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In article , Richard Clark
writes: On 10 Apr 2004 14:59:24 GMT, PAMNO (N2EY) wrote: That's quite understandable, given that the original Lattin designed used tubular Twin Lead and countd on a velocity factor of 0.8. What sort of test gear and design methods did you folks use? Hi Jim, This hard to accept given the timelines offered by those who have reported the references. For one, the antenna was invented in the late 40's and patented 26 Dec. 1950, and reported in 1960. ALL such dates precede the introduction of tubular Twin Lead in the mid 60s. Hello again! Direct quotes from the 1960 QST article: "If open line with a velocity factor near unity is used for the stubs, the over-all lenght for a two-band antenna would be nearly a full free-space wavelength at the higher frequency and and the whole antenna would resonate at something less than half that frequency. Very fortunately, the the velocity factor of 300-ohm tubular Twin-Lead (0.8) gives such lenghts for the stubs that that, in most cases, the adding the stub makes the antenna resonate at just half the original frequency." "Fig. 3 shows how tubular Twin-Lead can be used for the antenna itself as well as the stubs and includes dimensions for 10- and 20-meter operation. The foam-filled type of Twin-Lead is recommended to keep out moisture." So it must have existed when W4JRW wrote the article, some time before the December 1960 QST went to press. In addition, my 1953-54 RESCO (Radio Electronic Service Company, once a great source of all things radio and TV here in the Philly area) catalog lists Amphenol "flat and tubular Twin Lead". The tubular stuff is number 14-271 and was 5 cents a foot - less in quantities of 100, 500 or 1000 feet. And it wasn't a new item. All of this supports both your experiences and those of others. If the exact characteristics of tubular Twin Lead are important to the design, it's no wonder that the reported results cannot be obtained. One more point. The SWR graphs shown for the 5 band version show quite narrow SWR bandwidths. If anyone is interested I can report them in a future post. 73 de Jim, N2EY |
N2EY wrote:
"Fig. 3 shows how tubular Twin-Lead can be used for the antenna itself as well as the stubs and includes dimensions for 10- and 20-meter operation. The foam-filled type of Twin-Lead is recommended to keep out moisture." Jim, I haven't been following very closely. Is it possible to describe this antenna with an ASCII diagram. Apparently on one band, the stub is installed at the 1/50 conductance circle to SWR circle intersection. -- 73, Cecil, W5DXP -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Cecil Moore wrote:
Jim, I haven't been following very closely. Is it possible to describe this antenna with an ASCII diagram. Apparently on one band, the stub is installed at the 1/50 conductance circle to SWR circle intersection. Never mind, I found the information at: http://www.g3ycc.karoo.net/lattin.htm -- 73, Cecil, W5DXP -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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In article , Richard Clark
writes: On 10 Apr 2004 18:25:04 GMT, PAMNO (N2EY) wrote: All of this supports both your experiences and those of others. If the exact characteristics of tubular Twin Lead are important to the design, it's no wonder that the reported results cannot be obtained. One more point. The SWR graphs shown for the 5 band version show quite narrow SWR bandwidths. If anyone is interested I can report them in a future post. Hi Jim, I stand corrected on the tubular twin lead (must've died in the mid-60s then). No biggie. I did not expect to find it in the 1953 catalog, but there it was, and not a new item either. Probably unobtanium now. It offers nothing substantially different to the physics of design however, just a different velocity factor which is scalable to suit any implementation. Lattin seemed to think it was important. Do you have the 1960 QST article? However, my data to this point confounds the "theory" of it all by exhibiting stubs that do NOT resonate at their computed length (complete with correction for ANY velocity factor commonly observed). More data is always appreciated. Well, here's the info from the 1960 QST article. Dipole dimensions: Innermost section (not a stub; shorted at both ends): 8' Next section (stub; open at inner end): 6' 11" [resonant at 10 meters?] Next section (stub, open at inner end): 13' 10" [resonant at 20 meters?] Outermost section (stub, open at inner end): 27' 5" [resonant at 40 meters?] Entire antenna 57' 2" per side (plus connections) SWR, 50 ohm coax, coax length not given (all numbers guesstimated from graph): 80 meters: Minimum SWR: 3725 kHz - 1.1:1 2:1 SWR points: 3625 & 3800 kHz (175 kHz) SWR at 3500: 5:1 SWR at 4000: 4.5:1 40 meters: Minimum SWR: 7225 kHz - 1.6:1 2:1 SWR points: 7150 & 7275 kHz (125 kHz) SWR at 7000: Off end of scale (5:1 at 7075 kHz) SWR at 7300: 3:1 20 meters: Minimum SWR: 14250 kHz - 1.3:1 2:1 SWR points: 14100 & 14375 kHz (275 kHz) SWR at 14000: 3.5:1 SWR at 14350: 1.8:1 10 meters: Minimum SWR: 28600 - 1.6:1 2:1 SWR points: 28500 & 28750 kHz (250 kHz) SWR at 28900: 3:1 Chart for 10 meters covers 28500 to 28900 only. No chart for 15 meters but text says it will work there on 3/2 wavelength resonance of 40 meter section and SWR of not less than 3:1. Note how tight the 2:1 SWR points are, even on the higher bands. -- Also described is an 80/40 dipole. Inner section is 28' and shorted both ends, outer stub section is 27' 5". Interesting feature of this one is that in order to achieve 40 meter resonance there are pieces of wire 2' 6" long hung from the junction of the two sections. The text and diagram say the outer section resonates on 40 but the inner section has to be kept at 28 feet or the 80 meter resonance will be too low. -- Seems to me that the classic W3DZZ trap dipole would be a lot less aggravation to model and get working, plus more flexible in choice of minimum SWR points. Particularly if additional "resonance wires" were added if needed. Certainly easier to make mechanically strong traps than stubs, and adjusting single wire lengths with Burndys is a lot easier than fooling with tubular Twin-Lead. 73 de Jim, N2EY |
N2EY wrote:
Innermost section (not a stub; shorted at both ends): 8' No wonder it didn't work on EZNEC. The web page I referenced had that as a stub. -- 73, Cecil, W5DXP -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
On Sun, 11 Apr 2004 02:07:31 GMT, Irv Finkleman
wrote: Hey Guys, Hi Irv, I have the original article here. If you want it I can scan it and send it to those requesting. Put me on your distribution list. If I were ever to go near this antenna again, I'd build a two band model which might be simpler, and of course now I have a MFJ-259B which might help a bit. I've got two and three band models right now. Just not the right bands is all. One alternative would be to make a vertical model operating against a good ground -- it would be simpler! That's exactly how I start. It gives me a faster running model so I can go through the iterations quicker. 73's Richard Clark, KB7QHC |
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N2EY wrote:
Dipole dimensions: Innermost section (not a stub; shorted at both ends): 8' Next section (stub; open at inner end): 6' 11" [resonant at 10 meters?] Next section (stub, open at inner end): 13' 10" [resonant at 20 meters?] Outermost section (stub, open at inner end): 27' 5" [resonant at 40 meters?] Is this just an attempt at a trapped antenna using stubs for traps? It doesn't seem to model out to be very functional. The outermost stub on 40m needs to have a very high impedance, i.e. 1/4WL shorted. That works well to resonate the vertical on 40m, but 1/8WL on 80m makes the antenna resonant at 3 MHz according to EZNEC. -- 73, Cecil, W5DXP -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Richard Clark wrote:
On Sun, 11 Apr 2004 02:07:31 GMT, Irv Finkleman wrote: Hey Guys, Hi Irv, I have the original article here. If you want it I can scan it and send it to those requesting. Put me on your distribution list. ............................................... It's in the e-mail! Just fired it off now! Irv -- -------------------------------------- Diagnosed Type II Diabetes March 5 2001 Beating it with diet and exercise! 297/215/210 (to be revised lower) 58"/43"(!)/44" (already lower too!) -------------------------------------- Visit my HomePage at http://members.shaw.ca/finkirv/ Visit my very special website at http://members.shaw.ca/finkirv4/ Visit my CFSRS/CFIOG ONLINE OLDTIMERS website at http://members.shaw.ca/finkirv5/ -------------------- Irv Finkleman, Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP Calgary, Alberta, Canada |
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