On Wednesday 16 February 2005 23:15, David Kirkby wrote:
> Steve Thompson wrote:
> >On Tuesday 15 February 2005 09:11, David Kirkby wrote:
> >>Steve Thompson wrote:
> >>>Bill L. Fuqua wrote:
> >>>>While you are at it.
> >>>>20 meters is not 14 mhz. that should be MHz
> >>>
> >>>or even 20 metres :-)
> >>>
> >>>As for commas and suffix letters in part numbers, I have other things to
> >>>worry about. To me it's only a problem if there's ambiguity
> >>
> >>Well it does as far as search engines are concerned. Google interprets
> >>them differently with or without the commas. Trying to find data on the
> >>Eimac 3CX15,000B7 has problems, as Eimac's web page will not be found
> >>by Google unless you put the comma in. Yet it will return more hits
> >>without the comma, as most people do it wrong.
> >
> >Putting it very simplistically, if someone hasn't the wits to find their
> > way round such issues, they shouldn't be messing with things so
> > dangerous. If you want academic precision in all things, this is not the
> > place to be.
> >
> >Steve
>
> Steve,
> you failed to address the other (more important) issue I raised. You said.
Its importance is in the eye of the beholder.
>
> > I could be very pedantic in specifying that I'd made linearity
> > measurements on a 4CX350A, and someone might gain the impression that the
> > figures only applied to that variant, when they will apply just the same
> > to 4CX350F.
>
> Whilst the 4CX350A and 4CX350F differ only by heater voltage (and so one
> would assume have the same linearity), the 4CX350FJ is different, in
> that it is designed for low intermodulation distorsion - i.e. high
> linearity.
Eimac only say 'improved IMD..' without quantifying it. The data I have
doesn't quote any figures for the '350A to give a starting point, so the
'350FJ could have any linearity Eimac wants to give it and meet the
description, especially as the 'typical' figures are given at different
powers for the two types.
>
> So specifying the exact tube would not be being 'very pedantic' but
> *absoluttely essential* for the numbers to have any sensible meaning.
> Without the suffix, there would be no point in reporting the results.
>
> Would you agree or not?
Would I agree if... what?
Do I agree? No, in the context of a discussion on this reflector about amateur
equipment I believe that the differences in linearity between the versions
are immaterial.
>
> Likewise would you agree you would need to state the manufacturer of the
> tube too? It's highly likely the linearity might be different from one
> make to the next?
Is it? If devices are sufficiently similar to warrant the same part number
then it's likely they will have similar characteristics. Slight linearity
differences might matter in meeting type approval specs. for broadcast
equipment, but won't matter a jot in normal amateur operation.
I'll forward a copy of the '350FJ data for your website when I receive it.
Steve
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