Stacked Yagi 2m over 70 cm
 

Single feed to the 2 meter with the 70 cm about 6 ft above , suggestions
on the simplest way to achiieve this , tx is an ft 5100

On Fri, 29 Apr 2005 18:06:09 +1000, atec wrote:

Single feed to the 2 meter with the 70 cm about 6 ft above , suggestions
on the simplest way to achiieve this , tx is an ft 5100

Do not no...rite agn w/more info

Wes Stewart wrote:
On Fri, 29 Apr 2005 18:06:09 +1000, atec wrote:


Single feed to the 2 meter with the 70 cm about 6 ft above , suggestions
on the simplest way to achiieve this , tx is an ft 5100


Do not no...rite agn w/more info

Not sure about your reply , but here a go ,
13 element 2 metre under a 15 element 70 cm , I need to feed these
with a simple harness and single feed from an FT5100 and am wondering
about a plausable method of copnnection .

15 elements \

2 metre gap - single feed

13 elements /

"atec" wrote in message
...
Single feed to the 2 meter with the 70 cm about 6 ft above , suggestions
on the simplest way to achiieve this , tx is an ft 5100

I'm not sure if you could or would want to do this but could you use a
2m/70cm diplexer at the top of the tower.. single feedline to the diplexer
splitting out to one for each antenna?
might not be the best way but i should work. other wise i don't know how the
phasing would work with the two different freqs.


Adair - KD5DYP

Wes Stewart, N7WS wrote:
"Do not no.."

6-ft seems sufficient separation at 2-meters or 70-cm to avoid tight
coupling.

First MW BC plant I worked in was in 1949. It had stations at 950 KHz
and 1320 KHz. Both stations used the same antenna tower. Pass / reject
filters kept them out of each other`s final amplifiers.

I think in the VHF / UHF range one might get lucky and select the right
length of coax between an individual antenna and the common feed point
where individual antennas are paralleled and make the antenna at that
point look like a high imprdance to the wrong transmitter. For practical
purposes the wrong antenna disappears, but the right antenna does not.
It matches the coax.

Best regards, Richard Harrison, KB5WZI

Richard Harrison wrote:
Wes Stewart, N7WS wrote:
"Do not no.."

6-ft seems sufficient separation at 2-meters or 70-cm to avoid tight
coupling.

First MW BC plant I worked in was in 1949. It had stations at 950 KHz
and 1320 KHz. Both stations used the same antenna tower. Pass / reject
filters kept them out of each other`s final amplifiers.

I think in the VHF / UHF range one might get lucky and select the right
length of coax between an individual antenna and the common feed point
where individual antennas are paralleled and make the antenna at that
point look like a high imprdance to the wrong transmitter. For practical
purposes the wrong antenna disappears, but the right antenna does not.
It matches the coax.

Best regards, Richard Harrison, KB5WZI

Pretty much what I was thinking . Will work it out later as I have only
one length of the right feeder to go up that tower and as I said the rig
is an ft 5100 , one rig and so239 with dual band . Thanks .

"Richard Harrison" wrote in message
...
Wes Stewart, N7WS wrote:
"Do not no.."

6-ft seems sufficient separation at 2-meters or 70-cm to avoid tight
coupling.

First MW BC plant I worked in was in 1949. It had stations at 950 KHz
and 1320 KHz. Both stations used the same antenna tower. Pass / reject
filters kept them out of each other`s final amplifiers.

I think in the VHF / UHF range one might get lucky and select the right
length of coax between an individual antenna and the common feed point
where individual antennas are paralleled and make the antenna at that
point look like a high imprdance to the wrong transmitter. For practical
purposes the wrong antenna disappears, but the right antenna does not.
It matches the coax.

Best regards, Richard Harrison, KB5WZI

Richard,
Since the 70 cm antenna will be a low impedance at 2m, how about connecting
the 70 cm antenna to the 2 (and feedline) with a piece of coax that is an
add multiple of 1/4 wave at 2m? At 70 cm they might both be active. I might
try EZNECing it for a pair of dipoles. Or how about 2 pieces of coax, with a
T connector to the feedline? Personally, I would buy the filters.
Tam/WB2TT.

Tam/WB2TT wrote:
"Richard Harrison" wrote in message
...

Wes Stewart, N7WS wrote:
"Do not no.."

6-ft seems sufficient separation at 2-meters or 70-cm to avoid tight
coupling.

First MW BC plant I worked in was in 1949. It had stations at 950 KHz
and 1320 KHz. Both stations used the same antenna tower. Pass / reject
filters kept them out of each other`s final amplifiers.

I think in the VHF / UHF range one might get lucky and select the right
length of coax between an individual antenna and the common feed point
where individual antennas are paralleled and make the antenna at that
point look like a high imprdance to the wrong transmitter. For practical
purposes the wrong antenna disappears, but the right antenna does not.
It matches the coax.

Best regards, Richard Harrison, KB5WZI


Richard,
Since the 70 cm antenna will be a low impedance at 2m, how about connecting
the 70 cm antenna to the 2 (and feedline) with a piece of coax that is an
add multiple of 1/4 wave at 2m? At 70 cm they might both be active. I might
try EZNECing it for a pair of dipoles. Or how about 2 pieces of coax, with a
T connector to the feedline? Personally, I would buy the filters.
Tam/WB2TT.


Exactly what I did , patterns seem fine and they certainly work fine
with a little trimming the VSWR is good in the shack ( yes I know about
the other things but it works fine)

Tam, W2TT wrote:
"At 70 cm they might both be active."

The impedance of the 2-meter antenna is unknown at 70-cm. With 1/4-wave
or less of cable at 70-cm, velocity factor considered, you should be
able to make the 2-meter antenna appear a very high impedance at the
common point where the 2-meter and 70-cm antennas are oaralleled.

Best regards, Richard Harrison, KB5WZI