[AMRadio] AM Amps

Geoff w5omr at w5omr.shacknet.nu
Tue Jan 11 21:41:03 EST 2005

Gary Schafer wrote:

> I know full well that there is no such thing as a 375 watt carrier limit 
> to AM power in the FCC rules. I never said there was.

Ok, good.  I was just making sure ;)  Too many people believe 
that there's some 'magical mystification' about 375w of carrier 
output being the 'legal limit'.

> I was trying to "clarify" Ronnie's statement about how much power he 
> runs his 813's at when he says he runs them at legal power out.
> And since we don't know if Ronnie has a symmetrical voice pattern or 
> otherwise, we can only assume it is symmetrical when discussing general 
> power principles.
> Maybe he has the peaks phased so maximum peaks are in the negative 
> direction? I don't know. Either way it appears as though he only has 
> enough headroom for less than 50% modulation in the positive direction.

Agreed, there.  And, I've been to Ronnie's shack.  I'm pretty 
sure he doesnt' do any audio shaping, or phasing, or any other 
audio tricks on either the Ranger or the Globe King 500 he's 
running there.

> On top of that the plate dissipation is around 380 watts per tube if the 
> amp is tuned properly, which it can't be if it is not burning up tubes.
> That is the whole point, if you are paying attention. :>)

I was... it was just the 'legal limit' that caught my attention 
(yet again ;->)

> Maybe you could tell us how much peak envelope power would be available 
> from a pair of GG 813's at 375 watts carrier out with 100% modulation?

I'm not sure you can get more than around 1kW PEP output of a 
pair of 813's... and probably more like 800w.  (3) in parallel 
would be a different story, though.

73 = Best Regards,

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