[AMPS] Peak reading watt meter

[Tom Rauch]

> [snip]
> :Well that's not actually true... any wattmeter that is not op amp driven
> :is not a true peak reading meter. The Yaesu YS-60 is op amp driven and a
> :true peak reading meter and it sells for about 130.00. Its not a Bird,
> but :if you understand its limitations its a pretty good meter...

There is no requirement the meter have an "op-amp". The 
requirement is the load across the storage capacitor be many 
times the reactance of the capacitor at the lowest modulation 
frequency, and the supply source charging the capacitor have 
many times less impedance than the storage capacitor.

There many ways to do that, and an op-amp is just one way of 
many. 

The problem is an impedance ratio problem. The source needs to 
be very low impedance and the load very high compared to the 
capacitor impedance. That normally requires some active 
components, or a very sensitive meter movement (with a 50 uA 
meter you can come within a few percent of a Bird 43P on speech 
with no active components).


73, Tom W8JI
w8ji@contesting.com

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