SSB reflected power?

[Keith]

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. 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?

 

[Vito]

Yes. I'd start by putting a few clamp-around ferrites on the coax at both
the antenna and radio and on the power line where it enters the radio. If
that don't work ....
Good luck.

..... Is there anything I can do about this, or should I even be worried

about it?

 

[Larry]

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. 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?

That's typically caused by reflected power. You can check with an SWR
meter. If it's high, you'll need an antenna tuner connected to the output
of your transceiver.

 

[Bruce in Alaska]

The radio tech that got me up and
running said these were symptoms of reflected power. 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?

And you let this "tech" walk off the boat before he fixed the radio
installation, why????

What is a 23' "Digital" antenna?????

What you have is a very high impedance "Ground System" and maybe
a nonresonant antenna. First off, 23 feet of antenna is marginal for any
frequency below 12 Mhz. Does you HF installation include an Antenna
Tuner? If so, is it tuning the antenna, and how do you know this?
Again, why did you let the guy leave before he fixed the antenna
problems? How much power is the transmitter puting out? Does the
Mic burn your hand when your transmitting?

Gives us more information, and maybe we can help you out.

Bruce in alaska

 

[Dennis Gibbons]

As I was told by a local radio pro, "Welcome to the world of HF".

I installed ferrites and line isolators and still all kinds of weird shit
happens when I broadcast. Unless you want to get into Faraday Cages etc, it
is just something you learn to live with.

 

[Gary Schafer]

www.digitalantenna.com

The VHF digitals got great reviews in PC a few years ago. I suspect
the SSB antennas are high quality as well.

Doug, k3qt
s/v Callista

Everybody tries to cash in on the word "digital" like it is some kind
of magic. Kind of deceptive if you ask me. Even if it is only their
name.

I see on their web site that they have discovered some new laws of
physics!
A 24 foot HF antenna that has an swr of less than 2:1 over the entire
2-30 mhz range when used with a tuner. Isn't that amazing!

Likewise with their VHF antenna they have discovered a new ground
system that lowers the radiation angle of their 6 db antenna to make
it more efficient than others. Just amazing!

I wonder if it is digitally encoded to perform those miracles.

Regards
Gary

 

[Gary Schafer]

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. 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?

Kieth,

It sounds more like symptoms of installer tech bullshit than anything
else. I have to agree with Bruce, it sounds like you have a poor
ground system. SWR does not cause RF to be all over the place. RF on
the outside of your coax will cause some of your symptoms. RF on the
outside of your coax is not caused by swr but is caused by a poor
ground system.

If you have an automatic antenna tuner and it is working properly
there shouldn't be any high swr on the coax line to the radio. Did he
check?

Where is the tuner mounted and how long is the ground foil from the
tuner to ground?

Regards
Gary

 

[Harry Krause]

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!

Do you really believe what you posted here, Larry, or is it just another
of your booze-induced meanderings into psychosis?

 

[Short Wave Sportfishing]

Everybody tries to cash in on the word "digital" like it is some kind
of magic. Kind of deceptive if you ask me. Even if it is only their
name.

I see on their web site that they have discovered some new laws of
physics!
A 24 foot HF antenna that has an swr of less than 2:1 over the entire
2-30 mhz range when used with a tuner. Isn't that amazing!

Likewise with their VHF antenna they have discovered a new ground
system that lowers the radiation angle of their 6 db antenna to make
it more efficient than others. Just amazing!

I wonder if it is digitally encoded to perform those miracles.

I remember back when ICOM marketed an "automatic" tuner for long wires
when I first retired and was working part-time at the ARRL as an
Assistant Tech Editor. The ARRL lab purchased one and had it xrayed
at a local orthopods office - turns out it was a really big dummy load
that you could attach a piece of wire to. ;>)

Today, I imagine it would be called a digital tuner. ;>)

Later,

Tom
S. Woodstock, CT
----------
"The wildness and adventure that are in
fishing still recommend it to me."

Henry David Thoreau
"Walden" (1854)

 

[Short Wave Sportfishing]

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. 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?

If it's a symptom of reflected power, then why didn't he check for it
and correct it?

Do you have an SWR meter and know how to use it? Does the radio have
a automatic tuner? Do you have good grounds? These are all things
the "tech" should have checked for you if he knew what he was doing.

It does sound like you are radiating all over the neighborhood - there
are some things you can do to cure the problem if you are comfortable
with the technical side of things. Check the grounds on the radio and
the antenna and make sure they are good (clean connections, good
connections, etc.), make sure the antenna is placed as far away from
the radio as practical, the antenna lead is not frayed or possibly
broken internally (you can use an ohm meter to check for that -
continuity), make sure the lead is long and routed properly, just
those kind of common sense things.

If that doesn't cure the problem, then it's ferrite beads, clamp on
chokes, antenna trimming - stuff a tech SHOULD be able to do.

Later,

Tom
S. Woodstock, CT
----------
"The wildness and adventure that are in
fishing still recommend it to me."

Henry David Thoreau
"Walden" (1854)

 

[Keith]

OK, more details on the system. Icom 802 going to the AT-140 automatic
antenna tuner. Yes, the tuner is working, you can hear the relays clicking
when you press the "tune" button or transmit. The antenna (made by the
Digital company... I should have specified!) is on the flying bridge, as is
the tuner. The tuner is about 3' from the antenna. The antenna is right
behind and above the pilothouse. The base is maybe 10' from the wheel and
electronics, etc.

2" copper foil runs from the radio to the antenna tuner, and splits off
about midway and goes to the bilge, where it's connected to a dynaplate. I
plan to add some more foil and connect the fuel tanks and run some radials
down there as well. Lets see: the run from the radio to the antenna tuner is
about 25', and the run from that one to the dynaplate is about 10'.

No, we didn't check the SWR. I wanted to add more foil and some ferrite
cores to see how this helps out. I wanted to do the things I can do rather
than pay the tech all those $$$ for basically grunt work. I can call him
back out whenever.

No, my hand doesn't burn when transmitting! ;-)

Yes, I believe the VHF cable needs replacing. It's old and probably cracked
somewhere along the line. The Link 20 DOES have the sheilded cabling as
Larry described, but the ground foil runs right alongside in the same chase.
I don't think I connected the sheild to ground though... I'll fix that.

--


Keith
__
Money can't buy happiness, but it sure makes misery easier to live
with.

 

[Gary Schafer]

An antenna tuner does not belong on the bridge! That is the worst
place for it.

The first thing I would do is to get that tech back and make him put
the tuner where it belongs, In the bilge! Right next to the ground.
You must have a very short ground lead. The length you have now comes
no where near being ground. You might get away with it on 2 Mhz but
not anything higher.

Mount the antenna down near the deck if you have to. Keep the antenna
as far away from other electronics AND wiring as you can.

It will not hurt to have a long antenna lead from the tuner to the
antenna as long as it is in the clear and away from other wires.
Remember that the antenna lead IS part of the antenna, just as much as
the whip is.

The most important thing is to have a SHORT ground lead. Right now
your ground lead is acting as part of your antenna and coupling into
all the other wiring. Especially your LINK system with the leads right
next to the ground lead. (which in your case is part of the antenna)!!

Once you have the proper ground then it is a much easier job to start
to eliminate RF being picked up directly from the antenna. The problem
now is that it is probably being picked up from both the ground lead
and the antenna. It is very difficult to deal with both.

Once a lead leaves the ground connection (connection at the dynaplate)
then the rest becomes antenna. It doesn't matter what side of the
tuner it is on.

Remember "if it isn't ground then it is antenna".

Regards
Gary

 

[Bruce in Alaska]

OK, more details on the system. Icom 802 going to the AT-140 automatic
antenna tuner. Yes, the tuner is working, you can hear the relays clicking
when you press the "tune" button or transmit. The antenna (made by the
Digital company... I should have specified!) is on the flying bridge, as is
the tuner. The tuner is about 3' from the antenna. The antenna is right
behind and above the pilothouse. The base is maybe 10' from the wheel and
electronics, etc.

2" copper foil runs from the radio to the antenna tuner, and splits off
about midway and goes to the bilge, where it's connected to a dynaplate. I
plan to add some more foil and connect the fuel tanks and run some radials
down there as well. Lets see: the run from the radio to the antenna tuner is
about 25', and the run from that one to the dynaplate is about 10'.

No, we didn't check the SWR. I wanted to add more foil and some ferrite
cores to see how this helps out. I wanted to do the things I can do rather
than pay the tech all those $$$ for basically grunt work. I can call him
back out whenever.

No, my hand doesn't burn when transmitting! ;-)

Yes, I believe the VHF cable needs replacing. It's old and probably cracked
somewhere along the line. The Link 20 DOES have the sheilded cabling as
Larry described, but the ground foil runs right alongside in the same chase.
I don't think I connected the sheild to ground though... I'll fix that.

Well Keith,
Sounds like the rest of the folks have chimed in on your problems, and
nailed down the fixes. I really like Gary's comments, as he seems to
have a good handle on what is going on. Larry is ok for some things,
but Larry, 100 watts will certainly burn you from the grounded Micholder
button on the mic during transmit, If the ground system isn't good
enough to support the antenna at the freuqency of transmission. The
Radio Ground becomes part of the antenna, and you then also become part
of the antenna, and if you are lower impedance than the ground system
you get the Rf Current instead of the Ground system. It happens, not
alot but it does happen, less now with autotuners, but it still happens.

Keith, you need to get a new Marine Radio Service Tech! One who actually
has been around since BEFORE autotuners existed. The guy you had was an
idiot, and needs to go back and get a refund on his training. You should
also get a refund on anything you paid him, BIGTIME. I know that
COMPITANT Marine Radio Service Tech's are hard to come by, as most have
left the field because there just ins't any money in the Service end of
the business anymore, but look around some more and find one.


Bruce in alaska

 

[Gary Schafer]

It will probably make a big difference if you have a crappy ground to
start with.
If you have a half decent ground you should not notice any difference.

A long trailing wire in the sea is nothing more than a false ego trip.
After the first couple of feet in the water the rest does nothing for
the radio. It may make the operator feel more powerful though.

Regards
Gary

 

[Gary Schafer]

And what makes you think that the long ground lead(s) are not part of
the antenna system?
What is going to keep them from coupling into other wires on the boat?

That long ground lead is just as much an antenna on one side of the
tuner as the hot wire connected on the other side of the tuner is.

Keeping the ground side of the tuner above ground lets the coax and
the tuner control cable also become part of the antenna.

Regards
Gary

 

[Vito]

"Ground" is a relative thing in RF. You don't even need a "ground"
ground. What you need is a slightly longer than 1/4 wavelength radial
system from the tuner laid out flat.

Or a dipole.

Nope....doesn't wash. The tuner needs to be as close to the antenna
as possible and the antenna needs to be as far away from any other
metal objects as you can get it. .... Go visit any Navy ship ....

See "Shipboard Antennas", Library of Congress #86-70448, especially the
AS-1867 in fig 2-33 on p105.

 

[Gary Schafer]

Or a dipole.

See "Shipboard Antennas", Library of Congress #86-70448, especially the
AS-1867 in fig 2-33 on p105.

Maybe you could tell us what it says, provided it is relevant to
yachts. :>)

Regards
Gary

 

[Vito]

Maybe you could tell us what it says, provided it is relevant to yachts. :>)

Shows the "tuner" directly attached to the antennae

 

[Vito]

I'd go to a dipole in a second if I could figure out a practical
way of implementing it on my boat. Eliminates the whole counterpoise
issue.

Has anybody tried center feeding an insulated backstay - eg using it as a
dipole, perhaps with loading coils or traps - or insulating and top feeding
one or more pairs of shrouds to yield inverted Vs?
73, K3DWW

 

[Gary Schafer]

Shows the "tuner" directly attached to the antennae

And where is the ground located? Directly under the tuner?

Regards
Gary