[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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