On 2021-02-04 3:12 PM, Grant Youngman wrote:
Actually, that assumes that peak to avg is exactly 4. Which it
rarely (never?) is with a real human voice.
It also assumes the modulation is symmetrical and that the mic is
wired with the correct polarity.
> A monitor scope on the output is essential …
... and that the deflection on the scope is accurately calibrated
to PEP level (peak voltage across 50 Ohms).
73,
... Joe, W4TV
On 2021-02-04 3:12 PM, Grant Youngman wrote:
Actually, that assumes that peak to avg is exactly 4. Which it rarely (never?)
is with a real human voice.
Aside from the legal (and oft disputed) aspects of AM power limits, you’re
better off being conservative and setting drive levels for something under 375W
carrier from the amp. Maybe 250-300W. That will ensure you have some headroom
for voice peaks (especially if you have a good bit of positive voice
asymmetry), keep the amp cooler, etc. And no one on the receiving end will
know the difference, anyway. The referenced article is a good place to start.
A monitor scope on the output is essential …
Grant NQ5T
On Feb 4, 2021, at 2:22 PM, Morgan Bailey <[email protected]> wrote:
The max that you can legally run is 375 watts carrier. That on AM will get
you 1500 watts PEP. YMMV. I do not know the spex on the 1500 but that may
put you in the ballpark. Understanding linearity, for AM is covered here:
https://www.w8ji.com/am_linear_amplifiers.htm
If you want to run AM, this is where I would start reading.
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