens to be the hot lead, the radio will quit, and barefoot
Doofus will take the radio back to the squire for a rewire job. If that wire
happens to be the safety ground lead, the chassis of the FT101E will now be
at full power line potential (current passing from hot lead through the radio's
circuits, to the chassis/hot- connection), and barefoot Doofus will be
pushing up daisies.

The safety ground must NEVER be connected to the neutral at the load!
NEVER!

Be safe, allow for multiple failures, and fix the cord so that the hot lead
goes to hot+, the neutral goes to hot-, and the safety ground lead goes to
the chassis.

-Chuck Harris