On 5/23/2011 5:10 PM, Wimpie wrote:
On 22 mayo, 20:04, 'Captain' Kirk
wrote:
I'm living in a wooded area and am trying to hit our club repeater
reliably. It's cloudy now so I'm and getting a bit of ducting but I
have a lot of trees, mostly poplars, in the direct path. I would have a
line of sight if not for the trees as I'm up enough in altitude. I can
cut the trees, they're mine, but finding the right ones is difficult and
i don't want to waste the whole grove.

I go from keying the repeater with no intelligible signal to not being
able to hit it. Today I actually have an S meter reading due to the
clouds. I am currently using a J-pole and will put up a Yagi soon but
wonder if NVIS would work on 2m? I have only seen references to it
being applied in HF.

'Captain' Kirk DeHaan
N6SXR

Hello,

As you can see from the replies, we are in the speculation phase. If
you would like to receive more specialized feedback, you should
provide us with more details about the path, antenna height, nearby
obstacles, vegetation in between, etc (maybe some pictures).

As we are discussing 2 m wavelength, obstacles that may be optically
in the path may introduce less attenuation then expected, but
obstacles that are outside the optical path can still introduce
attenuation.

At 10m (33ft) from your antenna, the first Fresnel zone is about 9m
(30 ft) wide. In addition, the tree attenuation at these frequencies
is not that high. I think of 0.15 dB/m (I hope somebody can confirm
this). It can be less due to diffraction (bending) of the waves around
and over the trees.

I am almost sure, removing some poplar treetops at 10m from your
antenna or more will not change the situation from marginal to good
(because of the relative low attenuation).

Just to be curious, what type of poplar do you have at your site.

With kind regards,

Wim
PA3DJS
www.tetech.nl


According to his lat/lon numbers, he is 19 miles from the repeater and
its bearing is 185 degrees (ref true north) from him. The repeater is
about 2000 feet above him (not including the tower height). He is in a
valley that has little altitude variation until his signal reaches the
mountain.

This info is available from Google Earth using his numbers.

All of this leads me to think that something else is wrong. I can hit a
repeater 20 miles from me with 5 Watts and its antenna is on a 300 ft
tower. My antenna (half wave end-fed dipole) is on a 20 ft mast.

I have tons of deciduous trees between me and the repeater but the
signal is always solid with no noise on it (I don't have an S-meter) and
I have never had a report of noise on my signal until I tried to carry
on a conversation with 200 mw output power.

Cheers,
John

On 24 mayo, 05:06, John KD5YI wrote:
On 5/23/2011 5:10 PM, Wimpie wrote:



On 22 mayo, 20:04, 'Captain' Kirk
wrote:
I'm living in a wooded area and am trying to hit our club repeater
reliably. *It's cloudy now so I'm and getting a bit of ducting but I
have a lot of trees, mostly poplars, in the direct path. *I would have a
line of sight if not for the trees as I'm up enough in altitude. *I can
cut the trees, they're mine, but finding the right ones is difficult and
i don't want to waste the whole grove.

I go from keying the repeater with no intelligible signal to not being
able to hit it. *Today I actually have an S meter reading due to the
clouds. I am currently using a J-pole and will put up a Yagi soon but
wonder if NVIS would work on 2m? *I have only seen references to it
being applied in HF.

'Captain' Kirk DeHaan
N6SXR

Hello,

As you can see from the replies, we are in the speculation phase. If
you would like to receive more specialized feedback, you should
provide us with more details about the path, antenna height, nearby
obstacles, vegetation in between, etc (maybe some pictures).

As we are discussing 2 m wavelength, obstacles that may be optically
in the path may introduce less attenuation then expected, but
obstacles that are outside the optical path can still introduce
attenuation.

At 10m (33ft) from your antenna, the first Fresnel zone is about 9m
(30 ft) wide. In addition, the tree attenuation at these frequencies
is not that high. I think of 0.15 dB/m (I hope somebody can confirm
this). It can be less due to diffraction (bending) of the waves around
and over the trees.

I am almost sure, removing some poplar treetops at 10m from your
antenna or more will not change the situation from marginal to good
(because of the relative low attenuation).

Just to be curious, what type of poplar do you have at your site.

With kind regards,

Wim
PA3DJS
www.tetech.nl

According to his lat/lon numbers, he is 19 miles from the repeater and
its bearing is 185 degrees (ref true north) from him. *The repeater is
about 2000 feet above him (not including the tower height). *He is in a
valley that has little altitude variation until his signal reaches the
mountain.

This info is available from Google Earth using his numbers.

All of this leads me to think that something else is wrong. *I can hit a
repeater 20 miles from me with 5 Watts and its antenna is on a 300 ft
tower. My antenna (half wave end-fed dipole) is on a 20 ft mast.

I have tons of deciduous trees between me and the repeater but the
signal is always solid with no noise on it (I don't have an S-meter) and
I have never had a report of noise on my signal until I tried to carry
on a conversation with 200 mw output power.

Cheers,
John

Hello John,

With Google maps, results (distance and bearing) are similar (based on
the data given by Kirk).

If the trees south of his antenna are the problem (I am not
convinced), he needs to cut lots of them. They are about 150m from
his antenna, and at that distance first Fresnel zone width is about
30m (100ft).

It seems flat when looking to the activities in the valley. I hope
somebody can make a path profile and loss simulation to see what is
the real obstacle.

With kind regards,


Wim
PA3DJS

Wimpie said the following on 5/24/2011 6:47 AM:
On 24 mayo, 05:06, John wrote:
On 5/23/2011 5:10 PM, Wimpie wrote:



On 22 mayo, 20:04, 'Captain' Kirk
wrote:
I'm living in a wooded area and am trying to hit our club repeater
reliably. It's cloudy now so I'm and getting a bit of ducting but I
have a lot of trees, mostly poplars, in the direct path. I would have a
line of sight if not for the trees as I'm up enough in altitude. I can
cut the trees, they're mine, but finding the right ones is difficult and
i don't want to waste the whole grove.

I go from keying the repeater with no intelligible signal to not being
able to hit it. Today I actually have an S meter reading due to the
clouds. I am currently using a J-pole and will put up a Yagi soon but
wonder if NVIS would work on 2m? I have only seen references to it
being applied in HF.

'Captain' Kirk DeHaan
N6SXR

Hello,

As you can see from the replies, we are in the speculation phase. If
you would like to receive more specialized feedback, you should
provide us with more details about the path, antenna height, nearby
obstacles, vegetation in between, etc (maybe some pictures).

As we are discussing 2 m wavelength, obstacles that may be optically
in the path may introduce less attenuation then expected, but
obstacles that are outside the optical path can still introduce
attenuation.

At 10m (33ft) from your antenna, the first Fresnel zone is about 9m
(30 ft) wide. In addition, the tree attenuation at these frequencies
is not that high. I think of 0.15 dB/m (I hope somebody can confirm
this). It can be less due to diffraction (bending) of the waves around
and over the trees.

I am almost sure, removing some poplar treetops at 10m from your
antenna or more will not change the situation from marginal to good
(because of the relative low attenuation).

Just to be curious, what type of poplar do you have at your site.

With kind regards,

Wim
PA3DJS
www.tetech.nl

According to his lat/lon numbers, he is 19 miles from the repeater and
its bearing is 185 degrees (ref true north) from him. The repeater is
about 2000 feet above him (not including the tower height). He is in a
valley that has little altitude variation until his signal reaches the
mountain.

This info is available from Google Earth using his numbers.

All of this leads me to think that something else is wrong. I can hit a
repeater 20 miles from me with 5 Watts and its antenna is on a 300 ft
tower. My antenna (half wave end-fed dipole) is on a 20 ft mast.

I have tons of deciduous trees between me and the repeater but the
signal is always solid with no noise on it (I don't have an S-meter) and
I have never had a report of noise on my signal until I tried to carry
on a conversation with 200 mw output power.

Cheers,
John

Hello John,

With Google maps, results (distance and bearing) are similar (based on
the data given by Kirk).

If the trees south of his antenna are the problem (I am not
convinced), he needs to cut lots of them. They are about 150m from
his antenna, and at that distance first Fresnel zone width is about
30m (100ft).

I was up on my neighbors property along the path to the repeater and the
quantity of trees is a lot more than I had remembered. Since this is
tree growing/logging country it is not feasible for me to be cutting
huge amounts of trees. The deciduous can go but there are to many
conifers on both properties to cut just for signal. You are correct on
the distance to the grove and it is the, I believe, the only impediment.

It seems flat when looking to the activities in the valley. I hope
somebody can make a path profile and loss simulation to see what is
the real obstacle.

I download the Radio Mobile SW that someone suggested but am still
trying to figure out how to use it.

With kind regards,


Wim
PA3DJS


--
'Captain' Kirk DeHaan
N6SXR

"Beam me up Scotty, there's no intelligent life here"

John KD5YI said the following on 5/23/2011 8:06 PM:
On 5/23/2011 5:10 PM, Wimpie wrote:
On 22 mayo, 20:04, 'Captain' Kirk
wrote:
I'm living in a wooded area and am trying to hit our club repeater
reliably. It's cloudy now so I'm and getting a bit of ducting but I
have a lot of trees, mostly poplars, in the direct path. I would have a
line of sight if not for the trees as I'm up enough in altitude. I can
cut the trees, they're mine, but finding the right ones is difficult and
i don't want to waste the whole grove.

I go from keying the repeater with no intelligible signal to not being
able to hit it. Today I actually have an S meter reading due to the
clouds. I am currently using a J-pole and will put up a Yagi soon but
wonder if NVIS would work on 2m? I have only seen references to it
being applied in HF.

'Captain' Kirk DeHaan
N6SXR

Hello,

As you can see from the replies, we are in the speculation phase. If
you would like to receive more specialized feedback, you should
provide us with more details about the path, antenna height, nearby
obstacles, vegetation in between, etc (maybe some pictures).

As we are discussing 2 m wavelength, obstacles that may be optically
in the path may introduce less attenuation then expected, but
obstacles that are outside the optical path can still introduce
attenuation.

At 10m (33ft) from your antenna, the first Fresnel zone is about 9m
(30 ft) wide. In addition, the tree attenuation at these frequencies
is not that high. I think of 0.15 dB/m (I hope somebody can confirm
this). It can be less due to diffraction (bending) of the waves around
and over the trees.

I am almost sure, removing some poplar treetops at 10m from your
antenna or more will not change the situation from marginal to good
(because of the relative low attenuation).

Just to be curious, what type of poplar do you have at your site.

With kind regards,

Wim
PA3DJS
www.tetech.nl


According to his lat/lon numbers, he is 19 miles from the repeater and
its bearing is 185 degrees (ref true north) from him. The repeater is
about 2000 feet above him (not including the tower height). He is in a
valley that has little altitude variation until his signal reaches the
mountain.

This info is available from Google Earth using his numbers.

All of this leads me to think that something else is wrong. I can hit a
repeater 20 miles from me with 5 Watts and its antenna is on a 300 ft
tower. My antenna (half wave end-fed dipole) is on a 20 ft mast.

There may well be something wrong with the antenna. I don't have an SWR
meter handy but will try and borrow one from a club member. The J-pole
was beat around quite a bit over the years but since the radio has a
limiting circuit if the SWR is too far out of whack I am assuming it is
fairly close. It will transmit of full power. I'm using 75' of
professionally assembled RG8X which is required to get from the radio to
the antenna.


I have tons of deciduous trees between me and the repeater but the
signal is always solid with no noise on it (I don't have an S-meter) and
I have never had a report of noise on my signal until I tried to carry
on a conversation with 200 mw output power.

Not to make light, one of these poplars is tons in itself. They are
easily 70' tall and 24" diameter. I truly appreciate all the help from
everyone.


Cheers,
John


--
'Captain' Kirk DeHaan
N6SXR

"Beam me up Scotty, there's no intelligent life here"

On Mon, 23 May 2011 15:53:28 -0700, 'Captain' Kirk DeHaan
wrote:

You'll see my crazy driveway
and the house. The J-pole sits about 30' above the house. Plenty of
trees in sight.

That's quite a drive. Thanks for the numbers. I've ignored the
antenna heights as they don't seem to make much difference. 31 km (19
mile) path length. The K7JEP repeater seems to be on a wide flat part
of a hilltop. Pointing downward, it may not clear the edge of the
flat part if the antenna isn't high enough. Difficult to tell without
photos or numbers. Not much you can do at your end to fix that. Any
chance you have a photo of the K7JEP repeater antenna location?

Otherwise, the path is line-o-sight, and should be quite usable with
your American Legion J-Pole. Of course, a yagi would be better, but I
think tinkering with your J-pole, coax, connectors, and radio may be a
better solution (assuming the repeater is working properly).

KML file:
http://802.11junk.com/jeffl/kml/N6SXR-to-K7JEP.kml

JPG image:
http://802.11junk.com/jeffl/kml/N6SXR-to-K7JEP.jpg

Hint: In Google Earth, enable 3D. When you have the KML file
displayed, stomp on the MIDDLE mouse button to tilt the image.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Tue, 24 May 2011 08:17:46 -0700, 'Captain' Kirk DeHaan
wrote:

I download the Radio Mobile SW that someone suggested but am still
trying to figure out how to use it.

Radio-Mobile will give you the expected coverage area and signal
strengths from your location. However, it's a tricky program to
master and will require some patience and practice. There are
tutorials. For example:
http://www.pizon.org/radio-mobile-tutorial/index.html
http://www.bcwireless.net/moin.cgi/RadioMobile/Tutorial
http://radiomobile.pe1mew.nl/
etc.
Also check YouTube for various video tutorials.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Tue, 24 May 2011 08:24:09 -0700, 'Captain' Kirk DeHaan
wrote:

There may well be something wrong with the antenna. I don't have an SWR
meter handy but will try and borrow one from a club member. The J-pole
was beat around quite a bit over the years but since the radio has a
limiting circuit if the SWR is too far out of whack I am assuming it is
fairly close. It will transmit of full power.

The American Legion J-pole is rather critical, especially the dual
band flavor. The vertical section of electrical wire between the coax
connector and the part where it's wound around the driven element is
the tuning adjustment. Move it slightly and it's mistuned. You'll
need a VSWR meter to re-tune it.

I'm using 75' of
professionally assembled RG8X which is required to get from the radio to
the antenna.

RX-8x is 4.5dB loss per 100ft. Half your power is being lost in the
coax.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann said the following on 5/24/2011 8:47 AM:
On Mon, 23 May 2011 15:53:28 -0700, 'Captain' Kirk DeHaan
wrote:

You'll see my crazy driveway
and the house. The J-pole sits about 30' above the house. Plenty of
trees in sight.

That's quite a drive. Thanks for the numbers. I've ignored the
antenna heights as they don't seem to make much difference. 31 km (19
mile) path length. The K7JEP repeater seems to be on a wide flat part
of a hilltop. Pointing downward, it may not clear the edge of the
flat part if the antenna isn't high enough. Difficult to tell without
photos or numbers. Not much you can do at your end to fix that. Any
chance you have a photo of the K7JEP repeater antenna location?

Otherwise, the path is line-o-sight, and should be quite usable with
your American Legion J-Pole. Of course, a yagi would be better, but I
think tinkering with your J-pole, coax, connectors, and radio may be a
better solution (assuming the repeater is working properly).

I have heard from a club member that the repeater is weak and it has
been overrun by one on the coast! He is much farther away than me and
in a much less desirable location, signal wise.

I have been out of HAM radio for about 15 years so am having to relearn
quite a lot. Had a brain injury, doh!, so lot's of what I knew went bye
bye. Lot's of holes in the memory. I will find out about the repeater
during the next club meeting. Specs and all.


KML file:
http://802.11junk.com/jeffl/kml/N6SXR-to-K7JEP.kml

JPG image:
http://802.11junk.com/jeffl/kml/N6SXR-to-K7JEP.jpg

Hint: In Google Earth, enable 3D. When you have the KML file
displayed, stomp on the MIDDLE mouse button to tilt the image.


--
'Captain' Kirk DeHaan
N6SXR

"Beam me up Scotty, there's no intelligent life here"

In article ,
John KD5YI wrote:

All of this leads me to think that something else is wrong. I can hit a
repeater 20 miles from me with 5 Watts and its antenna is on a 300 ft
tower. My antenna (half wave end-fed dipole) is on a 20 ft mast.

I wonder whether he might have his antenna sitting in a particularly
deep multipath cancellation null.

I help run a repeater located about 4 miles from my house, which is up
at about 80' AGL on a hospital roof. There's an office building
blocking direct line-of-sight path from my house to the repeater.

For a few weeks, several years ago, I found myself unable to
successfully open up the repeater using my base station, even while
transmitting 50 watts of power from a good-quality commercial 2-meter
antenna located a few feet above my roofline. Had no trouble with any
other repeater in the area, or with simplex operations. The
feedline/antenna system measured out just fine... no reflected power
worth speaking about.

I moved the antenna mast about 2' to one side, and was then able to
open up the repeater full-quieting with 100 milliwatts.

All I can figure is that there must have been a *very* deep multipath
cancellation effect playing out... maybe interference between a
edge-diffraction path involving the office building, and reflections
from nearby trees. Moving the antenna a fraction of a wavelength
changed the path lengths enough to eliminate the cancellation (or
reduce it by a large factor).

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

In article ,
'Captain' Kirk DeHaan wrote:

All of this leads me to think that something else is wrong. I can hit a
repeater 20 miles from me with 5 Watts and its antenna is on a 300 ft
tower. My antenna (half wave end-fed dipole) is on a 20 ft mast.

There may well be something wrong with the antenna. I don't have an SWR
meter handy but will try and borrow one from a club member. The J-pole
was beat around quite a bit over the years but since the radio has a
limiting circuit if the SWR is too far out of whack I am assuming it is
fairly close. It will transmit of full power.

One of the things to know about the American Legion J-pole (and most
vaguely-similar J-poles) is that it has no feedline or mount-point
isolation to speak of. The outside of the feedline coax, and any pipe
or tower or other metal to which you strap the antenna, become part of
the antenna's ground system, and can radiate a significant amount of
RF. This can interact with the RF coming from the main radiator, and
significantly alter the antenna's pattern... it no longer behaves like
an idealized half-wave vertical radiator.

In most installations this doesn't seem to matter all that much... but
it's possible that you've got some sort of weird interaction (feedline
emissions, reflections from the ground or nearby metal, etc.) which is
creating a null in the antenna's pattern in just the wrong direction.
If this is an issue (not all that likely but perhaps possible) you
could insulate the antenna from the mounting mask, and install a choke
(e.g. a few ferrite cores) on the feedline just below the antenna.

Also, the American Legion J-poles are subject to a couple of forms of
mechanical/electrical failure after a few years. The plastic
insulator which spaces apart the radiator and matching arm can degrade
(UV from sunlight is the main offendor, I believe) and crack, allowing
the two arms to change spacing. More subtly, the connection between
the two arms and the metal base can degrade... it's aluminum-to-
aluminum using a set-screw, and the connection can loosen and corrode.

It might be worth checking the spacer (replace if necessary), and
checking and tuning up the set-screw connections (squirt with Liquid
Wrench if necessary, loosen and remove, take out the rods, clean the
ends of the rods and the mounting holes in the place, dab with NoAlOx
or a similar corrosion-blocker, reassemble and tighten).

I'm using 75' of
professionally assembled RG8X which is required to get from the radio to
the antenna.

That's probably costing you about half of your power (assuming a
typical RG8X-type coax). Some lower-loss types (e.g. LMR-240 are
better than this.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!