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Re: [CQ-Contest] Multiple direction antennas on one radio...why?

To: Igor Sokolov <ua9cdc@gmail.com>
Subject: Re: [CQ-Contest] Multiple direction antennas on one radio...why?
From: e73m@e73m.com
Date: Thu, 20 Oct 2011 03:14:43 -0500
List-post: <cq-contest@contesting.com">mailto:cq-contest@contesting.com>
Yes Igor, I guess any stack match can be used.

Here is another commercial product, note the underlined text:"Those 
splitters are use at different contest-stations worldwide !

link is here http://www.qro-shop.com/Powersplitters.htm

73 Danny E73M

On Thu, 20 Oct 2011 09:58:01 +0600, Igor Sokolov wrote:
> Danny, Microham stack switch can split into 2 or 3 amp
> http://www.microham.com/index1.html
> Then one can split output of each amp into 2 or 3 antenna with
> anpther stack switch.
> 73, Igor UA9CDC
>
> ----- Original Message ----- From: <e73m@e73m.com>
> To: <cq-contest@contesting.com>
> Sent: Thursday, October 20, 2011 5:48 AM
> Subject: Re: [CQ-Contest] Multiple direction antennas on one 
> radio...why?
>
>
>> Update, I found the other place to buy splitters, even for 4 amps,
>> http://www.communication-concepts.com/new_page_17.htm
>>
>> 73 Danny E73M
>>
>>
>> On Wed, 19 Oct 2011 00:30:48 -0400, Tom W8JI wrote:
>>> This has my curiousity.....does anyone know what stations doing 
>>> this
>>> really
>>> do?
>>>
>>> When I have a splitter, power divides from the exciter. Each amp 
>>> has
>>> fixed
>>> gain. If I have one 10 dB gain amp and a 100 watt exciter I have 
>>> 1000
>>> watts.
>>> If I split the power into two 10 dB amplifiers, I have 500 watts 
>>> per
>>> amp
>>> minus splitter losses. If I split it four ways, I have less than 
>>> 250
>>> watts
>>> per amp. It doesn't matter if I split before the amps or after,
>>> except for
>>> the size of the splitter.
>>>
>>> I would either have to have a variable gain amplifier driving the
>>> splitter
>>> that would increase power into the splitter just over 3 dB  for 
>>> each
>>> two-way
>>> split, or I'd have to have dummy loads and replace amplifiers with
>>> dummy
>>> loads as I pulled antennas out of line.
>>>
>>> How do they do it?
>>>
>>> On receiving, summing receive signals from four antennas in 
>>> different
>>> directions would hurt MDS, because at minimum every additional pair
>>> of
>>> antennas would decrease receiver S/N by at least 3 dB. There would 
>>> be
>>> at
>>> least 6 dB of S/N loss and probably more in most cases.
>>>
>>> Why would someone do that?
>>>
>>> Or do they really use four radios with four amplifiers and four
>>> antennas,
>>> and transmit on all and only listen on one???
>>>
>>> Does anyone actually know how these systems really work, because it
>>> seems
>>> pretty strange to me on the surface. Are these systems planned, or 
>>> is
>>> a case
>>> of just throwing something at the wall and hoping more sticks to 
>>> the
>>> wall
>>> than falls off?
>>>
>>> One way it would work well is with four listening operators on four
>>> separate
>>> receivers so there is no S/N loss, and one transmitter at a time
>>> driving all
>>> four amps through one additional amplifier so there is minimal 
>>> phase
>>> distortion if someone hears more than one TX antenna at once.
>>>
>>> I'm just trying to learn something useful here. I would never think
>>> of
>>> running four antennas in different directions into one radio for
>>> receiving
>>> except as a last possible resort.
>>>
>>> 73 Tom
>>>
>>> _______________________________________________
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>>> CQ-Contest@contesting.com
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>>
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