I understand the processes, old and new.
The power bill is of no concern to ham like me who runs AM about 4 hours per
month at 50% Duty cycle.
Best regards - Bry Carling
> On Aug 2, 2014, at 5:28 PM, Wade Staggs <tvman1954@gmail.com> wrote:
>
> Many of the newer Shortwave transmitters produce very little Carrier. They
> have always placed a much smaller LSB signal on the air and really punch the
> USB side hard. Instead of using Modulation Transformers..... They now use
> Digital Pulse Modulation where the VCC (( for clarity )) of the PA Section is
> controlled by (( varied )) by Very Large and High Power Switching Devices at
> Audio Frequencies. By doing this they save Tons of money on their Power
> Bills. Which as you can imagine is quite expensive. I know that I could not
> afford any kind of... 100 Kilowatt at a 24/7 rate ....Power Bill. We are
> trying to explain the process in simple terms. Even though Miss Brenda, Burns
> me up each Winter and Freezes me all Summer.... Why do some women do that?
>
> Wade/KJ4WS
>
>
>> On Sat, Aug 2, 2014 at 3:43 PM, <bcarling@cfl.rr.com> wrote:
>> I have read this through twice and still can't figure out what the point is
>> that you are making
>> - sorry - my bad!
>>
>> I also have the two year AEET degree. Thanks to Georgia Tech. I haven't
>> worked on very
>> many commercial AM broadcast transmitters, but I understand a number of them
>> use
>> modulation methods that the expert hams find anathema, such as screen grid
>> mod or low
>> level mod. with a linear amplifier.
>>
>> The transmitters don't worry about some 3 dB loss or other, they just do
>> their job, and are not
>> smart enough to go around looking worried! Hence my 422 is still not
>> complaining to me.
>>
>> On 2 Aug 2014 at 11:55, Wade Staggs wrote:
>>
>> > *I will try to explain AM Transmitting while using an Amplifier designed
>> > for SSB, as taught to me by my old Elmer((( SK. )))*
>> > * Since SSB only outputs power when you
>> > speak into the microphone. The SSB mode of operation averages out to be
>> > about 30% Duty Cycle where the Tubes and Power Supply are concerned. This
>> > allows an Amplifier built for SSB Service to employ a much lighter duty
>> > power supply. And also the Power Rating for the Tubes and The Cooling
>> > System, can be much higher. BUT, AM operation with Full Carrier is 100%
>> > duty Cycle. Running an Amplifier in AM at Full Carrier Output will soon
>> > kill the tubes and power supply. When I run my SB-220 Amplifier on AM. All
>> > I want is about a 200 to 250 Watt Carrier at most. This is done by reducing
>> > the drive on the radio. With a 200-250 Watt Carrier from an Amp rated for
>> > an easy 1000 Watts you will now say..... what's the use? Well, when you
>> > modulate an AM signal, the sidebands go up to 4 times the carrier output.
>> > You are effectively going from 200 Watts to about 800 Watts PEP ((( Peak
>> > Envelope Power ))) ...... The reason I chose 200 Watts carrier from a 1000
>> > Watt amplifier is that this works out to about 20% duty cycle. Then the
>> > 100% Modulated AM Signal does the real work. We can't speak as to Alpha
>> > and Ten Tec Amps but would bet that this rule still applies. An RMS type
>> > Meter will not show this power increase but a Peak Reading Watt Meter will.
>> > *
>> > * My Friend, there are people here with more
>> > Degrees than a Thermometer. While I only have the 2 years of College to
>> > fall back on. But, I have worked on some of the Biggest and Smallest
>> > Transmitters in the World. So, if I am wrong about this in my tried and
>> > true simple explanation. There will be others onboard soon to correct me.
>> > This is however the way we run our equipment. *
>> > * 73 for now from Wade/KJ4WS*
>> >
>> >
>> >
>> > On Sat, Aug 2, 2014 at 11:03 AM, Brian Carling <bcarling@cfl.rr.com> wrote:
>> >
>> > > Yes they can. At least they did this morning in a FB QSO on 7293 KHz from
>> > > FL to KY.
>> > > Omni VII and a mighty 422 Centurion.
>> > >
>> > > Best regards - Bry Carling, AF4K
>> > >
>> > >
>> > >
>> > > > On Aug 1, 2014, at 8:46 PM, Barry N1EU <barry.n1eu@gmail.com> wrote:
>> > > >
>> > > > On Sat, Aug 2, 2014 at 12:28 AM, george fritkin via TenTec <
>> > > > tentec@contesting.com> wrote:
>> > > >
>> > > >> 200 to 250 watts AM results in 800 to 1000 watts PEP at 100%
>> > > >> modulation.
>> > > >> Three 811 tubes can not handle that power.
>> > > >
>> > > > How about two 3-500Z's?
>> > > >
>> > > > 73, Barry N1EU
>> > > > _______________________________________________
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>> > >
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>>
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