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160M Mobile
Anyone out there know of any decent solution to getting 160M working in
a mobile? The application is a semi-truck. I've got the Iron Horses for 75, 40, 20, 15, and 10M, but I'd like to work something out for 160 meters that will work on the truck. I know I'm going to take an efficiency hit, but you're doing that for everything except 10M on a Semi anyway.. Just so I can get a signal out there to be heard, in the off chance. ANY suggestions or ideas would be greatly appreciated. 73 de AI8W, Chris |
"SideBand" wrote in message m... Anyone out there know of any decent solution to getting 160M working in a mobile? The application is a semi-truck. I've got the Iron Horses for 75, 40, 20, 15, and 10M, but I'd like to work something out for 160 meters that will work on the truck. I know I'm going to take an efficiency hit, but you're doing that for everything except 10M on a Semi anyway.. Just so I can get a signal out there to be heard, in the off chance. ANY suggestions or ideas would be greatly appreciated. 73 de AI8W, Chris Big screwdriver with a proper top hat and a good impedance match at resonance. The resonant feed point impedance must be a bit less than 10 ohms. I recall in QST a while back a guy who'd done WAS on 160 from his pickup, so it can work. 73 H. |
H. Adam Stevens, NQ5H wrote:
"SideBand" wrote in message m... Anyone out there know of any decent solution to getting 160M working in a mobile? The application is a semi-truck. I've got the Iron Horses for 75, 40, 20, 15, and 10M, but I'd like to work something out for 160 meters that will work on the truck. I know I'm going to take an efficiency hit, but you're doing that for everything except 10M on a Semi anyway.. Just so I can get a signal out there to be heard, in the off chance. ANY suggestions or ideas would be greatly appreciated. 73 de AI8W, Chris Big screwdriver with a proper top hat and a good impedance match at resonance. The resonant feed point impedance must be a bit less than 10 ohms. I recall in QST a while back a guy who'd done WAS on 160 from his pickup, so it can work. 73 H. And where, on a semi-truck, would you mount a big screwdriver with a proper top-hat? I'm not discounting the suggestion, but at the same time, I can't think of where I could possibly mount one. I was thinking something more along the lines of a mono bander that I could mount on one of the mirrors, that wouldn't be too large. Say, something with a loading coil somewhere along its length, and something that wouldn't be too expensive (Hopefully less than $50.00 US) to construct. However, I'm not sure that's the best solution, either, which is why I asked here. A screwdriver is not in my near future. I'm recovering financially from 3 months off last year due to a gallstone the size of a golf ball, and an accident in the truck earlier this month. Thanks for the suggestion. Any other thoughts? de AI8W, Chris |
On Thu, 27 Jan 2005 22:37:24 GMT, SideBand wrote:
Thanks for the suggestion. Any other thoughts? Hi Chris, Is this a tractor/trailer rig? Put a monster whip up front and pull it back to the trailer (where-ever) with a monster coil at the end and make the trailer the -ahem- top hat. Everything that could go wrong probably will.... 73's Richard Clark, KB7QHC |
"Richard Clark" wrote in message ... On Thu, 27 Jan 2005 22:37:24 GMT, SideBand wrote: Thanks for the suggestion. Any other thoughts? Hi Chris, Is this a tractor/trailer rig? Put a monster whip up front and pull it back to the trailer (where-ever) with a monster coil at the end and make the trailer the -ahem- top hat. Everything that could go wrong probably will.... 73's Richard Clark, KB7QHC Richard, you beat me to it. H. |
Richard Clark wrote:
On Thu, 27 Jan 2005 22:37:24 GMT, SideBand wrote: Thanks for the suggestion. Any other thoughts? Hi Chris, Is this a tractor/trailer rig? Put a monster whip up front and pull it back to the trailer (where-ever) with a monster coil at the end and make the trailer the -ahem- top hat. Everything that could go wrong probably will.... 73's Richard Clark, KB7QHC That's a great idea.. A long wire along the trailer... It's a flatbed, too, so I could use the stake posts to hold PVC pipes for antenna supports... Hrm.. Now if only the AH-4 tuner for my 706 would do 160M, I could just set up the wire and tune it, much like I did with the one on the old truck. I'll have to give that one some thought. Thanks Richard. de AI8W, Chris |
"SideBand" wrote in message m... Anyone out there know of any decent solution to getting 160M working in a mobile? The application is a semi-truck. I've got the Iron Horses for 75, 40, 20, 15, and 10M, but I'd like to work something out for 160 meters that will work on the truck. I know I'm going to take an efficiency hit, but you're doing that for everything except 10M on a Semi anyway.. Just so I can get a signal out there to be heard, in the off chance. ANY suggestions or ideas would be greatly appreciated. 73 de AI8W, Chris ============================= For design and performance of a 160 meter band vertical antenna, download program HELICAL3 from website below. There are other loaded vertical programs.. Use 1.5" or 2" diameter plastic pipe, with helical winding of thick enamel insulated wire, mounted on vehicle roof, as tall as possible, stayed, with short, top caapacitance tuning rod. Range on 160m with a few hundred watts = 100 miles at noon on groundwave. 1700 miles on very quiet, wiinter nights at midnight via F-layer. ---- .................................................. .......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. .......... |
stake posts around the perimeter and a wire around them... looks like a 160m
halo to me. "SideBand" wrote in message om... Richard Clark wrote: On Thu, 27 Jan 2005 22:37:24 GMT, SideBand wrote: Thanks for the suggestion. Any other thoughts? Hi Chris, Is this a tractor/trailer rig? Put a monster whip up front and pull it back to the trailer (where-ever) with a monster coil at the end and make the trailer the -ahem- top hat. Everything that could go wrong probably will.... 73's Richard Clark, KB7QHC That's a great idea.. A long wire along the trailer... It's a flatbed, too, so I could use the stake posts to hold PVC pipes for antenna supports... Hrm.. Now if only the AH-4 tuner for my 706 would do 160M, I could just set up the wire and tune it, much like I did with the one on the old truck. I'll have to give that one some thought. Thanks Richard. de AI8W, Chris |
Reg Edwards wrote:
"SideBand" wrote in message m... Anyone out there know of any decent solution to getting 160M working in a mobile? The application is a semi-truck. I've got the Iron Horses for 75, 40, 20, 15, and 10M, but I'd like to work something out for 160 meters that will work on the truck. I know I'm going to take an efficiency hit, but you're doing that for everything except 10M on a Semi anyway.. Just so I can get a signal out there to be heard, in the off chance. ANY suggestions or ideas would be greatly appreciated. 73 de AI8W, Chris ============================= For design and performance of a 160 meter band vertical antenna, download program HELICAL3 from website below. There are other loaded vertical programs.. Use 1.5" or 2" diameter plastic pipe, with helical winding of thick enamel insulated wire, mounted on vehicle roof, as tall as possible, stayed, with short, top caapacitance tuning rod. Range on 160m with a few hundred watts = 100 miles at noon on groundwave. 1700 miles on very quiet, wiinter nights at midnight via F-layer. ---- .................................................. ......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. ......... Chris's problem is that he has to keep the tip of the antenna below about 13.5 feet from the ground to be legal with the various DOT's. Dave WD9BDZ |
http://moonrakerukltd.com/amateur/mobile_w.htm
7 feet/160 METRE HELICAL WHIP WITH 3/8 BASE, BANDWIDTH (15 kHz) £49.95 |
Power mount to raise it up when you're parked, otherwise leave it retracted, lest a bridge give you a severe re-tuning incident. |
"David G. Nagel" wrote in message ... Reg Edwards wrote: "SideBand" wrote in message m... Anyone out there know of any decent solution to getting 160M working in a mobile? The application is a semi-truck. I've got the Iron Horses for 75, 40, 20, 15, and 10M, but I'd like to work something out for 160 meters that will work on the truck. I know I'm going to take an efficiency hit, but you're doing that for everything except 10M on a Semi anyway.. Just so I can get a signal out there to be heard, in the off chance. ANY suggestions or ideas would be greatly appreciated. 73 de AI8W, Chris ============================= For design and performance of a 160 meter band vertical antenna, download program HELICAL3 from website below. There are other loaded vertical programs.. Use 1.5" or 2" diameter plastic pipe, with helical winding of thick enamel insulated wire, mounted on vehicle roof, as tall as possible, stayed, with short, top caapacitance tuning rod. Range on 160m with a few hundred watts = 100 miles at noon on groundwave. 1700 miles on very quiet, wiinter nights at midnight via F-layer. ---- .................................................. ......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. ......... Chris's problem is that he has to keep the tip of the antenna below about 13.5 feet from the ground to be legal with the various DOT's. Dave WD9BDZ Chris Must the antenna also only mount on the tractor? I just thought of a multi-turn loop, corners as far forward and back, wide as possible, above the cab. Use a tuner and balanced feed. 73 H. |
H. Adam Stevens, NQ5H wrote:
"David G. Nagel" wrote in message ... Reg Edwards wrote: "SideBand" wrote in message .com... Anyone out there know of any decent solution to getting 160M working in a mobile? The application is a semi-truck. I've got the Iron Horses for 75, 40, 20, 15, and 10M, but I'd like to work something out for 160 meters that will work on the truck. I know I'm going to take an efficiency hit, but you're doing that for everything except 10M on a Semi anyway.. Just so I can get a signal out there to be heard, in the off chance. ANY suggestions or ideas would be greatly appreciated. 73 de AI8W, Chris ============================= For design and performance of a 160 meter band vertical antenna, download program HELICAL3 from website below. There are other loaded vertical programs.. Use 1.5" or 2" diameter plastic pipe, with helical winding of thick enamel insulated wire, mounted on vehicle roof, as tall as possible, stayed, with short, top caapacitance tuning rod. Range on 160m with a few hundred watts = 100 miles at noon on groundwave. 1700 miles on very quiet, wiinter nights at midnight via F-layer. ---- ............................................... ............ Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp ............................................... ............ Chris's problem is that he has to keep the tip of the antenna below about 13.5 feet from the ground to be legal with the various DOT's. Dave WD9BDZ Chris Must the antenna also only mount on the tractor? I just thought of a multi-turn loop, corners as far forward and back, wide as possible, above the cab. Use a tuner and balanced feed. 73 H. That's an idea, but most balanced tuners I know of are manual only, and it's hard enough keeping a 70-foot long, 80,000 lb vehicle on the road without trying to tune, too.. Thanks for the idea. de AI8W, Chris |
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Reg Edwards wrote:
"SideBand" wrote in message m... Anyone out there know of any decent solution to getting 160M working in a mobile? The application is a semi-truck. I've got the Iron Horses for 75, 40, 20, 15, and 10M, but I'd like to work something out for 160 meters that will work on the truck. I know I'm going to take an efficiency hit, but you're doing that for everything except 10M on a Semi anyway.. Just so I can get a signal out there to be heard, in the off chance. ANY suggestions or ideas would be greatly appreciated. 73 de AI8W, Chris ============================= For design and performance of a 160 meter band vertical antenna, download program HELICAL3 from website below. There are other loaded vertical programs.. Use 1.5" or 2" diameter plastic pipe, with helical winding of thick enamel insulated wire, mounted on vehicle roof, as tall as possible, stayed, with short, top caapacitance tuning rod. Range on 160m with a few hundred watts = 100 miles at noon on groundwave. 1700 miles on very quiet, wiinter nights at midnight via F-layer. ---- .................................................. ......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. ......... Reg: Thanks for this.. it'll help allot.. Question, though.. What should I put down for "earth electrode loss resistance"? I'll be using the truck's body as the ground plane. I'd just thought about doing this with a 2 foot (or so) 2 inch PVC pipe with end caps, feed point at the one end of the PVC, and a 102" whip out the other end. Now that I know this program exists, it's easier to think about! Since the SS whips are tapered, what would be a good guess for the diameter of it? Average it to 3mm? Or will it make that much of a difference? Thanks de AI8W, Chris |
"SideBand" wrote in message m... H. Adam Stevens, NQ5H wrote: "David G. Nagel" wrote in message ... Reg Edwards wrote: "SideBand" wrote in message y.com... Anyone out there know of any decent solution to getting 160M working in a mobile? The application is a semi-truck. I've got the Iron Horses for 75, 40, 20, 15, and 10M, but I'd like to work something out for 160 meters that will work on the truck. I know I'm going to take an efficiency hit, but you're doing that for everything except 10M on a Semi anyway.. Just so I can get a signal out there to be heard, in the off chance. ANY suggestions or ideas would be greatly appreciated. 73 de AI8W, Chris ============================= For design and performance of a 160 meter band vertical antenna, download program HELICAL3 from website below. There are other loaded vertical programs.. Use 1.5" or 2" diameter plastic pipe, with helical winding of thick enamel insulated wire, mounted on vehicle roof, as tall as possible, stayed, with short, top caapacitance tuning rod. Range on 160m with a few hundred watts = 100 miles at noon on groundwave. 1700 miles on very quiet, wiinter nights at midnight via F-layer. ---- .............................................. ............. Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .............................................. ............. Chris's problem is that he has to keep the tip of the antenna below about 13.5 feet from the ground to be legal with the various DOT's. Dave WD9BDZ Chris Must the antenna also only mount on the tractor? I just thought of a multi-turn loop, corners as far forward and back, wide as possible, above the cab. Use a tuner and balanced feed. 73 H. That's an idea, but most balanced tuners I know of are manual only, and it's hard enough keeping a 70-foot long, 80,000 lb vehicle on the road without trying to tune, too.. Thanks for the idea. de AI8W, Chris You don't have to use a balanced tuner. Terminate the loop into the truck body. What auto tuners cover 160? I never checked. 73 es gud luck de NQ5H |
H. Adam Stevens, NQ5H wrote:
"SideBand" wrote in message m... H. Adam Stevens, NQ5H wrote: "David G. Nagel" wrote in message ... Reg Edwards wrote: "SideBand" wrote in message gy.com... Anyone out there know of any decent solution to getting 160M working in a mobile? The application is a semi-truck. I've got the Iron Horses for 75, 40, 20, 15, and 10M, but I'd like to work something out for 160 meters that will work on the truck. I know I'm going to take an efficiency hit, but you're doing that for everything except 10M on a Semi anyway.. Just so I can get a signal out there to be heard, in the off chance. ANY suggestions or ideas would be greatly appreciated. 73 de AI8W, Chris ============================= For design and performance of a 160 meter band vertical antenna, download program HELICAL3 from website below. There are other loaded vertical programs.. Use 1.5" or 2" diameter plastic pipe, with helical winding of thick enamel insulated wire, mounted on vehicle roof, as tall as possible, stayed, with short, top caapacitance tuning rod. Range on 160m with a few hundred watts = 100 miles at noon on groundwave. 1700 miles on very quiet, wiinter nights at midnight via F-layer. ---- ............................................. .............. Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp ............................................. .............. Chris's problem is that he has to keep the tip of the antenna below about 13.5 feet from the ground to be legal with the various DOT's. Dave WD9BDZ Chris Must the antenna also only mount on the tractor? I just thought of a multi-turn loop, corners as far forward and back, wide as possible, above the cab. Use a tuner and balanced feed. 73 H. That's an idea, but most balanced tuners I know of are manual only, and it's hard enough keeping a 70-foot long, 80,000 lb vehicle on the road without trying to tune, too.. Thanks for the idea. de AI8W, Chris You don't have to use a balanced tuner. Terminate the loop into the truck body. What auto tuners cover 160? I never checked. 73 es gud luck de NQ5H The AT-180 does.. so does Alinco's long wire tuner (which can be made to interface to my 706Mk][G).. There are others, I'm sure It'd be nice to just press a button and tune the sucker, that's for sure. But I'd also like to do it for as few dollars as I can.. de AI8W, Chris |
SideBand wrote:
Reg Edwards wrote: "SideBand" wrote in message m... Anyone out there know of any decent solution to getting 160M working in a mobile? The application is a semi-truck. I've got the Iron Horses for 75, 40, 20, 15, and 10M, but I'd like to work something out for 160 meters that will work on the truck. I know I'm going to take an efficiency hit, but you're doing that for everything except 10M on a Semi anyway.. Just so I can get a signal out there to be heard, in the off chance. ANY suggestions or ideas would be greatly appreciated. 73 de AI8W, Chris ============================= For design and performance of a 160 meter band vertical antenna, download program HELICAL3 from website below. There are other loaded vertical programs.. Use 1.5" or 2" diameter plastic pipe, with helical winding of thick enamel insulated wire, mounted on vehicle roof, as tall as possible, stayed, with short, top caapacitance tuning rod. Range on 160m with a few hundred watts = 100 miles at noon on groundwave. 1700 miles on very quiet, wiinter nights at midnight via F-layer. ---- .................................................. ......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. ......... Reg: Thanks for this.. it'll help allot.. Question, though.. What should I put down for "earth electrode loss resistance"? I'll be using the truck's body as the ground plane. I'd just thought about doing this with a 2 foot (or so) 2 inch PVC pipe with end caps, feed point at the one end of the PVC, and a 102" whip out the other end. Now that I know this program exists, it's easier to think about! Since the SS whips are tapered, what would be a good guess for the diameter of it? Average it to 3mm? Or will it make that much of a difference? Thanks de AI8W, Chris I know.. bad form to reply to your own post... Got something here I think will work... Resonant at 1.903 h=.61 d=510 (around 2", plus the insulation thickness.) n=28 w=3 l=2.49 r=3 e=5 ohms Makes for a 4.6kHz bandwidth (not wide, but I knew that going into this...) with an efficiency of 2.4 %.. 16.2dB down from "ideal", and 50ohms (or close) with a 4.1uF cap. Of course, this is assuming that the whip doesn't have to be perpendicular to the centerline of the coil. If it can be parallel to the coil (perpendicular to the winds), then this might work... I hope. I'm gonna play with it some more, and see what I can dig up.. Maybe a larger coil form will give a wider bandwidth? de AI8W, Chris |
SideBand wrote: H. Adam Stevens, NQ5H wrote: "SideBand" wrote in message m... Anyone out there know of any decent solution to getting 160M working in a mobile? The application is a semi-truck. I've got the Iron Horses for 75, 40, 20, 15, and 10M, but I'd like to work something out for 160 meters that will work on the truck. Are the "iron horses" like hamsticks, but another brand? What I would do is get another one. Doesn't really matter what band, but I would get the one that is tallest physically, and uses a tall "stinger" whip. Then strip it down, and make a "plastic bugcatcher" with a new wider coil. I use this type of antenna myself, except that mine is 80-10 with a coil than can be tapped for each band. For a 160m whip with no hat, coil position will have a large influence on efficiency. So if say you used a junk 6 ft tall hamstick, I would wind the new coil at the top of that glass whip, and then clamp a tall "4-5 ft" whip to the top of that. Use a thin plastic form to wind the coil on. On mine, the the coil is wound on an appx 3 inch plastic tube, and is capped on each end with a plastic peanut butter jar cap. Melt a hole large enough for the glass whip to insert snugly up the middle of that coil form, and apply some glue, etc to hold it in place. For an 80m antenna built in this manner, you would need appx 80-85-90 turns or so, plus or minus...That is about a foots worth of winding on the 3 inch form, if the windings are made from an insulated wire, say 18 gauge or so. The insulation will add some spacing to the windings, which is good.. My antenna is a 6 ft glass stick, with the coil at the 5 ft level. The coil is about a foot tall, end extends to the top of that glass mast. I use a 5 ft stinger whip, so my total length is 10 ft, or appx 3.3 m. To use 160m on the same stick, your coil will be slightly more than 3 times as long, to keep the same winding ratio. So if say on 80, the coil was at the 5 ft level, on a 6 ft "1.5m" base mast stick, ".3 m coil length in Reg's vertload program", on 160m, the coil would be 1 meter long, and the bottom of the coil would drop to about the .8 m level, but still extend to the top of that glass mast. Thats a pretty tall coil, and will have some weight with all that wire..So I wouldn't get carried away with wire gauge...I'd use 16-18 gauge or so... Anyway, thats about the cheapest way to make a 160m antenna that will work halfway well. It's a bugcatcher electrically...Of course, you will need a matching device.. To see a picture of mine, go to... http://web.wt.net/~nm5k/fd03-1.jpg Thats about the only pix I can dig up that shows the whole antenna. It's on the truck utility bed, about 4 ft off the ground at the base... Even with the distant picture, you can make out the stinger whip at top... Will give you an idea what I'm talking about... That one is 10 ft total. The glass whip was a 6 ft 20m hamstick, that was stripped of it's top coil. The stinger whip is 5 ft tall. You can see the homebrew coil at about the 5 ft level, extending to the top of the glass whip. The stinger is held on by two small hose clamps. That's the 80m coil, which is nearly a foot tall. If you converted that to 160m, the base of the coil would have to drop 2-3 ft, in order to have the top of the coil at the top of the glass stick. I know I'm going to take an efficiency hit, but you're doing that for everything except 10M on a Semi anyway.. Just so I can get a signal out there to be heard, in the off chance. Yep...Using vertload, my antenna has about a 14.7 % efficiency on 80m, using 6 ohms as the ground loss number...On 160m, using the described 160m coil, and same overall length, ground loss number, efficiency would drop to about 2.07 % ... But, thats the way the ball rolls....It will still work... I've worked many 160m mobiles.. A small amp would help... I think one of the "hamstick" type companies makes a 160m "hamstick", if you don't feel like making one... One thing to remember....On 160m, ground losses will almost certainly overshadow coil losses, so trying to make a super duper efficient coil, with real thick wire, is generally a waste of time. Always use the longest stinger you can get away with..I also have a solid 3 ft base mast that I can add, and make the antenna longer "13 ft" and more efficient. In that case, the coil is 8ft up, instead of 5 ft. Efficiency jumps up a good bit. It's not the prettiest thing, but it works real well on all bands 80-10. And the best part was it didn't cost me a dime. There is a black wire that taps the coil, but you can't really see it in that picture. I also would like to make a 160m antenna, and might just make me one like I described. I'll probably have a stand alone 160m antenna, and go back to that one, on the other bands. I have a quick disconnect. MK BTW, if you are curious...That truck is my 68 F-250...It's kinda old... I now also have yet another old ford..."74 F-100" It's got a camper also... I'm trying to decide where to mount the antenna on it...Not as easy as that 68. ...I'll probably have to install a ball mount on the cab on the other truck... I have a thing about old trucks...Kind of an illness...:/ I may eventually swap one out, and buy another small car...Can't decide which one I like best though.. That 68 in the pix has nearly been rebuilt mechanically...New engine, front end, etc, etc, etc...Needs to be repainted though... But the 74 is a bit smoother, being a 1/2 ton, instead of a 3/4 like the 68..Maybe better for long trips. The camper is a bit bigger and about a ft taller on the 74 also... Yes, we have newer cars too, but I don't drive them too much myself...:/ I like my "war wagons". People stay out of my way... |
It would be quite
simple to weld up some angle-iron to make a mount for this, and keep the feed point low to the ground, so I can have a longer whip (higher efficiency! Yay!) on top of the load coil..................... I'd ground that angle iron as well as possible. Myself, I tried angle iron one time, and it didn't work too well. I did run an extra grounding strap to body/frame. But it wasn't enough...I think the problem was from a lack of metal area directly underneath the antenna. That seems to be fairly critical. When I moved it from that angle iron support behind the back window, and moved to the side toolbox, the low band performance was much better. The top of that utility bed toolbox is a pretty good platform, and is a few inches wide, and naturally, pretty well grounded. Maybe use real wide angle iron?? I think you will find the bandwidth to be fairly narrow. And swaying of the antenna vs body of the truck will vary the SWR a lot at that low freq. If it's rigid, or guyed some way, it will be more stable. Should be plenty enough for SSB bandwidth, but for multiple freq's, I'd add extra taps on the coil, to allow you to move around. I have three or four 80m taps on my coil... BTW, I was thinking about coil length vs wire size, and I may have been a bit off. An 80m coil of insulated 14 gauge would probably be about a foot... But 16 or 18 gauge would probably be a bit shorter. About wire size... In the past I had made coils using larger dia wire thinking it really mattered.. It does make a slight improvement, but I'd say slight...Hardly worth the extra weight...I made one using thick 14 gauge, and I can't tell a heck of a lot of difference compared to 16 or even 18 gauge. I think my present coil is 16 gauge wire. That antenna is *light*. About like a fishing rod and reel. Using thick wire will make the coil much heavier, and then you have to worry about it overly swaying, unless guyed. So I don't use overly thick wire anymore. If I make a 160 antenna, it will probably be 16 gauge...Maybe even 18... If you mount the antenna low, it does increase ground loss, but I think getting the coil that much higher from the base *should* override the increased ground loss. Or as good as I can calculate anyway...I've never actually mounted one real low yet to compare..I do have hitches...Maybe I could try an experimental antenna on my bumper/bumper hitch...Would give me about a 3 ft longer base under the coil, compared to it's current mount on the toolbox. Yea, vertload is pretty handy...I think probably the "Reg" program I use the most out of his vast collection. But I've been running these "plastic bugcatchers" for years...Since about 1990 I guess...I like the light weight. I've got a "real" 80 m bugcatccher coil, and just that coil alone probably weighs 5 times the total weight of that 10 ft antenna I have. It's heavy and requires heavy hardware to support it. But heavy hardware doesn't "talk" any better than light hardware..:/ MK |
Chris,
Diameter of whip or loading rod is not critical. Enter average diameter over its length. If not stated, bandwidth is between 3dB points when transmitting. When receiving, bandwidth is broader, say the 2 dB points, because the receiver input resistance damps down the very high antenna Q. Earth electrode resistance depends on size of vehicle and type of soil under it. For a mobile home enter 3 ohms. For a volkswagon beetle enter 14 ohms. A larger coil form will give a narrower bandwidth. Double length and height and for the same inductance (fewer turns), coil Q will also be doubled. You can't have high efficiency without high Q and narrow bandwidth. If a flexible whip is used, to reduce overall height it can be curved backwards in parallel with the vehicle's roof. This also allows fewer turns of thicker wire on the helix and a higher coil Q with greater efficiency. There will be an overall gain but not so great as if the whip is vertical throughout its length. Leave a gap equal to helix diameter between the bottom of the helix and a metal roof. The helix is in fact the L&C Z-matching coil. On 160m, in order to resonate with its own self-capacitance, it needs a large inductance. There will be several hundred turns. Therefore, to have a loss as low as possible it has to be physically large. The only space available is in the antenna - and that's why it's there. Ignore silly irrelevant done-to-death arguments about whether the current at one end of the helix is or is not the same as the other. The most important dimension of short verticals is overall height. Next comes physical size of helix. The fatter it is the better. Obesity is not a problem. Only the wind. ---- Reg, G4FGQ |
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"SideBand" wrote I've also changed my mind on using a SS whip on the top. 1" copper pipe would be better, and easier to guy/stabilize. 73 de AI8W, Chris Chris, a whip could however, be tied-down for streets with low hanging wires! 73, Jack |
Reg Edwards wrote:
Chris, Diameter of whip or loading rod is not critical. Enter average diameter over its length. If not stated, bandwidth is between 3dB points when transmitting. When receiving, bandwidth is broader, say the 2 dB points, because the receiver input resistance damps down the very high antenna Q. Earth electrode resistance depends on size of vehicle and type of soil under it. For a mobile home enter 3 ohms. For a volkswagon beetle enter 14 ohms. A larger coil form will give a narrower bandwidth. Double length and height and for the same inductance (fewer turns), coil Q will also be doubled. You can't have high efficiency without high Q and narrow bandwidth. If a flexible whip is used, to reduce overall height it can be curved backwards in parallel with the vehicle's roof. This also allows fewer turns of thicker wire on the helix and a higher coil Q with greater efficiency. There will be an overall gain but not so great as if the whip is vertical throughout its length. Leave a gap equal to helix diameter between the bottom of the helix and a metal roof. The helix is in fact the L&C Z-matching coil. On 160m, in order to resonate with its own self-capacitance, it needs a large inductance. There will be several hundred turns. Therefore, to have a loss as low as possible it has to be physically large. The only space available is in the antenna - and that's why it's there. Ignore silly irrelevant done-to-death arguments about whether the current at one end of the helix is or is not the same as the other. The most important dimension of short verticals is overall height. Next comes physical size of helix. The fatter it is the better. Obesity is not a problem. Only the wind. ---- Reg, G4FGQ Reg: Thanks for all the pointers. I've since found "vertload" as well.. I think I'm going to go that route. I can make something that will work for my purposes, and that's the point of all of this. Thanks for all these great programs. If the "real world" works as predicted, then I should have something set up for next winter. Back about 10 years ago, I built an antenna for my CB base (I wasn't a HAM then), and I was shooting blind. The SWR was, at best, 1.7:1, but boy did it get out. On the roof of the apartment, (2 stories tall) 3 blocks from the ocean in Oceanside, CA, I was able to hit Escondido on a legal 4 watts AM, 12 watts SSB, with an S7 or better... That's when I decided I liked working with building things. I've built every base antenna for both CB and HAM radio since then... Mobiles seem to act differently, and everything I've tried for mobile before now has come with mixed results. These programs you wrote for us will definitely be a big help. Thanks again.. I'm gonna play with these and see what I can come up with for high efficiency, decent bandwidth (10-15KC would be enough!), for the sizes I have to deal with. Then, when I build it, I'll play with getting it to behave as designed. 73 de AI8W, Chris |
Jack Painter wrote:
"SideBand" wrote I've also changed my mind on using a SS whip on the top. 1" copper pipe would be better, and easier to guy/stabilize. 73 de AI8W, Chris Chris, a whip could however, be tied-down for streets with low hanging wires! 73, Jack Jack: We're talking about a Semi tractor here.. It's already 13'4" tall, and in order to get this antenna where it would do the most good, it would have to be on one side or the other of the truck. Mounting it on the front bumper would make me over length, and make it impossible to open the hood for maintenance. Putting it behind the sleeper would raise it another 3 feet, and allow it to couple to the exhaust stacks, not to mention the back of the sleeper and the bulkhead on the trailer, and would kill the signal even more, not to mention the risk of having the trailer hit the antenna during turns, etc... A whip will also blow around and change the SWR depending on how close/far it got to/from the metal sides of the sleeper. I think a copper pipe will do better, and be easier to guy and keep out of the way. Thanks 73 de AI8W, Chris |
Chris:
I see you got lots of answers, but I don't think anyone mentioned the old WW2 approach. Back in the '40s, police radios were on 1600-1700 kHz, and mobile antennas were bumper mounted 8 or 10 foot bamboo fishing poles wrapped close wound with as much bell wire as you could put on them. And they worked amazingly well. I've never seen a shootout between one and a good loaded whip with a capacity hat, but for whatever reasons, I suspect the bamboo pole would come close. And it meets your other criteria, cheap. And which, now that I think about it, is equivalent to these fiberglass things they sell for other bands now. Hmmmm. -- Crazy George Remove N O and S P A M imbedded in return address "SideBand" wrote in message m... Anyone out there know of any decent solution to getting 160M working in a mobile? The application is a semi-truck. I've got the Iron Horses for 75, 40, 20, 15, and 10M, but I'd like to work something out for 160 meters that will work on the truck. I know I'm going to take an efficiency hit, but you're doing that for everything except 10M on a Semi anyway.. Just so I can get a signal out there to be heard, in the off chance. ANY suggestions or ideas would be greatly appreciated. 73 de AI8W, Chris |
Reg Edwards wrote:
"SideBand" wrote in message m... Anyone out there know of any decent solution to getting 160M working in a mobile? The application is a semi-truck. I've got the Iron Horses for 75, 40, 20, 15, and 10M, but I'd like to work something out for 160 meters that will work on the truck. I know I'm going to take an efficiency hit, but you're doing that for everything except 10M on a Semi anyway.. Just so I can get a signal out there to be heard, in the off chance. ANY suggestions or ideas would be greatly appreciated. 73 de AI8W, Chris ============================= For design and performance of a 160 meter band vertical antenna, download program HELICAL3 from website below. There are other loaded vertical programs.. Use 1.5" or 2" diameter plastic pipe, with helical winding of thick enamel insulated wire, mounted on vehicle roof, as tall as possible, stayed, with short, top caapacitance tuning rod. Range on 160m with a few hundred watts = 100 miles at noon on groundwave. 1700 miles on very quiet, wiinter nights at midnight via F-layer. ---- .................................................. ......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. ......... Reg, et al: On the Vertload program, I've been playing with the numbers a bit, and I've found some things that I have questions from the pro's on.. First, let me explain the situation: The Truck in question is a Ford LTLA9000. I plan on mounting this antenna 6-8 inches from the side of the tractor on a mount coming off of one of the fuel tanks, which are mounted just below the driver's/passenger's door. The cab (driving area) of the truck is about 4 feet shorter than the top of the sleeper. The cab is all steel. I use a mag mount 5/8 wave 2M antenna on top of the cab, with great results. The fuel tanks are aluminum. The straps mounting the fuel tanks to the frame are steel, and mount directly to the frame of the truck under the cab. The sides of the sleeper are steel, up to the level of the top of the cab. The top of the sleeper is fiberglass, with steel runner supports inside. I plan to mount the antenna off of the fuel tank straps, which will put it roughly 8" to a foot away from the cab, and the steel sides of the sleeper. I have several places I can guy the coil to on the side and top of the cab. I have one or two places I can put PVC standoffs on the cab and sleeper to keep the antenna away from the cab, and to keep it from "flying out" while rolling down the road. This truck, with a trailer on it and a full load (80,000 lbs gross weight) is capable of traveling at 117 MPH on a straightaway. Faster if I "turn around" the transmission again (no plans on that.. I'm getting too old for high speed "chicken truckin" anymore). I usually keep it down to around 70MPH when the speed limits allow. So, I've planned on using 1" copper pipe for both the mast and the "whip" at the top, for ruggedness. Inside the coil, I can use some 1" ID PVC for support, and put the 3" coil over those supports, with end caps, etc... Now, on the antenna, I've found that moving the loading coil up higher on the whip increases the efficiency. So: 1. Does that efficiency increase come at the cost of bandwidth? 2. Does having the load closer to the base increase the bandwidth, if all other numbers (coil diameter, coil length, etc) are the same? 3. Would getting the loading coil above the "steel" increase my chances of making a usable antenna with the bandwidth and efficiency I desire? I know I'm asking the impossible here; that is a wider bandwidth, higher efficiency, shortened 160M antenna for mobile operations. Like I said, I'd like to get about 10-15KC of usable bandwidth, with an efficiency that'll let me get an ERP of more than a watt or two with 100 watts in. On top of that, I'd like to build it. Hope this wasn't too much information, and I hope you all can make sense of this. 73 de AI8W, Chris |
1. Does that efficiency increase come at the cost of bandwidth?
Not sure...Never tested that...But it wouldn't suprise me if it did a little.. 2. Does having the load closer to the base increase the band width, if all other numbers (coil diameter, coil length, etc) are the same? Ditto....Not sure....But again, probably a bit... 3. Would getting the loading coil above the "steel" increase my chances of making a usable antenna with the bandwidth and efficiency I desire? Yes, as far as efficiency. Also using a hat would help a lot, although I know you may not be able to. But if you could design a hat, that would help current distribution a lot. Take a few turns off the coil too...But the more linear current distribution is the main benefit, I think more than any decrease in coil losses.... MK |
2. Does having the load closer to the base increase the band width, if
all other numbers (coil diameter, coil length, etc) are the same? ......... P.S...One reason I've never tested this, is because I've never base fed my antenna...MK |
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