High SWR on G5RV

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KE5UKI, Aug 2, 2008.

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  1. ZL3GSL

    ZL3GSL Ham Member QRZ Page

    Try adding a short length of coax (say 1/8 of 20m) to your feedline. You might be on one of the magic quarterwave multiples.

    It's called a G5RV antenna. That means it's a dipole with some ladderline and coax. The measurements of each part might not match anything ever built by G5RV. ;)
     
  2. K5TEN

    K5TEN XML Subscriber QRZ Page

    I hope you get it worked out.

    I had a G5RV many years ago and could not get it to work on 10M under any circumstances, tuner or no tuner. I ditched the G5RV.




    Bruce
     
  3. N4AJZ

    N4AJZ Ham Member QRZ Page

    Running the G5RV on 20 meters, no problem. 1:5 - 1, 1:9 -1, SSB phone,
    by- passing the tuner. 75' ft of RG-8X to the 300 feed line(29') mounted
    at 30'. Coax coiled (8 turns @ 10") at the 300 feed point.
    Only band I can't tune is 10 meters which is not a problem as that band
    is dead.
     
  4. W0UZR

    W0UZR Ham Member QRZ Page

    No one asked the questions I have

    Did you measure the antenna, the wire on both sides and see if this Radio Waves cut the wire accurate? Should be 51 feet per side.

    Did you measure the ladder line on it? It should read 31 feet. (that's what mine was anyway. Seems the ladder line has different lengths depending on who makes it)

    And you say that has a balun. So did mine and I cooked it with my amplifier right away. I took it off and it worked just fine. The Recieve 'CAME ALIVE!!'

    Are you near a metal building with it? That will make all kinds of difference

    Is the antenna up at least 40 feet or so? If not the ladder line will be on the ground. If it isn't very high, then do you have the ladder line following the shield side of the antenna or the other side.? I made sure mine followed the shield side.

    Do you make sure you have at least 70 feet of coax going to it? They will have problems and not work right if there isn't 70 feet of coax going to it.

    More later if I think of them
     
    Last edited: Aug 27, 2008
    LA4GPA likes this.
  5. W0UZR

    W0UZR Ham Member QRZ Page

    Hello....?
     
  6. K5TEN

    K5TEN XML Subscriber QRZ Page

    Back in the day when I had a G5RV the thing worked "ok" on 80 to 15M. I could work some DX on the (then) brand new 17M band--and on 20.

    I wasn't impressed on 40M or 80M. My apex was up about 55'.

    The thing wouldn't tune on 10M worth a darn. I wasn't the only one back then having problems getting it to tune on 10M either, so I got a decent 10M vertical and used that instead.

    In the meantime, I have far better antenna projects for HF in the works.





    Bruce
     
  7. KD5SPQ

    KD5SPQ Ham Member QRZ Page

    g5rv swr

    I was looking to build a antenna that would fit on my lot at my Memphis QTH so I made a G5RV out of some spare wire.I was running low on wire when I did this last night on side of dipole is 50' the other is about 52' and fed it with 29' of 450 ohm ladder line then I put a MFJ 4:1balum, indoor type balum don't remember model #. I installed it in a large plastic coffee can.And it fed with 100' of cheap radio shack coax with 8 turns of the coax at balum end and before it comes thru the window .I am using a Ten-Tec Jupiter with built in tuner , it shows good swr 20 thru 10 no higher 2:1 with tuner bypass .40 and 80 show about 5:1 with tuner bypass still no problem for the auto tuner .Was in a hurry to get on the air last night so I didn't put a antenna analyzer on it.Weather permitting I might try a different balum 1:1 and a straight line to line connection and see if swr looks as good. looks like it might be a good antenna 73..
     
  8. VE3PP

    VE3PP XML Subscriber QRZ Page

    I have had several home made G5RV's up and not once did I use a 4:1 balun at the ladder line and coax connection.

    Connect your coax to the ladder line, coil up 8-10 turns of the coax in a 8 inch diameter coil right at that connection point. That helps the coax from radiating.

    No balun required in that antenna.

    I have a half size G5RV up now, fed with 17 feet of 450 ohm ladder line. I use it for 30 meters and it tunes up easily with a Dentron MT-2000A manual tuner. I do not use it on 20 meters as I have a beam for that band.

    I know when I had my full size G5RV up like others it did not tune up great on 10 meters but I could get it to tune. Now I found on 12 meters it was a dud!
     
  9. NO6L

    NO6L Ham Member QRZ Page

    First, quit messing with the G5RV and put up a multiband fan dipole. It's less lossy, you don't need open line feeder and the headaches that come with it and it's native FP impedance is close to 50 ohms. You should use a W2DU balun at the feedpoint though. A three wire "V" with 75/80, 40 and 20M wires will also cover 15M. My TS-2000 tunes one on all bands except obviously 160 and 60M. I even use it on 6m for close it repeater access, and, yes , it tunes.

    I've had a few people follow my advice, took down the G5Rv, put ut the "Fan V" and BAM! World at your doorstep.

    I'm sorry, but I put G5RVs in the same class as "J" poles. Good for nothin' but a source of parts for a real antenna.

    That's my take.

    Cheers and hasta...
     
  10. N8YX

    N8YX Ham Member QRZ Page

    Those who readily dismiss the G5RV as a "junk" or "gimmick" antenna would do well to read the following:

    The G5RV..as analyzed by Rouch, W8JI

    The late R.L. Cebik also had a few things to say about Varney's design, none of which were overly negative.

    Personal experiences are as follows:

    IF the antenna is constructed as originally designed, it will operate as a 3/2w, bi-directional gain antenna on 20M...with a very low SWR...and will work on 80-40-12 if an antenna tuner is used in conjunction with it.

    One must pay attention to things such as element length (51' each side), twinlead feeder length (31') and the incorporation of common-mode suppression at the balanced-to-unbalanced transition point. Which is moot if one uses a balanced-wire tuner, of course...you simply run the twinlead straight to the tuner. But then, the antenna ceases to be a "true" G5RV...

    Mine covers the lower 250KHz of 20M with an SWR of under 2:1. I can use a tuner with it and get good results on 40 and 75/80, but I have other antennas for those bands. What I wanted was a decent, fixed-pointed gain antenna for 20 and in that capacity my 'RV works very well. If I had ample space to run another one in a N/S direction, I would do so.

    A 5-element monobander at 100ft it isn't, but I've not had any problem raising a station on the 1st or 2nd call with mine, either.
     
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