Re: Topband: ITINERANT 160 M ANTENNA - Response Summary
Well said. - Wes Attaway (N5WA) --- 1138 Waters Edge Circle, Shreveport, LA 71106 318-797-4972 (Office) - 318-393-3289 (Cell) Computer Consulting and Forensics -- EnCase Certified Examiner --- -Original Message- From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com] On Behalf Of Tom W8JI Sent: Friday, August 03, 2012 8:49 PM To: bills stuff; topband@contesting.com Subject: Re: Topband: ITINERANT 160 M ANTENNA - Response Summary So gently getting back to the topic of the original post which was: Getting thoughts on relatively simple and relatively inexpensive portable 160 m antenna, potentially deployable by one person, that allows for flexibility and somewhat predictable tuning for use on modest Dxpeds or rare location indigenous ops.>>> Asking for the best antenna is like asking someone else to pick out a bride. All you can do is say a few universal things to look out for. It's almost impossible to tell someone what specific system would be best. Most of the differences are related to physical restrictions, unless something electrically important is done incorrectly. Most of the things we argue endlessly about, or work tirelessly on, are really for fractions of a dB or personal taste. 1.) If you use a small counterpoise, don't ground it with RF paths. Isolate the feedline from the counterpoise and isolate the counterpoise from earth. 2.) Don't fold back antennas in high current areas, because current causes EM radiation. Keep the high current area straight and as long as possible. 3.) Use the largest counterpoise possible, and use one that does not concentrate current, zig-zag current all around, or produce unnecessarily high voltages. 4.) Build something that you can install, and that will stay up. 5.) Most of all, pick the best location you can. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: ITINERANT 160 M ANTENNA - Response Summary
So gently getting back to the topic of the original post which was: Getting thoughts on relatively simple and relatively inexpensive portable 160 m antenna, potentially deployable by one person, that allows for flexibility and somewhat predictable tuning for use on modest Dxpeds or rare location indigenous ops.>>> Asking for the best antenna is like asking someone else to pick out a bride. All you can do is say a few universal things to look out for. It's almost impossible to tell someone what specific system would be best. Most of the differences are related to physical restrictions, unless something electrically important is done incorrectly. Most of the things we argue endlessly about, or work tirelessly on, are really for fractions of a dB or personal taste. 1.) If you use a small counterpoise, don't ground it with RF paths. Isolate the feedline from the counterpoise and isolate the counterpoise from earth. 2.) Don't fold back antennas in high current areas, because current causes EM radiation. Keep the high current area straight and as long as possible. 3.) Use the largest counterpoise possible, and use one that does not concentrate current, zig-zag current all around, or produce unnecessarily high voltages. 4.) Build something that you can install, and that will stay up. 5.) Most of all, pick the best location you can. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: ITINERANT 160 M ANTENNA - Response Summary
If youre stuck with on ground radials figure you wont have room for full size. In that case see if 50'x 2' rolls of galvanized chicken wire is available locally. Put out 4 rolls as spokes and wire together at the far ends and at the antenna base. Also solder the points where they start to overlap and several more places. The idea is to create an as complete ground screen as you have time for. If there is close salt water run some bare copper wire into it from the screen ends; lead fishing sinkers work well to keep them in place. Carl KM1H - Original Message - From: "bills stuff" To: Sent: Friday, August 03, 2012 3:44 PM Subject: Topband: ITINERANT 160 M ANTENNA - Response Summary So gently getting back to the topic of the original post which was: Getting thoughts on relatively simple and relatively inexpensive portable 160 m antenna, potentially deployable by one person, that allows for flexibility and somewhat predictable tuning for use on modest Dxpeds or rare location indigenous ops. Strawman proposal was for Inv L 50’(or more) alum mast with elevated radials all tuned with “hairpin” shunt coil – plus a request for suggestions and potential actual physical assistance with testing/assembly/distribution. Principal thoughts to date by TB types posted and direct: 1. More top wires than just one – doable with minimum additions provided the site has space. Should improve performance somewhat, requires top wire supports in other directions (which may only be a minor issue) and some more wire. 2. Mast higher than 50’ - I believe at 55’ (~17 m) it is still quite possible to hoist it up (maybe not walk up but a rope attached 1/3+ of the way up) 3. Use 18 m fiberglass telescope instead of alum. - Doable and can be walked up they say, but nearly twice as heavy as alum, more expensive and bending at top reduces effective height a bit. But still if you’ve got one . . . 4. Ground radials instead of elevated. - Could be good for some locations but requires 20+ m radius circle thick with wires. The innkeeper might not be pleased and also space may not be available unless you go the tent/generator route. I suppose the antenna product could be in two flavors, ground and elevated, with possible different tuning of the top wire. 5. Go to a site that has nicely spaced high palm trees (on the good propagation side of course) and then . . . - I welcome volunteer advanced palm tree scouts. Yet perhaps not all (or even most) interesting 160 m entities have palm trees. - Yet the point is well taken that a good site with advanced planning (Google Earth/eyeballs) is important (when possible). This matter has been looked at for KH8 but I am looking at broader uses as well. 6. Matching not worth the effort with modern ATUs - Yes but I would not think of trying a semi-serious 160 m effort with low power (or difficult to match antenna), and the high power matching units have $, size and weight issues. The current plan has the charm of a simple, flexible matching coil even at the expense of tuning by fiddling with top wire and/or elevated radial lengths 7. Receive antenna use - I purposely did not mention this just to see if it would be seen as an oversight among TBers. My only personal experience is I don’t have one and there have been a significant number of high end 160 stations (who surely have Rx ants) I could hear but could not hear me (my ant is a bit better than the one proposed here and with 500 w). Of course, his story may not hold up for a rare-ish DX station. Anything else? Bill N6MW ___ UR RST IS ... ... ..9 QSB QSB - hw? BK - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1424 / Virus Database: 2437/5174 - Release Date: 08/03/12 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: ITINERANT 160 M ANTENNA - Response Summary
So gently getting back to the topic of the original post which was: Getting thoughts on relatively simple and relatively inexpensive portable 160 m antenna, potentially deployable by one person, that allows for flexibility and somewhat predictable tuning for use on modest Dxpeds or rare location indigenous ops. Strawman proposal was for Inv L 50’(or more) alum mast with elevated radials all tuned with “hairpin” shunt coil – plus a request for suggestions and potential actual physical assistance with testing/assembly/distribution. Principal thoughts to date by TB types posted and direct: 1. More top wires than just one – doable with minimum additions provided the site has space. Should improve performance somewhat, requires top wire supports in other directions (which may only be a minor issue) and some more wire. 2. Mast higher than 50’ - I believe at 55’ (~17 m) it is still quite possible to hoist it up (maybe not walk up but a rope attached 1/3+ of the way up) 3. Use 18 m fiberglass telescope instead of alum. - Doable and can be walked up they say, but nearly twice as heavy as alum, more expensive and bending at top reduces effective height a bit. But still if you’ve got one . . . 4. Ground radials instead of elevated. - Could be good for some locations but requires 20+ m radius circle thick with wires. The innkeeper might not be pleased and also space may not be available unless you go the tent/generator route. I suppose the antenna product could be in two flavors, ground and elevated, with possible different tuning of the top wire. 5. Go to a site that has nicely spaced high palm trees (on the good propagation side of course) and then . . . - I welcome volunteer advanced palm tree scouts. Yet perhaps not all (or even most) interesting 160 m entities have palm trees. - Yet the point is well taken that a good site with advanced planning (Google Earth/eyeballs) is important (when possible). This matter has been looked at for KH8 but I am looking at broader uses as well. 6. Matching not worth the effort with modern ATUs - Yes but I would not think of trying a semi-serious 160 m effort with low power (or difficult to match antenna), and the high power matching units have $, size and weight issues. The current plan has the charm of a simple, flexible matching coil even at the expense of tuning by fiddling with top wire and/or elevated radial lengths 7. Receive antenna use - I purposely did not mention this just to see if it would be seen as an oversight among TBers. My only personal experience is I don’t have one and there have been a significant number of high end 160 stations (who surely have Rx ants) I could hear but could not hear me (my ant is a bit better than the one proposed here and with 500 w). Of course, his story may not hold up for a rare-ish DX station. Anything else? Bill N6MW ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
