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Author Topic: antenna location, radial length  (Read 1348 times)
KB3SXC
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Posts: 6




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« on: March 09, 2012, 11:18:28 AM »

Have a hustler 5btv that I just got.  Is there any definitive distance this antenna should be located from my home?  I know that I will need radials but am hearing that radialls should be  speciofic lengths for each band and on the other hand, radial length doesn;t matter.  My home is on a very sandy soil and a poor conductor.  Thanks
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WB2WIK
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« Reply #1 on: March 09, 2012, 11:43:26 AM »

If you're going to ground-mount the antenna, of course you'll need radials.  They needn't be "tuned."  A good rule of thumb is to use 16 radials as long as the antenna is tall (which in your case is probably about 26 feet or so).  More can sometimes help.

As such it would be great to get the antenna that distance (~26') away from the house, so the radials can lay symmetrically around the antenna.
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W5DQ
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« Reply #2 on: March 09, 2012, 01:24:26 PM »

If you're going to ground-mount the antenna, of course you'll need radials.  They needn't be "tuned."  A good rule of thumb is to use 16 radials as long as the antenna is tall (which in your case is probably about 26 feet or so).  More can sometimes help.

As such it would be great to get the antenna that distance (~26') away from the house, so the radials can lay symmetrically around the antenna.

Steve gives good advice on the Hustler BTV series.

For a real world example, I installed a 6BTV recently and it is appx half way between the shack in my shop building and the house, a equidistant of 35-40' both ways with the back yard opening to the North for 100 feet. The radials run in a spoked pattern . The base of the antenna is located about 20' from a wooden property fence but I had to place it there for 'political' reasons, i.e. satisfy the wife and her open back yard philosphy.  I have 48 radials with average length appx 40' (min 18' max 65' in group). The feedline is run under the radials a few inches down and has 6 Amidon FB-77-1024 cores for a current choke at the feedpoint. I'm using the DX Engineering Impedance Matching Coil to bring the 80M and 40M SWR down to a reasonable level with 80M 1.1:1 and 40M 1.2:1 on the MFJ-259. I'm also installed a mod using the Hustler 40M Super resonator with a DX Engineering Hot Rodz top hat assembly in place of the stock 80M Super resonator to increase the efficiency and broaden the 80M bandwidth some for a 2:1 bandwidth of appx 100Khz on 80M and 175Khz on 40M. If you want to try this mod, please note I had to add appx 30" of 1.25" tubing between the 30M trap and the 40M/top hat w/48" stingers setup (I built an extension to fit above 30M trap and attach the top stock 30" section of the 6BTV too) to achieve resonance on both 80M and 40M. But after it was all done and tuned, this setup is working great and I am getting good reports with it.

I took the 80M resonator I removed for the first mod and added another DX Engineering Hot Rodz top hat assemble but this time using the 72" stingers. Temporarily removing the 80M load (40M resonator / top hat assembly (it just unscrews off the top threaded stud)), I screwed on the old 80M resonator and added the top hat assembly and tuned for 160M. Note that in doing this, you temporarily you lose 80M and 40M since the other resonator assembly which tuned those band is not there. With the 160M, I get appx 22 Khz of 2:1 SWR bandwidth and use my external MFJ-989 tuner to tweak around that as needed. It seems to work fairly well as I worked 74 QSOs, 23 states, 6 CA Prov's and 3 DX countries in the CQ 160M contest in one evening, first time out of the gate. As I had nothing before on 160M, it was sheer joy to add to my 160M count. Is this a 160M 4-square compatible setup ...... not in any imagination that can be thought but it will get you on 160M cheaply (appx $50) since you already have the 5BTV.

Gene W5DQ

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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
K3VAT
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Posts: 709




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« Reply #3 on: March 10, 2012, 05:08:46 PM »

Both Gene and Steve supplied good advice; I see Gene went 'all out' on his 6BTV setup  Grin

Have a hustler 5btv  ... My home is on a very sandy soil and a poor conductor.  Thanks

Sandy soil may or may not be a poor conductor - depends what is the other constituents of the soils along with the amount of ground moisture.  If you at your QRZ location (Silver Spring MD) which is not far from where I used to live (Bethesda), then don't be overly concerned with your soil.  As long as your lot doesn't turn into a desert then the vertical should do well, especially with lots of radials (shoot for a couple dozen ~35', [I know that this is more that Steve recommended, but your 40M signals could be a couple db stronger]) - your lot dimensions may limit you in some directions).

GL, 73, Rich, K3VAT


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K3VAT
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Posts: 709




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« Reply #4 on: March 10, 2012, 05:13:46 PM »

John:
Ops, I incorrectly typed your call into QRZ and see that you're nowhere near Washington DC area - sorry about that.
But anyway, generally, the same recs hold for your location. 

GL, 73, Rich, K3VAT
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W5DQ
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« Reply #5 on: March 11, 2012, 01:45:19 AM »

John:
Ops, I incorrectly typed your call into QRZ and see that you're nowhere near Washington DC area - sorry about that.
But anyway, generally, the same recs hold for your location. 

GL, 73, Rich, K3VAT


Rich,

You were right the first time only off a few miles for John's QRZ address. Lusby, Maryland is on Solomon's Island just south and east a bit from DC on Hwy 4(come south out of Baltimore, hit Hwy 50 West for a fewmiles and then take 4 South and you're there). I used to go through that area every time I went down to Pax River, MD when I traveled back to that part of the country years ago for work. John's soil should be great for a vertical as he is in proximity to salt water / brackish water being in the Chesapeake Bay area. Wish I had his 'dirt' and he had mine Smiley

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
N0AZZ
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Posts: 241




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« Reply #6 on: March 11, 2012, 05:28:22 AM »

I have a HyGain HyTower 10-160m and have the minimum amount of radials IMHO for a vertical to work properly 64 and they range in lengths from 15'-120' mine was setup to work best on 80m so a large amount of 1/4 waves for 80m and it's a real DX antenna for that band.

All verticals need radials to work and the more the better I installed mine the way that it was intended to be. Installed it using the 6 8' ground rods with everything bonded with the 1/4 wave radials and I guess that's why it is the #1 rated veritcal it works. I did install more but they did not help the lower bands so I lengthened them to 120' for 160m and it improved top band because I only had 16 down for it before now have 32 total for 160 and receive did pickup a little.
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WX7G
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Posts: 6043




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« Reply #7 on: March 11, 2012, 07:31:39 AM »

I mounted a 5BTV 12' from the house (stucco construction) and placed 90 radials around it covering a 25 x 50 foot yard. The ground loss resistance was measured (by base impedance measurements) to be approximately 10 ohms on 80 meters and 5 ohms on 40 meters on up.

Bottom line: The radials do not have to be really long and the antenna does not have to be very far from the house.
« Last Edit: March 11, 2012, 10:49:17 AM by WX7G » Logged
K3GM
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Posts: 1799




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« Reply #8 on: March 11, 2012, 12:09:27 PM »

Looking at your QTH from a satellite image, it appears that you have plenty of room to move the antenna site farther away from your house.  Is there a reason that you plan to have it so close?  The information given to you so far is good.  I'd add that you wanthe bottom of the antenna close to the ground; Several inches or so.
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