[TowerTalk] TowerTalk Digest, Vol 104, Issue 21

Sun Aug 14 16:45:34 PDT 2011

On using two amplifiers:

I tried that back about 15 years ago. I used an FT-1000D feeding two SB-220 
amplifiers with separate 1/2 wave 75 meter dipoles spaced about 200 feet 
apart. Most of the time, it produced somewhat stronger signal reports, 
particularly out of Europe, but overall it didn' t appear to be worth the 
trouble. I discontinued using both amps together after a couple of months. 
It was fun to try, but the advantage was slight. Using different types of 
antennae might have resulted in better results.

73,
Kent - K4MK

----- Original Message ----- 
From: <towertalk-request at contesting.com>
To: <towertalk at contesting.com>
Sent: Sunday, August 14, 2011 7:13 PM
Subject: TowerTalk Digest, Vol 104, Issue 21

Send TowerTalk mailing list submissions to
towertalk at contesting.com

To subscribe or unsubscribe via the World Wide Web, visit
http://lists.contesting.com/mailman/listinfo/towertalk
or, via email, send a message with subject or body 'help' to
towertalk-request at contesting.com

You can reach the person managing the list at
towertalk-owner at contesting.com

When replying, please edit your Subject line so it is more specific
than "Re: Contents of TowerTalk digest..."

Today's Topics:

   1. Re: Two signals on the same frequency? (Chet)
   2. Re: Two signals on the same frequency? (Andy)
   3. Re: Two signals on the same frequency? (Jim Brown)
   4. Re: Two signals on the same frequency? (K8RI on TT)
   5. Re: Two signals on the same frequency? (Jim Brown)
   6. Re: Two signals on the same frequency? (K1TTT)
   7. Wanted: Rohn 25 WA, OR, ID, MT (Rob Frohne)
   8. Re: Two signals on the same frequency? (K8RI on TT)
   9. Re: Two signals on the same frequency? (Gary Schafer)
  10. Re: Two signals on the same frequency? (Gene Smar)

----------------------------------------------------------------------

Message: 1
Date: Sun, 14 Aug 2011 16:48:55 -0400
From: "Chet" <chetmoore at cox.net>
Subject: Re: [TowerTalk] Two signals on the same frequency?
To: <jari.jussila at oh2bu.pp.fi>, <towertalk at contesting.com>
Message-ID: <03eb01cc5ac3$95b37370$c11a5a50$@net>
Content-Type: text/plain; charset="us-ascii"

I don't think you will be any louder but At least one consequence of tx's on
the same freq is a much wider bandwidth.
"Hypothetically" It would likely  keep the other contesters from as cq'ing
close to your frequency as they could running a single xmtr.

Chet N4FX

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Jari Jussila
Sent: Sunday, August 14, 2011 12:25 PM
To: towertalk at contesting.com
Subject: [TowerTalk] Two signals on the same frequency?

A hypothetical question:

I have two antennas for the same band. The antennas might be same kind
(eg. two dipoles, two yagis) or different (one dipole, one vertical).
I transmit with two separate transmitters - one to one antenna - but
modulate the transmitters simultaneousl*y *with same key or microphone.

How does my signal-strength change on the other side in comparison if I
used only one transmitter and one antenna? The antennas are not phased
to each other and they might be quite apart from each other.

I know that the advanced contest stations have one beam to eg. JA and
one to Europe etc.  But if they turned both antennas to JA, would the
signal-strength go up?

Jari, OH2BU
_______________________________________________

_______________________________________________
TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

------------------------------

Message: 2
Date: Sun, 14 Aug 2011 17:18:37 -0400
From: Andy <ai.egrps at gmail.com>
Subject: Re: [TowerTalk] Two signals on the same frequency?
To: towertalk at contesting.com
Message-ID:
<CAN_saPJzS44-WAR6eC2W2xo9naYQXdd3qL=Xm4jQwvy6Cvr4Ow at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

> I don't think you will be any louder but At least one consequence of tx's 
> on
> the same freq is a much wider bandwidth.

How's that?

Andy

------------------------------

Message: 3
Date: Sun, 14 Aug 2011 14:23:10 -0700
From: Jim Brown <jim at audiosystemsgroup.com>
Subject: Re: [TowerTalk] Two signals on the same frequency?
To: towertalk at contesting.com
Message-ID: <4E483CBE.9090309 at audiosystemsgroup.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On 8/14/2011 1:48 PM, Chet wrote:
> A hypothetical question:

Study the fundamentals of antennas, antenna arrays, and fields in the
ARRL Handbook and ARRL Antenna Book. The short answer is that the
signals from multiple antennas will ADD algebraically, taking their
magnitude and phase into account. That is, in some directions they will
be exactly in phase and will be stronger, in other directions they will
be varying degrees of out of phase and either add less, or cancel each
other. if they are equal in level and 180 out of phase, they will cancel
perfectly.

EXACT:LY the same thing happens with reflected signals -- the vertical
patterns of simple dipoles and vertical antennas are the result of
reflections from the earth either adding or cancelling the direct
signal.  Ditto for multi-path, and even for much of what we call
selective fading.

73, Jim K9YC

------------------------------

Message: 4
Date: Sun, 14 Aug 2011 17:37:18 -0400
From: K8RI on TT <k8ri-on-towertalk at tm.net>
Subject: Re: [TowerTalk] Two signals on the same frequency?
To: towertalk at contesting.com
Message-ID: <4E48400E.3010809 at tm.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On 8/14/2011 4:48 PM, Chet wrote:
> I don't think you will be any louder but At least one consequence of tx's 
> on
> the same freq is a much wider bandwidth.

How so?  1 or 10 all on the same frequency, the strength adds
algebraically, not the width.  They are the same frequency and would
serve as one transmitter with twice the power in this case, but only if
as others have pointed out the signals were in phase.

As pointed out there is the difficulty of keeping two transmitters not
on the same frequency, but other than that it's simple math.

73

Roger (K8RI)
> "Hypothetically" It would likely  keep the other contesters from as cq'ing
> close to your frequency as they could running a single xmtr.
>
> Chet N4FX
>
> -----Original Message-----
> From: towertalk-bounces at contesting.com
> [mailto:towertalk-bounces at contesting.com] On Behalf Of Jari Jussila
> Sent: Sunday, August 14, 2011 12:25 PM
> To: towertalk at contesting.com
> Subject: [TowerTalk] Two signals on the same frequency?
>
>
> A hypothetical question:
>
> I have two antennas for the same band. The antennas might be same kind
> (eg. two dipoles, two yagis) or different (one dipole, one vertical).
> I transmit with two separate transmitters - one to one antenna - but
> modulate the transmitters simultaneousl*y *with same key or microphone.
>
> How does my signal-strength change on the other side in comparison if I
> used only one transmitter and one antenna? The antennas are not phased
> to each other and they might be quite apart from each other.
>
> I know that the advanced contest stations have one beam to eg. JA and
> one to Europe etc.  But if they turned both antennas to JA, would the
> signal-strength go up?
>
> Jari, OH2BU
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>

------------------------------

Message: 5
Date: Sun, 14 Aug 2011 14:47:54 -0700
From: Jim Brown <jim at audiosystemsgroup.com>
Subject: Re: [TowerTalk] Two signals on the same frequency?
To: towertalk at contesting.com
Message-ID: <4E48428A.6090503 at audiosystemsgroup.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On 8/14/2011 2:23 PM, Jim Brown wrote:
> The short answer is that the
> signals from multiple antennas will ADD algebraically,

One VERY important point is that for the signals to ADD, they must be
SYCHRONOUS -- that is, on precisely the same frequency, coming from the
same oscillator.  In practical terms, this means a signal generated by a
single transmitter, then fed to two power amps that feed different
antennas. Or a single transmitter (with or without a single power amp),
split between multiple antennas.

If the two signals were not synchronous (that is, from two independent
transmitters) their phase relationships will be random, and addition and
subtraction will be quite unstable and unpredictable.

73, Jim K9YC

------------------------------

Message: 6
Date: Sun, 14 Aug 2011 22:00:50 +0000
From: "K1TTT" <K1TTT at ARRL.NET>
Subject: Re: [TowerTalk] Two signals on the same frequency?
To: <towertalk at contesting.com>
Message-ID: <E362D2530E1F4366A3C7252500D232F3 at k1tttibm>
Content-Type: text/plain; charset=US-ASCII

Separate amplifiers could also be problematic unless very carefully designed
and tuned to keep the phase delays the same when changing frequency across a
band.

David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net

> -----Original Message-----
> From: Jim Brown [mailto:jim at audiosystemsgroup.com]
> Sent: Sunday, August 14, 2011 21:48
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Two signals on the same frequency?
>
>
> On 8/14/2011 2:23 PM, Jim Brown wrote:
> > The short answer is that the
> > signals from multiple antennas will ADD algebraically,
>
> One VERY important point is that for the signals to ADD, they must be
> SYCHRONOUS -- that is, on precisely the same frequency,
> coming from the
> same oscillator.  In practical terms, this means a signal
> generated by a
> single transmitter, then fed to two power amps that feed different
> antennas. Or a single transmitter (with or without a single
> power amp),
> split between multiple antennas.
>
> If the two signals were not synchronous (that is, from two
> independent
> transmitters) their phase relationships will be random, and
> addition and
> subtraction will be quite unstable and unpredictable.
>
> 73, Jim K9YC
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>

------------------------------

Message: 7
Date: Sun, 14 Aug 2011 15:05:44 -0700
From: Rob Frohne <rob.frohne at wallawalla.edu>
Subject: [TowerTalk] Wanted: Rohn 25 WA, OR, ID, MT
To: <towertalk at contesting.com>
Message-ID: <4E4846B8.1010409 at wallawalla.edu>
Content-Type: text/plain; charset="iso-8859-1"

Hi,

My friend Vernon near Polebridge, MT needs another 30-60 feet of Rohn
25.  Anyone have any they are ready to part with?

73,

Rob
KL7NA

-- 
Rob Frohne, Ph.D., P.E.
E.F. Cross School of Engineering
Walla Walla University
100 SW 4th Street
College Place, WA 99324
(509) 527-2075 http://people.wallawalla.edu/~rob.frohne

------------------------------

Message: 8
Date: Sun, 14 Aug 2011 18:05:16 -0400
From: K8RI on TT <k8ri-on-towertalk at tm.net>
Subject: Re: [TowerTalk] Two signals on the same frequency?
To: towertalk at contesting.com
Message-ID: <4E48469C.6070108 at tm.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On 8/14/2011 5:47 PM, Jim Brown wrote:
> On 8/14/2011 2:23 PM, Jim Brown wrote:
>> The short answer is that the
>> signals from multiple antennas will ADD algebraically,
> One VERY important point is that for the signals to ADD, they must be
> SYCHRONOUS -- that is, on precisely the same frequency, coming from the
> same oscillator.  In practical terms, this means a signal generated by a
> single transmitter, then fed to two power amps that feed different
> antennas. Or a single transmitter (with or without a single power amp),
> split between multiple antennas.
>
> If the two signals were not synchronous (that is, from two independent
> transmitters) their phase relationships will be random, and addition and
> subtraction will be quite unstable and unpredictable.

Even then the signals remain synchronous only if they travel equal
distances to the antennas.  IOW same electrical length of coax between
transmitter, splitter, and amps assuming no phase difference in the
power divider. Then the same electrical distance of feed line to the
antennas from the amps with no intervening hardware such as tuners.
Maintaining true phase over distance even in split systems is, or can be
a real PITA. <:-))  Fortunately, except in phased arrays (which are a
bit forgiving), or selectable stacked arrays. This type of problem is
rarely encountered in ham radio.

73

Roger (K8RI)

>
> 73, Jim K9YC
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>

------------------------------

Message: 9
Date: Sun, 14 Aug 2011 19:09:31 -0400
From: "Gary Schafer" <garyschafer at comcast.net>
Subject: Re: [TowerTalk] Two signals on the same frequency?
To: "'K8RI on TT'" <k8ri-on-towertalk at tm.net>,
<towertalk at contesting.com>
Message-ID: <AF64845398F64C3CB3EB912FF0EAA4FF at garyPC>
Content-Type: text/plain; charset="us-ascii"

A ham that I knew some years ago (an avid Do's) claimed that he and his
buddy across town would sometimes get on the same frequency and one would
zero beat the other by holding the telephone up to the speaker at one
station and to the mike at the other station as they were both keyed up.
Then one would talk into the mike and phone at the same time.

He claimed that in a pileup that neither could break by themselves, got done
easily with the two stations.

If you think about a stacked array with the ability to feed in phase or out
of phase, sometimes one is better than the other. It all depends on how the
two or more signals are arriving at the other end when there is diversity
involved.
When the array looks more like a point source then absolute phase is more
important. But I suspect that when there is significant separation in
antennas then arrival phase at the other end is not as predictable.

73
Gary  K4FMX

> -----Original Message-----
> From: towertalk-bounces at contesting.com [mailto:towertalk-
> bounces at contesting.com] On Behalf Of K8RI on TT
> Sent: Sunday, August 14, 2011 6:05 PM
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Two signals on the same frequency?
>
> On 8/14/2011 5:47 PM, Jim Brown wrote:
> > On 8/14/2011 2:23 PM, Jim Brown wrote:
> >> The short answer is that the
> >> signals from multiple antennas will ADD algebraically,
> > One VERY important point is that for the signals to ADD, they must be
> > SYCHRONOUS -- that is, on precisely the same frequency, coming from
> the
> > same oscillator.  In practical terms, this means a signal generated by
> a
> > single transmitter, then fed to two power amps that feed different
> > antennas. Or a single transmitter (with or without a single power
> amp),
> > split between multiple antennas.
> >
> > If the two signals were not synchronous (that is, from two independent
> > transmitters) their phase relationships will be random, and addition
> and
> > subtraction will be quite unstable and unpredictable.
>
> Even then the signals remain synchronous only if they travel equal
> distances to the antennas.  IOW same electrical length of coax between
> transmitter, splitter, and amps assuming no phase difference in the
> power divider. Then the same electrical distance of feed line to the
> antennas from the amps with no intervening hardware such as tuners.
> Maintaining true phase over distance even in split systems is, or can be
> a real PITA. <:-))  Fortunately, except in phased arrays (which are a
> bit forgiving), or selectable stacked arrays. This type of problem is
> rarely encountered in ham radio.
>
> 73
>
> Roger (K8RI)
>
> >
> > 73, Jim K9YC
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk at contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk

------------------------------

Message: 10
Date: Sun, 14 Aug 2011 19:13:14 -0400
From: "Gene Smar" <ersmar at verizon.net>
Subject: Re: [TowerTalk] Two signals on the same frequency?
To: <towertalk at contesting.com>
Message-ID: <5BEBF49967B9434A997C3DE2FEA73E0F at downstairs>
Content-Type: text/plain; format=flowed; charset=iso-8859-1;
reply-type=original

TT:

     For a commercial implementation of the subject configuration, Google
"MIMO."

73 de
Gene Smar  AD3F

----- Original Message ----- 
From: "Gary Schafer" <garyschafer at comcast.net>
To: "'K8RI on TT'" <k8ri-on-towertalk at tm.net>; <towertalk at contesting.com>
Sent: Sunday, August 14, 2011 7:09 PM
Subject: Re: [TowerTalk] Two signals on the same frequency?

>A ham that I knew some years ago (an avid Do's) claimed that he and his
> buddy across town would sometimes get on the same frequency and one would
> zero beat the other by holding the telephone up to the speaker at one
> station and to the mike at the other station as they were both keyed up.
> Then one would talk into the mike and phone at the same time.
>
> He claimed that in a pileup that neither could break by themselves, got
> done
> easily with the two stations.
>
> If you think about a stacked array with the ability to feed in phase or
> out
> of phase, sometimes one is better than the other. It all depends on how
> the
> two or more signals are arriving at the other end when there is diversity
> involved.
> When the array looks more like a point source then absolute phase is more
> important. But I suspect that when there is significant separation in
> antennas then arrival phase at the other end is not as predictable.
>
> 73
> Gary  K4FMX
>
>> -----Original Message-----
>> From: towertalk-bounces at contesting.com [mailto:towertalk-
>> bounces at contesting.com] On Behalf Of K8RI on TT
>> Sent: Sunday, August 14, 2011 6:05 PM
>> To: towertalk at contesting.com
>> Subject: Re: [TowerTalk] Two signals on the same frequency?
>>
>> On 8/14/2011 5:47 PM, Jim Brown wrote:
>> > On 8/14/2011 2:23 PM, Jim Brown wrote:
>> >> The short answer is that the
>> >> signals from multiple antennas will ADD algebraically,
>> > One VERY important point is that for the signals to ADD, they must be
>> > SYCHRONOUS -- that is, on precisely the same frequency, coming from
>> the
>> > same oscillator.  In practical terms, this means a signal generated by
>> a
>> > single transmitter, then fed to two power amps that feed different
>> > antennas. Or a single transmitter (with or without a single power
>> amp),
>> > split between multiple antennas.
>> >
>> > If the two signals were not synchronous (that is, from two independent
>> > transmitters) their phase relationships will be random, and addition
>> and
>> > subtraction will be quite unstable and unpredictable.
>>
>> Even then the signals remain synchronous only if they travel equal
>> distances to the antennas.  IOW same electrical length of coax between
>> transmitter, splitter, and amps assuming no phase difference in the
>> power divider. Then the same electrical distance of feed line to the
>> antennas from the amps with no intervening hardware such as tuners.
>> Maintaining true phase over distance even in split systems is, or can be
>> a real PITA. <:-))  Fortunately, except in phased arrays (which are a
>> bit forgiving), or selectable stacked arrays. This type of problem is
>> rarely encountered in ham radio.
>>
>> 73
>>
>> Roger (K8RI)
>>
>> >
>> > 73, Jim K9YC
>> > _______________________________________________
>> >
>> >
>> >
>> > _______________________________________________
>> > TowerTalk mailing list
>> > TowerTalk at contesting.com
>> > http://lists.contesting.com/mailman/listinfo/towertalk
>> >
>>
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk at contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk

------------------------------

_______________________________________________
TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

End of TowerTalk Digest, Vol 104, Issue 21
****************************************** 