Re: Topband: New TX antenna for 80 and 160?
Hi Rick- In regards to copperweld near the ocean, here in California wire near the coast, my copperweld has not held up too well as the steel rusts then fails due to intrusion through any damage to the copper surface. solid copper will last much better. BTW I understand the utilities use solid copper wire instead of copperweld or aluminum for same corrosion reasons. Someone else may be able to verify this info. I'd feed the dipoles with open wire and use a good matching unit.. possibly a remote unit and real open wire feed is also less noticeable. ( old Johnson Matchbox works for me everywhere except 160, I'm building one for 160. the 2 small holes coming into the shack easy to insulate and easy to fix laterit does take some ingenuity to route though) another possibility is a loop corner fed w/open wire, open at opposing corner for 160. makes a low visibility antenna, try modeling and see, my 235m square loop at 10m high does ok for a stealth antenna on 75/80/30/40. sometimes all you can do is try some things and see what works for u at a particular location. 73, Renée K6FSB Rick Kiessig wrote: Until recently, I was planning to put up an inverted-L as a TX antenna for 80 and 160. However, things have changed, and it no longer looks like I'll be able to run the radials I would need to have an effective vertical. Now I'm leaning toward a low dipole. My site is highly constrained: it's near the top of a ridge, on a slope, facing the ocean (100m above sea level, 300m from the water). The highest spot above sea level is the top of my tower: it's only 8.5m above immediate ground level (next to the house), although the ground 10m away is 7m lower. I can't run more than a wire or two and a coax feed on (not above) the ground - an FCP, for example, would be much too large. Due to limitations imposed by the city, I can't go higher than 10.5m above ground level. If I run a wire around three sides of my property in a U shape, hung from the tower near (but not at) the feedpoint, I can just hit 80m total length, with a 46m long center section and two 17m long end sections. The wire would attach to 10m high fiberglass poles near each of the four corners of the property. I recently built a dipole for 40/20/15 using 300 ohm twinlead, which worked out very well, so I'm thinking of using a similar approach for this antenna, using the full length for 160, and trimming one wire to be resonant on 80. I'd like to do whatever I can to maximize bandwidth. If I could cover both 80 and 75, for example, that would be great. Questions: -- Is a low dipole for 80 and 160 on a sloping site like mine worth the effort? I'm interested in DX, not NVIS. -- Given my constraints, are there other types of TX antennas I should consider? -- What's the best wire to use to minimize stretching and to maximize bandwidth and efficiency, and that can handle full legal power? I will need at least two (maybe three?) wires to cover both bands. Copperweld is strong, but I've heard it can be lossy, too. Twinlead has two wires, but it's stranded and doesn't feel very strong. -- I'm thinking about using Spiderbeam black fiberglass telescopic poles at the corners. However, I'm concerned about durability in high winds and having enough strength to be able to tension the wires so they don't droop terribly. Is there a better choice? -- I'm planning to put a common mode choke at the feedpoint and run coax from there, as I've done with the other dipole. Any reason to do it differently? 73, Rick ZL2HAM ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: New TX antenna for 80 and 160?
Hi Rick, I've been down this same road as you - starting with a low (18 metre) dipole, and after 1+ year of using it, I was only able to copy & work just (1) DX station from here in the Northeast US - that being DF2PY. I couldn't even work to the west coast of the US with the low dipole. Later, I replaced this dipole and installed an Inverted L with just (3) radials and worked lots of DX straight away - including VK / ZL. The difference between antennas was immeasurable - it was really that good. If you can manage just (1) bent radial with your Inverted L, it will still beat the low dipole if your interest is DX - especially at your QTH near the ocean. It won't be optimum, but it will work for you - and with just one radial you'll probably have 150-200 Khz of 2:1 bandwidth on 160m. Your questions: 1) Yes 2) I use a single 10 gauge copper clad wire for my "L". Even heavily loaded with ice every winter, I've never noticed this wire stretching in 4 years of use. Takes full power easily. 3) I have no experience with a Spiderbeam. 4) My Inverted L is fed direct from 50-ohm 7/8" hardline - no matching network whatsoever. 1:3 minimum SWR at resonance. 73, Dan KK3AN Rick Kiessig wrote: Until recently, I was planning to put up an inverted-L as a TX antenna for 80 and 160. However, things have changed, and it no longer looks like I'll be able to run the radials I would need to have an effective vertical. Now I'm leaning toward a low dipole. My site is highly constrained: it's near the top of a ridge, on a slope, facing the ocean (100m above sea level, 300m from the water). The highest spot above sea level is the top of my tower: it's only 8.5m above immediate ground level (next to the house), although the ground 10m away is 7m lower. I can't run more than a wire or two and a coax feed on (not above) the ground - an FCP, for example, would be much too large. Due to limitations imposed by the city, I can't go higher than 10.5m above ground level. If I run a wire around three sides of my property in a U shape, hung from the tower near (but not at) the feedpoint, I can just hit 80m total length, with a 46m long center section and two 17m long end sections. The wire would attach to 10m high fiberglass poles near each of the four corners of the property. I recently built a dipole for 40/20/15 using 300 ohm twinlead, which worked out very well, so I'm thinking of using a similar approach for this antenna, using the full length for 160, and trimming one wire to be resonant on 80. I'd like to do whatever I can to maximize bandwidth. If I could cover both 80 and 75, for example, that would be great. Questions: -- Is a low dipole for 80 and 160 on a sloping site like mine worth the effort? I'm interested in DX, not NVIS. -- Given my constraints, are there other types of TX antennas I should consider? -- What's the best wire to use to minimize stretching and to maximize bandwidth and efficiency, and that can handle full legal power? I will need at least two (maybe three?) wires to cover both bands. Copperweld is strong, but I've heard it can be lossy, too. Twinlead has two wires, but it's stranded and doesn't feel very strong. -- I'm thinking about using Spiderbeam black fiberglass telescopic poles at the corners. However, I'm concerned about durability in high winds and having enough strength to be able to tension the wires so they don't droop terribly. Is there a better choice? -- I'm planning to put a common mode choke at the feedpoint and run coax from there, as I've done with the other dipole. Any reason to do it differently? 73, Rick ZL2HAM ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Topband: New TX antenna for 80 and 160?
Until recently, I was planning to put up an inverted-L as a TX antenna for 80 and 160. However, things have changed, and it no longer looks like I'll be able to run the radials I would need to have an effective vertical. Now I'm leaning toward a low dipole. My site is highly constrained: it's near the top of a ridge, on a slope, facing the ocean (100m above sea level, 300m from the water). The highest spot above sea level is the top of my tower: it's only 8.5m above immediate ground level (next to the house), although the ground 10m away is 7m lower. I can't run more than a wire or two and a coax feed on (not above) the ground - an FCP, for example, would be much too large. Due to limitations imposed by the city, I can't go higher than 10.5m above ground level. If I run a wire around three sides of my property in a U shape, hung from the tower near (but not at) the feedpoint, I can just hit 80m total length, with a 46m long center section and two 17m long end sections. The wire would attach to 10m high fiberglass poles near each of the four corners of the property. I recently built a dipole for 40/20/15 using 300 ohm twinlead, which worked out very well, so I'm thinking of using a similar approach for this antenna, using the full length for 160, and trimming one wire to be resonant on 80. I'd like to do whatever I can to maximize bandwidth. If I could cover both 80 and 75, for example, that would be great. Questions: -- Is a low dipole for 80 and 160 on a sloping site like mine worth the effort? I'm interested in DX, not NVIS. -- Given my constraints, are there other types of TX antennas I should consider? -- What's the best wire to use to minimize stretching and to maximize bandwidth and efficiency, and that can handle full legal power? I will need at least two (maybe three?) wires to cover both bands. Copperweld is strong, but I've heard it can be lossy, too. Twinlead has two wires, but it's stranded and doesn't feel very strong. -- I'm thinking about using Spiderbeam black fiberglass telescopic poles at the corners. However, I'm concerned about durability in high winds and having enough strength to be able to tension the wires so they don't droop terribly. Is there a better choice? -- I'm planning to put a common mode choke at the feedpoint and run coax from there, as I've done with the other dipole. Any reason to do it differently? 73, Rick ZL2HAM ___ Topband reflector - topband@contesting.com
Topband: Beverages 2 basic questions----Tnks from LU2DKT
Martin, Carl and Bruce, many thanks for the graphics and suggestions. I think I can install one temporally to compare the results of a 900 feet against 600 feet. Many thanks to all for sharing opinion and experiencies. Eddy, LU2DKT ___ Topband reflector - topband@contesting.com
Re: Topband: ARRL 160CW from W7DRA
And I would like to add KH7X to that list, who was very patient and worked through the QRM and QRN to get my call correct. My first KH6 on 160, DXCC #85 on 160. It's a marathon, not a sprint, and I need more patience like KH7X. Mark WD4ELG -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of mike l dormann Sent: Sunday, December 02, 2012 3:02 PM To: ei4hq.m...@gmail.com Cc: topband@contesting.com Subject: Re: Topband: ARRL 160CW from W7DRA and I would like to thanks the magic ears and infinite patience of WD5R for picking me out of the wispy either mike w7dra this was a much tougher contest than last year from my chair Woman is 53 But Looks 25 Mom reveals 1 simple wrinkle trick that has angered doctors... http://thirdpartyoffers.juno.com/TGL3141/50bbb430b8adb34300729st03vuc ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: Inverted L + FCP Report
... and I ditto this! Worked better then previous Tees and L's with 32 radials for me. My L goes up 65' and the remainder of the 150' straight out. Worked perfect 1st shot, no trimming. Length was recommended by Guy! T U Guy K2AV! 73 de NS9I On 12/2/2012 7:47 PM, Markus Hansen wrote: Inverted L + FCP Report (December 2, 2012) Over the last approx. 20 Years I have operated in quite a few 160 contests from my city lot situated on a mountain side on rocky poor soil in North Vancouver BC which is located in the south west corner of the province. I have tried many different 160 meter antenna configurations to try and improve my score without much success. My latest antenna was a full wave very odd shaped 160 meter loop which was better than previous, loaded dipoles, dipoles and inverted L's fed against odd length radials in the ground. Several months ago I decided to give the inverted L another try but this time with a FCP replacing my ground radials. The FCP is located 15 feet above the ground over one end of our home. The vertical wire is 61 feet and then horizontal for 64 feet with another 51 feet of wire sloping down at 40 degrees from the end of the 64 foot length of wire for a total wire length of 176 ft. (I have two 90 foot trees on opposite sides of our city lot to support wire antennas) This puts the maximum radiating current in the top 1/16th section of the vertical wire above all the surrounding houses, trees, power line poles etc. Since the radiating element is longer than a ¼ wave length I matched it to 50 ohms at 1824 kHz with a series connected high voltage capacitor of 300 pf. The isolation balun was purchased from Balun Designs, Model 1142s as recommended by K2AV. The measured 2:1 BW is 52 KHz. I was active this weekend during the ARRL 160 meter contest running 100 Watts. I am very happy to report that I was able to hold a CQ freq. for lengthy periods and many stations called me. This has never happened before. Also in S&P most often I was heard on the first call even when the calling station was right at my receiver noise level. In addition I worked the following prefixes with little difficulty. PJ2, C6 XE, KH6, KH8, KL7 and JA's. I even had a JA call me when I was calling CQ. This never happened before. I called CE/K7CA several times and he came back with VE7? but he was unable to get the rest of my call. In addition, several times I heard local hams who run high power ( approx. +12 db advantage to my 100 watts) call someone and make a contact. I would call as well and every time I was also able to make the contact. Obviously my new antenna is working and my conclusion, it is working very well. Thank you Guy, K2AV for you research and Jack, W0UCE for publishing Guy's information on your web site at http://www.w0uce.net/K2AVantennas.html Markus North Vancouver, BC CANADA WEB: www.ve7ca.net ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Topband: Inverted L + FCP Report
Inverted L + FCP Report (December 2, 2012) Over the last approx. 20 Years I have operated in quite a few 160 contests from my city lot situated on a mountain side on rocky poor soil in North Vancouver BC which is located in the south west corner of the province. I have tried many different 160 meter antenna configurations to try and improve my score without much success. My latest antenna was a full wave very odd shaped 160 meter loop which was better than previous, loaded dipoles, dipoles and inverted L's fed against odd length radials in the ground. Several months ago I decided to give the inverted L another try but this time with a FCP replacing my ground radials. The FCP is located 15 feet above the ground over one end of our home. The vertical wire is 61 feet and then horizontal for 64 feet with another 51 feet of wire sloping down at 40 degrees from the end of the 64 foot length of wire for a total wire length of 176 ft. (I have two 90 foot trees on opposite sides of our city lot to support wire antennas) This puts the maximum radiating current in the top 1/16th section of the vertical wire above all the surrounding houses, trees, power line poles etc. Since the radiating element is longer than a ¼ wave length I matched it to 50 ohms at 1824 kHz with a series connected high voltage capacitor of 300 pf. The isolation balun was purchased from Balun Designs, Model 1142s as recommended by K2AV. The measured 2:1 BW is 52 KHz. I was active this weekend during the ARRL 160 meter contest running 100 Watts. I am very happy to report that I was able to hold a CQ freq. for lengthy periods and many stations called me. This has never happened before. Also in S&P most often I was heard on the first call even when the calling station was right at my receiver noise level. In addition I worked the following prefixes with little difficulty. PJ2, C6 XE, KH6, KH8, KL7 and JA's. I even had a JA call me when I was calling CQ. This never happened before. I called CE/K7CA several times and he came back with VE7? but he was unable to get the rest of my call. In addition, several times I heard local hams who run high power ( approx. +12 db advantage to my 100 watts) call someone and make a contact. I would call as well and every time I was also able to make the contact. Obviously my new antenna is working and my conclusion, it is working very well. Thank you Guy, K2AV for you research and Jack, W0UCE for publishing Guy's information on your web site at http://www.w0uce.net/K2AVantennas.html Markus North Vancouver, BC CANADA WEB: www.ve7ca.net ___ Topband reflector - topband@contesting.com
Topband: From the QRP point of view.
Wish I could thank all 140 stations that answered my call and wonder if the bone crushing signals like K8OO that didn't would care to know how many times I tried ? I especially want to thank TM6M, my only EU contact for the many, many repeats but most of all the US operators who patiently stood by moaning and groaning as this exercise went on (and on). Made some antenna changes Saturday in the snow and seemed to hear more but worked about the same. Experimenting continues. Thanks again, and looking forward to the Stew. 73, W1FMR / QRP ___ Topband reflector - topband@contesting.com
Re: Topband: Beverages 2 basic questions
- Original Message - From: "Tom W8JI" To: "topband" Sent: Sunday, December 02, 2012 12:46 PM Subject: Re: Topband: Beverages 2 basic questions resistors. Id guesstimate the general F/B to be over 20dB on 160. My feeling is that performance could not be duplicated by various other loading methods. If somebody wants to make real world comparisons it might be beneficial. I looked at slinkys when I lived in Conyers. None of this is magical or difficult, nor are antenna slinkys or helical loads "special". ** After I brought Slinkys up on the forums and on 160 in the late 80's and 90's. Your comments then were just what I expected. The behavior is the same as a series of lumped inductors spaced fractional wavelengths along the antenna. ** Maybe on paper which is why Ive asked others to make the real world comparisons. I find it hard to believe that a wire being randomly interrupted by a lossy lumped inductance plus capacitance can privide identical results. There is a certain optimum phase shift along an antenna's length. There are many ways to accomplish that, and if the resulting current distribution and phase is the same the results will also be exactly the same. ** Nothing beats a helice for a loading device for a steadily progressing phase shift. No guesswork needed. It even worked for high gain UHF transmitting antennas. Sometimes, like with long antennas fired away from the feedpoint, we don't want that delay. We actually might need a phase advance. ** Thats not related to the subject under discussion. The only thing magical about slinkys is how they can go down steps without feet, and without holding on to the banister! I never have figured that out. ** No magic involved in how they work as an antenna or as a toy, the toy part has been thoroughly explained ages ago. Carl KM1H ___ Topband reflector - topband@contesting.com
Re: Topband: ARRL 160CW from W7DRA
and I would like to thanks the magic ears and infinite patience of WD5R for picking me out of the wispy either mike w7dra this was a much tougher contest than last year from my chair Woman is 53 But Looks 25 Mom reveals 1 simple wrinkle trick that has angered doctors... http://thirdpartyoffers.juno.com/TGL3141/50bbb430b8adb34300729st03vuc ___ Topband reflector - topband@contesting.com
Topband: The Stew Perry TopBand Distance Challenge 2012
Greetings to the LowBand RF Benders, The Stew Perry TopBand DX Challenge is happening Dec 29/30 2012. Please click on: www.kkn.net/stewfor the exact times, rules, exchange, plaque info and a bunch of other cool stuff. Since you are an astute TopBander, you'll notice that The Stew Perry Challenge is a contest that uses distance in determining your score. It also utilizes your power to figure your score. Plus it even awards you more points when you work a low power or QRP station than a QRO one. Wow! It pays to scrounge up and dig out those QRP signals that are ignored in all other contests because it'll enhance your final number. The Boring Amateur Radio Club also requests that the contest combatants come up with what categories that they feel need to be honored. Listed below are the Radio Stalwarts who have already decided what categories need to be honored. They've communicated their ideas and sent in $60 to create a plaque that will be vigorously fought over by our audience. If you meet up with one of these radio giants personally, then shake their hand, buy them a beverage and thank them for their part in creating true peer recognition. KL7RA Top # of QSOs North Pole Contest Group TBD W2GD Team Top # of NA+SA QSOs by EU station AA6VB Top Score base loaded vertical <60' tall AA6VB Top Score Big City (>50K pop), Little pistol (<100W) K7CATop Score Southern Hemisphere K7CATop Score JA TF4M Longest QSO-Hi Power (both ends get a plaque) TF4M Top Score 160 mobile (must be truly mobile, not portable) W7RHTop Score S/O Low Power Zone 3 K7FL Top Score 100% Search & Pounce N5IA Top # of Grids worked K6ND Top Score World- K6SE Memorial NA0Y Top Score USA KR2Q Golden Log- Top # of Qs without a bust KH6LCVK-ZL Challenge- Top Score VK/ZL KE3X Top Score single element inv. L or T config, <70' max height VK6VZ N. Hemisphere station that works the most S. Hemisphere stations (Winner gets Flying Doctors of VK Baseball hat) The ARRL 160M test has concluded so you now have time to improve what you thought was a killer 160M station. The secret is to be able to hear. Most anybody can erect a verticalish monopole, sprinkle the ground liberally with radials and run QRO. That will make you affectionately known as an alligator or deaf or stupid but you must be able to receive the weak dits and dahs to complete a QSO. So go do what you can! If you don't know the Morse Code, then go learn it. 15-20 minutes a day with any of the several code practice programs will double the amount of contests you can participate in. Yes, I know you're old but you can learn a new trick. If you'd like to sponsor a non-prurient plaque then email me with your suggestion. We can do PayPal also. Thank you for your rapt attention. There will be further Stew Perry TopBand Challenge bulletins sponsored by The Boring Amateur Radio Club in the near future. 73 and I remain, LewW7EW The Boring Amateur Radio Club Committee on Exhortation w...@arrl.net ps. The 2011 plaques have been created and will be sent out soon! ___ Topband reflector - topband@contesting.com
Topband: Vertical vs. Shunt-Fed Tower
After many frustrating experiences with unwelcome interaction between various 160 antennas and towers, I am thinking about going back to basics by removing all the other 160 wires, and shunt feeding the 110 foot tower (which has a number of yagis on it). All else being equal (such as ground system), are there reasons why a shunt-fed tower would work differently than a vertical of the same height, on an insulated base ? 73, Steve, N2IC ___ Topband reflector - topband@contesting.com
Re: Topband: Patience in ARRL 160 Contest
TX antenna, never gave me so much as a QRZ for the several dozen times I called, and had his auto CQ set for a very short recycle time. One of the reasons why people do the short CQ recycle is to be able to hold the frequency. This morning a well known op who should have known better sent "?", waited 500 ms, and started CQ'ing on my frequency. Leaving the frequency "unattended" to listen to weak signals leaves the running station open to this kind of thing. Bottom line is that if you want to encourage QRP/weak DX, etc. learn proper frequency etiquette. QRL and LISTEN for at least 30 seconds before firing up your CQ machine. During the recent contest, in spite of running only 150W, I had the usual ESP level callers. Here is some advice for those with weak signals from my perspective as a running station: 1. Call EXACTLY (within 50 Hz or better) on my frequency. If you don't know how to do this, figure it out. If you are off frequency, I don't know if you are coming back to me, or some other station CQ'ing on the east coast. Also, I use a very narrow filter for weak signals. (There is the counter argument of multiple stations at zero beat, which is a problem if they are all weak.) 2. Call at my code speed. Not 10 WPM faster or slower as I often get. Turn down your keyer to QRS, rather than sending at 35 WPM and spacing out the characters. 3. Use a memory keyer with your call, 5NN, and section, so that you don't make sending mistakes, or make me guess at your bug or straight key fist. 3. Send only 5NN . Do not send my call, BK, etc 4. Respond with proper timing of about 1/2 second delay, so I don't miss the first character. The 1/2 second delay is also necessary to make sure I have stopped sending. However, don't wait more than a second. Again, this is necessary to make sure you are calling me, not some other station on the same frequency. I always get some calls 3 seconds or more after my CQ. Is he calling me? Often, this is clue that I have company on the frequency. 5. QSB. Often, a station will pop up out of the QSB briefly where I can get his call, but then waste time (see above) and fall back into the QSB before I can get his section. Be aware of this. 6. Antenna: if possible use a vertical, with top loading if you can. If you only have a dipole, operate it as a top loaded vertical if possible. Especially if the dipole is for some other band or a so called G5RV. I guarantee you will get out better in most cases. If you don't follow the suggestions above, I will still try to work you if I can; we both need the points. However, I do need to be cognizant of holding the frequency. Rick N6RK ___ Topband reflector - topband@contesting.com
Topband: 160m ARRL contest
Topbanders, thank you all for your advice and suggestions over the last days. DL0WH spent about 10 hours in the contest , managed to log 48 qso, scored 23 us-states (that is almost half the WAS over a single weekend!) and the virgin islands plus 4 canadian provinces. Heard FM5CD , CO6YAC, PJ2T , CE1/K7RA. I listened exclusively on the beverage me and my friend DM2GM installed here. I heard a lot more stations and a few more states than i could work, but can imagine the band was very noisy over there. We also set up an inv L over a FCP. Looks more like a Z or the figure 7, but seems to work very well. In direct competition with other EU-stations, DL0WH was copied first many times. Thanks to K2AV for his pile of informative Mails from earlier this year. I was very happy when i worked you in the test, Guy. Next step is to make the Bev reversible, i just began today make the transformers. I believe the virus has gotten me... -- Ohne CW ist es nur CB.. 73, Martin DM4iM ___ Topband reflector - topband@contesting.com
Re: Topband: Rationalizing my radial field through measurement
If I wanted to measure the radial and feedline AC current, not having any RF ammeters, I might just take a #47 lamp or other small pilot lamp and stick it in series with the radial and transmit into it. 40 mA will make a #47 lamp glow very dimly. Is this a good thing to check on? Probably not with series lamps, unless the radial impedance is pretty high. The measuring device or system must not significantly change the series impedance of the path or it will alter the results. If I find that some radials don't carry enough current to light up the lamp... is that a sign that the low current radial is not needed? Usually, but it also depends. Radials can have standing waves. What we measure at one point might not be what is happening 1/10th wave away. If other radials are carrying way more than average current... is this a sign I need more radials in that direction? Or is it the other way around? Or is this all academic and I just need another few thousand feet of copper wire? :-) I use one of these: http://www.mfjenterprises.com/Product.php?productid=MFJ-854 I designed that device to measure very low current levels, and (if they calibrate it correctly and still build it the same) to be accurate. It also does not change the circuit much. It's really a handy device for measuring current, it has a very wide dynamic range. I'm just not sure if, for what you are doing, it is necessary. I'd just use as many radials as I could as straight and long as possible, but not over a quarter wave or more than 30-40. I think sometimes we make too much worry or magic over things. :-) ___ Topband reflector - topband@contesting.com
Re: Topband: Beverages 2 basic questions
resistors. Id guesstimate the general F/B to be over 20dB on 160. My feeling is that performance could not be duplicated by various other loading methods. If somebody wants to make real world comparisons it might be beneficial. I looked at slinkys when I lived in Conyers. None of this is magical or difficult, nor are antenna slinkys or helical loads "special". The behavior is the same as a series of lumped inductors spaced fractional wavelengths along the antenna. There is a certain optimum phase shift along an antenna's length. There are many ways to accomplish that, and if the resulting current distribution and phase is the same the results will also be exactly the same. Sometimes, like with long antennas fired away from the feedpoint, we don't want that delay. We actually might need a phase advance. The only thing magical about slinkys is how they can go down steps without feet, and without holding on to the banister! I never have figured that out. ___ Topband reflector - topband@contesting.com
Topband: Rationalizing my radial field through measurement
My 160 TX antenna is also my 130-foot-doublet. It's up about 80 feet and fed with ladder line. To use on 160, I tie the feedline together at the bottom and feed against ground as something like a "Marconi T" using a L-network match right at the base. The rest of this post is about our favorite subject, "ground". The base of the T is the corner of the house. At this corner... one quadrant is the house. Another quadrant is the garage. The third quadrant is the driveway. And the fourth quadrant is the back patio. Everything is covered by building, concrete, or asphalt except for like a 45 degree wedge towards the back patio. So the radial system is at best haphazard. On contest weekends I make an effort to go out and unreel about 1500 feet of wire over the backyard, across the driveway to the yard, and across the garage floor and out the garage windows and over the lawn, and across the basement ceiling to the far side of the house. In all there ends up being about 24 radial wires of lengths ranging from 30 feet to 120 feet (the corner of the house is in no way, in the center of the yard, which is rectangular but also with some odd triangle corners too!). I might take a picture and post it just so you guys can laugh at it. If I were to measure RF current in each radial when TX at the 100 watt level, with the antenna system impedance of 30+100j (from modeling and in good agreement with actual L match), I would expect that antenna RF current equals ground current equals about one amp. So if one amp is evenly spread amongst 24 radials, an average AC current of maybe 40mA. There's probably some net RF current back through feedline too even though I've got a #31 ferrite core with coax round through it to serve as a choke there. If I wanted to measure the radial and feedline AC current, not having any RF ammeters, I might just take a #47 lamp or other small pilot lamp and stick it in series with the radial and transmit into it. 40 mA will make a #47 lamp glow very dimly. Is this a good thing to check on? If I find that some radials don't carry enough current to light up the lamp... is that a sign that the low current radial is not needed? If other radials are carrying way more than average current... is this a sign I need more radials in that direction? Or is it the other way around? Or is this all academic and I just need another few thousand feet of copper wire? :-) Tim N3QE ___ Topband reflector - topband@contesting.com
Re: Topband: Beverages 2 basic questions
- Original Message - From: "Eduardo Araujo" To: Sent: Sunday, December 02, 2012 12:48 AM Subject: Topband: Beverages 2 basic questions Many thanks Dean, Carl, Mike, Joel and the rest of you who shared your opinions about "why so many", probably I missed the point that 3 or 4 db in directivity loss because of deeps is much more important that I figured out and that could make a difference in a QSO or not. Keep in mind that without considering a very few stations, being in LU land I am really far away from all highly ham populated zones About my second question.. no takers ?? I repeat it here again just in case I modified the text of the second test for more clarity Is there a meaninfull or simple way to determine if at my location is worth to go from 600 to 900 feet? Ive no idea what the propagation data for signal arrival angles are for Argentina of if they even exist. To say its similar for US to AF as it is for LU to EU as an example would be guesswork. My suggestion would be to install a longer one and make A:B comparisons. Since a Beverage is non resonant distance seperation doent have to be extreme, 30-50' should be fine. Carl KM1H ___ Topband reflector - topband@contesting.com
Re: Topband: Beverages 2 basic questions
The same holds with loaded element yagis. Gain decreases due to RF losses but directivity is the same using the same boom length and number of elements as a full size version. Carl KM1H - Original Message - From: "Mike Waters" To: "topband" Sent: Saturday, December 01, 2012 2:47 PM Subject: Re: Topband: Beverages 2 basic questions It does? http://www.w8ji.com/slinky_and_loaded_beverages.htm Maybe Tom and Carl are both in on this conspiracy. ;-) 73, Mike www.w0btu.com On Sat, Dec 1, 2012 at 1:34 PM, Bob Eldridge wrote: You know very well that only the physical length matters for narrowing the lobe. ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5430 - Release Date: 12/01/12 ___ Topband reflector - topband@contesting.com
Re: Topband: Beverages 2 basic questions
Mike, Im pretty sure a group buy would convince the manufacturer to sell them. Supposedly an Ebay seller has an "exclusive" but since our use is non competitive to his SWL and cave dweller ham customers it could be negotiated. The large diameter steel ones work well but rust away in 15-18 months in this area of acid rain and salt water fogs. Using spray cans of Rustoleum, etc would be time consuming and likely needing periodic touchups. Plus the steel further slows down the incoming wave so it might not be possible to build an effective 1 wavelength + version. I had 5 stretched over about 175' and calculated a Vp of .57 but it sure worked gangbusters for those LP sunset signals over Africa. For many I was the only US station working them and the almost total lack of even EU QRM was a huge advantage. Switching to a 750' regular Beverage pointing right down the Med heard only a EU din; I'll let you estimate the F/S rejection of the Slinky. Using a high frequency local BCB station right off the back the null was at 1250-1300 Ohms using a 2K pot and replaced with 3 x 3900 Ohm 2W carbon resistors. Id guesstimate the general F/B to be over 20dB on 160. My feeling is that performance could not be duplicated by various other loading methods. If somebody wants to make real world comparisons it might be beneficial. Carl KM1H - Original Message - From: Mike Waters To: ZR ; topband Sent: Saturday, December 01, 2012 2:41 PM Subject: Re: Topband: Beverages 2 basic questions Please let us know how that works, Carl. I'd love to experiment with a Slinky. If brass Slinkys aren't available anymore, then we could wind one from some #14 or #12 solid copper wire using a long piece of plastic pipe as a form. Close-wind it first, then stretch it to the desired (?) pitch. 73, Mike www.w0btu.com On Sat, Dec 1, 2012 at 9:52 AM, ZR wrote: Next year Im planning to try a couple of Slinky Beverages again in order to get a 2-3 wave electrical equivalent for particular paths and narrow the beamwidth No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5430 - Release Date: 12/01/12 ___ Topband reflector - topband@contesting.com
Topband: electrical QRM during contest!
Did anyone hear massive QRM around 6:00Z during the ARRL contest last night? I've been trying to isolate a noise source but this was unlike than anything I have heard since the woodpecker and it had a fast attack like the woodpecker but was not the same sound. It extended into 80M as well and my local QRM I am DFing does not do that. When it started it seemed like the band activity dropped concurrently & I wonder if it was more than local. Thanks Gary, KA1J ___ Topband reflector - topband@contesting.com
Topband: ARRL 160CW from EI100T
Just a quick heads-up on what the ARRL160CW looked like from my chair (operating as EI100T from IO51uu near Cork); my log has just gone in with the grand total of 4 QSOs ;-) About 6 hours in the chair split evenly between Friday/Sat and Sat/Sun... Thanks to the magic ears of W2BC, N4UA, K3ZM & VY2ZM (the strongest signal by far), assuming of course I managed to copy the calls right. It wasn't easy. The complete list of got-aways (none of them were other than "very weak" to "extremely weak" on my K9AY); VE2OJ, VE3PN, NO3M, N4FX, W1WMU and K1DG. My pea-whistle 100w (into a 60' base loaded vertical with 32 quarter wave radials) failed to make the trip across the pond I'm afraid. Roll on the Stew, the contest highlight of my year :-) I'll be running as EI100T (Titanic 100th commemoration special event call) one last time before the licence expires on Dec31. -- Regards Cormac, EI4HQ [Cobh / UTC] ei4hq.cloudaccess.net www.corkharbourweather.ie ___ Topband reflector - topband@contesting.com
