Jim Lux wrote:
Mike Coslo wrote:
wrote:

Sure, there are losses with the balun used in most tuners, but I
consider that a price to pay for a multi band antenna.


Chiming in late on this one...


Mythical attributes aside, I believe the real reason that ladder line
has become more popular is:

1. Almost all rigs are All HF band these days.

2. Many people have just one antenna they can put up at any given
time. Whether it is space considerations, maintaining a low profile
or keeping the XYL happy I remember the discussions with my wife when
I wanted to put up the HF vertical. "Why do you need two antennas?"
"Are you going to transmit two signals at the same time?". Twasn't
easy, and a lot of Hams might lose that argument.

So assuming it is a doublet, and I wanted to run 80 to 10 meters, I'd
put up much wire as I could, not mess with coax, just run ladder line
to a window panel, then into the house, into a tuner that can handle
balanced line. And pay attention to the lengths that might make for
trouble in matching.


Or, put up as much wire as you can, put an autotuner at the feedpoint,
and run coax back to the shack.

probably a six of one, half dozen of the other, depending on what you
already have, what kind of support structures you have (if you are
putting up an inverted V, then supporting the weight of the tuner isn't
an issue..), etc.


Speaking of autotuners, I just got my MFJ933, and have been working
with it this last week. MFJ has an interesting reputation, but I have to
say they pretty much got this one right. For $224, it is one impressive
piece of hardware/programming.

I run my window line directly to the tuner, which was a big selling
point. NOt many other auto tuners have that feature.

Construction was quite acceptable, performance has been fine so far, and
appearance good with only one exception. One of the front panel's
letters had a little rub mark on it. No biggie, just cleaned it with an
eraser.

The analog meter is a little small, but the whole unit would have to be
made bigger to put in a larger one, so that was a tradeoff. It also has
the digital readout, so I find myself looking at the analog meter for
initial reference on a frequency, then at the readout after that. It has
a lot of other features that I'm still learning.

I give the unit an A, at least on my experience so far.

- 73 de Mike N3LI

Michael Coslo wrote in news:h1geb3$do4i$1
@tr22n12.aset.psu.edu:

MFJ933

???

On Jun 19, 11:28�am, Michael Coslo wrote:
Jim Lux wrote:
Mike Coslo wrote:
wrote:

Sure, there are losses with the balun used in most tuners, but I
consider that a price to pay for a multi band antenna.

Chiming in late on this one...

Mythical attributes aside, I believe the real reason that ladder line
has become more popular is:

1. Almost all rigs are All HF band these days.

2. Many people have just one antenna they can put up at any given
time. Whether it is space considerations, �maintaining a low profile
or keeping the XYL happy I remember the discussions with my wife when
I wanted to put up the HF vertical. "Why do you need two antennas?"
"Are you going to transmit two signals at the same time?". Twasn't
easy, and a lot of Hams might lose that argument.

So assuming it is a doublet, and I wanted to run 80 to 10 meters, I'd
put up much wire as I could, not mess with coax, just run ladder line
to a window panel, then into the house, into a tuner that can handle
balanced line. And pay attention to the lengths that might make for
trouble in matching.

Or, put up as much wire as you can, put an autotuner at the feedpoint,
and run coax back to the shack.

probably a six of one, half dozen of the other, depending on what you
already have, what kind of support structures you have (if you are
putting up an inverted V, then supporting the weight of the tuner isn't
an issue..), etc.

Speaking of autotuners, �I just got my MFJ933, and have been working
with it this last week. MFJ has an interesting reputation, but I have to
say they pretty much got this one right. For $224, it is one impressive
piece of hardware/programming.

I run my window line directly to the tuner, which was a big selling
point. NOt many other auto tuners have that feature.

Construction was quite acceptable, performance has been fine so far, and
appearance good with only one exception. One of the front panel's
letters had a little rub mark on it. No biggie, just cleaned it with an
eraser.

The analog meter is a little small, but the whole unit would have to be
made bigger to put in a larger one, so that was a tradeoff. It also has
the digital readout, so I find myself looking at the analog meter for
initial reference on a frequency, then at the readout after that. It has
a lot of other features that I'm still learning.

I give the unit an A, at least on my experience so far.

� � � � - 73 de Mike N3LI- Hide quoted text -

- Show quoted text -

The MFJ-933 is a manual loop tuner according to their catalog. Which
ever one you are using sounds nice, and is worth a look, but I don't
think it is a MFJ-933.

Gary N4AST

Dear N3LI: Might the MFJ model be 993?

73, MAc N8TT

--
J. McLaughlin; Michigan, USA
Home:

"Michael Coslo" wrote in message
...


Speaking of autotuners, I just got my MFJ933, and have been working with
it this last week. MFJ has an interesting reputation, but I have to say
they pretty much got this one right. For $224, it is one impressive piece
of hardware/programming.

I run my window line directly to the tuner, which was a big selling point.
NOt many other auto tuners have that feature.

Construction was quite acceptable, performance has been fine so far, and
appearance good with only one exception. One of the front panel's letters
had a little rub mark on it. No biggie, just cleaned it with an eraser.

The analog meter is a little small, but the whole unit would have to be
made bigger to put in a larger one, so that was a tradeoff. It also has
the digital readout, so I find myself looking at the analog meter for
initial reference on a frequency, then at the readout after that. It has a
lot of other features that I'm still learning.

I give the unit an A, at least on my experience so far.

- 73 de Mike N3LI

J. Mc Laughlin wrote:
Dear N3LI: Might the MFJ model be 993?


Sorry, Germs, I typo'd. It is indeed a 993.

- 73 de Mike N3LI -

Jim Lux wrote in
:

Dave Oldridge wrote:
"Kash J. Rangan" wrote in


If your antenna is balanced, it would probably be better to simply
split the ladder line onto the center conducters of two identical
short coaxes and then run ladder line inside to your tuner. If you
MUST ground the shields that's OK and you can use lightning arrestors
on both coaxes. But remember, no lighning arrestor is as good for
protecting equipment as a foot or two of air. Disconnecting during
thunderstorms is solid policy!


If you have a direct hit, a one foot air gap isn't necessarily going to
do you much good, unless the antenna end of the gap is on the ground
surface. (i.e. the wire going from where the coax ends to your
lightning dissipation ground has some non-zero inductance/resistance)

If you're worried about induced voltages from adjacent strikes, then a
good transient suppressor will help, but almost all suppressors have
"let through" voltage that is above the damage threshold for, say, a
FET front end. Depends on what your equipment sensitivity is.

Shorting the input of the radio and tying it to chassis ground.. that
WILL protect the radio.

I have been through some VERY violent storms. I always disconnected all
antenna and power leads from the radio. Outside arrestors will help keep
it out of the house but you need airspace to protect receiver front ends.
Also disconnect any ethernet runs.

Surge protection can only do so much. I learned the hard way about
disconnecting stuff. My neighbour across the street had a direct hit and
it danced across the phone lines into my equipment. I lost several
modems, a couple of ethernet cards and a monitor and considered myself
lucky that none of the computers was totalled. But my radios were
disconnected and unscathed.

Now the coast station I worked for had a direct hit on our Nautel 500khz
transmitter's tower. Blew out half the solid state final modules but the
damn thing kept right on ticking on the others!



--
Dave Oldridge+
ICQ 454777283
VA7CZ

MUST ground the shields that's OK and you can use lightning arrestors
on both coaxes.

This is probably not going to work in most cases. Remember an open wire
feedline can have
rather high voltages on it compared to a matched coax liine. This is
because they are often
mismatched at the antenna.
If a voltage peak should happen to occur at the place where you have the
arrestor, it can fire
the gas tube because of the rf voltage.
For example, a gas tube arrestor made for legal limit typically has a firing
voltage of about 800 volts. In a matched
50 ohm system, even with a full 1500 watts into 50 ohms the peak rf voltage
is in the neighborhood of
600 volts. But even a moderate power into a high impedance open line could
be enough to fire
the gas tubes. Neither the transmitter nor the gas tube would be happy with
this situation.

Rick K2XT

"Rick" wrote in
:

MUST ground the shields that's OK and you can use lightning
arrestors on both coaxes.

This is probably not going to work in most cases. Remember an open
wire feedline can have
rather high voltages on it compared to a matched coax liine. This is
because they are often
mismatched at the antenna.
If a voltage peak should happen to occur at the place where you have
the arrestor, it can fire
the gas tube because of the rf voltage.
For example, a gas tube arrestor made for legal limit typically has a
firing voltage of about 800 volts. In a matched
50 ohm system, even with a full 1500 watts into 50 ohms the peak rf
voltage is in the neighborhood of
600 volts. But even a moderate power into a high impedance open line
could be enough to fire
the gas tubes. Neither the transmitter nor the gas tube would be happy
with this situation.

That's true. You would probably need air-gap arrestors that can be
adjusted to not arc on normal transmitted voltages.

Still, the only really effective way of feeding a non-trap wire system on
several bands that I've encountered is to use open wire.

--
Dave Oldridge+
ICQ 454777283

In article ,
Dave Oldridge wrote:

That's true. You would probably need air-gap arrestors that can be
adjusted to not arc on normal transmitted voltages.

Still, the only really effective way of feeding a non-trap wire system on
several bands that I've encountered is to use open wire.

--
Dave Oldridge+
ICQ 454777283

One of the best "air-gap arrestors" of the home-brew variety I have seen,
was made with a couple of Wide Gapped Spark-Plugs, threaded into a 1/4
Steel Plate that was bonded to a very deep Grounding System. The fellow
used GTO15000 to connect the spark-plugs to the Wire-Feeders. Worked
very well.......

--
Bruce in alaska
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