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Author Topic: 2 Meter SSB  (Read 2349 times)
KI4DLK
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Posts: 16




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« on: February 20, 2004, 05:57:07 PM »

Im going to try 2 meter SSB and i would like to know the distance of 2m SSB with a directional antenna putting out 50 watts?
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WB2WIK
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Posts: 20595




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« Reply #1 on: February 20, 2004, 06:36:02 PM »

As has been discussed right here dozens of times, this cannot be predicted because there are too many variables.

Working "range" on two meter SSB is dependant upon...

-Antenna height above ground (note 1)
-Antenna height above average terrain (note 1)
-Antenna height above near field obstacles (note 1)
-The actual path between station 1 and station 2, including elevation contours over that path
-Antenna gain (note 1)
-Transmission line loss (note 1)
-Transmitter power (note 1)
-Receiver sensitivity (note 1)

(Note 1: For both your station, and the station you're trying to contact.)

With 8 major variables greatly influencing the outcome, usually it's anybody's guess how far you'll be able to work.  If you operate from atop the highest mountain in your area and have a 100-mile horizon, chances are your average working radius with a decent, horizontally-polarized two meter beam and 50 Watts will be 300+ miles, 24/7, without any extraordinary propagation.

There's no truth to the silly rumor that 2 meter propagation is "line of sight."  That's ridiculous, and not even close to the truth.  However, your visible horizon does play a role in your working "range," and the longer it is, the better.  And in all cases, the higher your antenna is above ground, the greater your working range will be -- without exception.  This single factor is probably the largest contributor to "long range" success on VHF!

Obviously, for SSB, you want to use horizontal polarization.  The larger your antenna (beam) is, the more gain it will have, but the narrow its pattern will be.  Good for "DX," not so good for general tuning around to find activity.  You can end up with a very high-gain antenna that's so "sharp" you can only hear stations in one direction, and have enormous rejection everywhere else.  Again, great if you know who you're aiming at, and not so great if you don't.

Everything's a compromise, but after 39 years on two meters working "weak signals" ("DX" stations, so to speak), my impression is that antenna height is paramount; location is very important but often cannot be changed, so shoot for the height!  Then, feedline loss, antenna gain, and having your antenna as much "in the clear" (above all local obstacles) are all very important.  Transmitter power, receiver sensitivity and actual equipment used falls much farther down the list, and should only be optimized after the "antenna" factors are.

BTW, from my modest home station in Los Angeles, on two meter SSB my average "working range" is about 250 miles in most directions, most of the time, when contacting similarly-equipped stations.

WB2WIK/6


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KI4DLK
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Posts: 16




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« Reply #2 on: February 20, 2004, 06:42:28 PM »

Ok Thanks for the info and the antenna im looking at is a cushcraft 20 element i think with 11.1dbi gain. I have alot of trees beside my house which might be a problem so i am trying to find a big enough mast to get the antenna im buying above them.
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WB2WIK
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« Reply #3 on: February 20, 2004, 07:08:19 PM »

Absolutely, positively get above those trees!

The CC 20 element 2m beam is really only a 10 element 2 meter beam in the horizontal plane, and another 10 element 2 meter beam in the vertical plane, so you can use it for both SSB and FM if you use both sets of elements.  It's not a *bad* antenna, but there are many available that are lighter and have less wind loading, with substantially more forward gain for use on 2 meter SSB (ignoring the FM stuff).

One example: The M2 model 2M9SSB.  It's only 9 elements, but it's on a 14-1/2' long boom (longer than the Cushcraft 20 element), and gain comes from *boom length*, not the number of elements.  It's also completely optimized for the SSB portion of the band, and it has substantially better performance for SSB work than the 20 element Cushcraft (sacrificing FM use).  Not only that, but it weighs less, so installing it up higher is easier!

Height is everything, until your antenna is up so high that it's absolutely the highest thing in your neighborhood and nothing is higher.  When you're at that level, then additional height will only gain you a bit longer horizon, with tropospheric propagation about 3x that improvement.  (For example, if your horizon is 10 miles with an antenna at 50 feet above ground and your antenna is already the highest thing in the neighborhood for several blocks around...increasing your antenna height so that your horizon becomes 12 miles will only gain you about 6 miles more in typical strong-signal working radius.  Not much.  But if your antenna at 50 feet high is blocked by trees or other obstacles, and increasing its height to 60 feet will get it above those obstacles, you can count on a tremendous improvement in working radius -- possibly the difference between working stations 50 miles away vs. working stations 200 miles away.  There *is* that much difference, once you get clear of everything.)

I remember an "Elmer" of mine, Neal Hubach W2KME of Springfield, NJ, who was a radio engineer with AT&T for many years and a very active ham, answering my question to him when I was a new ham and a kid: "On two meters, when do I know my beam is really high enough?"

Neal's answer: "When you're driving towards your house, and you're still a couple of miles away, and you look up, and the first thing you can see is your beam, before you see anything else in your neighborhood, it's high enough."

That's just about exactly right.

WB2WIK/6
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KI4DLK
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Posts: 16




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« Reply #4 on: February 21, 2004, 09:19:24 PM »

Alright Thanks for all the information im still looking for a big enough mast to get above those trees though.
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N9DG
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Posts: 314




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« Reply #5 on: February 27, 2004, 01:01:17 AM »

WB2WIK/6 is on the mark with his comments but I would add this additional consideration:

Do not under estimate the importance of the feedline.

There is a definite trade-off between antenna height and feed line length (and therefore losses). If for example there are a relatively small number of trees (that you can mostly see through for example) it may be actually be better to put more of the available $ into the feedline and not bust the bank trying to get the antenna above the those trees. If however you are in the deep woods then yes by all means be sure to get the antennas up above them, and still use the best feedline you can afford to feed the antenna.

Regular RG-8, RG-213, etc. types aren't really worth much at 2M unless the run is 25ft or less. The 9913fx, and LMR-400 (or equivalents) types are pretty good to about 50 feet and are passably OK to about 100 feet or so. If you can find (also can read as "afford" in many cases) a larger LMR600 or a 7/8 inch type of cable it is well worth the effort and expense to install it for a 100 foot or longer run. It will also add complexity since you will not be able to make rotor loops with it. As for the small diameter RG-58, RG-8x types? They aren't really worth bothering with except for really short jumpers inside the shack.

The other thing that can't be over stressed is the importance of matching polarization. The far majority of the 2M SSB types are all running horizontal antennas. The textbook 20dB loss due to polarization miss-match between vertical and horizontal is very real. 15 years ago I had an antenna with a rotator on the boom, I could easily loose a S7-9 signal by simply rolling the antenna from one polarity to the another. So if you can't afford a horizontal beam then a simple dipole or horizontal loop will pretty much outperform just about any other vertically polarized antenna (beam or otherwise) that you may already have when trying to work someone who is horizontal.
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WA9SVD
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Posts: 2198




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« Reply #6 on: February 28, 2004, 12:34:28 AM »

I have to agree and emphasize the importance of polarization matching.  While FM work is usually vertically polarized, weak signal and almost ALL SSB work is horizontal.  And the "theoretical" loss between cross (i.e., vertical vs. horizontal) polarized antennas is infinite, the real-world loss (due to real-world designs and anteenna patterns) will be 20 - 30 dB, and that's a substantial signal loss.  If you want to appreciate all 2M SSB can provide, you will have to use a horizintally polarized antenna.  And for the greatest results and enjoyment, that means a Yagi or similar directional antenna, as high as reasonably possible.  Even a modest antenna above the roofs and trees will be a great start.
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K7VO
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Posts: 1010




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« Reply #7 on: February 29, 2004, 04:36:36 PM »

All the comments here have been great so far and absolutely correct.  Feed your antenna with 9913 or Times  LMR 400 at the least.  LMR 600 is better if you can afford it.

I use a Cushcraft 10 el. beam (all horizontal elements) which is roughly the same as what you have.  Mine is 35' up.  Here's the catch:  I live in a CC&R (HOA) restricted area.  What I got past the architectural committee meant I could not go above the tree line (mainly pine trees) at  55'+.  The old county ordinance (now changed) also restricted me to 35'.  I will probably add a tower section this spring but I'll still be below the tops of the trees.

The good news:  I still get out.  OK, I don't get out as well as I would if the antenna was up higher and in the trees, but I still get out.  By all means get up as high as you can but if you have to compromise in the short term you can do so.  Better to have a less than ideal situation than not to be on the air at all.

73,
Caity
K7VO/4
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K9ZF
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Posts: 76


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« Reply #8 on: March 21, 2004, 03:42:42 PM »

All of this has been great advice, from experts on the topic, but I would like to add one detail.

This has been some pretty scary stuff, 100' towers, 15' yagis, LMR 600, etc...  Don't let it scare you away!  Get on the air with what you have, and upgrade to better equipment as you can.  Even if you have to use the CC yagi, on a short mast, you can still make lots of QSO's.  Yes, you may not have a 300 mile radius, but you may be surprised just how far you can reach.  SSB will allow you to make contacts you wouldn't dream of on FM.  Activity is the key.  Finding other folks in your area that are active on 2m ssb, and listening.  You may also want to check out the VHF/UHF email reflectors for lots of good info.

The stations the other guys are recomending are awesome.  But you don't have to have a Ferrari to drive to work, hi hi.

The minimums:

Make sure you have a horizontal polarized antenna and good feedline.

As you can, upgrade your equipment as follows:
1.  Replace your feedline with the lowest loss line you can afford.
2. Antenna height, make it higher!
3.  Antenna gain, as long a yagi as you can get. [BTW, homebrewing 2m yagis is fun!]
4. Probably last on the list, after everything else is optimised,  would be raising transmitter power and adding rx preamps...


And most importantly, HAVE FUN!!

73
Dan
Dan Evans K9ZF
Scottsburg, IN 47170
{EM78}
K9ZF /R no budget Rover
ex-N9RLA
Check out the Rover Resource Page at:
http://www.qsl.net/n9rla
QRP-l #1269
Central States VHF Society
IN-Ham list administrator
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--
K9ZF
Amateur Radio Emergency Service, Clark County Indiana. EM78el
The once and future K9ZF /R no budget Rover
 ***QRP-l #1269
Check out the Rover Resource Page at:
<http://www.qsl.net/n9rla>
List Administrator for: InHam+grid-loc+ham-books
Ask me how to join the Indiana Ham Maili
W4GRW
Member

Posts: 11




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« Reply #9 on: May 28, 2004, 11:50:30 PM »

Hey Michael,
This is Bill W4GRW, from Charlotte, what kind of horizontal beam antenna do you have?
Let me know I will be glad to assist you, there is a big contest in 2 weeks that you will be able to try out your station.
73 de w4grw
Bill
wvfisher-at-@earthlink.net
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W4GRW
Member

Posts: 11




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« Reply #10 on: May 28, 2004, 11:51:05 PM »

Hey Michael,
This is Bill W4GRW, from Charlotte, what kind of horizontal beam antenna do you have?
Let me know I will be glad to assist you, there is a big contest in 2 weeks that you will be able to try out your station.
73 de w4grw
Bill
wvfisher-at-earthlink.net
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