[ICOM] 7600 and Dual Watch... "it's a mix"

Sun Aug 23 04:47:41 EDT 2009

Gordon,
    No equal lengths needed unless you want to run two or three as a 
stack on the same tower. Even with SWR of less than 1.7 on all antennas, 
check various combinations of 1, 2  or 3 to be sure the combos are all 
less than 1.7 and adding in another jumper on one or more of the 
antennas may bring the SWR down.
    73 Phil N0KE
   

J. Gordon Beattie, Jr., W2TTT wrote:
> Phil,
> No they are on different towers, but I was under the impression that the use
> of the Stackmatch required equal lengths of coax.  I guess I may be
> mistaken!
>
> Thanks & 73,
> Gordon Beattie, W2TTT
> 201.314.6964
>  
>
> -----Original Message-----
> From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net] On
> Behalf Of Phil Krichbaum
> Sent: Friday, August 21, 2009 6:44 PM
> To: ICOM Reflector
> Subject: Re: [ICOM] 7600 and Dual Watch... "it's a mix"
>
> Gordon,
>     I guess all your antennas are on the same tower so you can run then 
> as a stack in a single direction, hence the equal lengths of coax. I 
> typically feed antennas on different towers, usually pointed in 
> different directions for HF or 6m. sometimes I have to play with the 
> coax lengths to get less than 1.7:1 with all combinations.
>     Phil N0KE
>
> J. Gordon Beattie, Jr., W2TTT wrote:
>   
>> Phl,
>> I have access to one, but that doesn't protect the second rig...I guess
>>     
> your
>   
>> suggestion is that I consolidate to one rig and phase the antennas through
>> the Stackmatch with equal coax lengths et al.  I certainly could do that,
>> but I would need to think about what happens when the patterns interact as
>> the antennas are on separate rotators and sometimes point across each
>> other's paths.
>> Hmmm...
>> :-)
>> Nice problem to consider...
>> :-)
>> Thanks & 73,
>> Gordon Beattie, W2TTT
>> 201.314.6964
>>  
>>
>> -----Original Message-----
>> From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net]
>>     
> On
>   
>> Behalf Of Phil Krichbaum
>> Sent: Friday, August 21, 2009 6:48 AM
>> To: ICOM Reflector
>> Subject: Re: [ICOM] 7600 and Dual Watch... "it's a mix"
>>
>> Gordon,
>>     A simpler solution  is to use one of the WX0B StackMatches that 
>> allows one to TX/RX on one, two or three antennas at once. For TX the 
>> SWR on no one antenna can exceed about 1.7:1. These cover from 160 thru 
>> 6m. I live in CO and in a 6m contest it is often possible to have the 
>> band open in  two or three or even more directions at once. If you are 
>> running 1500w, you can CQ with 500w in three directions at once which is 
>> quite effective. It is also handy for HF contesting and even with QRP 
>> I'll split the power between multiple antennas. It is handy for S&P to 
>> listen in multiple directions and quite easy to switch all the juice to 
>> a single antenna to make the QSO. From TI5N I would CQ with 2.5w to 
>> Europe and 2.5 to the US and would run stations in both at the same 
>> time. Jay (WX0B) could not believe I was able to do it at that power
>>     
> level!
>   
>>     Be carefull with the II and III as the front ends are very poorly 
>> protected from nearby RF or ESD sources. Been there done that 5 times 
>> with my III at about $250 per repair!
>>     Phil N0KE
>>
>> J. Gordon Beattie, Jr., W2TTT wrote:
>>   
>>     
>>> Adam et al,
>>> I guess you could use a second receiver with an IC-756PROIII as well
>>>       
> using
>   
>>> the splitter et al?  
>>>
>>> I've been thinking a bit differently about this dual receive situation
>>> because of the performance issues that sometimes come up, but more
>>> importantly because of the operational requirements that I have.  It
>>>       
> might
>   
>>> be cool to set up my PRO3 and PRO2 in a SO2V/SO2R configuration using two
>>> separate 6M antennas and just protect whichever transceiver is idle when
>>>       
> I
>   
>>> transmit with the other one.  The same strategy could be done on 20M,
>>>       
> 40M,
>   
>>> etc.  I am blessed with separately rotatable antennas on different towers
>>> which allows me to look west and south or northeast toward Europe while
>>>     
>>>       
>> also
>>   
>>     
>>> looking west or south as needed.  
>>>
>>> I am thinking about using some small BNC Dow-Key relays and small dummy
>>> loads all triggered by reed relays from the rigs and the PTT lines, as I
>>> only use the exciters here with no amps.
>>> Thoughts?
>>>
>>> Thanks & 73,
>>> Gordon Beattie, W2TTT
>>> 201.314.6964
>>>  
>>> -----Original Message-----
>>> From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net]
>>>     
>>>       
>> On
>>   
>>     
>>> Behalf Of Adam Farson
>>> Sent: Thursday, August 20, 2009 6:25 PM
>>> To: 'ICOM Reflector'
>>> Subject: Re: [ICOM] 7600 and Dual Watch... "it's a mix"
>>>
>>> Hi Dick,
>>>
>>> Dual Watch exacts two penalties in terms of RF performance:
>>>
>>> 1. When DW is activated, the noise-band (idle-channel noise) at the Sub
>>> frequency is added to that at the Main frequency. This raises the system
>>> noise floor by 3 dB.
>>>
>>> 2. There is an RF make-up amplifier ahead of each first mixer, and an IF
>>> make-up amplifier at the IF output of each mixer. These amplifiers make
>>>       
> up
>   
>>> the insertion loss of the splitter and combiner, respectively. The
>>>     
>>>       
>> presence
>>   
>>     
>>> of these amplifiers in the RF and 1st IF signal paths will degrade
>>>     
>>>       
>> IMD-free
>>   
>>     
>>> dynamic range.
>>>
>>> http://www.ab4oj.com/icom/dw.html 
>>>
>>> There are other factors in the superior receiver performance of the 7700
>>>     
>>>       
>> vs.
>>   
>>     
>>> 7600. The 7700 first mixer is a passive DMOS switch vs. a more
>>>     
>>>       
>> conventional
>>   
>>     
>>> quad-JFET mixer in the 7600. The 770 mixer will thus have superior
>>> strong-signal handling. In addition, the 7700 receiver has dedicated,
>>> relay-switched RF bandpass filters and a tracking preselector (Digi-Del),
>>> vs. diode-switched shared filters and no preselector in the 7600. (Relay
>>> switching eliminates another IMD contributor.)
>>>
>>> It is not too difficult to multicouple a second receiver to the 7700.
>>>
>>> http://www.ab4oj.com/icom/ic7700/2rx.html
>>>
>>> Cheers for now, 73,
>>> Adam VA7OJ/AB4OJ
>>>
>>>
>>> -----Original Message-----
>>> From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net]
>>>     
>>>       
>> On
>>   
>>     
>>> Behalf Of Dick Flanagan
>>> Sent: 20-Aug-09 11:05
>>> To: ICOM Reflector
>>> Subject: Re: [ICOM] 7600 and Dual Watch... "it's a mix"
>>>
>>> Having Dual Watch compromises the performance of the receiver.  You can
>>>     
>>>       
>> have
>>   
>>     
>>> good performance with Dual Watch or better performance without it.  The
>>>     
>>>       
>> 7700
>>   
>>     
>>> chose to go the route of maximum performance.
>>>
>>> I would be curious to know if without Dual Watch the 7600 receive
>>> performance could have equaled that of the 7700.  If it could, it might
>>>     
>>>       
>> have
>>   
>>     
>>> impacted sales of the 7700.
>>>
>>> Dick
>>> --
>>> Dick Flanagan K7VC
>>> dick at k7vc.com
>>>
>>> ----
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>> Icom Users Net: Sundays, 1700Z, 14.316 MHz
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>>
>>   
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> ----
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> Icom Users Net: Sundays, 1700Z, 14.316 MHz
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