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10m ground wave expectations
Not enough info , who is at 2500 and how high are the inbetween bumps?
seriously its like asking how long do i cook bacon before its cooked.... "Joey" wrote in message ... Hi, I'm trying to determine if I could use 10 meters to contact a station about 75 miles away with about 2500ft elevation of a couple sets of hills in between with just simple antennas on either end. Perhaps a 10m dipole on one end and some kind of stealthy one on the other. I assume this would have to be ground wave only given the distance and current band conditions. My parents are both techs so we're currrently limited to parts of 10m as the lowest band and I'd like to have something reliable without need repeaters for disaster comms. We actually only have a few single hop VHF/UHF repeaters between us, though quite a few linked ones. I've also thought of 6m due to smaller antenna requirements, but I'm pretty sure this is too far... Thanks! |
10m ground wave expectations
On 28 Apr, 09:55, John Smith I wrote:
Joey wrote: Hi, I'm trying to determine if I could use 10 meters to contact a station about 75 miles away with about 2500ft elevation of a couple sets of hills in between with just simple antennas on either end. Perhaps a 10m dipole on one end and some kind of stealthy one on the other. I assume this would have to be ground wave only given the distance and current band conditions. My parents are both techs so we're currrently limited to parts of 10m as the lowest band and I'd like to have something reliable without need repeaters for disaster comms. We actually only have a few single hop VHF/UHF repeaters between us, though quite a few linked ones. I've also thought of 6m due to smaller antenna requirements, but I'm pretty sure this is too far... Thanks! Just off-hand, I would suspect for reliable and consistent communications a three element yagi and ~100 watts on each end would result in enjoyable rag chews ... same for 6m. Height? More the better. Seventy-five miles on omni antennas is very chancy, in my humble opinion. But then, power/height would be the main variables, enough height and power would certainly help. Regards, JS Hmmmm. I would think that going to a frequency such as 144 MHz would be the way to go as radiation would tend to hug the earths surface.With 28 MHz the height factor not only be impracticable (point to point) but no amount of extra power is going to lower the TOA. When my son was in a hospital over 100 miles away he used his hand held to a local repeater and I used 10 watts with a directional antenna to the distant repeater with intervening land less than 100 foot elevation variance. Contact was always assured. Art |
10m ground wave expectations
"Joey" wrote in message ... Hi, I'm trying to determine if I could use 10 meters to contact a station about 75 miles away with about 2500ft elevation of a couple sets of hills in between with just simple antennas on either end. Perhaps a 10m dipole on one end and some kind of stealthy one on the other. I assume this would have to be ground wave only given the distance and current band conditions. My parents are both techs so we're currrently limited to parts of 10m as the lowest band and I'd like to have something reliable without need repeaters for disaster comms. We actually only have a few single hop VHF/UHF repeaters between us, though quite a few linked ones. I've also thought of 6m due to smaller antenna requirements, but I'm pretty sure this is too far... Thanks! I have been on 10m myself lately, having just upgraded. I find it nearly worthless for anything over fifteen miles. Without skip, you need an elevated antenna, high ERP or both. 75 miles is inside the skip zone; that is, if 10 were going to skip, it is still overhead at 75 miles and is going to come down farther away. Sure, investigate NVIS, but I think it needs a particular anntenna at *both* ends. If you're not committed to 10m, I would recommend 2m, since at least one end can have a high gain antenna. I use a 13-element yagi for 2m at Field Day and I routinely work dozens of stations 75 miles away (or more). We are in southern San Diego County and I work Los Angeles all day and night on 35w with the yagi at 20 feet. 2m is almost noise-free, too, both with respect to QRM and to receiver noise in FM mode. 73 |
10m ground wave expectations
art wrote:
... Hmmmm. I would think that going to a frequency such as 144 MHz would be the way to go as radiation would tend to hug the earths surface.With 28 MHz the height factor not only be impracticable (point to point) but no amount of extra power is going to lower the TOA. When my son was in a hospital over 100 miles away he used his hand held to a local repeater and I used 10 watts with a directional antenna to the distant repeater with intervening land less than 100 foot elevation variance. Contact was always assured. Art A couple of decades ago on 10 meters with a 3 element yagi and 100 watts, I frequently chatted with a grass valley station from a location in calaveras county, a distance of over 75 miles as the crow flies (also made a few contacts in San Francisco.) Antenna was 35 ft in the air and the other guy in grass valley had a similar setup. You never know, 'ya just never know ... but with two omni antennas, I doubt it would have been done. Now australia with an omni and a 100 watts? No problem with good sun spots! JS |
10m ground wave expectations
art wrote:
[...] By the way, antennas never intimidated me much ... The stacked 6 element hygain or mosley (modified CB antenna) on a 100 ft. tower with a ham m rotor was a real signal magnet and ionosphere burner ... I still have that antenna leaning up against a shed in the back 40 ... Only real problem with that antenna was forgetting to face it into the high winds in a storm and ripping the gears in the rotor. Regards, JS |
10m ground wave expectations
I have been on 10m myself lately, having just upgraded. I find it nearly worthless for anything over fifteen miles. Without skip, you need an elevated antenna, high ERP or both. 75 miles is inside the skip zone; that is, if 10 were going to skip, it is still overhead at 75 miles and is going to come down farther away. Sure, investigate NVIS, but I think it needs a particular anntenna at *both* ends. If you're not committed to 10m, I would recommend 2m, since at least one end can have a high gain antenna. I use a 13-element yagi for 2m at Field Day and I routinely work dozens of stations 75 miles away (or more). We are in southern San Diego County and I work Los Angeles all day and night on 35w with the yagi at 20 feet. 2m is almost noise-free, too, both with respect to QRM and to receiver noise in FM mode. 73 I have always been amazed with the 10m band. I usually have a look see there before I go to any other band. Lately, I have had no luck. I recall that a long time ago I worked an Italian station on 10 who was on a holiday at the beach. He was using a quarter wave whip stuck in the sand on the beach and 10 watts. He sounded like a local to me in Ohio. Sometimes an opening comes and goes like a summer breeze... Sometimes the band is open and nobody knows until someone calls CQ! John Ferrell W8CCW "Life is easier if you learn to plow around the stumps" |
10m ground wave expectations
"John Ferrell" wrote in message ... I have been on 10m myself lately, having just upgraded. I find it nearly worthless for anything over fifteen miles. Without skip, you need an elevated antenna, high ERP or both. 75 miles is inside the skip zone; that is, if 10 were going to skip, it is still overhead at 75 miles and is going to come down farther away. Sure, investigate NVIS, but I think it needs a particular anntenna at *both* ends. If you're not committed to 10m, I would recommend 2m, since at least one end can have a high gain antenna. I use a 13-element yagi for 2m at Field Day and I routinely work dozens of stations 75 miles away (or more). We are in southern San Diego County and I work Los Angeles all day and night on 35w with the yagi at 20 feet. 2m is almost noise-free, too, both with respect to QRM and to receiver noise in FM mode. 73 I have always been amazed with the 10m band. I usually have a look see there before I go to any other band. Lately, I have had no luck. I recall that a long time ago I worked an Italian station on 10 who was on a holiday at the beach. He was using a quarter wave whip stuck in the sand on the beach and 10 watts. He sounded like a local to me in Ohio. Sometimes an opening comes and goes like a summer breeze... Sometimes the band is open and nobody knows until someone calls CQ! A very good description of 10 meters, I talked ro North Dakota from Florida and thought the band was dead it was so quiet. I heard someone talking and thought they were local at first. 10 M is a fun band. Jimmie |
10m ground wave expectations
The local station here is at 1500 ft + 35ft hi gain vertical at 50W,
with a 2200ft ridge less than 5 miles away... back down to probably 1500 ft until... About 60 miles from here is the tallish 3500ish ft. mountains and then its down basically to sea level for the remainder. This does seem to produce a rather sharp angle at the both ends. So much so that I have trouble hitting the 3500ft repeaters from here without going up to the big antenna. I do remember hitting some repeater off to the side of the direct path about 10 years ago with just a handheld and some gainy portable antenna (don't even remember which one)... but haven't been able to find it since! Doh! I'll probably end up just finding some 2m stuff to work. We have a few linked 440 systems (California) too... Joey On Fri, 27 Apr 2007 20:40:51 -0500, Tom Ring wrote: Joey wrote: Hi, I'm trying to determine if I could use 10 meters to contact a station about 75 miles away with about 2500ft elevation of a couple sets of hills in between with just simple antennas on either end. Perhaps a 10m dipole on one end and some kind of stealthy one on the other. I assume this would have to be ground wave only given the distance and current band conditions. My parents are both techs so we're currrently limited to parts of 10m as the lowest band and I'd like to have something reliable without need repeaters for disaster comms. We actually only have a few single hop VHF/UHF repeaters between us, though quite a few linked ones. I've also thought of 6m due to smaller antenna requirements, but I'm pretty sure this is too far... Thanks! 2m SSB or CW with modest power and antennas have a great chance of doing what you wish. A better description of the terrain would help. 2500 above mean average terrain? (I doubt that but have to ask) A couple of hills. Sharp ridges? Above the line of sight? Probably still quite doable. I used to work from Potsdam NY to Plattsburgh NY (and a good chunk of Vermont) virtually every evening on 144.200 with a 12 foot yagi at 25 feet on my end, a 17 foot on the other, using about 60 watts, and the Tug Hill Plateau and a couple small mountains in the way. 2m "weak signal" is an often overlooked mode for 60 to 150 miles that is very reliable for point to point. tom K0TAR |
10m ground wave expectations
On Sat, 28 Apr 2007 05:38:38 GMT, Owen Duffy wrote:
Joey wrote in news:dd64339h0kluu9d5kqu0tff6h9r6nmpbdl@ 4ax.com: Hi, I'm trying to determine if I could use 10 meters to contact a station about 75 miles away with about 2500ft elevation of a couple sets of hills in between with just simple antennas on either end. Perhaps a 10m dipole on one end and some kind of stealthy one on the other. I assume this would have to be ground wave only given the distance and current band conditions. My parents are both techs so we're currrently limited to parts of 10m as the lowest band and I'd like to have something reliable without need repeaters for disaster comms. We actually only have a few single hop VHF/UHF repeaters between us, though quite a few linked ones. I've also thought of 6m due to smaller antenna requirements, but I'm pretty sure this is too far... Thanks! Joey, You have given a lot of information, and yet too little. The distance you nominate can be a challenge, yet routinely possible on frequencies from 28MHz to 440MHz, depending.... My thoughts are that simplex contacts will be unlikely without effective outside antennas, though not necessarily directional antennas, but they would help. You note you may have access to several repeaters, than can certainly equalise bad locations or impossible paths (eg granite), but then you might not want to conduct family chat on repeaters (though that is they way they seem to have gone here since many of our new six hour hams with their shack on their belt seem to be family members). An FM repeater in a very good location may support contacts reliably out to 150+km for each station, depending... Another possibility might be using IRLP build a path. To give you an example, I can work the 2m repeater at Mt Ginini (exceptional site) from the car on my driveway here at Narooma, 155km (~ 95mi) over mountains etc (but we don't have real mountains here do we?), it would be easier with a 5dB gain omni on the house. I could use a handheld to make the trip to a repeater 90km (~56mi) away and use IRLP to anywhere in the world (if I liked IRLP). Then by contrast, there would be places where you couldn't work a repeater 10km away with a handheld. So, it may be that a path via a VHF or UHF repeater might be more viable than 10m. Perhaps some experimentation is in order, that is what ham radio was about once. Owen It sounds like I pictured 10 meters as a lot lower that it really is... Sounds like it's really VHF-like during low cycles .. I'll probably go back to 2 or 440 and mess around tho there only a couple repeaters on 2m but a bunch on 440 that are linked. I am going to try to get at least my dad to upgrade to General tho. I think he'd like to have something long distance while camping, and HF is of course perfect for that :) Yes, back to experimentation!! |
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