[TenTec] Centurion and AM

[Bob McGraw - K4TAX]

The original DX-60 and versions there after are controlled carrier 
modulation.  Thus they changed the voltage on the screen grid from some 
resting value, representing carrier with no modulation, to increasing the 
screen voltage to represent voice peaks.  There were various timing 
constants involved that determined just how fast the screen voltage could 
rise and how slow it decayed. In effect there was no portion of the envelop 
that was negative modulation.  If one observed the signal on a meter, 
average power detection, they would see the power increase with modulation 
and the station on the other end would see the S meter deflect upward.

True screen modulation is similar in some ways,  however the method has the 
ability to control the screen voltage value from near zero volts 
representing 100% negative modulation to a positive value representing 100% 
positive modulation.  In this case the actual carrier value does not change. 
Thus one observing the output on a average detection power meter would not 
see the power increase with modulation.

73
Bob, K4TAX


----- Original Message ----- 
From: "george fritkin via TenTec" <tentec at contesting.com>
To: <tentec at contesting.com>
Sent: Sunday, August 03, 2014 2:27 PM
Subject: Re: [TenTec] Centurion and AM


> Isn't the original DX60 scheme really screen modulation.....some 
> people call it controlled carrier
>
> George, W6GF
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