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Author Topic: Have I killed my antenna? Is that even possible?  (Read 1344 times)
K8JHR
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Posts: 29




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« Reply #15 on: September 19, 2009, 12:20:50 AM »

Hi - were these answers any better/different from what you received on the internet help group?  

=======  K8JHR  ========
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K1WJ
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Posts: 451




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« Reply #16 on: September 19, 2009, 09:34:04 AM »

Getting another set of eyes on the install is a great idea.

I was on 14.268 usb yesterday, as stated in this post yesterday.

I worked:

W7AML - In WA he was on a single 20m moble hamstick . Signals S7 with QSB. 100% copy.

AD7NI - In ID - S7 QSB - 100 percent copy

KB7QWW - In ID - S8 - little QSB - 100%

K7GSE - In WA - S7 - QSB - 100%

KI6NIC - In CA - S5 - qSB - 100%

I compared antenna on 4 of the contacts THE 20M HAMSTICK DIPOLE was about 2 S-Units better than a 4BTV with 30 ground radials of various lengths, mounted in the clear on ALL 4 contacts.
The hamstick dipole is at 28ft high, yeah thats all....

So thats not hearsay, or opinions, or B.S.

Just the Facts........David K1WJ
Good luck on your BTV. 73
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W9OY
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Posts: 1292


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« Reply #17 on: September 19, 2009, 11:07:35 AM »

Since you have a Z-100 why don't you put a 25ft vertical wire up in the tree, put the Z-100 at the bottom of the wire, run some radials and have some radio fun?  It should do 40-10.  You can run some realy voltage down the coax to force a tune on the Z-100 when you change bands using some voltage injectors as described on AD5X's website

http://www.ad5x.com./images/Articles/RemoteDC.pdf

73  W9OY
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KG6WHN
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Posts: 48




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« Reply #18 on: September 19, 2009, 05:50:11 PM »

Well, I tried 20M today with a new antenna.  Wow, it made a HUGE difference.  I didn't use a plain vanilla dipole though because I wanted something fairly easy for me to mount on a single push-up mast.  So I tried one of those hamstick dipoles....wooh, major difference.  Ideally I'd like to find some kind of dipole solution that would let me hang the whole thing on a single mast and be self-supporting from the central feed point (that's mostly why I picked a HSD).  Even with the HSD SWR off a bit from ideal (the whip was slightly too short on each end) I could clearly hear multiple stations on 20M, no QSOs though since it sounded like most folks were contesting.  Anyhow, I pulled down my 6btv and now I'm going to re-adjust it back to the factory dimensions and follow the recommended factory adjusts for ground mount w/radials and see how that works (and avoid checking SWR with my analyzer).
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N3OX
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« Reply #19 on: September 19, 2009, 08:14:32 PM »

Jeff,

The fact that you can't hear anything on your 6BTV compared to a hamstick dipole suggests that there's something worse wrong than the tuning.  You can't mistune it that badly; I think it's that wall.

I wouldn't even bother with the vertical if you're not going to stick it out in the yard somewhere and get it away from that wall.  At least get it, I dunno, 10 feet from the wall.  It sounds after this test that the wall's basically really badly shorting out your vertical.

One other thing... a 20m Hamstick dipole isn't a  bad antenna,  I estimate (without knowing for sure the effective loading coil Q) maybe not worse than 2-3dB down from a regular one.   K1WJ's results make sense especially if he's got bad ground or a lot of clutter at low angles.  Some height above ground on a horizontal makes up for a bit of lossy loading, and the antenna is not super-short in terms of a wavelength.  But as you make them *shorter* in terms of a wavelength, short antennas with similar loading get worse much more steeply than you might guess.  

A 40m hamstick dipole is probably around 10dB down from a full size dipole   and an 80m hamstick dipole is probably nearly 20dB down.   You'll be a QRPer on 80 for sure with 100W input.  That's still enough to do something... I worked a few Europeans on 80 CW with a couple watts to my full size 1/4 wave vertical just for kicks.  It was hard but I worked a few... so 100W to a 80m Hamstick vertical could have done that too ;-)

So I wouldn't go with Hamsticks all around.

I wouldn't give up on the vertical, but you really gotta get it away from the wall.  

73
Dan
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
KG6WHN
Member

Posts: 48




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« Reply #20 on: September 19, 2009, 08:45:53 PM »

Dan,

  Thanks.  I think you're right about the wall.  I actually experimented a bit more after the hamstick dipole.  I took down my 6BTV and readjusted it to the manufacturers spec for the trap dimensions and where the other clamps go, etc.  It seems to work somewhat better.  Basically 20M is gone, but 40M is working as well as a small portion of 80M.  I never hear anyone on 10M, but it sounds like possibly I'm picking up some data transmissions on 10M.  I definitely think the 6BTV placement is the problem, but where it is is pretty much the only choice as far as ground mounting.  I'm currently thinking about mounting it on the roof of my garage.  I need to figure out if that's managable based on the amount of foliage growing on the roof though.  Plus I need to find some sort of reliable stand to mount it on up there, then the final problem is getting a ladder ;-} As for ground mounting...I mounted the HSD 10' away from everything in my yard and it was in the exact center...so yeah the backyard is something like 20' x 20' (or maybe 25' x 25')..
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KT8K
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Posts: 1490




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« Reply #21 on: September 20, 2009, 08:45:34 AM »

The way you described the change, that you were adjusting the antenna and it suddenly got much worse, made me think a connection was undone, and your description of your reception results makes me think "LOSS", such as if your radials became somehow disconnected.  It also sounds like you may have some strong noise sources in the building.
My vertical installations have been lossy in proximity to other metal, so proximity to the building is probably a general issue, but the sudden worsening of performance would have me checking all connections.   If it had happened over a period of months I would have suspected water in the feedline, but that may not be your problem.

If there is a way to just elevate the vertical on a ten foot TV mast, or a taller push-up mast, or otherwise get it away from the building, you could see a big improvement both in escaping some of the noise and reducing loss.  If you elevate it even 8 feet off the ground You could also reduce the radials to 2 or 3 quarter wavelength radials per band, and make them out of thin magnet wire so they are nearly invisible.  I fooled a very picky neighbor with a setup like this for over ten years.  He came over and walked all over the yard with me, and never saw my 14 radials of 18 gauge magnet wire strung like a fan over my small subdivision yard, just 8 feet above his head.  I couldn't even see them from the kitchen window as little as ten feet away unless there was ice hanging on them.  That antenna would have been better higher, but it was a lot better than when I first had it ground mounted.

Your vertical has the potential to work well for you, but losses to the building can be huge, and may be somewhat band-specific depending on possible resonances in the nearby conductive materials.  Higher is better, and may move you away from objects that are sucking up the RF.

BTW, from my experience a properly tuned vertical over a good counterpoise/radial system will have an impedance of around 20-30 Ohms, so if your vertical gets down to an SWR of just under 2:1 you may be in fine shape.  Too low an SWR means loss problems, as does too wide an SWR bandwidth.  If your vertical is supposed to have a 25 kHz 2:1 SWR bandwidth on 80m and you are seeing 50 kHz or more, or if it is showing a 1:1 SWR, start looking for and eliminating causes of loss.

Best of luck with it.  73 de kt8k - Tim
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K1WJ
Member

Posts: 451




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« Reply #22 on: September 20, 2009, 04:59:53 PM »

Glad to see your 20mHamstick Dipole worked out.

If you want to step it up a a S-unit or 2 from the Hamstick dipole then you need to get the S9 20M rotatable 20m dipole, based on your stated needs.

Can not go wrong with the S9 20M dipole. Look at the concept - you could build one yourself.

Anyways, one of the QSO's I had to ID from MI yesterday lasted 50 minutes on the hamstick dipole, with signals down 2 s-units consistantly on my 4BTV - modified also for 12m/17m (easy) myself. Hamsticks dipoles ARE a resonable antenns for 6m/10m/12m/15m/17 & 20m.

If you can not get your BTV at least 24ft away from a major structure, & at least 30 ground radials - it will not work to potential - that's that. Use RG8, 213, LMR , only for coax. RG8X ok for cost.

Do not expect more than 15khz for 75-80m on your antenna (6btv) - most get about 5-7khz - for REAL less than 2:1.

Over & Out ...Look at S9....David - K1WJ - 8
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KG6WHN
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Posts: 48




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« Reply #23 on: September 20, 2009, 05:50:15 PM »

Yep the hamstick dipole seemed to work much better than my 6BTV in it's current compromised setup.  The main problem is that there is no way I can get this antenna (with a ground mount) to have 20+' around it on all sides.  However, I am thinking about a roof mount.  The only real problems I had with the hamstick dipole were that the push up mast I picked (the paint roller extension) was a bit too "bendy" for the weight of the dipole so I had to reduce the height a bit.  Basically it looked like it would bend (or snap) at its full extension when I tried to lift it.  I guess the alternative is to find a ladder (since the lowest adjustment is about 8' from the base).  The other problem (might be my imagination) was the concern that the neighbors might not appreciate the dipole whips aimed at their houses ;-)  Not terribly "stealthy" maybe.  However, since I'm enclosed by other houses..not too much choice...the whips have to point somewhere.  I also like that it's rotatable...a really good feature that can't be easily accomplished with a wire dipole.  I was also looking at a "Buddipole" antenna....what is the S9 20M dipole you mentioned?
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K1WJ
Member

Posts: 451




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« Reply #24 on: September 21, 2009, 05:23:18 AM »

www.s9antennas.com

You will find the S9 20m dipole at this site.

73 K1WJ
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WA3SKN
Member

Posts: 5439




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« Reply #25 on: September 21, 2009, 01:24:46 PM »

You have a short or open somewhere... Probably at the antenna.  Yes, it could be in a better location but the lack of signals getting to the radio is saying something.  Take a real close look at ALL the connections!
Good Luck!
73s.

-Mike.
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