Choke /BALUN
 

I want needinfo on the type of cores do I need to use with RG58 and RG 214
to make a choke type BALUN at 2m. I am building a vertical dipole out of 1
inch al tubing. coax will pass through the bottom half othe dipole with the
sheild fastend at the middle of the bottom piece and cneter conductor
fastened to the top piece of al. Initial test indicate I have RF on the
shield and need some decoupling. Winding the coax into a coil certainly
helped but this has prevented me from placing the antenna in a fiberglass
tube the way I had planned.

Choke /BALUN
 

"Jimmie D" wrote:
I want needinfo on the type of cores do I need to use with RG58 and RG 214
to make a choke type BALUN at 2m. I am building a vertical dipole out of 1
inch al tubing. coax will pass through the bottom half othe dipole with the
sheild fastend at the middle of the bottom piece and cneter conductor
fastened to the top piece of al. Initial test indicate I have RF on the
shield and need some decoupling.

For single band operation, a simple decoupling stub or sleeve will
probably work. This is discussed in the ARRL Antenna Book.
--
73, Cecil http://www.qsl.net/w5dxp

Choke /BALUN
 

Jimmie D wrote:
I want needinfo on the type of cores do I need to use with RG58 and RG 214
to make a choke type BALUN at 2m. I am building a vertical dipole out of 1
inch al tubing. coax will pass through the bottom half othe dipole with the
sheild fastend at the middle of the bottom piece and cneter conductor
fastened to the top piece of al. Initial test indicate I have RF on the
shield and need some decoupling. Winding the coax into a coil certainly
helped but this has prevented me from placing the antenna in a fiberglass
tube the way I had planned.

For the RG58, each Steward HFB143064-300 (sorry for the ridiculous
link length):
http://www.steward.com/web_part_no.a...=HFB143064-300
provides about 180 ohms choke impedance.

Each slightly longer and in a lower frequency ferrite, 28B0591-200:
http://www.steward.com/web_part_no.a...rt=28B0591-200
provides about 500 ohms choke impedance.

For the RG214, each Steward HFB259128-100:
http://www.steward.com/web_part_no.a...=HFB259128-100
provides about 120 ohms of choke impedance.

Each 28B1020-100:
http://www.steward.com/web_part_no.a...rt=28B1020-100
provides about 300 ohms of choke impedance.

You will have to string these on the coax before terminating it.

Choke /BALUN
 

John Popelish wrote:
For the RG58, each Steward HFB143064-300 (sorry for the ridiculous link
length):
http://www.steward.com/web_part_no.a...20Board%20Leve
l%20and%20Cable%20Core%20Products&family=Ferrite% 20Cores%20for%20Cables%
20-%20%20Wiring%20Harnesses%20-%20Connectors&product=High%20Frequency%20
Solid%20Ferrite%20Cores%20for%20Round%20Cables&pr ogroup=1.%20Round%20and
%20Cylindrical%20Cores&part=HFB143064-300
provides about 180 ohms choke impedance.

TinyURL.com is a great resource for condensing very long web links that
might become broken in transit. You only need to copy-and-paste the long
URL into their web page, and "TinyURL" does exactly what it says.

The above example comes right down to:
http://tinyurl.com/n6bt9


--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Choke /BALUN
 

How do you figure the lower "coaxial sleave" dimentions. My project is
converting/cutting down a old model PD83 (Phelps Dodge brass skirt
coaxial, aprox 50mHz) to 2 meters.

And I did use the ferrite bead on the J pole to cancel out the RF on
the coax, but do not know which core specs.

Choke /BALUN
 

"Will" wrote:

How do you figure the lower "coaxial sleave" dimentions.

It's usually 1/4WL long. The theory is to turn that 1/4WL of
feedline into a transmission line where the currents on the
outside of the original shield are balanced by the inside
shield on the sleeve which balances the antenna currents.
It functions over a certain single bandwidth.
--
73, Cecil http://www.qsl.net/w5dxp

Choke /BALUN
 

On Sun, 04 Jun 2006 18:29:11 GMT, "Cecil Moore"
wrote:

....

What's with the HTML format Cecil?

Owen
--

Choke /BALUN
 

"Owen Duffy" wrote:
What's with the HTML format Cecil?

I've switched over from Netscape to Outlook Express and have
no idea what I am doing. I can't seem to get Outlook Express
to compose anything in Courier fixed font.
--
73, Cecil http://www.qsl.net/w5dxp

Choke /BALUN
 

"Cecil Moore" wrote in message
.net...
"Jimmie D" wrote:
I want needinfo on the type of cores do I need to use with RG58 and RG 214
to make a choke type BALUN at 2m. I am building a vertical dipole out of 1
inch al tubing. coax will pass through the bottom half othe dipole with
the sheild fastend at the middle of the bottom piece and cneter conductor
fastened to the top piece of al. Initial test indicate I have RF on the
shield and need some decoupling.

For single band operation, a simple decoupling stub or sleeve will
probably work. This is discussed in the ARRL Antenna Book.
--
73, Cecil http://www.qsl.net/w5dxp


Would be difficult to incorporate into my design

Choke /BALUN
 

"Jimmie D" wrote in message
. ..
I want needinfo on the type of cores do I need to use with RG58 and RG 214
to make a choke type BALUN at 2m. I am building a vertical dipole out of 1
inch al tubing. coax will pass through the bottom half othe dipole with the
sheild fastend at the middle of the bottom piece and cneter conductor
fastened to the top piece of al. Initial test indicate I have RF on the
shield and need some decoupling. Winding the coax into a coil certainly
helped but this has prevented me from placing the antenna in a fiberglass
tube the way I had planned.

Thanks all, found what I was looking for at Wireman.

Choke /BALUN
 

:Cecil,

I will start a little long as this is a peimo piece of 2" dia brass.
According to swr-freq by R. J. Edwards, the 2" dia sleave is about 50
ohms
for the 1/4 wave. 146 mhz, 51.1 ohms, jXin 0.0 .

My thaught is with the 1"mast inside of the sleave (insulated and
centered only connected at the top) what does the added capacitance do
to the sleave lenght?

And RFS does not have the old cutting charts for the Phelps Dodge PD83,
I tried that.

"Will" wrote:

How do you figure the lower "coaxial sleave" dimentions.
Cecil Moore wrote
It's usually 1/4WL long. The theory is to turn that 1/4WL of
feedline into a transmission line where the currents on the
outside of the original shield are balanced by the inside
shield on the sleeve which balances the antenna currents.
It functions over a certain single bandwidth.

Choke /BALUN
 

Try Tools | Options | Compose | News: Font Settings

"Cecil Moore" wrote in message
. com...
"Owen Duffy" wrote:
What's with the HTML format Cecil?

I've switched over from Netscape to Outlook Express and have
no idea what I am doing. I can't seem to get Outlook Express
to compose anything in Courier fixed font.
--
73, Cecil http://www.qsl.net/w5dxp

Choke /BALUN
 

"Will" wrote:
My thaught is with the 1"mast inside of the sleave (insulated and
centered only connected at the top) what does the added capacitance do
to the sleave lenght?

I'm sorry, I don't know what the velocity factor would be
in that configuration. If you sampled the common mode
current and tuned the frequency for a minimum, it might
give you an idea of the velocity factor.
--
73, Cecil http://www.qsl.net/w5dxp

Choke /BALUN
 

"John, N9JG" wrote:
Try Tools | Options | Compose | News: Font Settings

Of course, I have set the font to Courier but right now, even
though I have "Plain Text" selected, the composing font is
Times New Roman. If I select "Rich Text", then it will
compose in Courier but that is HTML. I once forgot to switch
to plain text before sending and it apparently posted HTML.
--
73, Cecil http://www.qsl.net/w5dxp

Choke /BALUN
 

I've gotten a few emails asking how a 1/4WL wire stub can be
used as a balun on a single band like 2m. Just connect the
wire to the element driven by the coax center conductor and
connect the other end to the braid 1/4WL down the coax. In
fixed font:

|
|
| Dipole
|
|
+====================================coax braid

+------------------------------------coax center conductor
|
| ===================+==============coax braid
| spacing |
+---------------------+
| 1/4WL stub
|

The current at the feedpoint sees a very high impedance looking
back down the *outside* braid of the feedline because it is looking
into a shorted 1/4WL stub. Often, a piece of similar coax is used
for the 1/4WL stub.
--
73, Cecil http://www.qsl.net/w5dxp

Choke /BALUN
 

Cecil Moore wrote:
"Owen Duffy" wrote:

What's with the HTML format Cecil?


I've switched over from Netscape to Outlook Express and have
no idea what I am doing. I can't seem to get Outlook Express
to compose anything in Courier fixed font.


Outlook Express? Say it ain't so Cecil!!


- 73 de Mike KB3EIA -

Choke /BALUN
 

"Mike Coslo" wrote:
Outlook Express? Say it ain't so Cecil!!

I was running Netscape but Netscape 8.1 doesn't do newsgroups.
Someone recommended Thunderbird. Comments?
--
73, Cecil http://www.qsl.net/w5dxp

Choke /BALUN
 

This reply IS useing Thunderbird (and quite
stable, too-- Jim NN7K

Cecil Moore wrote:
"Mike Coslo" wrote:

Outlook Express? Say it ain't so Cecil!!


I was running Netscape but Netscape 8.1 doesn't do newsgroups.
Someone recommended Thunderbird. Comments?

Choke /BALUN
 

Jim - NN7K wrote:
This reply IS useing Thunderbird (and quite stable, too-- Jim NN7K

OK, I just downloaded Thunderbird and it looks pretty good.
--
73, Cecil http://www.qsl.net/w5dxp