[AMRadio] power ratings

Geoff w5omr at satx.rr.com
Tue Jul 12 14:36:45 EDT 2005

Donald Chester wrote:

>> The plate dissipation of the 6146's is the key. Your carrier steady on
>> should not exceed the dissipation rating. This is about 50 watts if I
>> remember right which would give you 200 watts PEP. So your power suppl;y
>> should be capable of about 150 watts continuous and it will handle 
>> the 200
>> watts on peaks. I would beef up the fan so that I had a good amount 
>> of air
>> passing the glass of the 6146's to keep the seals cool.
> In AM linear service, the carrier output should not exceed HALF the 
> total plate dissipation.  A 6146 runs about 25 watts plate 
> dissipation, so with a pair of them, you should be able to  run 25 
> watts out.  With 100% modulation in the positive direction, that would 
> be 100 watts pep.
> A properly functioning AM final capable of 100% modulation should run 
> about 33% carrier efficiency.  That means that two-thirds of the input 
> power is dissipated in the plates of the final, and one third is 
> delivered as rf output.
> When the carrier is modulated, the final actually  becomes more 
> efficient, so the plate dissipation is reduced under modulated 
> conditions.  The DC input should not vary, so that simply means that 
> some of the DC input that was being dissipated as heat is now being 
> converted to rf output in the form of sideband power.

Is that where sideband energy then is created and therefore exists as 
long as there's a modulate AM carrier?

I wasn't in on the big discussion about this, a few months ago.

73 = Best Regards,

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