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View Full Version : Looking for a simple antenna for 20,40, and 80 meter use.



N8MJS
09-18-2012, 08:05 PM
I will use this antenna as a example http://www.ebay.com/itm/320982768720?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
I already have a antennas for 6-17 meters. I would only use the above antenna for 20,40, and 80 meters.
The seller doesn't mention anywhere about grounding the antenna?
I was thinking of mounting the antenna as a sloper off my tower or as flat top off my tower to a tree.
I also wonder if my Kenwood TS480sat's internal tuner would tune this antenna or if I would need to purchase a wide range tuner.

WB2WIK
09-18-2012, 08:41 PM
That's "mostly" a shortwave receiving antenna. They claim it can be used for transmitting with an antenna tuner, as almost anything can be used for transmitting with a good enough antenna tuner.:p It has a pretty low power rating (250W PEP) which would tend to indicate small balun components (cores, and possibly the wiring); this implies "more loss" than using bigger components, as reasonably sized components could handle 1500W.

Since they indicate no connection to the second terminal, the design must use the coaxial cable outer conductor as a return current path -- probably not a great idea.

If possible, I'd go for a balanced antenna like a trapped dipole from the tower to a tree (assuming the tree is far enough away), or an inverted vee supported by the tower or a tree, with the two legs sloping back towards the ground, anchored to lower support points.

W9GB
09-18-2012, 08:48 PM
I was thinking of mounting the antenna as a sloper off my tower or
as flat top off my tower to a tree.
Non Sequiter.

1. You have a tower, How tall (feet)?
2. You have a tree, How far from tower and height (feet)?

You could use a shortened (loaded) 80/40 antenna, and add a 20 meter dipole, as 2-element, fan configuration.
===
Steve is correct that this N9HRP antenna looks like a RF common mode generator.
No YING for the YANG.

I also wonder if my Kenwood TS480sat's internal tuner would tune this antenna or if I would need to purchase a wide range tuner.
An internal antenna tuner is usually good for up to 3:1 SWR.

IF you really want a random wire, then purchase a random wire antenna tuner
at the power levels (100, 600, 1000, 1500 watts) you will be running.

KF6ABU
09-18-2012, 08:51 PM
That will not work as well as a simple trapped dipole, or fan dipole, by a large amount. I'd keep it simple with a fan or trapped dipole. Fan dipole could be inverted v from your tower.

K0RGR
09-18-2012, 08:58 PM
Actually, a G5RV style antenna should suit your needs. I would expect an OCF antenna like the Carolina Windom to give you good service on those three bands, as well. I like the Alpha Delta DX-CC myself. I'm using one to work DX on JT65HF right now.

WB2WIK
09-18-2012, 09:21 PM
Actually, a G5RV style antenna should suit your needs. I would expect an OCF antenna like the Carolina Windom to give you good service on those three bands, as well. I like the Alpha Delta DX-CC myself. I'm using one to work DX on JT65HF right now.

The DX-CC is a very good antenna. I've installed at least five of them over a period of many years; normally didn't even need to adjust them -- very "plug & play" for a wire antenna!

And it's short enough that an inverted vee version can be installed only about 35-40' above ground and still fit on a small city lot. It's got a lot of benefits.

KD2CJJ
09-18-2012, 09:26 PM
The real question is how your QTH is setup and what it can support..

Do you have at least 1 support point for an inverted V?
Do you have 2 support points for a typicaly deployed dipole?
Do you have the ability to get the feed line perpendiculaor to any of the two above?
Do you have area for a vertical with radials? If no radials do you have enough space and access for a ground plane vertical (no radials)?
Do you have access to the roof of your house? If yes can you put a tripod on the roof? If yes can you put a mast along side the roof?

There are too many options / limitations that would dictate the type of antenna..

All those bands can be had either by a horrizontal or a vertical anteanna - what will dictate the type of antenna are your QTH limitations. All of which you can build yourself... If your lazy and you have the $$ then you have a TON of options....

If you want easy to deploy in a vertical OR horizontal , Sloper, Inverted L, Inverted V, etc...then yes an end fed antenna is the way to go... typically end fed antennas do very poorly when they are multi band as they require a matching network which typically introduce a fair amount of loss - whats a fair amount of loss, I have read a few articles as high as 3 db - and this depends on the components used in the matching network... and yes a counter poise is definately needed or you will have significant common mode current interfering with the signal AND radiating back into the shack.

With tha said, If you want to buy an antenna I would recommend 3 mono band end feds by http://www.lnrprecision.com . I know MANY hams that have these and are extremely pleased with their performance and workmanship. They are expensive but are designed to work with no magic or smoke and mirrors - they just work and work well.

If your looking for a multi band solution then I would recommend a fan dipole - AlphaDelta Fan Dipole anteannas - you of course need the supports for a V, etc. setup -

Both the above deployed horizontal will need to be ABOVE 40 - 50 feet for them to perfrom DX - Ideally over 60 feet... if your satisfied with 1k or less miles then at around 30 feet is fine for 40 meters... for 80 its questionable.

If you want DX then the last option is a Vertical - the nice thing about the end fed is that its easy to make it vertical with a tree or fiberglass mast.... OR the S9s are nice cheap package (which you cant build for less) but require radials like most verticals. There is a ton more info on the vertals you need to get the best performance... but for 40 - 80 a vertical is almost always the most appropriate if you want to get out to other continents...

This is just a primer and without more info we can give much more advice...




I will use this antenna as a example http://www.ebay.com/itm/320982768720?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
I already have a antennas for 6-17 meters. I would only use the above antenna for 20,40, and 80 meters.
The seller doesn't mention anywhere about grounding the antenna?
I was thinking of mounting the antenna as a sloper off my tower or as flat top off my tower to a tree.
I also wonder if my Kenwood TS480sat's internal tuner would tune this antenna or if I would need to purchase a wide range tuner.

N8MJS
09-18-2012, 11:03 PM
Do you have at least 1 support point for an inverted V?
Yes I have a 40ft tower. Not sure where I would connect the ends for a inverted V?
Do you have 2 support points for a typicaly deployed dipole?
I could use the tower for 1 point and my shed for the second, although the shed is only about 15 tall at the peak of its roof. The shed is around 70 feet from the tower.
The trees are not tall and are very close to the house.
Do you have the ability to get the feed line perpendiculaor to any of the two above?
I believe I could with what I stated above.
Do you have area for a vertical with radials? If no radials do you have enough space and access for a ground plane vertical (no radials)?
Do you have access to the roof of your house? If yes can you put a tripod on the roof? If yes can you put a mast along side the roof?
Trying to stay away from a vertical or a tripod on my roof. I can access the roof and I could put a mast along side the roof but would rather not.
I currently only have a Kenwood TS-480sat. I don't plan on running any amplifiers or much more than 100 watts power output.
If I have to buy a wide range tuner I would.

W9GB
09-18-2012, 11:08 PM
Do you have 2 support points for a typicaly deployed dipole?
I have a 40 foot tower. I could use the tower for 1 point and my shed for the second, although the shed is only about 15 tall at the peak of its roof. The shed is around 70 feet from the tower.
The trees are not tall and are very close to the house.
This sounds like my parents house, my Novice/Technician operating QTH.
You have the classic high school geometry problem, with the Pythagorean theorem
http://en.wikipedia.org/wiki/Pythagorean_theorem

From the tower to shed is 70 feet (base); the difference of tower and shed height (40 - 15) is 25 feet (height). SO, you solve for the hypotenuse to determine how long of antenna can fit !!

74.33 feet

THEN, Install your desired wire antenna as a SLOPER !!

A 40 meter half-wavelength antenna (dipole) at 66 feet fits that space.
That antenna will work as 3/2-wave for 15 meters.
You can add a second half-wavelength (fan dipole) below the 40 meter wire for 20 meters.

WILL IT WORK DX ? Yes. In 2002, at parents house I put up a 40 meter 1/2-wave sloper.
Listened to QSO with Bob Heil on 40 meters broadside (120 miles south), then switched to 15 meters USB (3/2-wave) and worked Turkey .. off the end ... In direction of slope (east).
==
For 80 meters, I would build a second antenna.
The feed point would be near top of your 40 foot tower.

N8MJS
09-18-2012, 11:59 PM
An example to run from my tower to my shed?
My question is do you run the feed-line straight down to the ground and then into the shack or can you run it parallel in the air under one side of the dipole and then back into the shack?
http://www.ebay.com/itm/40-6-Meter-OCF-Dipole-Windom-Antenna-W-4-1-Balun-2kw-G5RV-Multi-Band-HF-/140694803630?pt=US_Radio_Comm_Antennas&hash=item20c21054ae

An example for a 80 meter sloper to run off of my tower?
http://www.ebay.com/itm/80m-Reduced-Half-Sloper-Antenna-Ham-Radio-HF-Dipole-/140544027634?pt=US_Radio_Comm_Antennas&hash=item20b913abf2

WB2WIK
09-19-2012, 12:31 AM
Never run a feedline for an antenna parallel to the radiating plane of the antenna! Parallel in the air under one side of the dipole seriously unbalances the antenna and causes considerable coupling of the radiated energy back into the outer conductor of the coax...not worth the problems.

A 90 degree angle works best for this, to keep the coax perpendicular to the antenna wire; however that doesn't mean it has to drop straight to the ground. It could also go "straight up" (unlikely scenario) or to either side, or a combination of to the side and dropping down...whatever creates a 90 degree angle, or close to it.

The 40-6m off center fed dipole looks to have merit but that 80m very shortened sloper looks like a very poor design. It's so short (1/8-wavelength) it will have very narrow operating bandwidth, and using a tuner in the shack may not overcome cable losses from the severe feedpoint mismatch when you deviate from the precise, single frequency where it might be matched. Such a short 80m antenna can only achieve a reasonable match over maybe 20-30 kHz of the 80m band, which is 500 kHz wide.

Tuners work miracles, but if the feedpoint mismatch is 40:1, which it could be, the feedline can have quite a lot of loss. Plus, "half slopers" (where one wire radiates, and the return is through the tower or a wire downlead) are very tricky to get working. If you want to experiment, that's fun but could take days or weeks to get it right.

Alpha-Delta http://www.alphadeltacom.com makes a "twin sloper" that actually works quite well in most cases. It's a better design, and a 40' tower is tall enough to make it work. I think it's model DX-A, although I didn't look it up. I've used that antenna at three different installations, and it worked at all three.

I wouldn't select useful antennas based on eBay ads. The "real stuff" is sold by major amateur radio equipment retailers.

W5DXP
09-19-2012, 12:35 PM
[QUOTE=KD8HBS;2652037]http://www.ebay.com/itm/40-6-Meter-OCF-Dipole-Windom-Antenna-W-4-1-Balun-2kw-G5RV-Multi-Band-HF-/140694803630?pt=US_Radio_Comm_Antennas&hash=item20c21054ae

Why does this antenna say "G5RV"?

W9GB
09-19-2012, 01:42 PM
You do KNOW that you can install a Half-Wavelength Antenna or Dipole (or shortened "loaded" dipole) with the Center Insulator in "Mid_Air",
but you coaxial feed would then come down to the ground in an area below that feedpoint, right?

==
Here is the Alpha-Delta information on their SLOPER antennas.
http://www.alphadeltacom.com/pg1.html

INSTRUCTIONS for INSTALLATION (READ before purchasing, to determine if appropriate for your site)
http://www.alphadeltacom.com/pdf/DX-A-%20DX-B_instructions-5.pdf

DX-A - 160-80-40 Meter 1/4-wavelength Twin Sloper - A top low frequency DX antenna.
Combines the tremendous DX firepower of the 1/4-wave sloper with the wide bandwidth of the 1/2-wave dipole.
One leg is 67 feet., the other 55 feet. Installs like an Inverted-V with ground return accomplished thru tower or down-lead.

DX-B - 1/4-wavelength DX Sloper- A single wire with high performance on 160, 80, 40 & 30 meters. Designed for limited space installations where room doesn't allow for the DX-A twin sloper.
Requires only 60 feet. overall and provides amazing DX performance at installation heights of only 35 feet., and with the low end at only 8 feet.
Pre-assembled & Pre-tuned. – just put it up and start enjoying low band operation. Utilizes stainless-steel hardware, 12 gauge solid copper wire and efficient Alpha Delta "Iso-Res" RF choke coils.
To gain the same broadbanded performance like the DX-A, the DX-B is also designed to be used with a wide range antenna tuner, so no trimming or tweaking is necessary. 50 Ohm coax feed, rated for full legal power.

The Models DX-A and DX-B Quarter-Wavelength Slopers require mounting on a grounded tower with an HF size beam on top to act as a "capacity hat".
This is necessary for proper tuning and operation. This is not a requirement for Half Wavelength dipoles, but unique to Quarter Wavelength Slopers for transmitting

N8MJS
09-23-2012, 01:30 PM
Thanks for all the help. I have never used a wire/dipole antenna before and still have much to learn. I have decided to make my own dipole for the 20 meter band. I believe I have enough room to hang it in a flap-top configuration in my backyard. I will update on my progress.

KB3UWC
09-23-2012, 02:44 PM
[QUOTE=KD8HBS;2652037]http://www.ebay.com/itm/40-6-Meter-OCF-Dipole-Windom-Antenna-W-4-1-Balun-2kw-G5RV-Multi-Band-HF-/140694803630?pt=US_Radio_Comm_Antennas&hash=item20c21054ae

Why does this antenna say "G5RV"?


It is listed that way so it would come up in a search for a G5RV antenna. I have seen auctions for lawn tractors that had every brand name listed in the auction.

73 Steve

NH7RO
09-23-2012, 04:48 PM
What Steve said; it's called a "keyword" and helps attract buyers that are shopping for similar items, that's all.

73, Jeff

G0GQK
09-23-2012, 10:07 PM
Good lad, make a dipole, you'll enjoy doing it and it will be cheaper. If you require a dual band wire antenna make one using 300 ohm ribbon, the top section to support the antenna for 40 metres, and the lower section for 20 metres, both cut to resonance and fed in the centre with 50 ohm coax. That will keep you busy for a few days, designing and working out the appropriate resonant lengths.

Mel G0GQK

G0DHZ
09-24-2012, 10:32 AM
lookup g7fek on inet

N8MJS
11-11-2012, 12:15 AM
Thanks for all the help. I have never used a wire/dipole antenna before and still have much to learn. I have decided to make my own dipole for the 20 meter band. I believe I have enough room to hang it in a flap-top configuration in my backyard. I will update on my progress.

I made the 20 meter dipole and have it hung in a temporary position this evening. It is about 5 feet off the ground in a flat top configuration. Upon tunning the VFO around the band I hear a operator using vulgar profanity and insulting other operators. I find it very disappointing that the first time I have a resonant antenna for the 20 meter band I hear such filth over the air. I look forward to moving the dipole to a higher permanent position.

KC8VWM
11-11-2012, 06:02 AM
Moving the dipole higher and moving the VFO away from 14.313 or so, will eliminate all the profanity heard in your receiver.

W0AAT
11-11-2012, 08:55 AM
The 43 foot vertical based tuned with an autotuner is very effective on 40, 30, and 20 meters and works okay on 80.

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