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Author Topic: Cushcraft R8 Vertical Antena  (Read 506 times)
KJ3LR
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Posts: 5




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« on: December 06, 2018, 03:56:37 PM »

Hi Folks,
I'm thinking of installing an R8 vertical and would like any comments and remarks about how high it should be mounted above ground.
I have a 40 foot push up pole that has a 2 meter monoband antenna on it for an echolink node. That antenna will be removed for the R8.
I've heard 10 foot high would work. Although, 10 foot at the base of the R8 wouldn't be above my roof line, but should be good for NVIS.
Thanks for any and all feedback.  de KJ3LR - Lou Smiley
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KL4QG
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Posts: 94




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« Reply #1 on: December 06, 2018, 04:25:36 PM »

I tried one could not get it radiate on 80/40
On my boat-Friends in Florida have good luck R8

Alpha Pro Master 17 foot mast with 24 foot NVIS ground wave wire -

This antenna needs no turner From 10/80 meters and radiates 360
With a strong signal




Captain Joe
Kodiak AK













Alpha Pro Master - What other antennas  want and try to be when they grow up

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K6JH
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Posts: 466




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« Reply #2 on: December 06, 2018, 04:50:42 PM »

I tried one could not get it radiate on 80/40


Maybe because an R8 is not an 80M antenna? 40-6M. An R9 include 80M.

I had an R8, mounted on a single section of mast at 10ft. It's a pretty flimsy antenna, and if I did mine over again, I would have tried guying it. Electrically it was OK, but kind of expensive. Didn't cover all of 40. And it's now made by MFJ, with all that that brings with it.
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73
Jim K6JH
KJ3LR
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Posts: 5




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« Reply #3 on: December 08, 2018, 01:26:49 PM »

Thanks for the relies! Actually, as every vertical is a compromise antenna, I decided to go with a ZEROFIVE 40-10 meter vertical.
With the ZeroFive, there are less electrical and mechanical parts that are prone to failure. Plus, it'll be cheaper than the cushcraft(mfj) antenna.
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KD6RF
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Posts: 756


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« Reply #4 on: December 08, 2018, 01:39:52 PM »

Don't forget, like any base driven vert that's less than about 3/8 wavelength, you will really benefit from a decent radial system on those low bands.  (Assuming you are talking about the 24 ft version?).

Sometimes mfrs downplay the need for radials, and you can start loosing dB hand over fist on those low bands! 

40 M has been been in good shape lately (EU from Texas in early afternoon was a first for me), so have fun and CU on the air!
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VTenn Antennas
Bay Area Technical Equip Rental and Test Range
http://vtenn.com/Blog/
KL4QG
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Posts: 94




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« Reply #5 on: December 08, 2018, 02:01:20 PM »

We dug hole put 50 pounds rock salt with 15 brown sugar than wet dirt

This bonds the dirt to make the best place Ground the antenna

My Alpha Pro Master is grounded to salt water on my boat R8 on 20/40 was proformance was very poor conspired to Pro Master



Captain Joe
Kodiak Alaska Famous Rock Star of Ham Radio
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KL4QG
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Posts: 94




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« Reply #6 on: December 08, 2018, 02:06:25 PM »

We dug hole put 50 pounds rock salt with 15 brown sugar than wet dirt

This bonds the dirt to make the best place Ground the antenna

My Alpha Pro Master is grounded to salt water on my boat R8 on 20/40 the  proformance was very poor conspired to Pro Master



Captain Joe
Kodiak Alaska Famous Rock Star of Ham Radio
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KD6RF
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« Reply #7 on: December 08, 2018, 02:24:28 PM »

I tried one could not get it radiate on 80/40
Maybe because an R8 is not an 80M antenna? 40-6M. An R9 include 80M.
This, along with the fictional numbers in QG's other posts on efficiency and relative "S-Meter" performance, tell us that there's not a lot to be learned from joseph the rock star's "measurements" or techniques Sad

The correct way to provide a ground system is to install a radial (or screen) field.  I suppose you could dig some holes too if you really like and make some brown sugar dirt cookies Smiley, but it won't matter, since radials are the correct and time-stable method to provide a low impedance ground on land.   Unless maybe you live on a 30 acre salt marsh!

If you enjoy looking through the details of counterpoise and radial systems (and who doesn't  Cheesy), Rudy N6LF has a good series of articles on the details of radial systems.  "Classic N6LF Radial and Counterpoise Articles" ===> http://vtenn.com/Blog/?p=26

If you only read one, this one cuts to the chase ===>http://vtenn.com/Blog/wp-content/uploads/2016/12/qex-ground-systems-part-4.pdf

The answer always seems to comes out to:  "around 15 radials" for these types of antennas, and you can add or subtract from that number depending upon whether or not you want to give up or gain that last dB of performance.

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VTenn Antennas
Bay Area Technical Equip Rental and Test Range
http://vtenn.com/Blog/
N2SR
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Posts: 973




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« Reply #8 on: December 08, 2018, 03:52:30 PM »

This, along with the fictional numbers in QG's other posts on efficiency and relative "S-Meter" performance, tell us that there's not a lot to be learned from joseph the rock star's "measurements" or techniques Sad

The correct way to provide a ground system is to install a radial (or screen) field.  I suppose you could dig some holes too if you really like and make some brown sugar dirt cookies Smiley, but it won't matter, since radials are the correct and time-stable method to provide a low impedance ground on land.   Unless maybe you live on a 30 acre salt marsh!

If you enjoy looking through the details of counterpoise and radial systems (and who doesn't  Cheesy), Rudy N6LF has a good series of articles on the details of radial systems.  "Classic N6LF Radial and Counterpoise Articles" ===> http://vtenn.com/Blog/?p=26

If you only read one, this one cuts to the chase ===>http://vtenn.com/Blog/wp-content/uploads/2016/12/qex-ground-systems-part-4.pdf

The answer always seems to comes out to:  "around 15 radials" for these types of antennas, and you can add or subtract from that number depending upon whether or not you want to give up or gain that last dB of performance.

Agreed Dave! 

I always love the posts here and on another message board, "What's the best vertical antenna that doesn't need radials."   

At a previous QTH, I had a Butternut HF2V (80m and 40m).   While it is just an 1/8 the wave on 80, I put 60+ radials under it.   Had it up for 10 years, and had 240 countries on 40 and 185 countries on 80/75 with it.   

Bottom line: you need radials, with a vertical.   As your links note, the performance of any vertical will be determined by how many radials you put down.  Of course the law of diminishing returns applies.

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If no one is doing it that way, there is a probably a very good reason.
KJ3LR
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Posts: 5




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« Reply #9 on: December 08, 2018, 04:07:13 PM »

Thanks again for the insight. I was going to put the vertical on a push-up pole at just above the roof line, 12 feet high, on the side of the house, without ground radials.
After reading the above link(s), I think I will just have to ground mount the antenna in the center of my backyard and run as many ground radials as I can.
Thanks again for the feedback!
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KL4QG
Member

Posts: 94




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« Reply #10 on: December 08, 2018, 04:18:00 PM »

Thanks again for the insight. I was going to put the vertical on a push-up pole at just above the roof line, 12 feet high, on the side of the house, without ground radials.
After reading the above link(s), I think I will just have to ground mount the antenna in the center of my backyard and run as many ground radials as I can.
Thanks again for the feedback!

Save your self some trouble buy Alpha Pro Master antenna

Just ground antenna connect coax you good good from 10/80 meters no tuner needed /





Captain Joe /Kodiak Alaska most powerful Marine Mobile

Talk us on 14245
3920
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K3GM
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Posts: 2424




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« Reply #11 on: December 08, 2018, 06:52:10 PM »

......I think I will just have to ground mount the antenna in the center of my backyard and run as many ground radials as I can.....
Before you go doing this, please download the R8 assembly manual.  First page will tell you to mount it a minimum of 10' above ground.  No radials are required with this antenna.  It is very sensitive to surrounding metallic objects and must be kept clear of them.
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KD6RF
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« Reply #12 on: December 09, 2018, 03:33:45 AM »

True /\

Personally, I am skeptical of "no radial" antennas like R8, and have seen data showing them somewhat down from a standard install like ZeroFive 24 footer, or other standard vertical against a decent ground radial system.  

But they can be used if you can't fit in a proper radial field, and thank you Tom for correctly pointing out the difference in counterpoise requirements.
« Last Edit: December 09, 2018, 03:41:31 AM by KD6RF » Logged

VTenn Antennas
Bay Area Technical Equip Rental and Test Range
http://vtenn.com/Blog/
RFRY
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Posts: 623


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« Reply #13 on: December 10, 2018, 05:19:55 AM »

The r-f loss for some number and length of radial wires buried in soil of relatively poor conductivity rises sharply, as seen in the graphic below.

Fewer and/or shorter radials may produce close to the lowest practical loss possible if the antenna site has soil of high conductivity.

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KM1H
Member

Posts: 4722




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« Reply #14 on: December 10, 2018, 01:17:01 PM »

CAREFULLY READ the R-8 manual and DO NOT mount on the ground if you want it to work as designed. Using it with a remote auto tuner makes it very convenient and near fool proof.

http://www.cushcraftamateur.com/Product.php?productid=R-8


http://www.cushcraftamateur.com/support.php?productid=R-8
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