White noise is definitely worst-case, and with max allowed ALC it makes an ugly
spectral plot. However, I'm not sure what you mean by "white noise with a
peak-to-average ratio typical of voice...". White noise will drive the rig
from the lowest to highest audio freq it will pass, and beyond at an equal
level. Also, max ALC and max *rated* PEP aren't necessarily the same level,
and would likely drastically change the measurement. My rig, for example has
substantial IMD products when driven into max ALC, but when driven with no ALC
at ~90W, they are WAY down even with white noise. I need to do this experiment
again and get pictures of the analyzer -- when I did it last time, I just made
notes. I'll do that this week and post the results...
But I'm glad to hear that you would be willing to tolerate wider occupied BW,
that logic has escaped a lot of folks, as well as the ARRL. Honestly though, I
doubt it would change anything even if the ARRL's proposal was implemented.
Those who operate a nasty station will probably continue to do so, and those
that operate a clean 4k station will continue to do so. I just wonder how many
"BW Cops" will be created running around with their ProIIIs (or whatever)
telling everyone they're "too wide" (hell, it already happens!!)...
Joe, N3JI
----- Original Message ----
From: Michael Tope <W4EF@dellroy.com>
To: Joe Isabella <n3ji@yahoo.com>; g3rzp@g3rzp.wanadoo.co.uk; Tom W8JI
<w8ji@w8ji.com>; zdtech <zdtech@iprimus.com.au>; amps@contesting.com
Sent: Monday, July 3, 2006 12:29:56 PM
Subject: Re: [Amps] Maximum RF output in practical application: 4-250A
----- Original Message -----
From: Joe Isabella
Okay, so how is that tested? White noise? Tones? Voice? Max power? Max
allowed ALC? No ALC?
Come on Michael, there's no way that would be anything but arbitrary, as a lot
of the ARRL's "measurements" already are.
Joe, N3JI
White noise with a peak-to-average ratio typical of voice
transmission, processor on, maximum allowed ALC, and
output power adjusted to maximum rated PEP output of
transceiver. IMO, this would provide a good measure of
whether the rig is capable of reasonably clean operation.
BTW, I am not as concerned about signal bandwidth (3KHz
vs 4 KHz vs 6KHz) as others appear to be. My concern is
with spectral regrowth caused by IMD. In my mind, a guy
running 2.6 KHz signal bandwidth with horibble IMD products
stretching +/- 10 KHz of his center frequency is much more
offensive than a guy running 4 KHz "Hi-Fi" bandwidth into a
class A amplifier that has very low IMD products resembling
a brick-wall spectral mask. IOW, I wouldn't have a problem
stretching or offseting the mask to accommodate variations
in the signal bandwidth.
73, Mike W4EF..................................................
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