Modulation impact when amplifying a DSB signal?

Fuqua, Bill L wlfuqu00 at UKY.EDU
Sun Feb 15 20:40:33 EST 2009


Linear DSB suppressed carrier generation is easy. Two amplitude modulated amplifiers fed out phase by RF and AF with summed outputs.
This put the carriers out of phase on the output but sidebands would be in phase and sum together. 
  Lets say you want the same Sideband levels as produced by an old 1000 Watt plate input power, plate modulated transmitter.
The carrier output would be about 750 watts and the PEP output would be 3000Watts at 100 percent modulation. Now if you 
eliminated carrier you would have average sideband (DSB) power of 375 watts.The PEP level of that would be 4 times since the average
power or 1500 watts PEP.
  
73
Bill wa4lav

________________________________________
From: Boat Anchor Owners and Collectors List [BOATANCHORS at LISTS.TEMPE.GOV] On Behalf Of kd4e [doc at kd4e.com]
Sent: Sunday, February 15, 2009 6:13 PM
To: BOATANCHORS at LISTS.TEMPE.GOV
Subject: Re: [BOATANCHORS-TEMPE] Modulation impact when amplifying a DSB signal?

Simple = grids & screens push-pull, plates parallel.

Perhaps using a single dual pentode tube, 6AR11.


>> I am thinking of this in terms of a QRP DSB exciter using low plate
>> voltage (125v) versus having to manage modulation at a higher power stage.
>>
>
> I'm a bit confused here.  Generating clean DSB with suppressed
> carrier requires a fair amount of circuitry.  If you really want
> AM (DSB plus carrier), why not modulate at the milliwatt level
> with something like a cathode modulator or the output-transformer
> scheme used in Clegg 22ers and follow it with class-A linear
> stages up to the 5-watt level.
>
> Jim Bromley, K7JEB
>

--

Thanks! & 73, doc, KD4E
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