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Author Topic: Repeatable, Reliable HF Contacts Without A Beam  (Read 3102 times)
KG6SII
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Posts: 27




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« on: October 27, 2012, 11:27:13 PM »

Elmers,

I'd like to be able to communicate via HF with a family member in Connecticut from California, but a huge tower or beam is not in the cards.  Currently I have a 63ft dipole at 20-30ft high, and run barefoot with a manual tuner.  This setup has worked fine for random QSO's.  However, I don't ever receive signals from New England.

Is it possible to have reliable/repeatable communications over this distance, without a tower or beam?

I am willing to change the following, to accomplish my goal.  Which of these would be most helpful?
 - get an amplifier
 - string a long wire antenna for 160 or 80 meters, possibly in trees of height ~50-60ft
 - make a directional loop antenna, but it would have to be at height of 20-30ft

Any help is appreciated.  73, Glenn KG6SII
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W8JI
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« Reply #1 on: October 28, 2012, 03:04:25 AM »

You are going to have a really tough time on 160 or 80 meters unless you both have large antennas and higher power.

20 meters (random times day or night) and perhaps 40 meters (late at night) would be much better. You'll have to pick a time when other activity is low, rather than a very busy time of day.

In that case you should be OK with a dipole antenna at each end and low power. You won't set the world on fire, but should be able to communicate on most days on 20 meters if the band is not crowded.

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KC4MOP
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Posts: 754




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« Reply #2 on: October 28, 2012, 07:23:52 AM »

I agree with Tom 8JI
but a little more horsepower  (WATTS) might definitely help, as you mentioned, repeatable/reliable contact. As with HF commo there is no steady way to gauge reliable/repeatable.
Your low dipole is only going to be good out several hundred miles on 40M......20M the dipole would have to be pointed in the right direction.
Calif to Connecticut is over 2000 mi. 20M would be interesting as a link but, you or your contact might skip over each other.
I'm in Western Pa. and I hear QSO's on 80M from Colorado and most times they are way in the noise. And I have a full length dipole at 65 feet high! And someone in Connecticut can hear and communicate perfectly,,,,,,,,,or almost 'armchair copy'
It's that time of day thing with HF
Fred
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KB1GMX
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Posts: 813




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« Reply #3 on: October 28, 2012, 08:31:00 AM »

W8JI is right.

Your antenna is too low for 80 and 160 for DX (1000+miles) except under
random conditions.

For that height 20M, 17M, or 15M might be the best shot and you might
consider other antennas like a delta loop or vertical dipole.
Other possible antenna include LazyH or 8jk birectional wire arrays for better
gain in a given direction. 

Of course power helps but only if both ends are equal otherwise one end
needs the tower and big beam to make up for lack of power at the other end.

Allison
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WX7G
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Posts: 6204




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« Reply #4 on: October 28, 2012, 09:24:25 AM »

Glenn, 20, 17, 15, 12, or 10 meters are the bands for what you want to do and daytime is the time.

If your 63' dipole is oriented North-South it is great for 20 meters if you are feeding it with ladder line and not coax. Coax is too lossy on all but the fundamental frequency of 7 MHz. The height is usable but could be higher.

Here how to optimize the situation for 20-10 meters with a wire antenna:

1. A 33' dipole oriented North-South and mounted high
2. Fed with ladder line to the tuner

Additional improvements:

3. Run an amplifier
4. Use CW rather than SSB
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WB6BYU
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Posts: 13475




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« Reply #5 on: October 28, 2012, 12:19:10 PM »

That particular path is not as easy as it sounds.  Typical single-hop distances via the F2
layer from the west coast get you about Pennsylvania or so, but it usually takes 2 hops
to reach New England.  That means that the ionospheric conditions need to be favorable
in two areas to make contact rather than just one:  you will be more dependent on
ionospheric conditions than is often the case for shorter paths.

There are a number of programs available that will help you to choose the optimum
operating frequencies based on current ionospheric conditions.  I have had good results
with some of the tools provided by the Australian Ionospheric Prediction Service, but
there are others that may also work for you:

http://www.ips.gov.au/HF_Systems/7/1


There are two general categories of changes you can make to your antenna that will
help make the path more reliable:  improve the radiation at the optimum vertical angle
for the path, and increase the gain in the desired azimuth direction.

Vertical angle is often a matter of getting the antenna up high enough.  Depending on
conditions, the required vertical angle is probably around 15 - 30 degrees or so.  If
we choose 25 degrees as an example, we can plot the relative radiation at this angle
for a dipole at various heights above ground:

25' . . 0.3 dB
40' . . 2.3 dB
50' . . 3.8 dB
60' . . 5.5 dB
70' . . 7.2 dB

Just raising your antenna from 25' to about 50' would increase your signal 3dB, which
is equivalent to running twice the power.  Going to 65' is like using a 400W amp.
This may not make or break the ability to make a contact, but it will certainly make it
easier in marginal conditions.

This is for 40m:  on 20m it doesn't require as much height to optimize the takeoff angle.

Sometimes vertical polarization may give better results if you are limited in height - this
will depend to a large extent on the local soil conditions.

But the concept is that, for a specific path, there will be an optimum range of vertical
angles of radiation, and antenna height (and polarization) can be adjusted to provide
the best radiation at that vertical angle.


We're more used to considering the azimuth directivity:  aiming your antenna in the
desired direction.  If you can string up your antenna broadside to the desired
direction and make it longer you can get some useful gain.  There are various other
sorts of wire beams you can try as well, depending on the orientation of your
supports relative to the required direction.


Each of these will improve your chances of making the desired contacts.  I'd start
by looking at plots of the optimum frequency vs. time of day to cover the path:
running more power isn't going to help if the ionospheric isn't cooperative.

« Last Edit: October 28, 2012, 12:23:45 PM by WB6BYU » Logged
KD2CJJ
Member

Posts: 369




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« Reply #6 on: October 28, 2012, 05:04:11 PM »

I have a dipole at 35 feet and almost never hear the west coast from Ny.  I hear and reach Eastern Europe about 10 times more than the west coast.  I hit Angola with psk but still nothing fromcalifornia.
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73

Mike
KD2CJJ
W8JI
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Posts: 9296


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« Reply #7 on: October 28, 2012, 05:13:50 PM »

I have a dipole at 35 feet and almost never hear the west coast from Ny.  I hear and reach Eastern Europe about 10 times more than the west coast.  I hit Angola with psk but still nothing fromcalifornia.

What band?

On 160 meters, 35 feet is far too low.

On 10 meters, 35 feet is decent height.
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WD4ELG
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Posts: 877




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« Reply #8 on: October 28, 2012, 08:51:30 PM »

When you say "communicate" do you mean SSB?  Because it's going to be harder with that mode than with CW.  Digital modes will be easier than SSB also.  Just something to consider.  RTTY and even PSK31 can do wonders on HF with lower power and simple wire antennas.
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KG6SII
Member

Posts: 27




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« Reply #9 on: October 28, 2012, 09:53:22 PM »

Thanks for all your responses.  I think I will hang a dipole for 80m-10m from the tallest trees, and orient the broadside more towards the North-East, and see how that works.  Then I will try bands, frequencies, and time of day. If that doesn't perform better than my current 20ft-tall dipole, I'll try one of the other wire configurations you mentioned.

Thanks again
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WX7G
Member

Posts: 6204




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« Reply #10 on: October 29, 2012, 02:31:44 AM »

I ran W6ELProp (free software) to see what the path from California to Connecticut is like with the solar conditions of today. It shows 80, 40 and 20 meters being the bands to use.

80 and 40 meters provide a path from 0200 to 1000 GMT and 20 meters from 1400 to 2200 GMT.

The take-off angle for all bands is 11 degrees. Getting the antenna high will help.

 



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W8JI
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Posts: 9296


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« Reply #11 on: October 29, 2012, 05:28:47 AM »

Thanks for all your responses.  I think I will hang a dipole for 80m-10m from the tallest trees, and orient the broadside more towards the North-East, and see how that works.  Then I will try bands, frequencies, and time of day. If that doesn't perform better than my current 20ft-tall dipole, I'll try one of the other wire configurations you mentioned.

Thanks again

If you are planning on a multiband doublet, like a 130 ft antenna fed with ladder line, it will only have maximum radiation broadside on 80-40 meters.

If you are planning on a fan dipole or trap dipole, it should have maximum radiation broadside on most bands.
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NA0AA
Member

Posts: 1042




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« Reply #12 on: October 29, 2012, 07:50:55 AM »

Hm.  If you want a point to point circuit, there are tools that can help you.

If you say no beams for price, wire beams since you won't need to rotate it.

Wire v beams and rhombics if you have the space.

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WB2WIK
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Posts: 20635




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« Reply #13 on: October 29, 2012, 10:03:01 AM »

Glenn, I know your area pretty well and also look at your location on Google Earth, which shows you're at about 1046' above sea level and have a pretty clean shot towards New England.

I'm in L.A., only about 150-200 miles down the coast from you and work New England every single day with strong signals on various bands, it's not hard.  I do have a beam on a tower, however I can work most of those guys without it (just with a dipole) until the band really fades.

One trick is, of course, following propagation: The band closest to the m.u.f. is almost always the one most "open," and this changes all the time.  There were times this past weekend when 10 meters was definitely the "most open" band and produced the strongest signals from 2500-3000 miles away (and farther).  There were times 10m died and 15m was much better, and when 15m dies, 20m will usually be best.  From where you are to New England, 80m would never be the best band unless you are both very well equipped.

Your wire antenna appears too low and maybe also too close to the house, from the pictures on your "home page."  New England from here isn't "east," it's pretty much "northeast."  If you had a 20m dipole (not 63' long, but more like 33' long), center with coax, up 25-30 feet and oriented so its broad sides looked NE and SW, that would almost undoubtedly work better than what you're using now (on 20 meters).  If your home has stucco or lightweight cement tile roofing, keep the antenna as far away from the house as possible!  Those things are terrible RF dielectrics. 

It appears you have some trees there, I'd be using those to support my antennas in lieu of a tower.





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KF6ABU
Member

Posts: 351




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« Reply #14 on: October 30, 2012, 12:11:08 PM »

your dipole is way to low, way to close to roof.

Put a wire 4 square in your trees on 40m, fixed location.

Make a 20m wire vertical yagi in the trees, fixed location.


All set.
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