[1000mp] IP3 on Rob Sherwood's site

[D. J.]

Another question I would ask is if the preamp is used is it in tuned or 
flat (menu 8-4)?

Dale, K9VUJ


On Oct 13, 2004, at 16:12, Chuck Lewis wrote:

> It appears, from the superscript (b), that Rob used the preamp when
> evaluating the Mk-V (and others). Is that everyone else's 
> interpretation? If
> so, it's a curious choice, because the Mk-V preamp adds little; my 
> radio is
> sufficiently sensitive even with the preamp off ("IPO"  illuminated) 
> and
> menu 9-1 reduced to 9 to accommodate the Inrad If mod. I have not 
> found it
> necessary to use the preamp even with 10 meter signals at the noise 
> floor on
> a quiet band. Perceived S/N (the 'practical' criterion, IMO) with the 
> preamp
> off is satisfactory. Surely the preamp affects IP3 adversely, right? 
> The
> question is how much a roofing filter would improve IP3 under the 
> conditions
> of a disabled preamp or additional attenuation. Even more basic is the 
> issue
> of why the test was conducted with the preamp on, if the preamp merely
> provides the factory s-meter settings and a market-competitive 
> sensitivity
> specification. The same question could be asked for other radios whose 
> data
> reflects their preamp enabled.
>
> I'm trying not to criticize here, just asking for some rationale other 
> than
> "That's the way the mfr. intended the device to be used". I'm looking 
> for
> someone to challenge the following premise:
>     "Any overall system gain beyond that which is required to hear and 
> copy
> the desired signal is unnecessary and probably detrimental."
>
> Anyone? Anyone?
>
> Chuck, N4NM
> (who uses his "Field" in the field, and not in the laboratory)
>
>
>
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