Co-phased yagis
 

Anyone know about this type of setup? My understanding is I must use 75 ohm
coax from the ground up to the "T" then to each antenna. Is this true?
Anyone have a formula?

Co-phased yagis
 

Hello Carly:

No you use the 75 ohm coax from the Tee to the antennas. You can use odd
mulitibles of (RG11 Coax) 1/4 wavelengths, from the Tee to the antennas.
But thew lead in coax can be 50 ohm coax. I suggest the flexable LMR400.

The ARRL Antenna Book has all this neat o stuff in it.

Here are a few neat yagi sites.

http://home.planet.nl/~poelm348/STAC...0ANTENNAS.html

http://www.grantronics.com.au/docs/StkYagis.pdf

http://members.fortunecity.com/xe1bef/yagi-antennas.htm

Jay in the Mojave

Caryl Duncan wrote:
Anyone know about this type of setup? My understanding is I must use 75 ohm
coax from the ground up to the "T" then to each antenna. Is this true?
Anyone have a formula?

Co-phased yagis
 

"Jay in the Mojave" wrote in message
...
Hello Carly:

No you use the 75 ohm coax from the Tee to the antennas. You can use odd
mulitibles of (RG11 Coax) 1/4 wavelengths, from the Tee to the antennas.
But thew lead in coax can be 50 ohm coax. I suggest the flexable LMR400.

The ARRL Antenna Book has all this neat o stuff in it.

Here are a few neat yagi sites.

http://home.planet.nl/~poelm348/STAC...0ANTENNAS.html

http://www.grantronics.com.au/docs/StkYagis.pdf

http://members.fortunecity.com/xe1bef/yagi-antennas.htm

Jay in the Mojave

I used to have a link on stacking moonrakers, but I lost it in a hard drive
crash.
It seems that you also have to have them a certain distance apart to be
effective. Also a 10 degree upward tilt will result in better DX if I
remember correctly.

Co-phased yagis
 

Hello Dr. Death:

I have that info if anyone needs it. It is the factory info from Avanti
or Antennas Specialists.

I remember that I would space the Moonraker 4 beam antennas more than
what the factory spec's say. But it's quit a project to have that muck
spacing.

Using a Moonraker 4 or 6, you will need a good tower and rotator. A TV
Push-up mast, and a light weight TV type rotator will not do.

Jay in the Mojave


Dr.Death wrote:

I used to have a link on stacking moonrakers, but I lost it in a hard drive
crash.
It seems that you also have to have them a certain distance apart to be
effective. Also a 10 degree upward tilt will result in better DX if I
remember correctly.

Co-phased yagis
 

"Caryl Duncan" wrote in message
...
Anyone know about this type of setup? My understanding is I must use 75
ohm coax from the ground up to the "T" then to each antenna. Is this true?
Anyone have a formula?

Use 75 ohm cable if your antennas are 50 ohm. Getting your antennas to be 50
ohms is nearly impossible. usually the actual impeadance of the antenna is
around 30 ohms so you can use 50 ohm cable instead of the 75. When you use
1/4 wavelength of 75 ohm cable on a 50 ohm antenna the the radio end of the
cable will look like 100 ohms. put the 2 100 ohms loads in paralell and now
they are 50 again. Use 75 ohm cable this with 30 ohm oantenna and you get 30
ohms at the radio one they are cophased. Use 50 cable and instead of
doubling the impedance of the antenna its now qradrupled so a single antenna
is seen as 120 ohms and the cophased set is seen as 60, a beeter match for
the 50 ohm radio.

Co-phased yagis
 

Captain Boss used to tell me about the 10 degree thing. He did lots of
"little things" like that.
"Dr.Death" wrote in message
...
"Jay in the Mojave" wrote in message
...
Hello Carly:

No you use the 75 ohm coax from the Tee to the antennas. You can use odd
mulitibles of (RG11 Coax) 1/4 wavelengths, from the Tee to the antennas.
But thew lead in coax can be 50 ohm coax. I suggest the flexable LMR400.

The ARRL Antenna Book has all this neat o stuff in it.

Here are a few neat yagi sites.

http://home.planet.nl/~poelm348/STAC...0ANTENNAS.html

http://www.grantronics.com.au/docs/StkYagis.pdf

http://members.fortunecity.com/xe1bef/yagi-antennas.htm

Jay in the Mojave

I used to have a link on stacking moonrakers, but I lost it in a hard
drive crash.
It seems that you also have to have them a certain distance apart to be
effective. Also a 10 degree upward tilt will result in better DX if I
remember correctly.

Co-phased yagis
 

" wrote in message
...

"Caryl Duncan" wrote in message
...
Anyone know about this type of setup? My understanding is I must use 75
ohm coax from the ground up to the "T" then to each antenna. Is this
true? Anyone have a formula?

Use 75 ohm cable if your antennas are 50 ohm. Getting your antennas to be
50 ohms is nearly impossible. usually the actual impeadance of the antenna
is around 30 ohms so you can use 50 ohm cable instead of the 75. When you
use 1/4 wavelength of 75 ohm cable on a 50 ohm antenna the the radio end
of the cable will look like 100 ohms. put the 2 100 ohms loads in paralell
and now they are 50 again. Use 75 ohm cable this with 30 ohm oantenna and
you get 30 ohms at the radio one they are cophased. Use 50 cable and
instead of doubling the impedance of the antenna its now qradrupled so a
single antenna is seen as 120 ohms and the cophased set is seen as 60, a
beeter match for the 50 ohm radio.

Sorry, got to thinking you were cophasing antennas on a truck Shouldnt do
post when Im this tired.

Co-phased yagis
 

Thats ok, I really can use this info too. I just found out the roofs onmost
of the newer Big Rigs aren't metal but fiberglass!

I got a long way to go.
" wrote in message
.. .

" wrote in message
...

"Caryl Duncan" wrote in message
...
Anyone know about this type of setup? My understanding is I must use 75
ohm coax from the ground up to the "T" then to each antenna. Is this
true? Anyone have a formula?

Use 75 ohm cable if your antennas are 50 ohm. Getting your antennas to be
50 ohms is nearly impossible. usually the actual impeadance of the
antenna is around 30 ohms so you can use 50 ohm cable instead of the 75.
When you use 1/4 wavelength of 75 ohm cable on a 50 ohm antenna the the
radio end of the cable will look like 100 ohms. put the 2 100 ohms loads
in paralell and now they are 50 again. Use 75 ohm cable this with 30 ohm
oantenna and you get 30 ohms at the radio one they are cophased. Use 50
cable and instead of doubling the impedance of the antenna its now
qradrupled so a single antenna is seen as 120 ohms and the cophased set
is seen as 60, a beeter match for the 50 ohm radio.

Sorry, got to thinking you were cophasing antennas on a truck Shouldnt do
post when Im this tired.

Co-phased yagis
 

"Miles Davis" wrote in message
...
Thats ok, I really can use this info too. I just found out the roofs
onmost of the newer Big Rigs aren't metal but fiberglass!

You can take down the headliner and line it with aluminum foil. This also
keeps the government from stealing your thoughts. LOL