[Amps] SPE 2K RTTY Duty Cycle

[Dave Hachadorian]

ARRL product review of the Yaesu FT-990 in November, 1991 QST 
showed IM3 at -38 dB.  I always remember that number, and wonder 
why modern 12 volt rigs can't equal it.


Dave Hachadorian, K6LL
Yuma, AZ


-----Original Message----- 
From: Kevin Stover
Sent: Friday, May 22, 2015 5:58 AM
To: amps at contesting.com
Subject: Re: [Amps] SPE 2K RTTY Duty Cycle

There are NO 12V final amateur transceivers that make -40dB IM3, 
none. Never have been, never will be. The best are at -33 to -35.

Those transceivers capable of 200 Watts are all usinng 28 or 50V 
finals and can reach -40 depending on the low pass filter used 
behind the PA.It's time for the manu's to get rid of this 
fascination with running evberything off a battery.

The most expensive part of any SS amp is NOT the finals 
themselves it's the LPF that will take 1500 watts and keep 
harmonics leagl (-43db HF, -60dB 6m). That's not IM3. Name the 
amp that hits an IM3 of -40. The 8877 will come close, the 
Russian triodes won't, none of the tetrodes will do it.


-- 
R. Kevin Stover
AC0H
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