[600MRG] FT8 Revisited

[Frank Lotito]

A few days ago I posted a question on 2 similar interest message boards asking if linear drivers and PAs are required for FT8 modulation.  I received 4 replies, 3 of which were e-mails only directed to me.  I am still confused.  One of the 4 replies said “yes”, the 3 others said “no.” Maybe in a more public forum, such as this message board, the topic can be discussed and my confusion resolved. 

Let me reference again the January 2018 QST article on FT8.  This time specifically page 44, center column, the second and third paragraphs.  This is the section of the QST article that is confusing me.  My reading is the author tells the readers that FT8 requires a linear RF driver and PA.  However, if FT8 is a FSK (frequency shift keyed) modulation method, why linear?

My radio acquaintances who have tried FT8 use modern HF transceivers.  As we know, for the last umpteen decades HF transceivers have been quite linear in design.  These acquaintances do not have LF or MF below the broadcast band equipment.  

Can one or more of the readership of this column post a reply on this message board clearing the  confusion w.r.t. what the QST author is saying?  Thank you, 73 Frank Lotito  K3DZ / WH2XHA