My HF rig was damaged earlier this month. I replaced
it (Yaesu FT-840) with a new FT-857D and all is working
fine but I'm getting wierd results from my antennas.

I have 2 HF antennas - a coax fed 160/80 trap dipole (uses
3-1/2" dia coax traps) and a shortened Van Gorden
"All Bander".

On all three bands with the new rig I'm getting about 1/3rd
more bandwidth between the 2:1 SWR points. The SWR
meter hasn't changed and the feedlines and antennas are the
same - only the transciever has changed. Power is as before
- 100 watts.

What could be causing this? The only thing I could think of
is that my old rig was "dirty" and the harmonics were adding
to the SWR.

--
73's es gd dx de Ken KG0WX
Grid EM17ip, Flying Pigs #1055,
List Owner, Yahoo! E-groups:
VX-2R & FT-857

On Sat, 22 Jan 2005 11:53:07 -0600, "Ken Bessler"
wrote:

My HF rig was damaged earlier this month. I replaced
it (Yaesu FT-840) with a new FT-857D and all is working
fine but I'm getting wierd results from my antennas.

I have 2 HF antennas - a coax fed 160/80 trap dipole (uses
3-1/2" dia coax traps) and a shortened Van Gorden
"All Bander".

On all three bands with the new rig I'm getting about 1/3rd
more bandwidth between the 2:1 SWR points. The SWR
meter hasn't changed and the feedlines and antennas are the
same - only the transciever has changed. Power is as before
- 100 watts.

What could be causing this? The only thing I could think of
is that my old rig was "dirty" and the harmonics were adding
to the SWR.

Dear Ken,

Are you saying that you have a separate SWR meter, external to the rig
and that you are using this instead of the rig's internal SWR meter?
Is their no internal autotuner or outboard manual tuner involved?



Bob, W9DMK, Dahlgren, VA
Replace "nobody" with my callsign for e-mail
http://www.qsl.net/w9dmk
http://zaffora/f2o.org/W9DMK/W9dmk.html

"W9DMK (Robert Lay)" wrote in message
...
On Sat, 22 Jan 2005 11:53:07 -0600, "Ken Bessler"
wrote:

Dear Ken,

Are you saying that you have a separate SWR meter, external to the rig
and that you are using this instead of the rig's internal SWR meter?
Is their no internal autotuner or outboard manual tuner involved?



Bob, W9DMK, Dahlgren, VA

I'm using a seperate SWR/Power meter. Both rigs, old and new,
had no internal tuner and used my MFJ-864. The FT-857D has
a SWR meter but it's not calibrated or even marked. So, I use a
seperate, dedicated & calibrated meter. I'm using a MFJ 941C
tuner but all my measurements have been with the tuner in bypass
mode, going direct to the antennas.

--
73's es gd dx de Ken KG0WX
Grid EM17ip, Flying Pigs #1055,
List Owner, Yahoo! E-groups:
VX-2R & FT-857

On Sat, 22 Jan 2005 17:07:18 -0600, "Ken Bessler"
wrote:

"W9DMK (Robert Lay)" wrote in message
...
On Sat, 22 Jan 2005 11:53:07 -0600, "Ken Bessler"
wrote:

Dear Ken,

Are you saying that you have a separate SWR meter, external to the rig
and that you are using this instead of the rig's internal SWR meter?
Is their no internal autotuner or outboard manual tuner involved?



Bob, W9DMK, Dahlgren, VA

I'm using a seperate SWR/Power meter. Both rigs, old and new,
had no internal tuner and used my MFJ-864. The FT-857D has
a SWR meter but it's not calibrated or even marked. So, I use a
seperate, dedicated & calibrated meter. I'm using a MFJ 941C
tuner but all my measurements have been with the tuner in bypass
mode, going direct to the antennas.

Dear Ken,

Then I'm going to suggest that which was my first thought - something
has probably been damaged by lightning, and it will probably require
that you take everything down and examine it inch by inch to find what
has happened. Be especially observent over the entire length of coax
for any sign of a burn.

I have had several strikes over the years that have caused varying
amounts of damage. Often, it is just a small burn through from the
inner conductor to the shield that leaves a lump of charred dielectric
at the point where it left the feed line and found some shorter path
to ground.


Bob, W9DMK, Dahlgren, VA
Replace "nobody" with my callsign for e-mail
http://www.qsl.net/w9dmk
http://zaffora/f2o.org/W9DMK/W9dmk.html

"W9DMK (Robert Lay)" wrote in message
...
On Sat, 22 Jan 2005 17:07:18 -0600, "Ken Bessler"
wrote:

"W9DMK (Robert Lay)" wrote in message
...

Dear Ken,

Then I'm going to suggest that which was my first thought - something
has probably been damaged by lightning, and it will probably require
that you take everything down and examine it inch by inch to find what
has happened. Be especially observent over the entire length of coax
for any sign of a burn.

I have had several strikes over the years that have caused varying
amounts of damage. Often, it is just a small burn through from the
inner conductor to the shield that leaves a lump of charred dielectric
at the point where it left the feed line and found some shorter path
to ground.


Bob, W9DMK, Dahlgren, VA

Thanks, Bob but lightning was not in the area or even in the state.
My HF rig was physically damaged by a falling branch sweeping
past the window where some of my coax lines went out.

The coax cables I'm using were not affected nor were the antennas.
The ice storm had already broken the support ropes and those
antennas were on the ground when the branches came down.

I deliberatly incorporate a physical weak spot in the support ropes
so that the antenna will survive in case of a snag.

The 2:1 SWR range on 40m was 303 kc before. Now it's 465 kc.

--
73's es gd dx de Ken KG0WX
Grid EM17ip, Flying Pigs #1055,
List Owner, Yahoo! E-groups:
VX-2R & FT-857

On Sat, 22 Jan 2005 17:49:33 -0600, "Ken Bessler"
wrote:

"W9DMK (Robert Lay)" wrote in message
...
On Sat, 22 Jan 2005 17:07:18 -0600, "Ken Bessler"
wrote:

"W9DMK (Robert Lay)" wrote in message
...

Dear Ken,

Then I'm going to suggest that which was my first thought - something
has probably been damaged by lightning, and it will probably require
that you take everything down and examine it inch by inch to find what
has happened. Be especially observent over the entire length of coax
for any sign of a burn.

I have had several strikes over the years that have caused varying
amounts of damage. Often, it is just a small burn through from the
inner conductor to the shield that leaves a lump of charred dielectric
at the point where it left the feed line and found some shorter path
to ground.


Bob, W9DMK, Dahlgren, VA

Thanks, Bob but lightning was not in the area or even in the state.
My HF rig was physically damaged by a falling branch sweeping
past the window where some of my coax lines went out.

The coax cables I'm using were not affected nor were the antennas.
The ice storm had already broken the support ropes and those
antennas were on the ground when the branches came down.

I deliberatly incorporate a physical weak spot in the support ropes
so that the antenna will survive in case of a snag.

The 2:1 SWR range on 40m was 303 kc before. Now it's 465 kc.

Dear Ken,

If I may be permitted another guess. When you check the bandwidth on
the higher bands, you probably do not see as much of an increase from
the original characterstics. If so, then there is another mechanism
that may have come into play. It does not take much of a droop on the
ends of a lower frequency antenna, center supported antenna to give an
effect of greater bandwidth. For example, I believe that you will
generally find that an inverted vee antenna has a wider bandwidth than
one that is near flat across the top (given that the center of each is
at same height above ground. If your antennas are center supported and
have a lower altitude at the ends than originally, that might account
for it. Unfortunately, your description of your antennas sounds more
like they are not center supported. As a general rule, as you surely
know, anything that increases the losses in an antenna will manifest
itself as greater bandwidth. That is the aspect that makes you really
want to find the cause, because it means something is eating your
watts.

With that I'm out of ideas.
Bob, W9DMK, Dahlgren, VA
Replace "nobody" with my callsign for e-mail
http://www.qsl.net/w9dmk
http://zaffora/f2o.org/W9DMK/W9dmk.html

"W9DMK (Robert Lay)" wrote in message
Dear Ken,

If I may be permitted another guess. When you check the bandwidth on
the higher bands, you probably do not see as much of an increase from
the original characterstics. If so, then there is another mechanism
that may have come into play. It does not take much of a droop on the
ends of a lower frequency antenna, center supported antenna to give an
effect of greater bandwidth. For example, I believe that you will
generally find that an inverted vee antenna has a wider bandwidth than
one that is near flat across the top (given that the center of each is
at same height above ground. If your antennas are center supported and
have a lower altitude at the ends than originally, that might account
for it. Unfortunately, your description of your antennas sounds more
like they are not center supported. As a general rule, as you surely
know, anything that increases the losses in an antenna will manifest
itself as greater bandwidth. That is the aspect that makes you really
want to find the cause, because it means something is eating your
watts.

With that I'm out of ideas.
Bob, W9DMK, Dahlgren, VA

Thanks for the ideas, Bob!

The antenna was never used on bands other than 40m before. Now,
it's my main antenna for use above 7mc. The only changes are the
addition of the tuner.

I know it's *not* the tuner because I've tested it with the tuner physically
out of line.

There are 2 other miniscule changes. Before the storm, I had trimmed
out the ends with 18g insulated speaker wire. Each leg had a butt splice
then about 2' of the stuff. Now the extra wire is standard 14g stranded
bare copper, soldered in place.

The feedline had 1 minor change, too. From the tuner I had 20' of rg58
going into a 9 turn, 5-1/4" dia air coil then 50' of 450 ohm ladder line.

The coil was wound on a CD-rom package with the turns held together
with superglue. The form was removed after the glue set up. Neat.

During the repairs, 1 turn of the coil broke loose and straightned out on
the side connected to the 20' of rg58 going indoors. The coil is 1 piece
still, just 1 turn less on the coax side.

The antenna is basically a flat dipole, supported by a wooden roof in
the middle and rope at the ends. The ends droop maybe 2-3 feet.

I suppose the replacement of the end wire with heavier wire could help
b/w but I wouldn't think that much.

I just checked my 160/80m dipole, where nothing changed so I don't
think it's the radio or the tuner......

Thanks for scratching your brain for me!

--
73's es gd dx de Ken KG0WX
Grid EM17ip, Flying Pigs #1055,
List Owner, Yahoo! E-groups:
VX-2R & FT-857

On Sat, 22 Jan 2005 19:10:56 -0600, "Ken Bessler"
wrote:

"W9DMK (Robert Lay)" wrote in message
Dear Ken,

If I may be permitted another guess. When you check the bandwidth on
the higher bands, you probably do not see as much of an increase from
the original characterstics. If so, then there is another mechanism
that may have come into play. It does not take much of a droop on the
ends of a lower frequency antenna, center supported antenna to give an
effect of greater bandwidth. For example, I believe that you will
generally find that an inverted vee antenna has a wider bandwidth than
one that is near flat across the top (given that the center of each is
at same height above ground. If your antennas are center supported and
have a lower altitude at the ends than originally, that might account
for it. Unfortunately, your description of your antennas sounds more
like they are not center supported. As a general rule, as you surely
know, anything that increases the losses in an antenna will manifest
itself as greater bandwidth. That is the aspect that makes you really
want to find the cause, because it means something is eating your
watts.

With that I'm out of ideas.
Bob, W9DMK, Dahlgren, VA

Thanks for the ideas, Bob!

The antenna was never used on bands other than 40m before. Now,
it's my main antenna for use above 7mc. The only changes are the
addition of the tuner.

I know it's *not* the tuner because I've tested it with the tuner physically
out of line.

There are 2 other miniscule changes. Before the storm, I had trimmed
out the ends with 18g insulated speaker wire. Each leg had a butt splice
then about 2' of the stuff. Now the extra wire is standard 14g stranded
bare copper, soldered in place.

The feedline had 1 minor change, too. From the tuner I had 20' of rg58
going into a 9 turn, 5-1/4" dia air coil then 50' of 450 ohm ladder line.

The coil was wound on a CD-rom package with the turns held together
with superglue. The form was removed after the glue set up. Neat.

During the repairs, 1 turn of the coil broke loose and straightned out on
the side connected to the 20' of rg58 going indoors. The coil is 1 piece
still, just 1 turn less on the coax side.

The antenna is basically a flat dipole, supported by a wooden roof in
the middle and rope at the ends. The ends droop maybe 2-3 feet.

I suppose the replacement of the end wire with heavier wire could help
b/w but I wouldn't think that much.

I just checked my 160/80m dipole, where nothing changed so I don't
think it's the radio or the tuner......

Thanks for scratching your brain for me!

Dear Ken,

Those things that you mention would not cause a change in bandwidth,
in my opinion.

Last suggestion:

If there were significant amounts of RF current on the outer surface
of the coax portion of the feed line, and if that has changes due to
the other changes, then there could possibly be unpredictable effects
on the SWR meter. They are not supposed to be sensitive to such
things, but in my shack any RF currents running around in the station
ground has always caused erroneous readings in the SWR meters. As a
last ditch experiment, I would try earthing the outer shield of the
coax to a good ground frame just before the coax comes into the shack.


Good Luck!


Bob, W9DMK, Dahlgren, VA
Replace "nobody" with my callsign for e-mail
http://www.qsl.net/w9dmk
http://zaffora/f2o.org/W9DMK/W9dmk.html