Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1] 2 3 Next   Go Down
  Print  
Author Topic: S9 31 FOOT VERTICAL  (Read 7772 times)
K2OWK
Member

Posts: 1065




Ignore
« on: November 02, 2012, 04:40:24 PM »

Hello, I just finished installing a 31 foot S9 antenna. I have the LDG radial plate with 20 radials most at the recommended 26 feet 9 inches, a few a little shorter due to room problems. I have the LDG 4 to 1 UNUN at the base of the antenna. The antenna is being fed with about 30 feet of RG 8x. At the shack I have an MFJ -914 Auto Tuner Extender. Now here is the problem (which might not be a problem). I have never used a vertical antenna before. Here is how it is working and what it is doing. It will tune 40, 15, 12 and 6 meters, and the upper portion of 80 meters (it is not supposed to work here). It will not tune 20, 17 or 10 meters. I know an S9 antenna is a non resonant vertical long wire, but I thought it would tune all the bands between 40 and 6 meters. I made my first contact on 40 meters today and got a 5 by 9 signal report from IL. He was running a kilowatt and he was hitting me with a 10+ signal. The receiving on the antenna is better by 2 S units then my 40 meter inverted "V" on 40.
So here is my question is this the way this antenna is supposed to work, or do I have a problem with the way I installed it? I was hoping to be able to use it on all bands from 40 thru 6. My antenna analyzer agrees with my auto tuner that the bands that do not work can not be adjusted with the MFJ-914 below 3 to one VSWR. The 914 has the capability to match antennas up to a 10 to 1 VSWR, but the bands indicated are greater then 10 to one and can not be brought down low enough.

Any help would be greatly appreciated.

73s

K2OWK
Logged
G0VKT
Member

Posts: 64




Ignore
« Reply #1 on: November 03, 2012, 06:12:49 AM »

My guess that the impedance on the bands that don't work are out of the range of your auto tuner. Sorry, but I am at the early stages of EZNEC so i can't model it.

I am curious about the 4:1 on 40M. The impedance will already be quite low and the UNUN may make it too low. The antenna may be more efficient on 40M without it. Perhaps others will comment.

From their website:

For multi-band use, a 4:1 Unun is recommended at the antenna feed point for coax runs over 50 feet long. A 4:1 unun lowers the higher impedance's presented by the antenna on frequencies above 40 meters. If you are using a quality antenna tuner and have a coax run under 50 feet, a 1:1 current choke balun located outside of the radial field will suffice.

There are a couple of things here that are confusing and a little suspicious. The comments about feed line length suggests to me that the coax is part on the antenna and is radiating. And why would you have a current balun outside of the radial field (i.e 26' from the feed point if I am understanding correctly) for runs <50'. Again, it suggests to me that the coax is part of the antenna.
Logged
KC7YE
Member

Posts: 97




Ignore
« Reply #2 on: November 03, 2012, 06:50:35 AM »

I use a home brew knock off of S9 and what ever the /portable location allows for radials. AH4 tuner at base of ant. 80 -10. Today it is set up at cabin in state park for CW SS operation, 1 radial, needed to keep this one low profile. I and several other WWA ops have had good results with set up.
Logged
WX7G
Member

Posts: 6131




Ignore
« Reply #3 on: November 03, 2012, 07:10:02 AM »

I assume you are using the autotuner in your transceiver along with the tuner extender. An external manual tuner will tune it but if you want to try using what you have here is what I would do:

1. Remove the 1:4 UNUN and feed it directly. See if it will tune all bands. If this is not satisfactory...
2. Increase the coax length to add loss. It may need 100' to tune.
Logged
W8JI
Member

Posts: 9296


WWW

Ignore
« Reply #4 on: November 03, 2012, 09:15:06 AM »

I don't know why people think, or are told, that a 30 foot vertical is an all band antenna. Especially one with a thin wire element.

The entire "vertical longwire" concept is strange to me.
Logged
W5DXP
Member

Posts: 3613


WWW

Ignore
« Reply #5 on: November 03, 2012, 10:37:59 AM »

I don't know why people think, or are told, that a 30 foot vertical is an all band antenna.

If it had something like an SG-230 at the base, with a good radial system, it wouldn't be all that bad of a 40m-15m antenna. It's too long on 6m for my tastes.
Logged

73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
K2OWK
Member

Posts: 1065




Ignore
« Reply #6 on: November 03, 2012, 05:32:27 PM »

Thanks for all the information. I tried adding an additional 50 feet of RG8X to my existing 30 feet with no change in VSWR noted. The instructions on the antenna says you can use RG8X in runs less then 50 feet. I used a short run to keep losses to a minimum. I guess the 914 range is not broad enough to cover all the frequencies. I will have to get a manual tuner to use the antenna to its full capability. Just for a note, the instructions say that the use of a 1 to 1 balun is recommended for a single frequency (in the case of this antenna 40/15 meters) when used as a ground plane with 4 tuned radials at elevated height. W8JI the antenna tunes great on 6 meters. The 914 allows me to tune the complete band. I will let everyone know how a regular manual tuner works on this antenna. I believe that is what is recommended. I know an auto tuner at the base is ideal, but they are to expensive for me.

Thanks again everyone.

73s

K2OWK

PS: The receiving  side of this antenna works great on all the bands.
Logged
WX7G
Member

Posts: 6131




Ignore
« Reply #7 on: November 03, 2012, 05:40:24 PM »

RG-8X is too lossy for this antenna. A short run of RG-213 or better and a good manual tuner and it should tune 80-10 meters.
Logged
N3HAM
Member

Posts: 27




Ignore
« Reply #8 on: November 03, 2012, 08:03:58 PM »

I've had mine up for almost 4 years with 40 radials with half bent on two axes to fit my yard. I use a 4:1 unun and a manual tuner, though the tuner in my FT990 will tune it. It can tune a bed spring. I use RG6 and it works 80 trough 10 fine enough for me. /http://http://vk1od.net/transmissionline/RG6/
Logged
W5DXP
Member

Posts: 3613


WWW

Ignore
« Reply #9 on: November 03, 2012, 08:09:50 PM »

W8JI the antenna tunes great on 6 meters.

With a take-off-angle of 40 degrees, who are you going to talk to?Smiley
Logged

73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
WB6BYU
Member

Posts: 13335




Ignore
« Reply #10 on: November 03, 2012, 09:08:22 PM »

Actually the 31' vertical has more radiation at +5 degrees above the horizon than a quarter wave
vertical does.  (In fact, increasing the height a couple feed would add another dB or so.)

But not too many serious 6m operators use a ground mounted vertical.
Logged
W5DXP
Member

Posts: 3613


WWW

Ignore
« Reply #11 on: November 04, 2012, 07:52:37 AM »

Actually the 31' vertical has more radiation at +5 degrees above the horizon than a quarter wave vertical does.

How about from 13 degrees to 30 degrees?Smiley
Logged

73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
K2OWK
Member

Posts: 1065




Ignore
« Reply #12 on: November 04, 2012, 10:05:24 PM »

I am back with one last question. The 4 to 1 UNUN I have is mounted with its bottom flush down against the aluminium radial plate. Could this cause any kind of coupling that might de-tune the UNUN? I have never used a UNUN before and I am wondering if I should move the UNUN so it is not in direct contact with the radial plate? For some reason I can not tune 40 meters today when I could yesterday. The only variation between today and yesterday was a large drop in temperature. I am going to remove the UNUN tomorrow and check for cold solder joints and bad connections. If I need to relocate the UNUN this would be a good time to know if I should.

Thank to all the answers I received all were very helpful.

73s

K2OWK
Logged
W5DXP
Member

Posts: 3613


WWW

Ignore
« Reply #13 on: November 05, 2012, 05:45:40 AM »

For some reason I can not tune 40 meters today when I could yesterday.

40m is the band where the 4:1 transformation makes things worse. According to EZNEC, it takes the SWR from 2.4:1 with a 1:1 unun up to 6.7:1 with a 4:1 unun. You would probably solve your 40m problem by using a 1:1 unun instead of a 4:1 on 40m. Of course, having to switch ununs at the feedpoint sorta defeats the purpose of that compromised vertical design, doesn't it? (There is no free lunch.)Smiley
Logged

73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
V47JA
Member

Posts: 113




Ignore
« Reply #14 on: November 05, 2012, 06:09:27 AM »

W8JI the antenna tunes great on 6 meters.

With a take-off-angle of 40 degrees, who are you going to talk to?Smiley

And the answer is: In 2 years, 37,000+ QSO's, 223 countries, 5 Band DXCC. All with a 31' , S9 Vertical, using the metal roof as the radials, with a Balun Design 4:1 Unun, and an AT-AUTO Tuner. which tunes it better then 1.2:1 on all bands 10-80m.

73,

John V47JA  -  W5JON

Logged
Pages: [1] 2 3 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!