[Amps] SB220 bias thread

[kingwood]

Greetings to all,

        An interesting thread.  If you use a trapezoid display to tune your 
linear amp, you will quickly see all the differences in tuning that are 
being mentioned.  The most obvious conclusion from these observation are:

    1. Every voice require a different loading condition.

    2. It is better, more linear, to err on the over-loaded side, than the.
        under loaded side (if you just have to err).

    3. If you tune with a carrier, loading will not be exact for voice.

          About twenty-five years ago, Richard Measures published a great 
paper on tuning linear amplifiers.  His suggestion was to use a pulser with 
a 3:1 ratio to approximate the "average" male voice.  I found his unit, with 
fixed 3:1 pulses, did not approximate my voice as close as I would like. 
So, I modified his design to allow variable pulse timing, and, by 
experimentation, found the ratio that best approximated my voice.  Now, I 
can use this pulser to tune any linear for my approximate voice, requiring 
no touch-up tuning.  It is inserting to note that Ameritron's tuning pulser 
has variable pulse rate and speed.

           Final conclusion:  All this discussion about tuning is really 
"much ado about nothing".  With the addition of fully adjustable CW keyer in 
nearly all transceivers,  everyone has the ability to pulse tune a linear to 
a very accurate degree (perhaps not perfect, but close enough).  True, CW 
will never match as closely to your voice as a properly adjusted pulser, but 
will be so close that the point is hardly worth discussing.  Unless you are 
tuning with a trapezoid pattern, you will not be able to see the difference.

73 de Lon, K5JV

1110 Golden Bear Ln.
Kingwood, TX 77339

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