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Kilowatt
Member
Username: Kilowatt
Post Number: 64
Registered: 2-2004
| | Posted on Tuesday, October 19, 2004 - 10:17 pm: | 
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I can normally don't have any trouble getting back to my base station from the mobile at up to 45 or so air miles away. After that, it get's "iffy."
However, there are lots of hills around here, and I'm not exactly in the best spot in the area for commnunicating on the CB.
I was wondering how far ya'll can usually talk. Can you notice any difference in range using AM instead of SSB? How about using FM? Or, do you hate SSB in general, and still get out good on the other modes? |
Road_warrior
Intermediate Member
Username: Road_warrior
Post Number: 133
Registered: 7-2004
| | Posted on Tuesday, October 19, 2004 - 10:39 pm: |
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Usually, you can talk farther on SSB than AM.
FM is for short range communication.
45 air miles with Hills is good.
Range of Communication depends on your equipment,
conditions, location & all that good stuff.
I like talking AM skip rather than SSB skip.
But, locally sometimes when i talk to my
friend while he's driving to work, we switch
to SSB for better & longer communication.
JIM/CENTRAL PA/CEF 375 |
That ELCO Guy (Unregistered Guest)
Unregistered guest
| | Posted on Wednesday, October 20, 2004 - 8:35 am: |
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I looked up the math to determine how far line of sight to the "Radio Horizon" would be for any given antenna.
If the CB antenna was a legal 60 feet the radio horizon in miles would be the square root of 120 (60 times 2) or almost 11 miles.
If you get confused an easy way to approximate the line of sight is to remember that an antenna, per the book, at a height of 98 feet (you can say 100 feet) has a line of sight to radio horizon of right at 14 miles. Using the CB example abve 60 feet is 60 percent of 100 feet or 14 times .6 (or 8.4 miles give or take a mile or two). Using the rule of thumb 100 feet equals 14 miles, close enough for government work.
So if you are talking to someone 40 miles away you are not talking direct but rather using Ground Wave (bouncing your signal in a low bounce off the ground) to communicate. Non VHF signals can and do bounce over their radio horizon for added distance making it appear that the line of sight between stations is greater then it actually is.
Another example of this appearance of distance is as follows. I can and frequently/routinely have had conversations to stations on the other end of my home state (Louisiana). The distance was over 200 miles. That distance (given my wire antennas) is way way too short for a sky bounce. And my antennas are by far and well way tooooo low for a line of sight to radio horizon of 100 miles. Those conversations happened because I bounced my 80 meter signal off the ground to achieve apparently added distance.
It is interesting to note that "IF" CB were in the VHF or UHF frequency range the distance of any communication would depend largly on height of the antenna. But being that the frequency used is not VHF but rathe High Frequency the distance traveled is largly dependant on atmospehric conditions rather than antenn height. Antenna Heights advantage comes in when one factors in ability to talk in a local fashion--high is good.
Just in case anyone wants to look up the math for determining line of sight, look up 'Line of Sight' in the index of any Amateur Handbook.
I hope I have not confused yall
Got to go to work.
Signed
That darned ol ELCO Guy
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Barracuda
Intermediate Member
Username: Barracuda
Post Number: 268
Registered: 3-2003
| | Posted on Wednesday, October 20, 2004 - 10:55 am: |
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Elco,
If you are talking 200 miles on 80M you may be operating NVIS (Near Vertical Incidence Skywave). This is a method used around 40m,80m and 160m by military and others for "short-range" HF communications.
The link below explains it for anyone interested.
NVIS Link
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Kilowatt
Member
Username: Kilowatt
Post Number: 65
Registered: 2-2004
| | Posted on Wednesday, October 20, 2004 - 10:07 pm: |
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Thanks for the posts, ya'll!
However, I was actually interested in how far folks PERSONALLY communicate on CB - especially in the desert regions over flat earth, from on top of mountains, etc. You know, just their personal experiences...
Hi Elco! Yep, you're probably running NVIS on 80 meters. I've got a 75 meter full wave loop at 35 feet for NVIS, and can cover a radius of about 300 miles to a similarly equipped station on SSB or AM. That's with 100 watts PEP on SSB and 25 watts carrier on AM.
Now running 1300 watts into my verticals-that's another story!
On 40 meters, the loop's lobes are a little lower, and I can cover out to 500 or so miles during the day. That's on AM or SSB, too.
On 6, 2, and 70cm I can troposcatter out to 400 miles 24/7. However, this is to a similarly equipped station. All this takes is at least 60 feet H.A.A.T., 100-plus watts, and a beam with over 10dBd gain. Oh yeah, and an unubstrocted horizon for at least two miles. I can usually get out about 150 miles on any of these bands to the mobile. (I use M2 loops, and an Icom 706 MK2G in the mobile.)
However, on cb, I only run an old PDL II quad at 40 feet and legal power. So, it is a real challenge to get out well.
Just curious about the experience of others.... |
Road_warrior
Intermediate Member
Username: Road_warrior
Post Number: 136
Registered: 7-2004
| | Posted on Wednesday, October 20, 2004 - 11:01 pm: |
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I live in PA with Mountains all around me.
So, distant talking isn't great around here.
There are others on this forum that live on
mountains, flat areas of the country ect.
Hopefully they will read this post & give
you there personal experences.
JIM/CENTRAL PA/CEF 375 |
That ELCO Guy (Unregistered Guest)
Unregistered guest
| | Posted on Wednesday, October 20, 2004 - 11:44 pm: |
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Re Barracuda....
Before I post my post let me explane what NV is. Near Vertical is when the antenna you are using shoots its signal strate up and it bounces off the ionized layers of the atmosphere reflecting down in an upside down V shape. The signal spreads out over a couple of hundred miles.
Back to the B guy...
It would be a near vertical thing if I were using a horizontal to earth full wave loop to focus the signal strate up with a bounce off the ground as a kicker. But my antenna in question is an Inverted V about 60 foot to the vertex feedpoint.
As near as I can figure out I am transmitting that distance with a combiation of a little of both short sky skip when the conditions are right and as conditions fail the little extra from the ground skip helps in the waining period.
Well at any rate I have been building my own wire antennas for more years then I care to think about and I have never "Completely" understood how any of them work under all conditions. Somethings must remain a mystery I guess.
Later
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Kilowatt
Member
Username: Kilowatt
Post Number: 67
Registered: 2-2004
| | Posted on Thursday, October 21, 2004 - 2:07 am: |
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Hi Elco!
Good deal with the inverted V at 60 feet. Those inverted V antennas are great!
I know what you mean about the wire antennas -they are lots of fun. However, I don't think I really understand exactly how they work, either! I guess the "mystery" keeps it interesting!
I just got the ARRL's "More Wire Antenna Classics" book in, and will be buying LOTS of wire very soon :-)
Ever made a 160 meter wire vertical? I'm thinking about doing it, but haven't found anyone who has actually built one, yet....
I notice that you live in Louisiana. I live in Florence, Mississippi. Maybe I can catch you on one of the ham bands sometimes? Got any 70cm SSB stuff? I just put up a beam for that band, and am always looking to talk to folks "up there..."
Road Warrior,
I live in the middle of some really big hills, so I know where you are coming from! (Luckily my folks live on a BIG hill, so I've got most of my stuff in their old fallout shelter ;-)
Maybe some of your "neighbors" will post, too!
73
Steve / AC5CH / CEF392
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2ir473
Member
Username: 2ir473
Post Number: 59
Registered: 7-2002
| | Posted on Thursday, October 21, 2004 - 8:04 pm: |
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Since the band conditions have fallen off for DXing, I am talking locally with operators that are 25-35 miles from me, and the signals are all S7 to S9 (using my Galaxy 2547 base and Imax 2000...36' at the feedpoint).
I can also talk with some operators that are 65-85+ miles away, when the band is quiet. A 2 tube power adder helps to boost the signal for a better copy at their end.
Base to mobile distances can easily be in the 30-40 mile range.
I talk to my wife every morning in our vehicles, as we both travel in opposite directions to work. That distance is probably close to 20 miles when we are both destinated. She uses a stock Grant LT and I run either a Ranger TR-696 FD1 CB radio or Magnum 257 (depending on vehicle used). Signal levels are probably S3 to S5 at the farthest distances, but still understandable.
Mobile antennas are a Larsen NMO-27B and a Wilson 5' Silverload or Wilson 1000.
All 11 meter communications are sideband mode.
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Barracuda
Intermediate Member
Username: Barracuda
Post Number: 270
Registered: 3-2003
| | Posted on Thursday, October 21, 2004 - 11:29 pm: |
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Elco,
I understand what the NV in NVIS is. I suggested you MAY be in that mode because you said you were using a low wire antenna on 80m. Not knowing the actual type and height of your antenna system I could not be too sure. |
That ELCO Guy (Unregistered Guest)
Unregistered guest
| | Posted on Friday, October 22, 2004 - 2:18 pm: |
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Re kilo man....
And yes I do have a 160 vertical (of sorts). I have an inverted L antenna in the back yard for 160 meters that consumes only 50 feet of horizontal space. I managed to get some rope over the top of a 60 foot plus pine tree and pulled up a quarter wave of wire with a little over 70 feet in a vertical mode--I pulled the base slightly away from perfect verticl so as to get 10 extra feet of vertical orientation. Then I ran a quarter wave counterpoise along the boundries of my property (which is 100 by 75 feet Approx).
Relults. OK for the compromise that it is. Half decent range.
BUT I would much rather have put up a 50 ft telescopic pole in the middle of the lot sitting the ground on top of a ceramic isolator with a biGGGGGG top cap hat at the top of the telescopic pole, feeding it with a matching of inductance/cap in parallel. I say I would have ;-), because unfortunately the lot size is not exactly friendly to the guy lines that would be required, not to mention the ground field wires that would be needed to make the system efficient.
In the next life perhaps I will inherit and or own 10 square acres with all the trees in all the right places ;-).
That OL ELCO Guy
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That ELCO Guy (Unregistered Guest)
Unregistered guest
| | Posted on Friday, October 22, 2004 - 2:23 pm: |
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Hi B...
Just letting the good folk know what a NV antenna is.
I noted that the NV mode is not used very much in CB circles. Why I do not know. It is a very nice way to communicate on a regional level and can at times yield some interesting distance contacts as well.
May your day be productive.
That Elco Guy |
Highlander
Advanced Member
Username: Highlander
Post Number: 640
Registered: 12-2001
| | Posted on Friday, October 22, 2004 - 4:11 pm: |
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Elco Guy, what are some practical antennas that a Cber could experiment with for NV? (Layman's terms if at all possible, ;) ) |
Kilowatt
Member
Username: Kilowatt
Post Number: 68
Registered: 2-2004
| | Posted on Saturday, October 23, 2004 - 1:25 am: |
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Hi Ya'll,
Highlander, for NVIS experiments on CB, you could set up two beams pointing straight up toward the sky. This MIGHT produce some NVIS under certain conditions. However, being that the 11 meters is above the MUF most of the time, you'll probably only notice NVIS under SIGNIFICANT periods of enhanced ionospheric propogation. (If you hear skip, it might work at that time, for example...) Hey, experimenting is FUN - Go for it!
However, NVIS only works RELIABLY from around 1.8-12 MHz. 7-12 MHz are usually the best frequencies to use during the day, and 1.8-6.9 MHz are usually the best frequencies to use at night.
Thanks for the information on the 160 meter vertical, Elco! I really want to get on 160 meters now that the sunspot cycle is almost in the basement.
I might try feeding an insulated-base tower for 160 meters. I've got enough Rohn 25 to put up a quarter-wave element (about 126 feet or so). It would take LOTS of radials to work well, though....
I don't have much space at my house, either. However, there is a lot of space at my folks home, and they don't mind antennas!
Ya'll have a great weekend-I've got to get back to working on my SB-220. It has decided to eat a couple of capacitors. ;-0 |
Brewdirect
Member
Username: Brewdirect
Post Number: 57
Registered: 7-2004
| | Posted on Saturday, October 23, 2004 - 5:29 am: |
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In Vancouver, BC I can talk to Vancouver Island (2 hour ferry ride) consistantly on SSB, but that's over water...in local land area about 35 miles daily, 60 miles on better days. |
Tech808
Moderator
Username: Tech808
Post Number: 3912
Registered: 8-2002
| | Posted on Saturday, October 23, 2004 - 6:21 am: |
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Generally 30 to 40 Miles all day long Monday thru Friday to Beerman CEF #322 as he makes about 5 trips round a day back and forth from Bloomington to Pontiac, IL. and then he lives 35 miles away and also and can hit him anytime when he is home 24/7/365 on AM or SSB |
Kraigs
New member
Username: Kraigs
Post Number: 4
Registered: 1-2004
| | Posted on Saturday, October 23, 2004 - 7:51 am: |
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In the San Joaquin Valley I can talk up to 80 miles, in the direction my Moon Raker IV is pointed. That distance is increased if the station I'm talking to is in the mountains that surround the Valley. |
that Elco guy (Unregistered Guest)
Unregistered guest
| | Posted on Saturday, October 23, 2004 - 12:51 pm: |
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Re Hl...
Good afternoon...
The Kilo guy is correct in that in order for the Near Vertical (NV) to work the signal has to be able to be bounced in the atmosphere aka skip is possible.
And he K guy is right in that the ham bands offer a wider variety of frequencies to operate on a skip producing condition.
By the way hi Kilo.
Having said all of the above, I can tell you that I have worked NV on 10 meter ham bands before. So it is possible to do NV on the CB band if conditions are right.
You asked about antennas you might use. The least expensive is a simple loop antenna. Cut a piece of wire--say about #14 with the insulation left on--36 feet long. I used the frequency 27.300 to determine this length. The length of wire can change if you wish to use a different focus frequency. The math is as follows....length in feet is equal to 1005 divided by frequency in Mhz. Dont worry too much about the length being extremely exact.
After you have cut the wire to the proper length use a ceramic or plastic insulator and attach the center of the coax to one side of the loop and the ground to the other side of the loop.
Install the wire antenna so that it forms a loop, square, triangle or any other form needed so as to get the biggest hole in the middle that you can. Try to avoid making rectangles if possible. Hang the loop from trees or whatever so that it is horizontal to the ground at the very least out of reach of passers by.
The antenna will transmith broadside to the loop aka as if you were looking thru the loop in a bi directional fashion, both up and down. The up signal of course goes up and the down signal will be relfected in part back up.
Charasitics:
The SWR will probably NOT be anywhere near 1:1. But do not let that bother you. This antenna does exhibit some gain charastics. If the higher SWR bothers you you can get it to 1.5 or below by feeding the loop with a 1/4 wave length of 70 ohm coax and then feeding the 50 ohm coax into the other end of the 70 ohm coax. To save posting space I will not go into details here but if you wish to add this matching section to bring the SWR down let me know and I will email you the details.
The easiest way of course to make your radio happy and lower the SWR at the radio input would be to use an Antenna Tuner.
In closing I offer you a second option...
If you can (as noted above) get your hands on an old 3 element or an old PDL2 you can shoot the signal strate up. The antenna would not have to be high in the air, only just off the ground and where people will not walk into it or the lawn mower will not eat it. ;-)
good luck and good hunting.
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Freebird
Intermediate Member
Username: Freebird
Post Number: 150
Registered: 1-2003
| | Posted on Sunday, October 24, 2004 - 2:49 am: |
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i talk on 11 meters (cb radio) all the time..i talk to a buddy of mine whos 20 miles away no problem.id say i can talk about 60 miles or so without any skip.if i go above channel 40 i can talk even more miles. |
Applejack
Intermediate Member
Username: Applejack
Post Number: 221
Registered: 8-2003
| | Posted on Sunday, October 24, 2004 - 1:50 pm: |
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on a regular basis, when i talk no one answers, so the distance i talk is just to myself, not very far
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