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How should I install my G5RV Lite antenna

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N1DE, May 18, 2010.

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  1. N1DE

    N1DE Ham Member QRZ Page

    I'm in the process of setting up my first HF station. Ready to install the antenna but not sure which choice is better.

    My options are:

    1. East to West as a flat top or inverted V
    2. Northwest to Southeast as an inverted V

    If it makes any difference I'm located in the San Francisco bay area.

    73's
    Jeff
    KJ6EHS
     
  2. W5DXP

    W5DXP Ham Member QRZ Page

    Not enough information. With whom do you want to QSO on what band(s)? The G5RVjr's coverage is broadside on 40m and 20m. It is a cloverleaf pattern on 10m. If you run it E/W, you will have the West Coast covered on 40m and 20m.

    In general, a G5RVjr (or G5RV) should be mounted as a flat top horizontal antenna.
     
  3. N1DE

    N1DE Ham Member QRZ Page

    Thanks for the response

    From what I have read it seams that the G5RV tends to work best on 20 and 40 so I imagine that is where I will be spending most of my time. However I would like to explore the other bands as well.

    As far as who I want to QSO with, being able to make international contacts i think would be great fun. But if it's not possible with this setup then I would be happy just getting on the air.

    Thanks
    Jeff
    KJ6EHS
     
  4. W5DXP

    W5DXP Ham Member QRZ Page

    For that, you probably need to run the G5RVjr North/South. Pizza, available for free at:

    http://www.tonnesoftware.com/

    ... will give you more perspective on the subject.
     
  5. N1DE

    N1DE Ham Member QRZ Page

    Thanks Cecil,

    I found a way to run it North South.
    I have an old TV antenna mast I could mount the center to; however that would mean I will be running the antenna about 5' above my metal roof. Should I be expecting any problems from this or is the 5' enough separation.

    The antenna has a 29' lead section, can that be run along the metal roof? If not how much separation will I need to avoid interference?

    Lastly what is the best way to support the ends up high?
    I've seen fiberglass masts online, but at the moment its not in the budget. I kind of need a diy option.
     
    Last edited: May 18, 2010
  6. G0GQK

    G0GQK Ham Member QRZ Page

    I don't think your dipole is going to like a metal roof under it. Is it not possible to hang it somewhere where its in unobstructed space ? What's a G5RV Lite ?
    Don't think Mr Varney knew about that.

    G0GQK
     
  7. N1DE

    N1DE Ham Member QRZ Page


    If i hang it in unobstructed space it will need to be hung East to West. Looking at the map it appears I will get better coverage if it is hung North to South. Only the center section(about 15') would be over the metal roof. The rest would be over unobstructed space.

    The G5rv Lite can be found here: http://www.radiowavz.com/html/g5rv.html


    Thanks
    Jeff
    KJ6EHS
     
  8. W5DXP

    W5DXP Ham Member QRZ Page

    I thought a G5RV-lite and a G5RVjr were the same thing but the G5RV-lite is 67 feet long with a 28 foot matching section. Here are what EZNEC says will be the SWRs on the coax on the different bands.

    7.2 MHz, 20:1; 10.125 MHz, 2:1; 14.2, > 100:1; 18.14 MHz, 51:1; 21.3 MHz, 10:1; 24.95 MHz, 1.5:1; 28.4 MHz, 45:1

    IMO, this is NOT a good antenna. The design frequency is somewhere around 15m. The "matching section" is doing more harm than good. It would be much better to run ladder-line all the way from the 67 foot dipole to the shack.

    My advice is to avoid the 67 foot RadioWave G5RV-lite.
     
  9. N0LWF

    N0LWF XML Subscriber QRZ Page

    By looking at the picture on radiowavz website the G5RV lite has loading coils on the ends of the wire. So would that make it electronicaly longer?
     
  10. W5DXP

    W5DXP Ham Member QRZ Page

    Sorry, I didn't scroll down to the second picture and completely missed the loading coils. Yes, that might result in a loaded G5RV - for hams who don't have 102 feet for an antenna.
     
  11. N1DE

    N1DE Ham Member QRZ Page


    Since I have this antenna in hand, I took it out and looked at the coils. They are at the mid point of both legs not at the ends.
     
  12. N1DE

    N1DE Ham Member QRZ Page


    With the coils, how will that affect the SWRs across the bands?

    Would you still recommend avoiding this antenna?
     
  13. W5DXP

    W5DXP Ham Member QRZ Page

    Unfortunately, EZNEC cannot model those coils using the helix option so they would have to be modeled using the lumped-inductance model which will not model self-resonance in coils. If you can determine the length, diameter, total turns, and size/kind of wire, the Hamwaves inductance calculator could be used to model the actual characteristics of the loading coils on all the HF bands.

    http://hamwaves.com/antennas/inductance.html

    If anyone can furnish the above information, I will model the coil and report back here. It appears from the picture that the coil specifications would be relatively easy to ascertain.

    Since I don't yet know anything about the loading coils, I am somewhat shooting at a noise in the dark. That said, I would personally not buy/use this antenna without knowing more about it. The coils have a self-resonance frequency above which they are known to be lossy. With the requested information above, I (or others) could model that coil on the various HF bands to see how lossy they are on the higher frequencies.

    The loading coils would work best on 80m which is the entire reason for their existence.

    The G5RV-lite is 1/2WL long on 40m with the "matching section" a little shorter than 1/4WL. That means the loading coils are increasing the electrical length on 40m to a little more than one wavelength, i.e. the effect of coil delays and phase shifts are more than half of the antenna. That cannot be good for efficiency. A 40m analysis of this antenna would be a good way to study the delay and phase shift effects caused by loading coils.

    The coil-loss problems probably increase as the frequency is increased. The 67' G5RV-lite seems to be 98% aimed at 80m operation for hams who don't have room for a 102' dipole. It probably performs that function relatively well at the expense of the higher frequency bands. If 80m is one's primary operating band and a 102' dipole won't fit, it might be a reasonable choice. Of course, one can do the same thing (for single band 80m operation) with loading coils and a coax fed antenna.
     
  14. N8WWM

    N8WWM Ham Member QRZ Page

    I think I'd can that G5RV lite and run either a random wire with radial grounding or a dipole fed with ladder line. That antenna is just ghastly compared to either one of the latter.
     
  15. N3JPB

    N3JPB Ham Member QRZ Page

    The nasty ol' G5RV Jr.

    I had to remove all operating verticals to put on a new roof so I have ZERO antennas available to me at the present (not for long). So I wanted to try out my new toy when I brought it home (FT-950) but had no antenna. A friend gave me a G5RV-Jr mostly as a joke (total length 51 feet with a 13 foot "matching stub"). I put it in the attic - one leg goes 13 feet south and then turns east for 12.5 feet (sloping down with the roof line). The other leg goes north 13 feet then turns west for 12.5 feet (sloping down with the roof line). The "matching stub" drops down from the center 9 feet then turns horizontal to the east for 4 feet where the coax is attached. It should be a horrible antenna but I thought why not do a little SWL with the FT-950.

    I was surprised to find that it was pulling in a LOT of action on 40 meters (remember, I had no intention of transmitting). The tuner was showing SWR at 1:6.....hmmmm. I couldn't resist so I returned a CQ and had a nice QSO with a station in Mexico - and I didn't let any smoke out of the new IC's<G>. Sometimes there is no reason at all to hope but you just get lucky.

    John (N3JPB)
     
  16. KK7EL

    KK7EL Premium Subscriber QRZ Page

    Vertical

    Sounds like you have similar size restrictions that I have, meaning not enough room for a good wire antenna. I ended up with a Cushcraft R8 vertical antenna (multiband: 6,10,12,15,17,20,30, and 40 meters), works reaasonably well (but a bit noisy and insensitive in Rx), and does not require any ground radials. I am sure other places sell it, but here is link to DX Engineering's listing:
    http://www.dxengineering.com/Parts.asp?PartNo=CUS-R8
     
  17. EI4GMB

    EI4GMB Ham Member QRZ Page

    Why not try a G5RV Jr ?

    Hi Jeff,
    Why not try a G5RV Jr (51ft)(10m,20m,40m)? I have had great success with this antenna and have even reached DXCC with it during sunspot minimum, using just 100W (See eHam Reviews).
    As W5DXP says it would work better for your purposes as a horizontal or flat-top antenna, configured north-south.
    Best of luck Jeff.

    Kind Regards

    Fred EI4GMB
     
  18. K9ASE

    K9ASE Ham Member QRZ Page

    What is meant by mounting Flat top vs. inverted V I'm also considering a G5RV Jr. as my first HF antenna. I probably have enough room to put it on a 20ft mast on a second story flat roof (dormer) measure 30X8 before it reaches the peak portion of the rest of the house. What is meant by "Flat Top" does that mean a loop around the roof?
     
  19. W7XTZ

    W7XTZ Ham Member QRZ Page

    Flat Top

    Flat top means the wire is completely horizontal, the ends are at the same level as the middle. I modified my G5RV so that it has 3 wires instead of 1. An extra 40' dogleg off of one end reduced my SWR on most frequencies to 1.5 : 1 or less.
     
  20. KI4SGQ

    KI4SGQ Ham Member QRZ Page

    Just to put it out there I'am running the alpha-Delta DX-EE and having very good luck with it from 40-10.It is only 40 feet long and i have it outside about 35 feet up.Maybe this antenna will fit your space better.
     
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