SW antena Balun

Status
Not open for further replies.

xwindows2

Member
Joined
May 2, 2008
Messages
42
Location
Fridley MN.
I have a grundig s750 portable,put up a long wire outside
82ft of speaker wire 16ga about 30 ft above ground fed with rg8x-mini
I dont have a matching transformer between ant. and feed line
not sure what type of balun to use
win radio sells a long wire balun
not sure if i need 4:1 or 9:1 or i could use a 75 to 300 ohm
the reception is good but tons of noise on 40 meters
thank you
 

SCPD

QRT
Joined
Feb 24, 2001
Messages
0
Location
Virginia
The 9:1 balun provides the best range for 2-30mhz.

This is just an example, but this is an excellent commerical antenna: Par Electronics EF-SWL End Fed Dipole SWL Antenna. Par EF-SWL.

Here are the reviews of it: PAR Electronics EF-SWL Antenna Product Reviews

FYI, RG-8x mini is not very good coax. If it's a short run say < 25ft, you should be okay. Ideally, you should use RG-8/U (available at Radio Shack) or better. (LMR400 or RG213)

Be sure to buy a PL-259 to BNC adapter for your 750. You'll plug it into the SW jack. (50 ohms)

BTW, here are a couple of sample audio outputs from a Grundig 800 with the PAR End-Fed SWL:

http://www.youtube.com/watch?v=-LZZkmAhJtM

http://www.youtube.com/watch?v=3uDGzzQBf6U

Be sure to ground your antenna to a ground rod for the best results.
 
Last edited:

xwindows2

Member
Joined
May 2, 2008
Messages
42
Location
Fridley MN.
long wire

I would like to use 80 ft long wire and replace the coax
right now the rg8-mini is hooked to the center,the ground is not hooked up at all
thats probablly why lots of noise,
what if i change to a offset dipole windom, one leg 80ft the other abt 35ft with a 9:1 balun?
appreciate your input
 

SCPD

QRT
Joined
Feb 24, 2001
Messages
0
Location
Virginia
Yes, you're likely getting a lot of noise (EMI pickup) from the shielding of the coax. The fact that the RG8-mini isn't well-shielded doesn't help either.

You could try just hooking your ground side to a ground rod. That could make a ton of difference.

The windom idea should work just fine especially if you have good ground conductivity in your area.

Feel free to experiment - that's what makes it a fun hobby - and "your" setup is almost always unique compared to anyone else.
 

ka3jjz

Wiki Admin Emeritus
Joined
Jul 22, 2002
Messages
25,361
Location
Bowie, Md.
I've never seen a windom fed with a 9:1 transformer - I have seen them fed with twin lead, then down to a 4:1 balun and coax from that. This particular variation - there are many - won't help with the noise issue.

There are about a 1/2 dozen or so basic low noise antennas diagrammed in the photos section of the SWL Antennas Yahoo group. These all use either 4:1 or 9:1 transformers, and look to be easy to
build.

You could also consider building a skyloop - our own LB uses a variation of one (about 125 foot total length, if I recall correctly). Loops have a nice side benefit of ignoring certain kinds of noise, depending on the environment, of course. You did imply you had some space to work with...

Here's a little antenna - takes a little doing to build it, particularly with the resistor at the far end that's grounded - but it has a nice little benefit of having a little directivity as well. The English is a bit rough, but it's understandable.

EWE Antenna review :: DXing.info

One thing to keep in mind - the further away from the house and power lines you can get the antenna, the more that's going to help your noise issues. As the other poster said, experiment! We have several tech links and other things in our antennas wiki. Simply slide your mouse over Wiki in the blue toolbar under the logo, then select Antennas then HF Antennas.

You will find the link to the Yahoo group at the bottom. 73 Mike
 

blinddog50

Member
Joined
Sep 17, 2005
Messages
254
Location
Undisclosed urban location.
PAR makes excellent end fed antennas.
However, if you use one make sure you keep it away from as many RF sources as possible.
Zep antennas are notorious noise magnets.
You can email Dale Parfitt at the shop in NC with any questions.
Great customer service people.
They're going to start selling antennas to the public again starting 08/01.
Finishing up their military contract.
 

xwindows2

Member
Joined
May 2, 2008
Messages
42
Location
Fridley MN.
sw long wire

Hey guys thanks for the help
I think i'll try using existing long wire with a 4:1 balun,replace the coax
and ground the sheild to my tri-pod which is grounded to
4ft rod or do i need to use 8ft ground rod,my wife tells me the soil is sandy,she gardens
73s
 

ka3jjz

Wiki Admin Emeritus
Joined
Jul 22, 2002
Messages
25,361
Location
Bowie, Md.
Getting a good RF ground is a tricky business - in sandy soil, you may indeed need to go much deeper than 4 foot to get anything in sandy soil. In fact, many people will say that a single rod really isn't much of a ground. But I'll let others talk about that; there are a couple of articles about grounding in our wiki.

73 Mike
 

SCPD

QRT
Joined
Feb 24, 2001
Messages
0
Location
Virginia
Yeah, it's likely sandy on top but about the 5-8ft level it should get more moist. A real ground rod is about 3m long (10ft) and should be fine. It's a simple solution and you should try this first.

But as Mike said, RF grounds can be either very easy or very frustrating to get perfect.

Here's a good site to check out: Ground Problems by dxzone.com
 

prcguy

Member
Joined
Jun 30, 2006
Messages
15,228
Location
So Cal - Richardson, TX - Tewksbury, MA
Replacing the coax will probably not change anything and adding a balun might help because it will act as an RF choke to common mode noise that may be on the shield of the coax. Grounding the coax may increase noise pickup on the antenna and if the ground rod is not connected to your AC mains ground you can introduce a shock hazard due to difference in potential between the ground rod and house ground. I did this once and got jolted every time I disconnected my antenna.

In my opinion an end fed antenna is generally not a good idea except for a specific frequency where the antenna is 1/2 wavelength and doesn't need a counterpoise. Otherwise the shield of the coax becomes the other half of the antenna and causes all sorts of problems.

As others have mentioned you want to get the antenna away from your house to minimize noise pickup. SW or HF reception is driven by signal to noise ratio more than absolute signal level. In most cases a larger antenna will not improve anything and a smaller antenna in a better location can make a big difference in reception.

With all that said, you mention 80ft of space available. My first choice for an all band SW antenna would be a center fed dipole using TV twinlead or 450ohm balanced line all the way to the radio if possible. If you must use coax use the shortest length to get through a wall or window with a 1:1 choke balun or maybe a 4:1 at the coax to balanced line junction.

The balanced line will all but ignore the terrible antenna to feedline mismatch over a wide frequency range where using coax on the same antenna would cause extra bonus loss. An 80ft dipole fed with balanced line will also work fine on 80-10m with a tuner for transmitting if you get an amateur license in the future.
prcguy
 

xwindows2

Member
Joined
May 2, 2008
Messages
42
Location
Fridley MN.
ok i am back just bought the Par Electronics EF-SWL
have it strung abt 12ft above ground (temp instal) horizontal with/rg58ua 65ft coax dont like this coax but thats what i have left from my discone. If i put this up on the roof
it will be abt 25ft above grnd,i will get some dif coax need abt 50ft
so rg8x is too noisy,what abt rg213 is that ok,and not to expensive
 

ka3jjz

Wiki Admin Emeritus
Joined
Jul 22, 2002
Messages
25,361
Location
Bowie, Md.
8x is too 'noisy'?? Never heard of that one - 213 probably has better shielding - personally I'd try the 8x first, as it's inexpensive to get as well...and as a OT on this topic, I hope you aren't using 58AU on your discone - as you go higher in frequency the losses can get significant. 73 Mike
 
Last edited:

xwindows2

Member
Joined
May 2, 2008
Messages
42
Location
Fridley MN.
no,i am using 58au for the EF-SWL,temporarlly till payday
till i get some rg8x or similar,the discone i use came with 65ft of 58au ? why i dont know
its the comit 150ds s i use LMR400 for discone works pretty well
 

xwindows2

Member
Joined
May 2, 2008
Messages
42
Location
Fridley MN.
Ok latest update put up ef-swl on roof running peak to peak roof top.. 30ft spread between the peeks and 15 more ft left running down to lowest point of roof using lmr240 coax.. antenna using 8ft ground rod
getting alot of am radio in the 160m band,works great on 80m, 40m and 20m and over seas air plane frequ.
thanks agian
 
Status
Not open for further replies.
Top