A Few Antenna Questions

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by K0DUC, Aug 14, 2021.

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  1. K0DUC

    K0DUC Ham Member QRZ Page

    I've been stuck in town, away from my shack in the hills, and not had the chance to do some antenna projects I've asked advice about previous. But, playing with some mobile whips when I get the chance had me curious about a few things.

    Playing around with my 102" whips, one with a spring for CB length and the other at regular 10 meter length, I was surprised at how good the 102" whip was for broadband reception, but the 108" length was not. If resonance isn't important to reception per se, why does the shorter whip do better than the long whip? The 102" was good through the phone parts of 20, 40, 80, and even 160 meters (in the middle of summer, no less)! Last night I could read 40 and 160 very well. The 108" electric length was not good at anything.

    I've talked to others about the possibilities of these whips for out of intended band operation. Indeed, I was able to get a good SWR on 20 meters with the 102" with a manual tuner, but how good is such a compromise setup, really? 20 was dead last night so I could not give it a decent try yet. I tried the 108" length with spring on 50 meters, where it should be half length, and I didn't seem to get anything that on the manual tuner that would work. I suppose there is something I'm missing.

    I also asked about a compromise vertical antenna for 160 meters recently, with good reply. I've asked on another forum, and also DX Engineering. Suggestions seem to be in favor of an inverted L antenna, even though I have the space for a full dipole, but not the ability to put it up at half wavelength height.

    A bit long winded, but any insight would be useful. Thank you.
     
  2. N8AFT

    N8AFT Ham Member QRZ Page

    If you are content to experiment using SS 102" whips then look into Wolf River Coils Silver Bullet loading coils.
    They come in two versions and one of them is for 160m...
    They're designed to work with the 102" stainless steel whip antennas either mobile or fixed use applications.
    I hv both the large and smaller versions. They are well made, low cost and effective...
    My mainstay 160 ant is the Cushcraft MA160V. A gnd mtd vert.
    It is great for 160m and loads / radiates vy well on a few other bands using a tuner.
    My tuner is a Drake MN2700.
    The bands other than 160 are 40, 30, 20 and 15m. 30 loads without tuning.
     
  3. W4HWD

    W4HWD Premium Subscriber QRZ Page

    Dipoles are cloudwarmers on 160. Go with the inverted-L. If you have the supports for a dipole an nverted-L will fit.
     
    K8PG likes this.
  4. WB5YUZ

    WB5YUZ Ham Member QRZ Page

    So few of us do, that two simple dipoles at 240 ft. will give you one of the best signals on the band.
     
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I suspect something is/was wrong with the 108" whip. If it's a simple SS rod, obviously you could see if it was broken; however the whip is normally swaged into a ferrule that makes it a 3/8"-24 base for a mating mount and if that connection is not rock solid internally, then you have a "no whip" antenna.

    I've never noticed any difference at all between a 102" and a 108" whip as long as each is connected perfectly; the only difference is a slight shift in resonance that almost any simple tuner can accommodate.
     
  6. W3TKB

    W3TKB XML Subscriber QRZ Page

    I'm very pleased with the performance I get from my inverted L antenna. I used a 12m Spiderbeam pole to get the vertical half of the wire up, then it runs another 65 feet horizontally towards a big Doug Fir in our yard. My remote ATU at the base of the pole quickly finds low SWR matches on all bands, except 30m for some reason; it has a hard time on that one band. I don't do a lot of work on 30m, but I can bypass the ATU and get a better match with a manual tuner if I decide to go there.

    Invest in putting in a good ground radial field and you should be happy with the inverted L's results.

    Brando
     
  7. WA4SIX

    WA4SIX Ham Member QRZ Page

    If I understand correctly, you have a 102" whip & use the spring to make it a 108" whip.
    Older springs always had a braided tinned wire in the middle & the newer ones I have seen do not. That may introduce the resistance of the spring steel into your receive path?

    Ed
     
    WZ7U likes this.
  8. WB2JIX

    WB2JIX XML Subscriber QRZ Page

    I agree with Ed. I've discovered that many times, the braid in the middle of the spring, is rusted off or broken. Be sure to do a continuity check.
    In my 70's CB days, two of us "kids" would bend a guys spring all the way over and cut that braid, just to hope we'd burn out the finals in the radio. Shenanigans back then. I'm all growed up now! 10-4?
     
  9. K8JD

    K8JD Ham Member QRZ Page

    My 160M Dipole Does Just Fine
    My dipole is about 5% of a wavelength AGL due to the tree branches along its length being overwhelming. I have worked coast to coast with 100 W on 160M and have good reports from 48 states.
    Earned the SKCC single band (160M) C and T endorsements in the last few years.
    I have worked all the DX I wanted to on 10 M, over the 5 or 6 solar cycle peaks !
    Not really expecting any on 160.
     
  10. K0DUC

    K0DUC Ham Member QRZ Page

    Checked the 102" whip with 6" spring, and no problems. Great SWR over 11 meters, workable in 10 meters even. Ran some power through it, good radio check reports. So, the 108" isn't shorted anywhere I can tell. I'll take another look at 6 meters tomorrow, it would be nice if I can get it to tune on the CB whip.

    Put in an order for a 160 and 80 meter monoband dipoles for experimentation when I can finally get back home to figure what I'm going to do with them. Been sizing up trees, looking at a hill, and thinking about what I can put up as high as I can possibly manage. Even talked to an old CB fellow, friend of the family, who might give me his old 30 foot tower!

    I'll ask one more question, if I do put up a few traditional diples, what is the best way so they don't interfere/interact with each other? When I get my G5RV dug out from under the tree it got crushed under, I might have a few wires to hang yet.
     

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