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Author Topic: 2m SSB  (Read 4411 times)
KC2NVL
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Posts: 2




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« Reply #15 on: April 12, 2017, 01:00:45 PM »

You may be a bit out of range but you can always check out the 205 Morning Rroup.  Stan KA1ZE serves as "net control" and helps get stations to connect with one another.  Check out his page at http://205morningreport.com
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KA4WJA
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Posts: 893




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« Reply #16 on: April 18, 2017, 06:21:15 AM »

Ed,
I'm coming in 2 weeks behind....but hope to offer some info/background that might help? Smiley

I assume by now, you've found good luck in your 2m SSB operating, and you probably also took N4OGW's advice to check out last nights 2m Spring Sprint...

(Bottom Line: get whatever antennas you have, up as high as you can....and get as much power as you can to these antennas, and you should find 150 mile communications to be easy-peasy!!)

First off, here are some brief, specific notes for you....
2 questions

1) Using a pair of A144 S5 with phasing harness, feed with 40w using Ft-897, should I be able to reach St. Louis, MO from Marion, IL 150 miles away?
Yes....but...
a) but, the height of your antennas will be of great impact here, especially getting them above obstructions (above buildings, hills, etc....and hopefully above the tree line)!!
b) but, 40 watts out of the radio, won't be 40 watts to the antennas....hence low-loss cabling can be of help here...or a higher-power transmitter...
c) but,  be aware that these antennas are not really optimum for this purpose...
Although Diamond spec's them at 9dbi....they are really a 4-element yagi on a 1/2-wavelength boom...probably about 7dbi to 7.5dbi...and stacking them should yield only 9.5dbi to 10dbi at best...
So, for calculations, use 10dbi as your overall antenna gain...


2) Anyone here in the Eastern Mo, Southern IL, Western KY or Southwestern IN willing to point their 2m array at me to try to make a contact on 2m SSB?
Recommend you take N4OGW's advice:
"K0TPP and KF4WE are not far from you and are quite active.
I suggest trying the 2M spring sprint coming up Monday, 4/17/17 from 7 - 11 PM local (central time):

https://sites.google.com/site/springvhfupsprints/home "


Thank you for the many replies.  I have taken many of the precautions and steps as noted above.

Fiber glass pole as mast
Except for the strength / durability issues,  there's nothing wrong with a fiberglass mast...BUT...
But, there's NO problem with metal mast either, it's perpendicular to the antenna elements, therefore no need to worry about a non-conductive mast...


Currently spaced 44 inches apart (manual says 40 - 48, so I split the difference)
They are horizontal with feed point in same orientation
Local test indicates I am getting out
Still waiting on longer cable and warmer/drier weather to get them higher.
Higher is always better...especially getting them up above obstructions!! Hills, buildings, etc. have serious effect on your range...and even trees/foliage has some effect on VHF/UHF (and trees will wipe out microwave signals altogether!)
I can't stress enough, having a high-gain antenna, high up!!

But need easy access because they are going to be used for Field Day.

I went to SSB because my FT-897 can do it and I still only have a Technician class license.  I am working to enourage our local Tech class to engage in
the operations our class allows as a learning tool.
Good for you!!
I also share this information with the local Boy Scout units under the STEM initiative to see if I can
generate some interest in Amateur Radio.


If you don't mind some further info / background??
Here goes... Smiley

Ed, as you may already know, the communications that you're referring to is called "tropo-scatter", and is the day-in / day-out normal mode of "beyond line-of-sight" communications on VHF/UHF frequencies...and if you overcome the path losses involved (which can be quite large, for the longer ranges), it is a VERY reliable (and predictable) 24/7/365 mode of communications.

Use of high-gain antennas, low S/N ratio modes (such as SSB, or even better CW)....with narrow bandwidth receivers, are all quite common, and allow for regular / reliable communications in the several hundred mile ranges, across VHF and UHF bands.


Here is an excerpt of some info I posted a couple years ago, for non-technical laypersons, when discussing "beyond-line-of-sight" VHF communications....

Quote
Beyond "line-of-sight"?? How is that possible??

  Is this something exotic?? Actually, No....
No, it is not exotic at all, to the contrary it is normal and common....and is actually VERY reliable and VERY predictable (out to the distance where path loss exceeds the available transmit powers and antenna gains).....And, this is called "tropo-scatter"
"Tropo-scatter" might sound exotic and rare, but it is anything but!  It is simply how almost all VHF and UHF signals (radio, TV, ham radio, data, etc.) travel beyond line-of-sight..."Tropo-scatter" is simply the spreading of the radiowaves in the troposphere, caused by the natural irregularities in our atmosphere...

  The troposphere extends from approx. 1000' - 3000' above sea level up to approx 35,000' above sea level....with most of our "scattering" occurring between 10,000' and 30,000' (although a "tropo-duct" is usually very narrow and defined, "tropo-scatter" uses most of the troposphere, and for longer ranges it uses the upper portion of the troposphere..)
 The atmosphere above the troposphere is fairly stable, has little humidity, and has a fairly even temperature cline, hence little irregularities to "scatter" VHF signals...but, using extremely large antennas and high-power transmitters it is possible to make reliable contacts beyond the "accepted maximum tropo-scatter range" of 600 - 700 miles.... (US military has had tropo-scatter links across sections of the ocean, spanning 900 - 1000 miles!)

  In addition to radio and TV broadcasting, VHF and UHF "tropo-scatter" has been in regular use by both military and commercial users for 60 some years now....and while some of the legacy commercial tropo-scatter communications links have been replaced by newer satellite data links, there are still many in operation.....not to mention the 10's of 1000's of ham radio operators that use "tropo-scatter" daily (some unknowingly, of course)...and if you've read about "over-the-horizon-radar", well this is "tropo-scatter-radar" (primarily UHF, but some VHF as well)....
 FYI, the first reported use of VHF "tropo-scatter" was way back in 1928, by Guglielmo Marconi, using a 30mhz system, for a link between Sardinia and the Italian mainland!!! (but, the elegance of this mode of propagation wasn't examined much until the early/mid 1930's...)

Let me be perfectly clear here:

VHF (and UHF) "Tropo-scatter" is a 100% / always-there, communications mode/path, and is NOT any special mode, does NOT rely on any special conditions to exist at all....It is simply the way that VHF, UHF, and SHF signals propagate beyond the direct-wave (beyond line-of-sight)....
  For these reasons, most laypersons will erroneously call this "ground-wave" (which it is NOT at all like, as VHF and UHF signals have no real "ground-wave" at all!!), but "tropo-scatter" is simply the way VHF, UHF, and SHF signals propagate beyond line-of-sight...and since the phrase "tropo" is in there, some will think that this is relying on some atmospheric enhancement and therefore could not be thought of as reliable, but to the contrary, it does not rely on any special atmospheric conditions, and hence is 100% reliable (up to the distance where the received signal no longer is useful, when the transmit powers and antenna gains, fail to over-come the "tropo-scatter path loss")

 Wide-bandwidth modes such as FM Voice are not the usual means of utilizing "tropo-scatter", due to their inherent noise-limited receivers and need to attain threshold in order to have any real useful signal-noise performance....but, if significant transmit power and high-gain antennas are employed, wide-bandwidth "tropo-scatter" can accomplish many wonderful things (such as provide multiple voice circuits and multiple high-speed data links to/from North Sea oil rigs and the mainland, etc.)




While having your antennas as high as possible is always a good idea, and it always increases your "line-of-sight", for vhf/uhf tropo-scatter the two primary reasons for increasing antenna height are:

a)  allowing signals to pass above any obstructions....even tree tops / foliage can have rather surprising effect, especially on UHF (and will block most microwave signals completely)...

b)  reducing the antenna's max lobe of radiation, thereby increasing the down-range location where you will have the most signal still within the troposphere, as it is the air molecules in the atmosphere that do the scattering, and the higher in the troposphere, the less air there is to scatter/reflect your signal....so, increasing your antenna height / reducing its radiation angle, increases your theoretical maximum tropo-scatter range (again, assuming you have enough transmitter power and antenna gain to overcome the path loss...)

In general, the higher the antennas the better....up until 10 to 15 wavelengths in height (for 144mhz, that's about 70' to 100' above average terrain)...after 15 to 20 wavelengths, there is little further advantage...


Although horizontal beamwidth can get quite narrow and if looking for extreme range you may end up missing some random contacts due to having too large of an antenna (stations outside of the beamwidth of your antenna)... Smiley
For absolute maximum tropo-scatter range, the higher (and higher gain) antennas, the better...and, if you want some more details, specifically why most will go with one large yagi, rather than stacking...here is some opinion from OZ1RH, in Denmark:
Quote
The angle of radiation for horizontal polarization is only dependent of the antenna height over reflecting ground. Using a vertical stack of two horizontal beams will concentrate the energy at the lowest radiation angle determined by the average antenna height, so stacking is recommended, but stacking does not "pull down" the radiation angle. The radiation angle of the stack is the same as from one antenna mounted at the average antenna height, but the stack will put more power (say +2.5 dB) out at this angle. Vertical stacking of two beams will mean the average antenna height will be in the middle of the two beams, that is half the stacking distance lower than the upper beam. This means higher radiation angle than using the upper beam alone. Stacking requires a higher tower in order to get the same angle of radiation. If your situation is a fixed tower height consider, that stacking will mean more power in the lowest loop, which will be at a higher radiation angle than using just one antenna at the top. The net result of stacking two beams relatively low over the ground will be more power below 1 degree where it counts for troposcatter, but not an improvement of the expected 2.5 dB. The net result is dependent of your tower height and the terrain (flat or sloping), so you should do some calculations for your situation. If you want a 2.5 dB improvement for troposcatter and your tower is only a few wavelengths high you might be better off putting up just one beam with the double boom length at the top of your tower.


Ed, I hope this helps....and while, there is an awful lot more to all of this ("tropo-scatter"), including lots of math and how you can quite accurately calculate your 99% reliable maximum VHF tropo-scatter range, etc.....
I think this should get you going... Smiley
(but, if you want more...just ask... Smiley )


73,

John,  KA4WJA

« Last Edit: April 18, 2017, 06:24:55 AM by KA4WJA » Logged
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