Re: RE: FC-20 power limits

Hi
There's a big difference between running 100% power output ICAS e.g a 10min per over rag-chew and full on 100% for hour after hour. Ham equip't is designed and sold as ICAS - Intermittent Commercial and Amateur Service (Commercial being PMR).
100% power will be achieved as Jeff states just before any ALC voltage is achieved. Power control is usually implemented by applying a false negative equivalent ALC voltage.
Put me right but I was under the impression that an attraction of digital comm's (not digital voice of course) is what can be achieved with low powers..
Not forgetting that if 100w gets you a 5 and 9 then 25W will get you a 5 and 8 !!
Cheers Bob G4KSG
----Original message----
From : [email protected]
Date : 09/07/2018 - 18:50 (BST)
To : [email protected]
Subject : Re: RE: [FT100] FC-20 power limits
 
 
  
    
      
      
      
The best way to eliminate distortion is NOT to reduce power when running digital modes.  All of the questions here are moot IF the digital mode is set correctly.  To properly run digital, set the radio for your standard output power for HF, VHF, whatever band you're going to run your digital mode, lets say PSK31 for now.  Once you do that, and lets assume you're going to use a Tigertronics Signalink.  Lets also assume we're going to use FLDIGI as the software.  Once you have your Signalink all connected, there is a "tune" button in the upper right of the Fldigi software.  If you press that while watching the FT-100 ALC scale on the display, adjust the transmit level on the signalink just until you see NO ALC.  If you do that, you should see approximately 30-35 watts out of the radio.  Press the "tune" button on the software again to unkey the radio.  
By setting the audio drive such that NO ALC action takes place, you are operating the radio in it's most linear portion, and therefore, producing minimum distortion of your transmit signal, which is what you want.  The side benefit is, it properly sets the output power so the radio isn't putting out a constant 100w on digital transmit, which might damage the finals of the radio, and those poor MRF-255's are impossible to find, and it won't damage any tuner either.
The duty cycle of the finals should never be run 100% at full power.  Digital modes are 100% duty cycle, but at a reduced power of 30w or so, and you can lower that even more by lowering the audio drive to the radio even further such that you're down to 25w, 20w, etc, nice for FT-8, that you don't have to worry about any menu adjustment of the FT-100.  
Happy digital contacting!!
Best 73 
Jeff - W5JGW 
 
 
 
 On Monday, July 9, 2018 8:58 AM, "BOB RALPH [email protected] [FT100]" <[email protected]> wrote:
  
 
 
  
    
      
      
      
Hi
That's limited in a positive sense not negative.  100W out is 100W out FM or digital - the FC20 or the 30 (mine) will handle matching between 16 ohms or 150 ohms 'impedance' with the aim of achieving 100W as close as possible but with reduction in efficiency (loss) within the matcher ('tuner' to most).
Bob G4KSG
----Original message----
From : [email protected]
Date : 09/07/2018 - 05:51 (BST)
To : [email protected]
Subject : RE: [FT100] FC-20 power limits
 
 
  
    
      
      
      
The FC-20 has a rather limited impedance range. Thus, it might be able to handle full 100 W. The installation instructions I found don’t mention any restrictions. 
That said, some digital modes are sensitive to distortion and the typical way of reducing distortion is to reduce output power. 
73, 
Wilko
Sent from my Windows 10 phone
From: John Geiger [email protected] [FT100]
Sent: Monday, July 9, 2018 4:19
To: [email protected]
Subject: [FT100] FC-20 power limits
  
Has anyone seen any mention from Yaesu about if the FC-20 autotuner has a lower power rating for the digital modes?  I know both the LDG and MFJ tuners have much lower power ratings for digital modes (like 25 to 33% of max for other modes) but I have never seen any mention of this in the FC-20 literature.  Have people been running 100 watts on digital modes using the FC-20 tuner with ok results?
73 John AF5CC
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