On Sun, 22 May 2011 20:56:52 -0500, John KD5YI
wrote:

You may be right, Jeff. But he may not have 120ft redwoods around and,
after all, this is a temporary fix until his yagi comes in.

30 years of trying to maintain a stable signal to several distant
repeaters is sufficient to convince me. Trees move and grow, causing
signals to change.

Also, temporary is a rather useless term. In my experience, if it
works, it's permanent.

Good for you! Pat yourself on the back.

Thank you for the traditional contentious remark.

You spent more words debunking the suggestion than admitting that you
don't really know whether it could help or not.

True. I spent more words explaining why I suspect it will not work,
what I expect will happen, and a bit of substantiation. I consider
this a substantial improvement over the traditional one-line
pontification.

Good move. And, by the
way, I have experience to the contrary at both 144 and 444 MHz. It all
depends on the location of the source and the receiver. At 2 meters,
some rotation of the antenna can sometimes be helpful.

Perhaps it would be helpful if you read what I had written. I said
that rotating the antenna might help temporarily, but that movements
of the trees, tree growth, swaying branches in the wind, and possibly
sources of reflections, will soon negate any temporary benefits. If
the yagi is going to arrive shortly, then tilting the antenna is
probably a useful exercise.

Note that we are not concerned with GHz.

Topic drift follows:
Since you mentioned GHz, one of the other problems with living in the
deep dark forest is that DBS satellite dish reception is a problem. I
hacked an 8ft diameter hole in the tree canopy by lopping off some
branches at about the 80ft level, through which I point my DirecTV
dish. Every year, the trees grow a little, requiring that I move the
dish around my roof. During the twice annual solar satellite outage:
http://en.wikipedia.org/wiki/Sun_outage
Twice a year, I photograph the sunlight shining through the hole and
onto the dish and roof. If there are shadows of branches on the dish,
I move it to a better location.
http://www.11junk.com/jeffl/pics/DBS/
Note the shadow at 12 o'clock on the dish.

--
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 22/05/2011 19:04, 'Captain' Kirk DeHaan 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

If you have line of sight to the repeater I find it hard to believe that
a few trees will cause you problems at 2m.

NVIS will not work at vhf it is an HF mode. 2m signals go straight
through the atmosphere they are not reflected back down.

You don't say how far away the trees are, but if they *really are* the
cause of you problems, if they are at any distance then they will
probably all have to go to give any sort of Fresnel zone clearance at 2m.

A simple map and compass will give you the bearing to the repeater, but
perhaps you would be better off running a propagation prediction program
such as Radiomobile to see if it is actually the terrain rather than the
trees that are the problem.

73
Jeff

On Sun, 22 May 2011 20:56:52 -0500, John KD5YI
wrote:

You may be right, Jeff. But he may not have 120ft redwoods around and,
after all, this is a temporary fix until his yagi comes in.

Ummm... I don't think the yagi is on order.
http://www.k7jep.org/node/107

#Begin speculation();

His area has a variety of repeaters available:
http://www.k7jep.org/node/107
I would guess(tm) N7JCT 145.230 on Schweitzer Mtn. Idaho.
http://www.repeaterbook.com/beta/repeaters/details.php?ID=64&state_id=16
Plugging the coordinates 48.367500 -116.628326 into Google Earth gives
me a view of the area. It seems to be in the middle of a ski resort,
that has been cleared of most trees and is full of trails. Plenty of
trees both up and down the slope, but not around the probable location
of the repeater. I can't identify the trees from the photo, but my
guess(tm) is Lodgepole Pine at about 60ft. The location is not at the
top of the hill and also has hills shading the view for about 270
degrees. I don't think this is going to be a foliage penetration
issue.

KML file for Google Earth:
http://802.11junk.com/jeffl/kml/N7JCT possible location.kml
JPG for those without Google Earth:
http://802.11junk.com/jeffl/kml/N7JCT possible location.jpg

Blundering forward, N6SXR is shown as getting his snail mail in
Sandpoint ID a distance of about 7 miles. However, there's quite a
bit of dirt in the way, which will be a problem.
http://802.11junk.com/jeffl/kml/N6SXR to N6JCT.jpg

At 7 miles, it should be possible on VHF, even with 450ft of dirt in
the way. My guess(tm) is that there's something wrong with the home
made J-pole, coax, radio, or all the aformentioned.

Again, this is a guess(tm) of both the repeater and it's location and
just might be totally wrong.

#End speculation();


--
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 5/22/2011 11:26 PM, Jeff Liebermann wrote:
On Sun, 22 May 2011 20:56:52 -0500, John
wrote:

You may be right, Jeff. But he may not have 120ft redwoods around and,
after all, this is a temporary fix until his yagi comes in.

30 years of trying to maintain a stable signal to several distant
repeaters is sufficient to convince me. Trees move and grow, causing
signals to change.

Also, temporary is a rather useless term. In my experience, if it
works, it's permanent.

The OP already said he will be putting up a yagi. Anthing he does
between now and then is temporary.

Good for you! Pat yourself on the back.

Thank you for the traditional contentious remark.

You earned it.

You spent more words debunking the suggestion than admitting that you
don't really know whether it could help or not.

True. I spent more words explaining why I suspect it will not work,
what I expect will happen, and a bit of substantiation. I consider
this a substantial improvement over the traditional one-line
pontification.

I find it more useful to encourage experimentation rather than the opposite.

Good move. And, by the
way, I have experience to the contrary at both 144 and 444 MHz. It all
depends on the location of the source and the receiver. At 2 meters,
some rotation of the antenna can sometimes be helpful.

Perhaps it would be helpful if you read what I had written. I said
that rotating the antenna might help temporarily, but that movements
of the trees, tree growth, swaying branches in the wind, and possibly
sources of reflections, will soon negate any temporary benefits. If
the yagi is going to arrive shortly, then tilting the antenna is
probably a useful exercise.

I did read what you had written. So?

Note that we are not concerned with GHz.

Topic drift follows:
Since you mentioned GHz,

*You* are the one who brought it up:

"The effect continues up to at least 2.4GHz. Above that,
at 5.7GHz, the signals seem to be going through the holes between the
leaves."

Perhaps you should read what you wrote.

John

On 5/23/2011 10:46 AM, Jeff Liebermann wrote:
On Sun, 22 May 2011 20:56:52 -0500, John
wrote:

You may be right, Jeff. But he may not have 120ft redwoods around and,
after all, this is a temporary fix until his yagi comes in.

Ummm... I don't think the yagi is on order.


Now you are just being argumentative. I never said it was on order. The
OP said he was planning to put one up. Therefore, it will most likely
come in some day.

I'll bet you are still waiting for your boat to come in.

On Mon, 23 May 2011 11:46:58 -0500, John KD5YI
wrote:

On 5/23/2011 10:46 AM, Jeff Liebermann wrote:
On Sun, 22 May 2011 20:56:52 -0500, John
wrote:

You may be right, Jeff. But he may not have 120ft redwoods around and,
after all, this is a temporary fix until his yagi comes in.

Ummm... I don't think the yagi is on order.

Now you are just being argumentative.

Not really. Methinks that you're being overly defensive. My litmus
test is "duz it answer the OP's question"? If not, you're wasting
your bytes. By asking for help with the design and contruction of a
yagi, it appears that the author is planning to build his own yagi. I
haven't seen any mention of a structure, pole, or tower, so that will
also need to be constructed. Perhaps also a rotator. Methinks
temporary might be a long time.

I never said it was on order. The
OP said he was planning to put one up. Therefore, it will most likely
come in some day.

At this point, I think were suppose to debate the definition of
temporary. I think I'll pass.

I'll bet you are still waiting for your boat to come in.

Nope, no waiting. I let the computah do that for me.
http://www.marinetraffic.com/ais/
The station I'm slightly involved with is at:
http://www.marinetraffic.com/ais/stationdetails.aspx?station_id=112
Watching the VHF propagation effects are fascinating.

--
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 5/22/2011 3:11 PM, Sal M. Onella wrote:
On May 22, 11:04 am, '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

I can't see that NVIS has any VHF backers.

Can you exploit Google Maps, satellite view, to establish a precise
line bearing from your antenna to the repeater site? If you need even
more help than you get from your new yagi, then such a line bearing
will help identify your "trouble trees."

I had to do it for a new FD site a few years ago. We're in San Diego
and I wanted to work 2m into Los Angeles. First, I used a protractor
to determine LA was X-degrees True (whatever it was) from us; next, on
a close-up print of the FD site, I plotted that same line bearing from
the antenna site to obvious local landmarks which we then used on the
the ground for pointing the 2m beam.


For this kind of thing "RadioMobile" from VE2DBE is the application of
choice. It will load the SRTM terrain DEMs, etc. and plot out the path
quite nicely.
http://www.cplus.org/rmw/english1.html


But, if you can get in sometimes, but not others, the next question is,
"can you hear it"?

How long is your coax?
If more than 20 ft, are you running a preamp?

Getting 10-15 dB gain over a jpole would be easy with a moderate length
Yagi. A M2 2M4 (4 elements, $115) is about 10dBi. A 2M9($240) is about
14dBi

On 22 mayo, 20:04, 'Captain' Kirk DeHaan
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

Jeff Liebermann said the following on 5/23/2011 8:46 AM:
On Sun, 22 May 2011 20:56:52 -0500, John
wrote:

You may be right, Jeff. But he may not have 120ft redwoods around and,
after all, this is a temporary fix until his yagi comes in.

Ummm... I don't think the yagi is on order.
http://www.k7jep.org/node/107

This is the repeater I am trying to access, 146.780, K7JEP. I have been
playing with Google Earth and getting coordinates so I can go over to my
neighbors property and stand on the ridge between our properties and see
if I can see the repeater and my house. Hopefully that will help me
locate the suspect trees.


#Begin speculation();

His area has a variety of repeaters available:
http://www.k7jep.org/node/107
I would guess(tm) N7JCT 145.230 on Schweitzer Mtn. Idaho.

This repeater is 59 on signal. I have direct line of site with no
obstructions.

http://www.repeaterbook.com/beta/repeaters/details.php?ID=64&state_id=16
Plugging the coordinates 48.367500 -116.628326 into Google Earth gives
me a view of the area. It seems to be in the middle of a ski resort,
that has been cleared of most trees and is full of trails. Plenty of
trees both up and down the slope, but not around the probable location
of the repeater. I can't identify the trees from the photo, but my
guess(tm) is Lodgepole Pine at about 60ft. The location is not at the
top of the hill and also has hills shading the view for about 270
degrees. I don't think this is going to be a foliage penetration
issue.

KML file for Google Earth:
http://802.11junk.com/jeffl/kml/N7JCT possible location.kml
JPG for those without Google Earth:
http://802.11junk.com/jeffl/kml/N7JCT possible location.jpg

Blundering forward, N6SXR is shown as getting his snail mail in
Sandpoint ID a distance of about 7 miles. However, there's quite a
bit of dirt in the way, which will be a problem.
http://802.11junk.com/jeffl/kml/N6SXR to N6JCT.jpg

Addresses here are not all they seem. My physical address is 14 miles
north even though the postal idiots label it in Sandpoint. Approx
location... lat 48.494070 lon -116.447788. You'll see my crazy driveway
and the house. The J-pole sits about 30' above the house. Plenty of
trees in sight.

At 7 miles, it should be possible on VHF, even with 450ft of dirt in
the way. My guess(tm) is that there's something wrong with the home
made J-pole, coax, radio, or all the aformentioned.

Again, this is a guess(tm) of both the repeater and it's location and
just might be totally wrong.

#End speculation();




--
'Captain' Kirk DeHaan
N6SXR

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

Jeff Liebermann said the following on 5/22/2011 6:05 PM:
On Sun, 22 May 2011 11:04:10 -0700, 'Captain' Kirk DeHaan
wrote:

I'm living in a wooded area and am trying to hit our club repeater
reliably.

I live in a dense mostly redwood forest. Signals vary from full
quieting to not copyable. We also have two co-channel repeaters
sharing the frequency, that also vary radically in strength. I can
often point my 5 element 2m beam in a totally insane direction, and
improve the signal.

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.

I just love technical posting with no numbers. It would be helpful if
you would offer a clue as to the distance you're trying to cover, what
manner of impervious to RF dirt is along the line of sight, antenna at
the repeater, power levels, etc. For extra credit, if you disclose
these plus your exact location, the repeater's exact location, and I
will contrive a Radio-Mobile path profile from you to the repeater.
That should give you a clue as to what challenges you are facing.

The repeater, 146.780, in on Gold Mtn., 48.219713, -116.482883 I do not
know the specs of the repeater. I am at 48.494070, -116.447788, at
2300' using an American Legion J-pole. It has worked very well in the
past but this is the first time it has been up in 15 years. It hits the
145.230 repeater on Schweitzer 59. I'm running a Kenwood 721 at 25
watts trying to hit the 780 repeater. Schweitzer can be hit at 5 watts
no problem.

http://www.cplus.org/rmw/english1.html
It will look something like this:
http://802.11junk.com/jeffl/coverage/RST/RST-KCRA.jpg

As for a seat-of-the-pants guess as to a solution, I don't like J-pole
antennas. Actually, the antenna is fine, but the way most people
build, tune, and position them, is what I find disgusting. The lack
of any commercially manufactured J-pole antennas (other than the
American Legion J-poles) should offer a clue. Plenty of plans:
http://www.google.com/search?q=j-pole+antenna&hl=en&prmd=ivns&tbm=isch
but nothing from a commercial antenna manufactory.

In my never humble opinion, if you can barely talk to the repeater
with a J-pole, then a yagi will offer a substantial improvement. The
problem is how much gain is going to be needed to make it reliable. My
guess(tm) is that the J-pole has a gain of about 2.5dBi (opinions vary
on the gain), and that you'll need about 5dB more gain to get a decent
link. That means you'll need a yagi with about 7.5dBi of gain. That
can be done with a 5 element 2m yagi. Obviously, more gain is better
as is more altitude.

Good luck.


--
'Captain' Kirk DeHaan
N6SXR

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