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Inverted V for 10 and 20 meters?

Discussion in 'General Technical Questions and Answers' started by N4ENT, Aug 9, 2008.

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  1. N4ENT

    N4ENT Ham Member QRZ Page

    Hello all. One last question as do not want to wear our my welcome and buying a antenna book will only be waste on me as I not planning on doing any more than 10 and possible 20 meters after I get a license upgrade. (NEVER SAY NEVER?)


    What are the merits of installing a full wave 10 meter Inverted V dipole and using it is a halve wave 20 meter down the road?

    Thanks again!!!

    Ed
     
  2. K9XR

    K9XR Ham Member QRZ Page

    Without a tuner it WILL act as an inverted V on 20 meters, and won't work very well on 10. You might consider feeding dipoles on both 10 and 20 metrs with the same feedline.
     
  3. KB3LIX

    KB3LIX Ham Member QRZ Page

    A full wave 10m inverted "V" (assuming you mean 1/2 wavelength on each side of the feedpoint) will present a VERY high impedance at the feedpoint. It will NOT work very well with a coaxial cable feeder.

    On the other hand, it will work reasonably well on 20m as it will then be a 1/2 wave dipole. (1/4 wavelength each side of the feedpoint)

    Don't poo-poo operation on the other bands (with the necessary upgrade of course) 30 & 40 are GREAT bands. 30 for CW and the digital modes and 40, well, all the modes are VERY viable there.

    One solution, make your dipole (or doublet as it is also known) 44' per side.
    Feed it in the middle with a balanced feeder (300, 450 or 600 ohm open line)
    Using a tuner (with an internal or external balun) you should be able to find a
    tuning "Sweet Spot" for all the bands from 10 down to at least 40, and perhaps 80m as well.

    By the way, the antenna book IS valuable investment.
    A little study goes a LONG WAY !!!
     
  4. N4ENT

    N4ENT Ham Member QRZ Page

    Thanks for the quick response.

    I would NEVER poo poo any other Band. I just am very limited on the antennas I can have here. I would love to run 40 and 80 (and hope to someday)....but the local subdivision police make it difficult to put up any decent antennas.

    I will put up a 1/2 wave 10 meter for now. It will keep me happy until I can get my General license.


    Thanks!!!

    Ed
     
    Last edited: Aug 9, 2008
  5. K8PJM

    K8PJM XML Subscriber QRZ Page

    You may want to think about a Hustler 5BTV ground mounted with some radials in the ground. If you paint it black most people won't even see it. I have a very small yard in the city and it works good. It will never replace a tower and a good set of beams but I'm having fun. This way you have some other bands to try out.

    73 Phil
     
  6. N4ENT

    N4ENT Ham Member QRZ Page

    Thanks for the idea Phil!


    Ed
     
  7. WJ5O

    WJ5O Ham Member QRZ Page

    check Your 10 meter antenna

    Ed,
    I just noticed that Your location is the same as a 24/7 propagation beacon on 10 meters...... Check for KG4GVV beacon on 28.2754 MHz......

    OK here is how I operate within the confines of HOA...... I have a ground mounted 4 BTV (4 band trap Vertical) by Hustler painted with camouflage paint to match the pine trees...... as mentioned above it's not a competitor for a tower & beam antenna but it does perform well enough to keep me busy.

    Don't forget to tune through the 10 meter beacon band ..... propagation beacons are the best "real time" indicators of band openings. :)
     
  8. N4ENT

    N4ENT Ham Member QRZ Page

    Thanks Bill.

    I hope to be up and running again this weekend. I have everything built and ready for the morning adventure on the roof.



    Ed
     
  9. W5DXP

    W5DXP Ham Member QRZ Page

    A 1/2WL 20m dipole fed with 450 ohm ladder-line will work well on all bands 20m-6m. If you vary the length of the ladder-line it will work well even without a tuner. For instance, feed it with a multiple of 1/2WL on 20m and an odd multiple of 1/4WL on 10m (at a current maximum point).

    I have a 20m rotatable dipole. By varying the length of the ladder-line, it works well on 20m-6m without a tuner.
     
  10. KA1YBS

    KA1YBS Ham Member QRZ Page

    For what it's worth, and I haven't read all the posts.

    I run under 100w with an inverted V and have, with a manual and auto tuner worked all bands on phone. I've used the same piece of wire for sstv and rtty.

    I used a 'Cobra Ultralight', but any tunable piece of wire should get you started. No need to compromise any band really, if you can do 10, why not 160? I am blessed with some tall trees and a little chunk of land, even the xyl can't tell I have the antenna! (trying to convince her towers and beams are pretty)

    Just get it up as safe, stable and high as you can, properly ground the equipment, and create a matching balance from tx to ant. You'll have plenty of fun, even if cycle 24 is still hiding.

    Have fun, any questions feel free to pm or post.

    73
     
  11. KJ4JON

    KJ4JON Guest

    I hope the original poster will not mind my jumping in with a question, I have a similar interest.

    I would like to operate in a portable mode, being able to take the rig and set up from place to place. I was thinking about a dipole for 20m phone. In order to do this, without needing a tuner, I was thinking about coax from the transceiver to a 1:1 current balun (I have a spare) and then two wires of off that, length of each leg cut for a 1/2 wave. Would this work well??

    An alternative could be a Carolina Windom, same set up as above.

    I have notice a good many posters writing about using a ladder line, changing the length of this line etc. I think I would prefer using coax cable to a balun.

    Could someone comment on this?

    Thanks

    73

    John
     
  12. W5DXP

    W5DXP Ham Member QRZ Page

    Speaking of balanced dipoles: If you are satisfied with single-band operation, e.g. 20m only, by all means feed a 1/2WL dipole with coax.

    However, if you want that same dipole to work just as well on all HF frequencies higher than 14 MHz, feed it with 450 ohm ladder-line through a husky 1:1 choke at the ladder-line/coax junction.

    If you want a matched system without a tuner, vary the ladder-line length per band to feed the system at a current maximum point where the impedance is purely resistive and probably between 35 ohms and 85 ohms.

    http://www.w5dxp.com/imax.exe

    That's a DOS BASIC program from my web page that will indicate the approximate optimum length for a ladder-line-fed dipole. Here are the lengths for a 33 foot dipole fed with 450 ohm ladder-line:

    14.2 MHz, 62 feet; 18.14 MHz, 66 feet; 21.3 MHz, 54 or 75 feet; 24.95 MHz, 63 feet; 28.4 MHz, 55 or 70 feet

    Using a tuner, only two different lengths would be required for optimum operation; 64 feet and 72 feet. Use 64 feet for 20m, 17m, and 12m operation. Simply add 8 feet of ladder-line for 15m and 10m operation.
     
  13. K8MHZ

    K8MHZ Ham Member QRZ Page

    Google 'Hamstick dipole'.

    I built one and am very happy with it. Michigan to Germany at the bottom of the cycle from a park using my portable HF station.

    They work well on 10 and 20 but I have heard that below 14 mHz they start to show a loss of performance due to their size.
     
  14. N4ENT

    N4ENT Ham Member QRZ Page

    OK, We are up and running. Already hear some chatter but will be fine tuning the antenna as the day goes on. (or until the heat kicks me off the roof!)

    Ed

    28.400 USB for now
     
    Last edited: Aug 9, 2008
  15. WA7KKP

    WA7KKP Ham Member QRZ Page

    Rtfm


    If you don't want to invest in reading a few books, or owning same, then I'd say there's another band you can hang out on . . . I won't mention where in the spectrum it is, but they have two score channels to play, and more if they've modified their radios.

    Ham radio is a continuous learning experience . . . I've been learning for 40 years now and still haven't scratched the surface. I've bought a shelf full of books on the subject (some better than others), and I go to them first before I lean on my fellow hams for common-sense information.

    Gary WA7KKP
     
  16. AI3V

    AI3V Ham Member QRZ Page

    Hi Gary,

    The forum the past couple day seems like it's been full of these type questions, Frustrating, isn't it?

    To the OP, There is no need to purchase any books, Here is the secret:

    When you first turn on your computer, select a web browser- I use Google, Then, in the little box where you typed qrz, INSTEAD type in your question, You will se displayed a list of sometimes THOUSANDS of articles on the subject you are interested in.

    Glad I could help.

    Rege
     
  17. KJ4JON

    KJ4JON Guest

    Thank you for the verification on my scheme for the dipole. My experiment worked out great and yeilded interesting results.

    I set up a dipole using a spare 1:1 current balun I had lying around. I also happened to have two lengths of 12g wire that were both 17.5ft in length (I know...not the correct length for 20m). I connected them to the balun and the balun to the transceiver via a cheap 20' coax cable, that I also had lying around.

    This is on a boat, by the way.

    First attempt with both legs lying flat on deck yeild minimal results, nothing much. Next try with it configured as an L dipole yielded very good results...QSO with a station in Maine from my location in the FL Keys (on 20m).

    This is using a Yaesu 857D that is new to me. I had the meter set to power (PWR) and saw that I was not getting out as much signal as I did when using the SGC-230 tuner and 60ft backstay (obviously insulated at both ends). Read the manual (gee, what an idea) and found that I could switch the meter to SWR. Great! Did that and found that it was higher than I would have liked, but still very acceptable and well below 1.5.

    Next tried 40m, thinking that perhaps the antenna might act as a 1/4 wave dipole....and ....you must be rolling on the floor laughing by now...of course....really good thing I had the meter set to SWR. It topped out almost instantly and that was that. (Probably should have read an antenna book...but no harm done).

    So...next step is to investigate the different dipole configurations...inverted V, L, horizontal and see what I like best. I realize that an inverted vee might be best, however, some configurations are not as easy to set up on a boat. And it is much cheaper to do an L config, since the coax can be shorter.

    I will also be trimming the length of each leg to see if I can achieve more optimal SWR. Obviously should be down to 16.5ft. And getting better coax.

    Good reminder about the Antenna book...would like to get one soon...just not enough hours in the day to do everything I would like to. The number of antenna configurations is quite large. Would also like to investigate a Carolina Windom....a lot of info on that on google....by the way.

    Someday, when I am back on land, it would be very useful to work on more antenna's. For right now, my goal is simply to have a good back up antenna on 20m should the backstay or tuner be damaged in any way. Looks as though this will work for me. It does not look as though it will beat a vertical long wire and a good tuner.

    The Hamsticks look like a decent solution...but not sure how much better they would be than my zero cost dipole and doubtful a Hamstick would beat my 60ft long wire and tuner.

    Are the above fair statements?

    73,

    John
     
  18. G0GQK

    G0GQK Ham Member QRZ Page

    If you only require two bands, 20 metres and 10 metres, make your antenna from 300 ohm ribbon feeder. Use the 20 metre longer portion as the support and underneath cut out a portion and bring this into resonance on 10 metres. Attach your 50 ohm coax and then you have both bands on your inverted V

    G0GQK
     
  19. N4ENT

    N4ENT Ham Member QRZ Page

    Gary (and the rest with smart ass comments on where I should go)

    Everything in Life is a learning experience. I choose to do much of mine on the internet. Books are great, but the experience of current experts is best whether it is in a forum or that person that took the time to put it on a web page.

    I am not some wet behind the ears 19 Year old. I am 50, Retired Navy, former Drag racer, clock and watch smith, computer geek and was hoping to get back into Amateur radio with a little help and some research. I have been on many a Forum, but am surprised on the return comments from a community I respected.

    OK, My questions are elementary, but I need to start over again. I thought I could get the "bug" again to have fun doing this and re-learn what I may have forgotten and check out the new technology.

    Time will tell.........


    73 Ed
     
    Last edited: Aug 13, 2008
  20. N5RMA

    N5RMA Ham Member QRZ Page

    Sound suggestion

    This suggestion is sound, quick, easy, and cheap. That is a pretty good combination. Don't let the nay-sayers get under your skin, Ed. I do not post very often, but I read a lot. Most often the nay-sayer just nay-says with never a post of assistance. That is too bad as I am sure many have much they could offer. :(

    n5rma
     
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