[AMRadio] AM Broadcast Quality


Bry Carling bcarling at cfl.rr.com
Tue Dec 17 16:06:13 EST 2013


Thank you for the specs. If it won't offend anyone, I would just like to add that some of this will depend on the characteristics of the microphone too. You could actually get lower bandwidths but no higher.

Bry Carling
http://af4k.com
Sent with my iPhone 6


> On Dec 17, 2013, at 2:09 PM, "W. Harris" <nbcblue at hotmail.com> wrote:
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> The specs on my Ranger audio chain and other Johnson transmitters is flat response from 250-3000 cycles. For the Collins 32V-3 it is 200-3000 cycles, which is all very adaquite  for good AM good voice  communications. I get very good audio reports on the Ranger. Any more response just ads to the bandwidth. For AM broadcast stations, 40-7,500 cycles is typical. We are not broadcast stations.
> 
> 97.307 Emission standards
> (a) No amateur station transmission shall occupy more bandwidth than necessary for the information rate and emission type being transmitted, in accordance with good amateur practice.
> 
> 10 or 20 kHz bandwidth is not necessary for good AM communications on the ham bands. We are communicating, not broadcasting. 
> 
> Bill - K5MIL
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>> Message: 2
>> Date: Tue, 17 Dec 2013 05:16:20 -0600
>> From: Rob Atkinson <ranchorobbo at gmail.com>
>> To: "W. Harris" <nbcblue at hotmail.com>
>> Cc: "amradio at mailman.qth.net" <amradio at mailman.qth.net>
>> Subject: Re: [AMRadio] AM Broadcast Quality
>> Message-ID:
>>    <CALWD7Z5ODW0AFUed0fheyKQ0-6+TbWmMYqz5N+AmoqZJYzrT+Q at mail.gmail.com>
>> Content-Type: text/plain; charset=ISO-8859-1
>> 
>> Let's rewind this whole thing had have a rational discussion with some
>> meaningful technical content instead of all this subjective stuff
>> about "broadcast quality" whatever that means.
>> 
>> Bill, since you started it, why don't you start over again and begin
>> with a statement about what you think, i.e. your technical definition
>> of broadcast quality (in other words, audio frequency response by
>> frequency and no. of dB down from the peak level) and what you think
>> it should be, again giving us some numbers.  Maybe you think ham AM
>> audio should be 20 dB down at 100 cyles, nothing lower, with a gradual
>> rise of 15 dB to 3 kc and a gradual attenuation to nothing above 4.5
>> kc.  That's an example.  You may have a different technical
>> specification, but such a description would actually give us something
>> to discuss in a rational way.
>> 
>> The other vague and subjective statement is the "communicate using no
>> more bandwidth than necessary" thing.   Why don't you tell us what
>> that means to you in specific terms once again?  Otherwise such a
>> comment is needlessly provocative and contentious.
>> 
>> 73
>> 
>> Rob
>> K5UJ
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> 
> 
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