Long inverted V not working well, why?
 

I just put up an inverted V that is up about 70 feet in the center and
about 15 feet at the ends. Each leg is about 130 feet long, or about 260
feet overall, which is right around a half wave for 160 meters. It is fed
with ladder line and an LDG auto-tuner.

I also have a dipole antenna that's up about 17 feet and is a half wave
for certain MARS / CAP frequencies above the 75 meter band, hence it's a
bit short for 75 meters. That antenna is coax fed and goes through a
different LDG auto-tuner which allows me to use it on 75/80 meters with a
good match.

The long and high inverted V doesn't work any better than the short and
low dipole, and in some cases doesn't work as well.

I have checked all the connections on the inverted V and even did a
continuity check from each side of the ladder line, up through the feed
point, out each leg to the end of each leg, and all seems OK.

I have tried switching auto-tuners (taking the one that's on the coax-fed
dipole and putting it on the inverted V) with no discernible difference.

Seems very strange. Any ideas that might account for why the V doesn't
work better?

Long inverted V not working well, why?
 

Rick (W-A-one-R-K-T) wrote:
Seems very strange. Any ideas that might account for why the V doesn't
work better?

The key is the combination of feedpoint impedance and
length of the ladder-line. Some lengths of ladder-line
at some frequencies are close to worst case. For instance,
if the feedpoint of the 160m dipole is 6000 ohms on 75m,
you certainly don't want to feed it with 1/2WL of
ladder-line on 75m.

The free demo version of EZNEC available from eznec.com
will probably tell you what is wrong with your installation.

There's a DOS program on my web page that will tell you
the optimum lengths for feedline. It can be downloaded
from http://www.w5dxp.com/imax.exe

For instance, with a 260 foot dipole used with 450 ohm
ladder-line on 3.8 MHz, the optimum feedline lengths
are ~55 feet and ~172 feet. If your feedline length is
halfway between those two lengths, i.e. ~113 feet, it
is a worst case impedance situation for 3.8 MHz.
--
73, Cecil http://www.w5dxp.com

Long inverted V not working well, why?
 

"Rick (W-A-one-R-K-T)" wrote in message
.. .

I just put up an inverted V that is up about 70 feet in the center and
about 15 feet at the ends. Each leg is about 130 feet long, or about 260
feet overall, which is right around a half wave for 160 meters. It is fed
with ladder line and an LDG auto-tuner.

I also have a dipole antenna that's up about 17 feet and is a half wave
for certain MARS / CAP frequencies above the 75 meter band, hence it's a
bit short for 75 meters. That antenna is coax fed and goes through a
different LDG auto-tuner which allows me to use it on 75/80 meters with a
good match.

The long and high inverted V doesn't work any better than the short and
low dipole, and in some cases doesn't work as well.

I have checked all the connections on the inverted V and even did a
continuity check from each side of the ladder line, up through the feed
point, out each leg to the end of each leg, and all seems OK.

I have tried switching auto-tuners (taking the one that's on the coax-fed
dipole and putting it on the inverted V) with no discernible difference.

Seems very strange. Any ideas that might account for why the V doesn't
work better?


It could depend on where the stations are you are trying to work. If they
are closer than about 200 to 300 miles on 75 meters then the lower antenna
probably will work beter. It is low to the ground and it tends to shoot the
signal up so it bounces down and covers the local area. The other antenna
will tend to send the signal out to more distance places. I have not done
the math for the angle of the higher antenna, but seems that it might too
steep. It should not be any less than about 120 deg where the wires come
together. It could also be the directions the stations are from you.

I have an off center fed antenna up about 50 feet that is about 130 feet
long and another dipole cut for 80 meters that is about 20 feet up. Most of
the locals are much stronger on the lower antenna.
I put it up because I like to talk to a couple of stations that are less
than 100 miles away.

Long inverted V not working well, why?
 

"Rick (W-A-one-R-K-T)" wrote in message
.. .

I just put up an inverted V that is up about 70 feet in the center and
about 15 feet at the ends. Each leg is about 130 feet long, or about 260
feet overall, which is right around a half wave for 160 meters. It is fed
with ladder line and an LDG auto-tuner.

I also have a dipole antenna that's up about 17 feet and is a half wave
for certain MARS / CAP frequencies above the 75 meter band, hence it's a
bit short for 75 meters. That antenna is coax fed and goes through a
different LDG auto-tuner which allows me to use it on 75/80 meters with a
good match.

The long and high inverted V doesn't work any better than the short and
low dipole, and in some cases doesn't work as well.

I have checked all the connections on the inverted V and even did a
continuity check from each side of the ladder line, up through the feed
point, out each leg to the end of each leg, and all seems OK.

I have tried switching auto-tuners (taking the one that's on the coax-fed
dipole and putting it on the inverted V) with no discernible difference.

Seems very strange. Any ideas that might account for why the V doesn't
work better?


you left out many details.
1. on what band did you do these tests?
2. what where your criteria for evaluating 'better'? swr, rx noise, rx
signal strength, tx field strength, tx signal measurements by someone at
some distance from you?
3. at what distance were the stations you compared, if that is what you did?
4. at what time of day/night, and on what date (important if there was some
kind of geomagnetic disturbance or some other propagation anomaly that day).
5. over how long of a period of time have you made these observations?
6. in what directions were the stations relative to each of the v's?
7. how close together are the v's?
8. what is supporting the v's?

Long inverted V not working well, why?
 

On Sat, 12 May 2007 08:02:52 -0400, "Rick (W-A-one-R-K-T)"
wrote:


I just put up an inverted V that is up about 70 feet in the center and
about 15 feet at the ends. Each leg is about 130 feet long, or about 260
feet overall, which is right around a half wave for 160 meters. It is fed
with ladder line and an LDG auto-tuner.

I also have a dipole antenna that's up about 17 feet and is a half wave
for certain MARS / CAP frequencies above the 75 meter band, hence it's a
bit short for 75 meters. That antenna is coax fed and goes through a
different LDG auto-tuner which allows me to use it on 75/80 meters with a
good match.

The long and high inverted V doesn't work any better than the short and
low dipole, and in some cases doesn't work as well.

I have checked all the connections on the inverted V and even did a
continuity check from each side of the ladder line, up through the feed
point, out each leg to the end of each leg, and all seems OK.

I have tried switching auto-tuners (taking the one that's on the coax-fed
dipole and putting it on the inverted V) with no discernible difference.

Seems very strange. Any ideas that might account for why the V doesn't
work better?


http://www.cebik.com/wire/vang.html

Long inverted V not working well, why?
 

On Sat, 12 May 2007 13:03:31 +0000, Dave wrote:

1. on what band did you do these tests?

Mostly 80 and 40, since those are the frequencies near where my two
reference dipoles are cut (the one I mentioned, cut a bit above 80 meters,
and a second 40-meter dipole at the same elevation, 17 feet, fed from the
same coax feedline).

2. what where your criteria for evaluating 'better'? swr, rx noise, rx
signal strength, tx field strength, tx signal measurements by someone at
some distance from you?

The only criterion I have available right now is received signal strength.
I don't yet have the resources to do transmit signal strength
measurements.

3. at what distance were the stations you compared,

Some were regional, less than 200 miles away, and so of course I would
have expected the low dipole to perform well, perhaps better than the
inverted vee. However, others were 500 to 1000 miles away, in places like
Virginia and Georgia (I'm in New Hampshire). Consistently, they came in
as well, or nearly so, and sometimes better, on the dipole than on the V.

4. at what time of day/night, and on what date

I work at home, and so I am able to get on the air several times during
each day. I ran some tests on the ECARS net at 7255 during the day,
generally from about 10 AM until about 3 PM EDT, and on 80 meter CW and 75
meter SSB during the early to mid evening. I did this every day for about
the last week and a half or so (for reference, today is Saturday, May 12).

5. over how long of a period of time have you made these observations?

As noted above, about the last week and a half or so.

6. in what directions were the stations relative to each of the v's?

There is only one V, and the other is a dual band dipole (75 and 40 meters
fed with one coax). The V and the 75-meter dipole are oriented roughly
east and west, and the 40-meter dipole is oriented roughly east-southeast
and west-northwest. Most of the stations I tested with were in Ohio down
through Florida, and so were about 260 degrees true down to about 210
degrees true ... especially in the case of the Ohio stations, not really
optimal for the antenna orientation, and yet an inverted vee should have
been much less sensitive to that than a dipole.

7. how close together are the v's?

The V and the dipole are approximately 30 feet apart horizontally and 50
feet apart vertically at their feedpoints, hence their feedpoints are a
bit under 60 feet apart.

8. what is supporting the v's?

The V is supported by a tall tree in the back yard. The tree doesn't have
many branches or much foliage, and what it does have are high up, mostly
higher than the feedpoint.

The dipole is supported by trees on each end.

Long inverted V not working well, why?
 

On Sat, 12 May 2007 06:42:30 -0700, Danny Richardson wrote:

http://www.cebik.com/wire/vang.html

Good morning, Danny.

Thanks for the pointer. That one was a real eye opener. I always thought
that any angle 90 degrees or greater at the feedpoint was OK. I think
mine is something like about 100 degrees. I'll see if I can raise the
ends up a bit and see what difference that makes.

Long inverted V not working well, why?
 

how far apart are the ends?

On May 12, 5:02 am, "Rick (W-A-one-R-K-T)"
wrote:
I just put up an inverted V that is up about 70 feet in the center and
about 15 feet at the ends. Each leg is about 130 feet long, or about 260
feet overall, which is right around a half wave for 160 meters. It is fed
with ladder line and an LDG auto-tuner.

I also have a dipole antenna that's up about 17 feet and is a half wave
for certain MARS / CAP frequencies above the 75 meter band, hence it's a
bit short for 75 meters. That antenna is coax fed and goes through a
different LDG auto-tuner which allows me to use it on 75/80 meters with a
good match.

The long and high inverted V doesn't work any better than the short and
low dipole, and in some cases doesn't work as well.

I have checked all the connections on the inverted V and even did a
continuity check from each side of the ladder line, up through the feed
point, out each leg to the end of each leg, and all seems OK.

I have tried switching auto-tuners (taking the one that's on the coax-fed
dipole and putting it on the inverted V) with no discernible difference.

Seems very strange. Any ideas that might account for why the V doesn't
work better?

Long inverted V not working well, why?
 

On Sat, 12 May 2007 10:37:13 -0400, Rick (W-A-one-R-K-T) wrote:

Thanks for the pointer. That one was a real eye opener. I always thought
that any angle 90 degrees or greater at the feedpoint was OK. I think
mine is something like about 100 degrees.

Actually I just calculated it out and it's more like around 130 degrees,
or each leg is just 25 degrees down from horizontal. So, according to
Cebik that should be pretty good.

Long inverted V not working well, why?
 

On Sat, 12 May 2007 09:27:47 -0700, herbert.don wrote:

how far apart are the ends?

Around 235 feet.