----- Original Message -----
From: "Peter Chadwick" <g3rzp@g3rzp.wanadoo.co.uk>
To: <amps@contesting.com>
Sent: Sunday, September 30, 2007 4:32 PM
Subject: [Amps] 4CX250 IMD
> carl said:
>>Two tone PEP has been mentioned several times as the reference used for
>>the
> 4CX250R under discussion.<
> But which RCA were talking about, I don't know. They don't say.
>
How did RCA sneak in here? I dont have any RCA specs on the 250 family to
compare to Eimac.
>>> Nobody has mentioned measurement uncertainty in this discussion,
>> either......
>
> Oh yes it has. I asked how Eimac measured PEP in the 50's. Some of the
> youngsters on here might be surprised to learn that the micropressor
> driven
> peak reading, self correcting and wash your windows sir, wattmeter hadnt
> been invented quite yet (;<
> Plus there's only a few of us old fogies from the pre - digital readout
> era appear to understand the difference between resolution and accuracy.
> And an accredited laboratory is expected to a 95% certainty to measure RF
> power to better than +/-1dB. To a tighter limit, the certainty
> drops.....So if your wattemeter tells me that the output is 275.123 watts,
> I'll give you a Bronx cheer!
But there are plenty who will pay loads of money for a meter that reads to 3
decimals but be absolutely clueless about the rated accuracy over 10 seconds
much less long term. When was the last time any of us had a cal lab check
our wattmeters for that matter?
Carl
KM1H
It's like the clock that strikes thirteen - you don't believe any of it.
(except in that case, at Saltaire in Yorkshire)
> 73
> Peter G3RZP
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