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]   Go Down
  Print  
Author Topic: Extended Double Zep  (Read 2328 times)
WB4ROA
Member

Posts: 10




Ignore
« on: February 06, 2013, 03:00:04 AM »

Hi folks. I plan to put up an extended double zep for 30M.  I was wondering if it would be possible to make this a 40/30M simply by adding 40M wire, connecting at junction with 30M wire and ladderline, and providing insulation between the two wires along the wire run.  Perhaps even providing different anchor points to provide more seperation between wires.  I realize this will screw up the length of the ladder line as it will be cut for 30M.  Is it worth the effort?

Thanks much, Hank WB4ROA
Logged
W5DXP
Member

Posts: 3580


WWW

Ignore
« Reply #1 on: February 06, 2013, 05:22:00 AM »

I was wondering if it would be possible to make this a 40/30M simply by adding 40M wire, ...

The fan dipole approach works for resonant dipoles where the current takes the path of least resistance. The EDZ is NOT a resonant dipole, at least not on the EDZ frequency.

A 30m EDZ (120' dipole + 16' ladder-line) will work with a tuner on some of the other HF bands like 80m, 20m, 15m, and 10m. Unfortunately, the coax SWR on 40m is very high. One solution might be to have the 120' dipole fed with 16' of ladder-line and then connect a 1/2WL 40m dipole to the other end of the 16' of ladder-line with the coax connected in parallel with the ladder-line at the 40m dipole feedpoint.

A 120' dipole (30m EDZ) fed with 100' of ladder-line using a tuner is a good 40m/30m antenna and works fairly well on most of the other HF bands with a wide-range tuner.
« Last Edit: February 06, 2013, 05:30:31 AM by W5DXP » 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: 13242




Ignore
« Reply #2 on: February 06, 2013, 07:10:38 AM »

Run the ladder line all the way to the shack and use a tuner there.
Then you can use the same antenna on 80m - 10m.

It gives you two half waves in phase ("Double Zepp") on 40m and
Extended Double Zepp on 30m.

If you add a pair of 40m EDZ wires to the same feedpoint they
may carry a significant amount of the 30m RF.
Logged
WB3CQM
Member

Posts: 117




Ignore
« Reply #3 on: February 08, 2013, 03:24:22 AM »

Hi folks. I plan to put up an extended double zep for 30M.  I was wondering if it would be possible to make this a 40/30M simply by adding 40M wire, connecting at junction with 30M wire and ladderline, and providing insulation between the two wires along the wire run.  Perhaps even providing different anchor points to provide more seperation between wires.  I realize this will screw up the length of the ladder line as it will be cut for 30M.  Is it worth the effort?

Thanks much, Hank WB4ROA

I do not have data on my EDZ due to computer crash . But couple years ago I built a 40 meter EDZ and used is all the time on 30 meters. I do not remember if I needed tuner or not for transmit @ the 30 meter band. But it worked very good on 40 / 30

When ever I have built or modified a antenna to work on higher freq I choose the route of longer is better. Example of of Super Loop 80 I added a wave length plus to get it to show a low swr on 12 meters. It is like 4 wave length or something on 12 meter band. Amazing performance with that set up on 12. But I wrecked the antenna for what it was designed for.

I do think the 40 EDZ had poor receive on 80 and 20 and up. I did not try using the tuner as I recall due to poor poor receive on those bands. Of course the EDZ is meant for one band operation .

Don't know what your reason for EDZ is or what freq of operation but you might just build it for 40 meters and see how well it works on 30. easy to make longer and cut latter. I used 450 ladder line for the matching stub and DXE Balun at feed point.

The matching stub was cut to the inch to as well as the wire it self for 40 meter cw

73 JIM

Logged
W5DXP
Member

Posts: 3580


WWW

Ignore
« Reply #4 on: February 08, 2013, 05:29:52 AM »

Don't know what your reason for EDZ is or what freq of operation but you might just build it for 40 meters and see how well it works on 30.

EZNEC says a 40' high, 168' dipole (40m EDZ) fed with a 25' tuned feeder of VF=0.9 450 ohm ladder-line will have a 50 ohm SWR of 2.8:1 on 40m, 2.4:1 on 30m, 5:1 on 12m, and 4:1 on 10m. Note the 25' of tuned feeder is optimized for an equal SWR on 40m and 30m.
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.
WB3CQM
Member

Posts: 117




Ignore
« Reply #5 on: February 08, 2013, 06:23:37 AM »

Very good information  W5DXP : good to know that . I have no modeling program.
I have a antenna for some one to model if they want a task.

But back to the EDZ. I had no intention on using it on 30 meter band when I built it. I think the tuning stub was 19'1 or something close to that measurement  , but like I said I have no data on it any more. I used it in many pile up on 40 and 30 switching between several wires in that old antenna test field. It was real good performer.

I did change the orientation a few times and what the on line modeling program showed , I would believe is very much how the EDZ works. I used A quad / g5rv-m/super loop 80 to test against the EDZ.

73 JIM
« Last Edit: February 08, 2013, 06:26:23 AM by WB3CQM » Logged
N4KD
Member

Posts: 134




Ignore
« Reply #6 on: February 12, 2013, 12:54:47 PM »

I thought I understood the EDZ antenna, so I tried these number in a Smith chart and in VK1OD's transmission line loss calculator and now I'm really confused.

I have a question... Can you get a match close to 1:1 with just a series transmission line?

My numbers for a 168 ft EDZ at 7.15 MHz, NEC real ground, average:
Wireman 551 TL, Z=400 ohms, v=0.902
Zload at antenna 210.2-j1070.1 ohms
TL length = 70.17 deg, or 7.372m = 24.2 ft.
Z at feed line = 26.95+j0.19
VSWR(50) = 1.86 (alright, slightly better than 2:1, and the SWR losses aren't that high.)

That's the best I can do on 40m. I see different calculations for feed line length. One says that the stub length should be 246/f for a single band antenna. That's around 34-1/2 ft and is a terrible match. Another source says use 108/f for the stub, around 15.1 ft and still at terrible match. Where do these rules come from? I guess I need to go back to Cebik's site and read up on his results.

Thanks for any insights that you can provide. Personally, I think the antenna is too directive for a fixed wire. I converted mine to a top-loaded vertical by shorting the feed line together and loading it against ground.

vy 73,
Dave N4KD

Don't know what your reason for EDZ is or what freq of operation but you might just build it for 40 meters and see how well it works on 30.

EZNEC says a 40' high, 168' dipole (40m EDZ) fed with a 25' tuned feeder of VF=0.9 450 ohm ladder-line will have a 50 ohm SWR of 2.8:1 on 40m, 2.4:1 on 30m, 5:1 on 12m, and 4:1 on 10m. Note the 25' of tuned feeder is optimized for an equal SWR on 40m and 30m.
Logged
W5DXP
Member

Posts: 3580


WWW

Ignore
« Reply #7 on: February 12, 2013, 01:13:41 PM »

That's the best I can do on 40m.

Nope, that's not the best you can do. Increase your tuned feeder by one foot to 25.2 feet and install a -j58.3 ohm (382 pf) cap across the ladder-line. Resulting purely resistive impedance is 52 ohms. Is an SWR of 1.04:1 acceptable?Smiley

Or try 22.8 ft. of Z0=550 ohm. VF=0.95 open-wire line.
« Last Edit: February 12, 2013, 01:34:44 PM by W5DXP » 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.
N4KD
Member

Posts: 134




Ignore
« Reply #8 on: February 12, 2013, 02:29:28 PM »

That's the best I can do on 40m.

Nope, that's not the best you can do. Increase your tuned feeder by one foot to 25.2 feet and install a -j58.3 ohm (382 pf) cap across the ladder-line. Resulting purely resistive impedance is 52 ohms. Is an SWR of 1.04:1 acceptable?Smiley

Or try 22.8 ft. of Z0=550 ohm. VF=0.95 open-wire line.

I agree. Other ways to get a good match include inductors and shorted stubs at the feedpoint of the antenna. You could probably do something like the trombone match that W8JK used on his lazy-H array.

I had seen several internet articles that indicated a length of 400 ohm feedline, used as a series stub, would provide a good match and was trying to duplicate the results. That doesn't appear to be possible, unless one makes their own 550 ohm ladder line.

Thanks very much. I always learn something here.

Vy 73,
Dave N4KD
Logged
K9SRV
Member

Posts: 121




Ignore
« Reply #9 on: February 12, 2013, 02:49:48 PM »

First, do what Cecil says! I picked his brain 3 or 4 times while building my 40 edz.
Here are the end results. Took a DXE 160 dipole kit. Course waayyy too long , so I thought every night on next best option. Result, a 170 ft. long 40 m. edz, fed w/ 300 ohm, legal limit  twinlead
into the shack. Here I have a Balun Designs 4:1 balun, which I may use or not, depending on swr that I can dial up with my Johnson Matchbox.
Works  well on 40, but what surprised me, was that I have NO AMP for 80 and 160. 160, I dont care 160 about because the matchbox won't work down there. However, I have woorked Europe on 80 barefoot many, many timess, when condx are right with just my old Kenwood ts 680 @ 100 watts. At first I was stunned, then I realized my 40 is actually almost 40 feet longer than a full sized 80 dipole.
I really think the performance comes from a great balanced tuner, and a piece of lmr 400 2 feet long. However, at this point, I'll let Cecil respond. Cecil, one question. Why all the talk of LL to coax. Wouldnt it be better just to get a great balanced tuner and run right to the tuner w/ balanced line and forget all about coax completely?

John
K9SRV
Logged
W5DXP
Member

Posts: 3580


WWW

Ignore
« Reply #10 on: February 12, 2013, 03:03:00 PM »

Wouldnt it be better just to get a great balanced tuner and run right to the tuner w/ balanced line and forget all about coax completely?

That will work just fine and that's what I would do. Just add an integer number of 1/2WL of ladder-line to the tuned feeder length to avoid having to use a tuner. The bonus is a multi-band antenna and ladder-line is cheaper than coax.
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.
K9SRV
Member

Posts: 121




Ignore
« Reply #11 on: February 12, 2013, 07:53:06 PM »

Oh Wow, I didn't realize the tuned feeder part, if done correctly, would eliminate the Tuner!  Would this work all bands w/o a balanced tuner, it the length of feeder ios exactly right?
John
Logged
WB6BYU
Member

Posts: 13242




Ignore
« Reply #12 on: February 12, 2013, 09:02:32 PM »

You'd probably have to switch in different line lengths for each band, and
possibly shunt or series matching capacitors / coils.  But you probably
can make it work one way or another.
Logged
W5DXP
Member

Posts: 3580


WWW

Ignore
« Reply #13 on: February 13, 2013, 06:16:49 AM »

Oh Wow, I didn't realize the tuned feeder part, if done correctly, would eliminate the Tuner!  Would this work all bands w/o a balanced tuner, it the length of feeder ios exactly right?

It would require something like my notuner ladder-line length selector for bands other than the one (40m) for which the EDZ is optimized.

http://www.w5dxp.com/notuner.htm

Otherwise, put the tuner in bypass mode for the band (40m) for which the EDZ is optimized and switch the tuner in as needed for the other bands. Here's what EZNEC sez the 50 ohm SWR will be for a 167 ft. dipole fed with 84.4 ft. of 450 ohm, VF=0.9 ladder-line.

80m, 4:1; 40m, 1.4:1; 30m, 35:1; 20m, 46:1; 17m, 1.6:1; 15m, 25:1; 12m, 60:1; 10m, 11:1

I would say that antenna (optimized for 40m) would not need a tuner on 40m and maybe not on 17m. It would need a tuner on 80m and 10m. On the other 4 bands, those high impedances may (or may not) give the balanced tuner a challenge. 20m would be the worst case with an impedance looking into the ladder-line of 1600-j1100 ohms, i.e. pretty close to a standing wave voltage maximum point (a condition that we once called anti-resonance).
« Last Edit: February 13, 2013, 06:31:19 AM by W5DXP » 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.
Pages: [1]   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!