[TenTec] Centurion and AM

[Tony Lelieveld]

My first "home brew" 2 meter TX, in 1968, started with an FT-243 crystal in 
the 8 MHz range.  Multiplied x3 x3 x2 put in the 144 MHz band.  The final 
was, I believe a QQE 06-20 can't remember anymore, the North American 
equivalent of a 6360.  The modulator was a dual triode 12AU7 or a 12AT7. 
The first triode was the mike audio amplifier and the second triode was in 
SERIES with the screen grid.  By setting the bias as such that I had a 
carrier of about 8 Watt I could talk it up to max power, I believe around 15 
Watt.  If biased for no carrier, it would play havoc with the fast AGC at 
the receiving station RX, unless, he had an AGC with fast attack and slow 
release time as we use in SSB.  It worked great with a low parts count and 
no big modulator.

Tony VE3DWI.

----- Original Message ----- 
From: "Bob McGraw - K4TAX" <RMcGraw at Blomand.net>
To: "george fritkin" <georgefritkin at yahoo.com>; "Discussion of Ten-Tec 
Equipment" <tentec at contesting.com>
Sent: Sunday, August 03, 2014 3:45 PM
Subject: Re: [TenTec] Centurion and AM


> 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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