[AMRadio] power ratings
Gary Schafer
garyschafer at comcast.net
Tue Jul 12 21:05:20 EDT 2005
The best quality audio of all can be gotten from low level modulation
and a linear amplifier.
73
Gary K4FMX
Bob Macklin wrote:
> A comment about AM transmitters. A plate modulated AM transmitter requires a
> modulator of 50% of the power of the final to produce 100% modulation. These
> transmitters like the Johnson Ranger produce better audo than the screen
> modulation units like the small Heaths. Only the Heath DX-100 and TX-1
> (Apachee) used plate modulation.
>
> But most of the airborne military transmitters used screen modulation to
> reduce the weight and power requirment. These all produce very good
> comunication audio.
>
> But if you want broadcast quality audio you need a real plate modulated rig.
>
> Bob Macklin
> K5MYJ/7
> Seattle, Wa.
>
> "REAL RADIOS GLOW IN THE DARK"
>
> ----- Original Message -----
> From: "kenw2dtc" <kenw2dtc at comcast.net>
> To: "Discussion of AM Radio" <amradio at mailman.qth.net>
> Sent: Tuesday, July 12, 2005 5:30 PM
> Subject: Re: [AMRadio] power ratings
>
>
>
>>"Ken, as I read the rules, we are only allowed to run 375 watts carrier.
>>With 100% modulation this will give us 1500 watts pep which is the max
>>output allowed."
>>
>>*******Don, You are correct about the 1500 watts PEP. It could also be
>>derived by 600 watts of carrier with much less than 100% modulation.
>
> There
>
>>are also schemes where the carrier is almost 1000 watts and it is
>
> modulated
>
>>downward at nearly 100% and still get the 1500 watts PEP. Another comment
>>about linears in AM service. Those who do the math and run an SSB linear
>>with the PEP equal to 4 times the carrier sometimes miss the calculation
>
> of
>
>>the male voice which will usually modulate higher than 100% unless limited
>>in the audio section. Thus many SSB amps do not have the headroom for
>
> good
>
>>AM.
>>
>>
>>
>>
>>
>>
>>
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>
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