What happens if you pipe the output of one radio in to 2 amps?
 

Ponder This wrote in
:



Just cusrious...

What happens if you pipe the output of one radio in to 2 different
amplifiers, and then take the output of the two amps and send them to
two identical vertical antennas spaced a half wave apart and with
equal length feedlines from the amplifiers.

Will the output of the two amplifiers add together in directions where
the signal is in phase, or will it act like two different signals and
interfere with each other?

-Curious


Why would you do that? It's the same as just splitting a single output
from the radio. Depending on spacing and phase you can get of variety of
different radiation patterns. You don't need to split it between two
amps.

I split the output from my radio, lag one 90 degrees, put one in one yagi,
put one in another yagi and get circular polarization.


sc

What happens if you pipe the output of one radio in to 2 amps?
 

Depends--, if in phase, Both INPUT, and OUTPUT,
would add (double power, if SAME power on both,
Also would add, if 180 degrees OUT of Phase, both
Input, and Output. And this would be the same as
with Push-Pull amp (both input, and output). but
if In Phase, on input, and OUT of Phase, on
Output,or vice versa, theoretically, would result
in 0 Output. And, if in different phases, probably
would make a great interference source!!!
(distortion, intermods, harmonics, oddball mixes,
ect!) Jim NN7K


Slow Code wrote:
Ponder This wrote in
:



Just cusrious...

What happens if you pipe the output of one radio in to 2 different
amplifiers, and then take the output of the two amps and send them to
two identical vertical antennas spaced a half wave apart and with
equal length feedlines from the amplifiers.

Will the output of the two amplifiers add together in directions where
the signal is in phase, or will it act like two different signals and
interfere with each other?

-Curious

What happens if you pipe the output of one radio in to 2 amps?
 

What happens if you pipe the output of one radio in to 2 different
amplifiers, and then take the output of the two amps and send them to
two identical vertical antennas spaced a half wave apart and with
equal length feedlines from the amplifiers.

Will the output of the two amplifiers add together in directions where
the signal is in phase, or will it act like two different signals and
interfere with each other?

-Curious


I would assume the following: If you use a splitter with an equal
length of coax to the two amps, you would be able to get 100 watts out
from the radio to be 50 watts into each amp. I would suspect that you
would have double the power out to the antenna assuming you used the
same length of coax from the amps to the antenna.

Of course, you have to deal with impedance problems with the splitting
of the coax, for example, two 50 ohm cables would result in 25 ohms to
the amps. Not good. then the two 50 ohm outputs from the amps would
result in 100 ohms to the antenna, not good again....


--
73 for now
Buck
N4PGW

What happens if you pipe the output of one radio in to 2 amps?
 

Curious wrote:
"Will the output of two amplifiers add together in directions where the
signal is in phase, or will it act like two different signals and
therefore interfere with each other?"

For stereo?

The signals are coherent from two amplifiers or from one.

Two close antennas fed the same signal in the same phase generally add
broadside to the plane containing the antennas and cancel at right
angles to the lobes containing the added signals.

See page 91 of Kraus` 3rd efition of "Antennas" for: "Two Isotropic
Point Sources of the Same Amplitude and Phase."

Another example is the pair af CB antennas used by truckers, one on
either side of the truck cab, to reinforce the signal fore and aft of
the truck.

The 1/2-wave dipole is another example. Its two elements have the same
cuerrent amplitude and direction. Its lobes are broadside and its nulls
are at right angles off the tips of the elements.

Best regards, Richard Harrison, KB5WZI

What happens if you pipe the output of one radio in to 2 amps?
 

Richard Harrison wrote:
Two close antennas fed the same signal in the same phase generally add
broadside to the plane containing the antennas and cancel at right
angles to the lobes containing the added signals.

One thought of interest is that the phasing for a phased
antenna system might be done at the input of one of the
amps, rather than having to manage high power. But I
wonder if two separate amps could maintain coherency
under all conditions of supply voltage, temperature,
humidity, etc.
--
73, Cecil http://www.qsl.net/w5dxp

What happens if you pipe the output of one radio in to 2 amps?
 

Cecil, W5DXP wrote:
"I wonder if two separate amps could maintain coherency under all
conditions of supply voltage, temperature, humidity, etc."

If reasonable control applies, it works.

I built a rat-race, hybrid-ring, diplexer to parallel two identical
shortwave broadcast transmitters. They were fed from the same RF
oscillator and from the same audio source. Both were adjusted for nearly
100% modulation. The pair produced nearly 100 KW, fully modulated into
the same antenna. It worked fine. No jerking around and little
unbalanced energy dissipated into the dummy load. This was no sweat for
the antennas which worked with our 100 KW transmitters every day. This
is what you need to do when frequency shortages become acute.

The votages in the transmitters were regulated by Sola transformers
which had been shipped to us as 60 Hz transformers but reresonated on
site for 50 Hz which was our European supply frequency.

Best regards, Richard Harrison, KB5WZI

What happens if you pipe the output of one radio in to 2 amps?
 

There is another potential problem if feeding two amps to two antennas that
are reasonably close: RF from one antenna is induced into the other antenna,
gets fed into the amp and causes some interference (mixing ?) that shows up
as a raspy signal.
Tried it, and heard it on another station attempting the same setup.
It seems that it would be easier to control the phasing at the input of the
PAs, but the above effect messes it up, unless antennas are widely separated
and they do not "feed" each other setup.
So, it appears that it is better to use one bigger amp and use proper
phasing to feed the two or more antennas.

--
Yuri Blanarovich, K3BU, VE3BMV

What happens if you pipe the output of one radio in to 2 amps?
 

Yuri Blanarovich wrote:

There is another potential problem if feeding two amps to two antennas that
are reasonably close: RF from one antenna is induced into the other antenna,
gets fed into the amp and causes some interference (mixing ?) that shows up
as a raspy signal.
Tried it, and heard it on another station attempting the same setup.
It seems that it would be easier to control the phasing at the input of the
PAs, but the above effect messes it up, unless antennas are widely separated
and they do not "feed" each other setup.
So, it appears that it is better to use one bigger amp and use proper
phasing to feed the two or more antennas.


Well, the expert, or should I say, the new GURU, has spoken. He seems
to know all about this complex subject.

I know I will never try this again, as my previous efforts, which seemed
to work, could not possibly have done so. Obviously Wilkenson hybrids
are useless, likewise any ring hybrids, and all other methods of
splitting/combining a transmitter feed.

Sorry guys, they won't work. Yuri said so.

tom
K0TAR

What happens if you pipe the output of one radio in to 2 amps?
 

On Wed, 24 May 2006 15:59:28 -0400, "Yuri Blanarovich"
wrote:

There is another potential problem if feeding two amps to two antennas that
are reasonably close: RF from one antenna is induced into the other antenna,
gets fed into the amp and causes some interference (mixing ?) that shows up
as a raspy signal.
Tried it, and heard it on another station attempting the same setup.
It seems that it would be easier to control the phasing at the input of the
PAs, but the above effect messes it up, unless antennas are widely separated
and they do not "feed" each other setup.
So, it appears that it is better to use one bigger amp and use proper
phasing to feed the two or more antennas.


OK, this brings up another thought... Would the transmitted signal
from antenna a, being close to b, cause b to have a high swr and vica
versa?


--
73 for now
Buck
N4PGW

What happens if you pipe the output of one radio in to 2 amps?
 

OK, this brings up another thought... Would the transmitted signal
from antenna a, being close to b, cause b to have a high swr and vica
versa?
________

Yes. Depending on the single-radiator pattern shapes and installation
geometry, mutual coupling between two adjacent antennas of the same
polarization, and cut for the same frequency can be -10 dB or less. An
"apparent reflected power" of -10 dBc = 1.92 SWR to each tx, plus
whatever SWR each antenna system has to the tx hardwired to it.

This performance may be OK for amateur radio, but not for broadcast
stations. To avoid this situation, broadcast system designs using
several r-f amplifiers combine the amplifier outputs to drive the
antenna system from a single set of terminals.

The antenna system design itself provides omnidirectional or
directional coverage in the horizontal plane as needed, but it is
always fed from a single set of terminals.

What happens if you pipe the output of one radio in to 2 amps?
 

"Tom Ring" wrote in message
.. .
Yuri Blanarovich wrote:

There is another potential problem if feeding two amps to two antennas
that are reasonably close: RF from one antenna is induced into the other
antenna, gets fed into the amp and causes some interference (mixing ?)
that shows up as a raspy signal.
Tried it, and heard it on another station attempting the same setup.
It seems that it would be easier to control the phasing at the input of
the PAs, but the above effect messes it up, unless antennas are widely
separated and they do not "feed" each other setup.
So, it appears that it is better to use one bigger amp and use proper
phasing to feed the two or more antennas.


Well, the expert, or should I say, the new GURU, has spoken. He seems to
know all about this complex subject.


Aaaah, here chimes in another W8JI worshipper, who can not read posting,
understand it and reply intelligently, but resorting to snotty, personal,
pathetic remarks. You may have noticed that I do not take crap and respond
in kind.

I know I will never try this again, as my previous efforts, which seemed
to work, could not possibly have done so. Obviously Wilkenson hybrids are
useless, likewise any ring hybrids, and all other methods of
splitting/combining a transmitter feed.


READ IT AGAIN carefully, I have not say that "Wilkenson" (learn spelling)
hybrid would not work or anything about dividing - combining signals. I have
noted that if TWO amplifiers are fed into TWO (separate) antennas that are
in close proximity (mutual impedance at play) then the signals from the one
antenna get picked up by the other antenna, fed back to the amplifiers and
cause distortion that manifests itself as a raspy CW tone or SSB modulation
on the air. I also mentioned that possible remedy is to separate the
antennas in a such way that there is no significant signal feedback between
them. Like you could have one amp feeding EU antenna, and another one
feeding SA antenna, separated properly, fed from the same TX and using
splitters, to satisfy the impedance match between the TX and AMPS.

Sorry guys, they won't work. Yuri said so.

I didn't say such a thing, I brought up potential problem to situation
(feeding 2 amps to 2 ants) in question and offered possible solution. I did
not even mention hybrids or ways of phasing the gizmos, where did you get it
from, private conversation with the other Tom? You got the GURU thing mixed
up. I do not play GURU on Internet by publicizing "wisdom pages" like W8JI
does, I would chime in with help when I see the need for it (and have time)
or when I see gross crap being paraded as "gospel".
Thank you for showing your feathers and displaying your depth!
Your picture would look pretier if you engaged in technical, civil
discussions, rather than that "W8JI thing".


tom
K0TAR


Yuri Blanarovich, K3BU, VE3BMV etc.

What happens if you pipe the output of one radio in to 2 amps?
 

On Thu, 25 May 2006 11:13:52 -0400, "Yuri Blanarovich"
wrote:

I do not play GURU on Internet by publicizing "wisdom pages" like W8JI
does

Hi Yuri,

http://www.k3bu.us/loadingcoils.htm
Looks like one of those GURU wisdom pages. A break-away from the Rome
church of QSL.NET. You even have publicized a new link to devotional
writings from your worshippers. They have all the steamy revelation
as the "Gospel of Judas Iscariot" just discovered.

73's
Richard Clark, KB7QHC
whose meek acolytes only whisper their prayers to him privately.

What happens if you pipe the output of one radio in to 2 amps?
 

"Richard Clark" wrote in message
...
On Thu, 25 May 2006 11:13:52 -0400, "Yuri Blanarovich"
wrote:

I do not play GURU on Internet by publicizing "wisdom pages" like W8JI
does

Hi Yuri,

http://www.k3bu.us/loadingcoils.htm
Looks like one of those GURU wisdom pages. A break-away from the Rome
church of QSL.NET. You even have publicized a new link to devotional
writings from your worshippers. They have all the steamy revelation
as the "Gospel of Judas Iscariot" just discovered.

73's
Richard Clark, KB7QHC
whose meek acolytes only whisper their prayers to him privately.

Not at all sireee!
This was response to W8JI baloney and to provide place for some explanation
and graphics, which reflectors and NGs do not afford.
If you followed my publishing career since 1958 and behind the Iron Curtain,
and if you knew me, you would find that I keep most of the stuff to myself,
even some groundbreaking ideas or inventions, I use them to my advantage to
gear up and operate in the contests, where I enjoy beating the competition,
there, stripped of pompous drivel and boasting. There, results are expressed
as points, placement in the ladder or record tables.

It is the most misleading junk science, that when I see it, I get stirred up
enough to respond with what I know to be the right or backed up by reality.
So if you look at my web site and see the "coil thing" and comparing this to
W8JI "guru thing" I wonder about your judgement. I am trying to be civil and
stay with technical discussions, but if someone resorts to personal attacks
and crap, I do not take it laying down with my mouth open.

I think you would be better off also to stick to matter o'fact technical
discussions rather than trying to display your literary talents of poking
people in the eyes.

I could care less what youze guyze here theoretize about or fight for number
one wize guy on the totem pole, or who you worship.
I enjoy ham radio as a means to keep in step with technology, enjoy
contacting and beating people in the contests and to keep my mind sharp.

Last thing I "enjoy" is arguing with an idiot or participate in a ****ing
contests with skunks. I hope I 'splained myself poetically enuf!

So I will not try to be the "last one standing - right" as W8JI philosophy
is. You can have it - argue all you want. I posted what I know, have seen,
am convinced of and can prove it. You can "figure" it all you want. I said,
described my piece, the reality is the judge and not some scientwists!

Have nice Memorial Day, remember those who gave their lives so you can live
in a freedom, otherwise sucks! Been there, paid with lives of dear ones!

73
--
Yuri Blanarovich, K3BU, VE3BMV

What happens if you pipe the output of one radio in to 2 amps?
 

On Thu, 25 May 2006 12:26:32 -0400, "Yuri Blanarovich"
wrote:

I do not play GURU on Internet by publicizing "wisdom pages" like W8JI
does

http://www.k3bu.us/loadingcoils.htm
Looks like one of those GURU wisdom pages. A break-away from the Rome
church of QSL.NET. You even have publicized a new link to devotional
writings from your worshippers. They have all the steamy revelation
as the "Gospel of Judas Iscariot" just discovered.

Not at all sireee!

Hi Yuri,

More surprising are most of those devotional writings come from a
heretic to your kool-aid chapter. Selective editing sure brings out
the hosannas though.

Have nice Memorial Day, remember those who gave their lives so you can live
in a freedom, otherwise sucks! Been there, paid with lives of dear ones!

I will be registering voters. Also on the calendar is my usual visit
to the Fort Lawton cemetery.

73's
Richard Clark, KB7QHC
5 generations of family service in the military (including the C.S.A.)

What happens if you pipe the output of one radio in to 2 amps?
 

Yuri Blanarovich wrote:

"Tom Ring" wrote in message
.. .

Yuri Blanarovich wrote:


There is another potential problem if feeding two amps to two antennas
that are reasonably close: RF from one antenna is induced into the other
antenna, gets fed into the amp and causes some interference (mixing ?)
that shows up as a raspy signal.
Tried it, and heard it on another station attempting the same setup.
It seems that it would be easier to control the phasing at the input of
the PAs, but the above effect messes it up, unless antennas are widely
separated and they do not "feed" each other setup.
So, it appears that it is better to use one bigger amp and use proper
phasing to feed the two or more antennas.


Well, the expert, or should I say, the new GURU, has spoken. He seems to
know all about this complex subject.



Aaaah, here chimes in another W8JI worshipper, who can not read posting,
understand it and reply intelligently, but resorting to snotty, personal,
pathetic remarks. You may have noticed that I do not take crap and respond
in kind.


I know I will never try this again, as my previous efforts, which seemed
to work, could not possibly have done so. Obviously Wilkenson hybrids are
useless, likewise any ring hybrids, and all other methods of
splitting/combining a transmitter feed.


READ IT AGAIN carefully, I have not say that "Wilkenson" (learn spelling)

snip
Thank you for showing your feathers and displaying your depth!
Your picture would look pretier if you engaged in technical, civil
discussions, rather than that "W8JI thing".



tom
K0TAR



Yuri Blanarovich, K3BU, VE3BMV etc.



Yuru

As far as replying in kind, I've been reading your posts for quite a
while, and I haven't noticed that you withhold any criticisms.

If the only errors you made were typos, this crowd wouldn't have a
problem with you.

And I know when I am out of my depth, and to keep my mouth firmly shut,
as apparently you do not.

tom
K0TAR

What happens if you pipe the output of one radio in to 2 amps?
 

"Tom Ring" wrote in message
.. .
Yuri Blanarovich wrote:

"Tom Ring" wrote in message
.. .

Yuri Blanarovich wrote:


There is another potential problem if feeding two amps to two antennas
that are reasonably close: RF from one antenna is induced into the other
antenna, gets fed into the amp and causes some interference (mixing ?)
that shows up as a raspy signal.
Tried it, and heard it on another station attempting the same setup.
It seems that it would be easier to control the phasing at the input of
the PAs, but the above effect messes it up, unless antennas are widely
separated and they do not "feed" each other setup.
So, it appears that it is better to use one bigger amp and use proper
phasing to feed the two or more antennas.


Well, the expert, or should I say, the new GURU, has spoken. He seems to
know all about this complex subject.



Aaaah, here chimes in another W8JI worshipper, who can not read posting,
understand it and reply intelligently, but resorting to snotty, personal,
pathetic remarks. You may have noticed that I do not take crap and
respond in kind.


I know I will never try this again, as my previous efforts, which seemed
to work, could not possibly have done so. Obviously Wilkenson hybrids
are useless, likewise any ring hybrids, and all other methods of
splitting/combining a transmitter feed.


READ IT AGAIN carefully, I have not say that "Wilkenson" (learn spelling)
snip
Thank you for showing your feathers and displaying your depth!
Your picture would look pretier if you engaged in technical, civil
discussions, rather than that "W8JI thing".



tom
K0TAR



Yuri Blanarovich, K3BU, VE3BMV etc.

Yuru

As far as replying in kind, I've been reading your posts for quite a
while, and I haven't noticed that you withhold any criticisms.

If the only errors you made were typos, this crowd wouldn't have a problem
with you.

And I know when I am out of my depth, and to keep my mouth firmly shut, as
apparently you do not.

tom
K0TAR

Typical response. Just read what happened in this thread.
Look at what I wrote, look at what you responded.
I am not criticizing, I respond to crap and personal attacks in kind, not
very nice, but I do not need to put up with snotty remarks and personal BS.
Looks like hurlers don't like when one responds in kind.
If discussion is about technical matters, I provide help where I can or feel
like. If jerk doesn't like it and comes riding high horse, then I get on my
horse too, which happened with W8JI (we go way back) and now with you.
I provided my opinion on 2 PAs to 2 ANTs, you twisted it and snapped GURU
crap on it, Richard Clark was right behind you. I hate to see you when you
are out of your depth. Now you come on with lecture about "crowd having
problem with me"?
You discuss technical matters in a civil way, I respond in kind, you pull
out snotty crap, and I don't take it. Mark it down and next time if you want
do the technical exchange I am open for dialog.
What you want me to do to be "nice"? Accept the "truth" that current along
the loading coil is ALWAYS the same, that shield IS the antenna, that
electrostatic shield can't possibly work, that antenna is not an antenna?
Where I come from, we fight for truth and if needed give life for it. If you
want me to bow to false teachings, or to take crap, look somewhere else.
So you want to try to be nice and discuss the problems with intermods
between two PAs feeding two antennas or play W8JI? I can also engage on
Wilkinson's hybrids, I use them.
Let's stay with the subjects of this NG and keep the crap for the toilets.
--
Yuri Blanarovich, K3BU, VE3BMV

What happens if you pipe the output of one radio in to 2 amps?
 

Yuri Blanarovich wrote:

As far as replying in kind, I've been reading your posts for quite a
while, and I haven't noticed that you withhold any criticisms.

If the only errors you made were typos, this crowd wouldn't have a problem
with you.

And I know when I am out of my depth, and to keep my mouth firmly shut, as
apparently you do not.

tom
K0TAR


Typical response. Just read what happened in this thread.
Look at what I wrote, look at what you responded.
I am not criticizing, I respond to crap and personal attacks in kind, not
very nice, but I do not need to put up with snotty remarks and personal BS.
Looks like hurlers don't like when one responds in kind.
If discussion is about technical matters, I provide help where I can or feel
like. If jerk doesn't like it and comes riding high horse, then I get on my
horse too, which happened with W8JI (we go way back) and now with you.
I provided my opinion on 2 PAs to 2 ANTs, you twisted it and snapped GURU
crap on it, Richard Clark was right behind you. I hate to see you when you
are out of your depth. Now you come on with lecture about "crowd having
problem with me"?
You discuss technical matters in a civil way, I respond in kind, you pull
out snotty crap, and I don't take it. Mark it down and next time if you want
do the technical exchange I am open for dialog.
What you want me to do to be "nice"? Accept the "truth" that current along
the loading coil is ALWAYS the same, that shield IS the antenna, that
electrostatic shield can't possibly work, that antenna is not an antenna?
Where I come from, we fight for truth and if needed give life for it. If you
want me to bow to false teachings, or to take crap, look somewhere else.
So you want to try to be nice and discuss the problems with intermods
between two PAs feeding two antennas or play W8JI? I can also engage on
Wilkinson's hybrids, I use them.
Let's stay with the subjects of this NG and keep the crap for the toilets.

Thank you for proving my points.

tom
K0TAR

What happens if you pipe the output of one radio in to 2 amps?
 

"Tom Ring" wrote in message
.. .
Yuri Blanarovich wrote:

Thank you for proving my points.

tom
K0TAR

Thank you for displaying your mental capabilities.
Enjoy unloading your personal digs!

73 Yuri, K3BU

What happens if you pipe the output of one radio in to 2 amps?
 

Yuri Blanarovich wrote:
Typical response. Just read what happened in this thread.
Look at what I wrote, look at what you responded.
I am not criticizing, I respond to crap and personal attacks in kind, not
very nice, but I do not need to put up with snotty remarks and personal BS.
Looks like hurlers don't like when one responds in kind.
If discussion is about technical matters, I provide help where I can or feel
like. If jerk doesn't like it and comes riding high horse, then I get on my
horse too, which happened with W8JI (we go way back) and now with you.
I provided my opinion on 2 PAs to 2 ANTs, you twisted it and snapped GURU
crap on it, Richard Clark was right behind you. I hate to see you when you
are out of your depth. Now you come on with lecture about "crowd having
problem with me"?
You discuss technical matters in a civil way, I respond in kind, you pull
out snotty crap, and I don't take it. Mark it down and next time if you want
do the technical exchange I am open for dialog.
What you want me to do to be "nice"? Accept the "truth" that current along
the loading coil is ALWAYS the same, that shield IS the antenna, that
electrostatic shield can't possibly work, that antenna is not an antenna?
Where I come from, we fight for truth and if needed give life for it. If you
want me to bow to false teachings, or to take crap, look somewhere else.
So you want to try to be nice and discuss the problems with intermods
between two PAs feeding two antennas or play W8JI? I can also engage on
Wilkinson's hybrids, I use them.
Let's stay with the subjects of this NG and keep the crap for the toilets.

I'm really sorry readers are subjected to this sort of thing in a
technical forum. Please don't associate me with the ranting.

73 Tom W8JI

What happens if you pipe the output of one radio in to 2 amps?
 

wrote:
I'm really sorry readers are subjected to this sort of thing in a
technical forum. Please don't associate me with the ranting.

Pot - Kettle, Kettle - Pot. Here's one of your rantings.

W8JI wrote:
I feel sorry for anyone who has to deal with you on a daily basis.
No wonder your wife split.

Your technical content is noted.
--
73, Cecil http://www.qsl.net/w5dxp

What happens if you pipe the output of one radio in to 2 amps?
 

Cecil Moore wrote:
Pot - Kettle, Kettle - Pot. Here's one of your rantings.

W8JI wrote:
I feel sorry for anyone who has to deal with you on a daily basis.
No wonder your wife split.

Your technical content is noted.
73, Cecil http://www.qsl.net/w5dxp

You're absolutely right Cecil.

There is no reason for anyone, including me, to personally attack
others or to rant and rave like a lunatic.

It absolutely ruins techincal forums when people get too personal, no
matter who does it. I think that is a major reason why this newsgroup
fell from being very popular to barely used.

73 Tom

What happens if you pipe the output of one radio in to 2 amps?
 

wrote:

Cecil Moore wrote:
Pot - Kettle, Kettle - Pot.

You're absolutely right Cecil.

Someone needs to tell W8JI that there's a nice person
forging postings from his ISP address. :-)
--
73, Cecil, W5DXP

What happens if you pipe the output of one radio in to 2 amps?
 

I'm gonna be like Brer Rabbit and say nuffin.

What happens if you pipe the output of one radio in to 2 amps?
 

So stick to technical questions and answers, keep comments about someone's
wife, license class, foaming, etc. to yourself. You start the crap and then
scream when "favor" is returned. Just go back and look who initiates that,
instead of answers to questions in question.

Bada BUm

wrote in message
oups.com...

Cecil Moore wrote:
Pot - Kettle, Kettle - Pot. Here's one of your rantings.

W8JI wrote:
I feel sorry for anyone who has to deal with you on a daily basis.
No wonder your wife split.

Your technical content is noted.
73, Cecil http://www.qsl.net/w5dxp

You're absolutely right Cecil.

There is no reason for anyone, including me, to personally attack
others or to rant and rave like a lunatic.

It absolutely ruins techincal forums when people get too personal, no
matter who does it. I think that is a major reason why this newsgroup
fell from being very popular to barely used.

73 Tom

What happens if you pipe the output of one radio in to 2 amps?
 

.. .
Yuri Blanarovich wrote:

There is another potential problem if feeding two amps to two antennas
that are reasonably close: RF from one antenna is induced into the
other
antenna, gets fed into the amp and causes some interference (mixing ?)
that shows up as a raspy signal.
Tried it, and heard it on another station attempting the same setup.
It seems that it would be easier to control the phasing at the input of
the PAs, but the above effect messes it up, unless antennas are widely
separated and they do not "feed" each other setup.
So, it appears that it is better to use one bigger amp and use proper
phasing to feed the two or more antennas.


I hope I did not cut incorrectly in the complex post...

The effect is that the *impedance* looking into each antenna will change due
to the mutual coupling of the two antennas. You can also think of it as
each antenna is not just staring into open space, but you can consider the
field of the other antenna to be changing the space around the first antenna
(and visa versa). It is also not umlike simply putting a reflecting plane or
other paracitic elements neat a driven element - the feed point impedance
changes. This power, being from the same transmitter, is coherent (phase
locked) and therefore changes the current that flows which manifests itself
as an impedance change. Given the current from the feed line voltage and
then the superposition of the current induced from the other antenna, you
get a new current that flows (aparently from the feed line voltage) and
therefore it appears as a different impedance (from the feed line's
perspective). I hope one of these analogies works for you.
This can indeed cause amplifiers to do funny things if they can't handle the
resulting SWR. If you correctly match to the new impedances, there should
be no problems, just the new antenna radiation pattern.

Side bar:
For some situations, the resistive part of this new impedance can even go
negative. This means that this antenna is absorbing power, not radiating
it. This can happen in phased, directive arrays used in broadcast. A
friend of mine described such a situation that vexed him for a while until
he improved his calculations to be more general to be applicable to this
situation (to get the correct result).
Don't ask me how to match to a negative resistance. All I know is that
given some certain directional pattern that is desired, this happens and
with the proper math you can design a matching network that works and
restores order to the universe and keeps the big bang happy (:-)

73, Steve, K9DCI

What happens if you pipe the output of one radio in to 2 amps?
 

Steve N. wrote:
. . .

Side bar:
For some situations, the resistive part of this new impedance can even go
negative. This means that this antenna is absorbing power, not radiating
it. This can happen in phased, directive arrays used in broadcast. A
friend of mine described such a situation that vexed him for a while until
he improved his calculations to be more general to be applicable to this
situation (to get the correct result).
Don't ask me how to match to a negative resistance. All I know is that
given some certain directional pattern that is desired, this happens and
with the proper math you can design a matching network that works and
restores order to the universe and keeps the big bang happy (:-)

Negative feedpoint resistances in phased arrays have of course been
known for a very long time. One of the example files (4Square.EZ) which
comes with EZNEC shows an element with a slightly negative feedpoint
resistance. The accompanying "antenna notes" file includes a brief
explanation of the phenomenon.

You can't "match to" a negative resistance, because matching
requirements are determined by the load, not source, impedance, and an
element with a negative resistance is a source rather than a load. But
there's no necessity to match individual elements and, in fact,
attempting to do so complicates the problem of achieving the desired
element current ratios. One thing you can count on, though -- the
resistance of the whole array will be positive. And that's what needs
matching.

Roy Lewallen, W7EL

What happens if you pipe the output of one radio in to 2 amps?
 

"Steve N." wrote in message
...
.. .
Yuri Blanarovich wrote:

There is another potential problem if feeding two amps to two antennas
that are reasonably close: RF from one antenna is induced into the
other
antenna, gets fed into the amp and causes some interference (mixing ?)
that shows up as a raspy signal.
Tried it, and heard it on another station attempting the same setup.
It seems that it would be easier to control the phasing at the input
of
the PAs, but the above effect messes it up, unless antennas are widely
separated and they do not "feed" each other setup.
So, it appears that it is better to use one bigger amp and use proper
phasing to feed the two or more antennas.


I hope I did not cut incorrectly in the complex post...

The effect is that the *impedance* looking into each antenna will change
due
to the mutual coupling of the two antennas. You can also think of it as
each antenna is not just staring into open space, but you can consider the
field of the other antenna to be changing the space around the first
antenna
(and visa versa). It is also not umlike simply putting a reflecting plane
or
other paracitic elements neat a driven element - the feed point impedance
changes. This power, being from the same transmitter, is coherent (phase
locked) and therefore changes the current that flows which manifests
itself
as an impedance change. Given the current from the feed line voltage and
then the superposition of the current induced from the other antenna, you
get a new current that flows (aparently from the feed line voltage) and
therefore it appears as a different impedance (from the feed line's
perspective). I hope one of these analogies works for you.
This can indeed cause amplifiers to do funny things if they can't handle
the
resulting SWR. If you correctly match to the new impedances, there should
be no problems, just the new antenna radiation pattern.


That could be a challenging task, if one wanted to have switchable or
tunable phasing. Some fancy detection and adjustments needed!?

Side bar:
For some situations, the resistive part of this new impedance can even go
negative. This means that this antenna is absorbing power, not radiating
it. This can happen in phased, directive arrays used in broadcast. A
friend of mine described such a situation that vexed him for a while until
he improved his calculations to be more general to be applicable to this
situation (to get the correct result).
Don't ask me how to match to a negative resistance. All I know is that
given some certain directional pattern that is desired, this happens and
with the proper math you can design a matching network that works and
restores order to the universe and keeps the big bang happy (:-)

73, Steve, K9DCI


Hi Steve,

That makes sense (and subject for scientwists to argue "it can't be" :-)

I was considering two scenarios for contesting.
One, mainly for expeditioning case, use two smaller amps (transportation
limitations) and low power (continuous) phasing network between the exciter
and two amps feeding two antennas.
Two, feeding two amps and two antenna systems firing in different directions
(offset stacks).
I tried the crude application of it, and was "bugged" that my CW tone or SSB
modulation was raspy. I knew that rig was OK, firing one leg was no problem
and had to conclude that the problem had to be mutual coupling, feedback and
"beating" back in the amp circuits. I did not pursue the rectification of
the problem, considered it too complicated for what I wanted to do. Learned
it to be a no-no trying to feed phased arrays with individual amplifiers, at
the same frequency.
Feeding antennas that are widely separated with no mutual coupling, firing
in different directions, should not be a problem, as long as there is no
significant signal being induced into the other system.
We will play with some outrageous combinations of about 40 rhombics and
other antennas, capable of being fed by 16 transmitters from the new Tesla
RC QTH of old AT&T Ocean Gate NJ site (makes old W6AM site look like
kindergarten :-). Antenna matrix (wall unit) switch that does the selection
is a piece of art in itself. We have to get rid of pigeons and "paintings"
they left and get the site operational by the fall contest season.

--
73, Yuri Blanarovich, K3BU, VE3BMV

What happens if you pipe the output of one radio in to 2 amps?
 

Yuri, K3BU wrote:
"Learned it to be a no-no trying to feed phased arrays with individual
amplifiers, at the same frequency."

I`m not sure separate amplifiers have anything to do with distortion
because I`ve seen distortion at certain azimuths from arrays driven by
a single amplifier.

Drive around a broadcast array with sharp nulls while listening. You
will notice severe distortion at the edges of sharp nulls. I always
attributed this to phase out of the carrier frequency at an azumuth
where the sidebands aren`t completely nulled out, and this produces the
overmodulation and distortion. It`s only a speculation to explain the
cause of an observed effect.

Best regards, Richard Harrison, KB5WZI

What happens if you pipe the output of one radio in to 2 amps?
 

"Roy Lewallen" wrote in message
...
Steve N. wrote:
. . .
Side bar:
For some situations, the resistive part of this new impedance can even
go
negative. ...

Negative feedpoint resistances in phased arrays have of course been
known for a very long time.

Roy,
I didn't mean to imply it wasn't known previously, only wanted to give a
real life example (as a preemptive attempt at heading off a potential "but
that's all theory" response -- perhaps a little gun-shy on this news group
(:-)). I also have no direct knowledge of this type of the network design,
but it has to be designed and the antenna with the neg real part is part of
the system that gets hooked to the network.


You can't "match to" a negative resistance, because matching
requirements are determined by the load, not source, impedance,

OOPS ! I *know* what you mean, but it takes knowledte of both ends -
We, me included, can eaily forget that we have an arbitrarily defined (50
ohm) system that we easily take for granted. ya gotta know you're in a 50
ohm (or whatever) system to "do" the match.

73, Steve, K9DCI

What happens if you pipe the output of one radio in to 2 amps?
 

"Reg Edwards" wrote in message
...


I'm gonna be like Brer Rabbit and say nuffin.



But you just did!

sorry, couldn't resist.
I wasn't gonna say anything, until I just thought of that:

73, Steve, K9DCI

What happens if you pipe the output of one radio in to 2 amps?
 

Richard Harrison wrote:

Yuri, K3BU wrote:
"Learned it to be a no-no trying to feed phased arrays with individual
amplifiers, at the same frequency."

I`m not sure separate amplifiers have anything to do with distortion
because I`ve seen distortion at certain azimuths from arrays driven by
a single amplifier.

Drive around a broadcast array with sharp nulls while listening. You
will notice severe distortion at the edges of sharp nulls. I always
attributed this to phase out of the carrier frequency at an azumuth
where the sidebands aren`t completely nulled out, and this produces the
overmodulation and distortion. It`s only a speculation to explain the
cause of an observed effect.

Best regards, Richard Harrison, KB5WZI


I wonder if we can really define that as distortion. It's distortion to
you at the time perhaps, since the whole signal as you'd like it to be
delivered is not there while you drive through the null. However, the
antenna system is just doing its job, and doing it well in the
directions it was intended. The nulls are by nature not supposed to
contain signals with smooth frequency response, since they aren't
supposed to contain any signal at all if perfect, correct?

tom
K0TAR

What happens if you pipe the output of one radio in to 2 amps?
 

"Richard Harrison" wrote in message
...
Yuri, K3BU wrote:
"Learned it to be a no-no trying to feed phased arrays with individual
amplifiers, at the same frequency."

I`m not sure separate amplifiers have anything to do with distortion
because I`ve seen distortion at certain azimuths from arrays driven by
a single amplifier.

Drive around a broadcast array with sharp nulls while listening. You
will notice severe distortion at the edges of sharp nulls. I always
attributed this to phase out of the carrier frequency at an azumuth
where the sidebands aren`t completely nulled out, and this produces the
overmodulation and distortion. It`s only a speculation to explain the
cause of an observed effect.

Best regards, Richard Harrison, KB5WZI


The effect, distortion, seemed to be noticeable in any or all directions and
over DX path. The only thing we could figure out, was that it had to do with
separate amps feeding separate ants. Switching to either one, signals were
clean. Feeding two antennas from one exciter through hybrid was no problem.
In my case it was 4 square and Inv Vee about 3/8 wave away.
I have heard the same effect on one YU station, and he was getting reports
of raspy signal and when I told him to turn the other amp off, he was clean.
The distortion was quite significant, it produced complaints from about one
in five stations worked. Closest thing to describe it, would like signals
distorted by Aurora.

73 Yuri, K3BU