Topband: Topband Digest, Vol 139, Issue 20

[Tom W8JI]

Poor guessing by Carl.

The control units are entirely different. One is just a switch, and the 
other is a microprocessor based system that has an omni function and a hot 
switch lockout for relay protection. It also has a relay clean function.

I this the original poster was asking about Array Solutions vs. DXE, and not 
Comtek.

The original poster might have been asking about the phasing box???

The control head is in the house on the desk. The phasing box is out at the 
antenna.  The various subparts of the system are very commonly called 
incorrect names, even by sales people. For example, the phasing box or 
outdoor unit is called a controller. The Q-sections that are nothing more 
than feedlines are called phasing lines. I never really am sure what part 
someone is asking about. :)

Another point about guessing...

The original error in hybrid 4 square design was from ignoring mutual 
coupling, and assuming element impedances were ~35 j0 for all four elements. 
The original thought was to transform the antennas to 100 ohms at the 
phasing box ports by using 1/4 wave 75-ohm Q sections. The 100 ohm ports 
were paralleled to get 50 ohms.

The problem with that idea is mutual coupling changes the antenna resonance 
and impedance. The antennas are not even close to the correct impedance, and 
are reactive with different signs when phased. The elements also require 
equal currents, not equal power. A hybrid tries to force equal power.

As far as I know, ****NONE**** of these units are true hybrids. This is 
because a true hybrid would have terrible F/B ratio and gain in this 
application. This is because:

1.) None of the elements or feedlines are 50 j0 when phased. They are all 
different impedances, except the center two elements. A hybrid ONLY provides 
the design phase when the termination is the design value, and that does not 
happen.

2.) None of the element groups require equal power. Equal power would result 
in a terrible F/B ratio.

The DXE outdoor unit, besides an omni function and sophisticated controller, 
is much better optimized for the impedances actually presented in the 
working system. Rather than accidentally working through a design shortfall 
in hybrid, like the original system many years ago was, it is planned for 
the loads presented by the system. Because none of these units are really 
hybrids (they would not work very well if they were), they are all 
different.

73 Tom



----- Original Message ----- 
From: "Carl" <km1h at jeremy.mv.com>
To: "Mike Greenway" <K4PI at BELLSOUTH.NET>; <topband at contesting.com>
Sent: Thursday, July 31, 2014 8:00 PM
Subject: Re: Topband: Topband Digest, Vol 139, Issue 20


> More like a Chevy vs one thats been dolled up a bit for more money (-:
>
>
> ----- Original Message ----- 
> From: "Mike Greenway" <K4PI at BELLSOUTH.NET>
> To: <topband at contesting.com>
> Sent: Thursday, July 31, 2014 2:25 PM
> Subject: Re: Topband: Topband Digest, Vol 139, Issue 20
>
>
>> Hi Paul.. I have used two Comteks for over 20 years and they have never 
>> had a problem.  The DXE looks like a very nice unit and it appears to me 
>> the circuitry is about the same..  Either should work well I think... 
>> Ford versus Chevy...  73 Mike K4PI
>>
>> From: topband-request at contesting.com
>> Sent: Thursday, July 31, 2014 12:00 PM
>> To: topband at contesting.com
>> Subject: Topband Digest, Vol 139, Issue 20
>>
>> Send Topband mailing list submissions to
>> topband at contesting.com
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>> http://lists.contesting.com/mailman/listinfo/topband
>> or, via email, send a message with subject or body 'help' to
>> topband-request at contesting.com
>>
>> You can reach the person managing the list at
>> topband-owner at contesting.com
>>
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of Topband digest..."
>>
>>
>> Today's Topics:
>>
>>   1. 4-square controllers (Paul Baldock)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Wed, 30 Jul 2014 21:32:30 -0700
>> From: Paul Baldock <pbaldock at frontier.com>
>> To: <topband at contesting.com>
>> Subject: Topband: 4-square controllers
>> Message-ID: <20140731043244.B6490AC9F9A at mx.contesting.com>
>> Content-Type: text/plain; charset="us-ascii"; format=flowed
>>
>> Does anybody have an opinion on the DX Engineering verses the Array
>> Solutions 4 square controller?
>>
>> - Paul  KW7Y
>>
>>
>>
>> ------------------------------
>>
>> Subject: Digest Footer
>>
>> _______________________________________________
>> Topband mailing list
>> Topband at contesting.com
>> http://lists.contesting.com/mailman/listinfo/topband
>>
>>
>> ------------------------------
>>
>> End of Topband Digest, Vol 139, Issue 20
>> ****************************************
>> _________________
>> Topband Reflector Archives - http://www.contesting.com/_topband
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 2014.0.4716 / Virus Database: 3986/7954 - Release Date: 07/31/14
>>
>
> _________________
> Topband Reflector Archives - http://www.contesting.com/_topband
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2014.0.4716 / Virus Database: 3986/7957 - Release Date: 07/31/14
>