[R-390] Distribution Amplifier

[Dennis L. Wade]

Bob brings up a good point that I think is easily overlooked.  

The project has two area in which gain is applied, the distribution 
section, and an optional rf amp ahead of that.  In correspondence 
with the author, I expressed my concern that unknowing builders would 
carelessly include as much gain as they could before the front end of 
their receivers and I suggested some article language cautioning its 
use.

As I'm sure all of us know, most HF receivers seldom need another rf 
stage, not to mention the '390 series.  As Bob points out, IMD and 
other bad things are more likely to happen even without the added 
gain block.  I hope potential builders of the distribution device 
keep that in mind.

               Dennis

> Hi
> 
> Well don't throw out all the glow in the dark stuff quite yet .....
> 
> The video amplifiers that form the heart of the ARRL project are
> pretty darn nice little chips. However they are not rated for IMD and
> their harmonic distortion numbers begin to climb as you go past about
> 10 or 12 MHz. That isn't to say they fall apart. Far from it they
> probably work pretty darn well considering what they are.
> 
> What they are not is the tuned RF front end on an R-390. I would be
> very interested to see how they do when attached to a couple hundred
> feet of wire with the bands open ...
> 
>  Take Care!
> 
>   Bob Camp
>   KB8TQ
> 
> 
> 
> On Apr 20, 2004, at 1:04 PM, Scott, Barry (Clyde B) wrote:
> 
> > Looks like a really well-designed project; however, I'm afraid if I
> > built it, I'd start looking for 6 more receivers...
> >
> > Barry(III) - N4BUQ
> >
> >
> >> Hi, Pete, and ALL,
> >>
> >> The author and designer of the multicontroller has a neat web
> >> site that
> >> describes the project pretty well.  Go to:
> >>
> >> 	www.w8zr.net/multicontroller/
> >>
> >> In speed reading the QST article just now, I did not see a
> >> noise floor
> >> specification mentioned, but he is using new Maxim MAX497CPE
> >> video amplifier ICs
> >> each containing four 275 Mhz low-noise amplifier/buffers.
> >>
> >> I, too, am very interested in getting his kit and building it
> >> for all my receivers.
> >>
> >> Marshall Dues  WB5MYO
> >> Katy, TX
> > _______________________________________________
> > R-390 mailing list
> > R-390@mailman.qth.net
> > http://mailman.qth.net/mailman/listinfo/r-390
> >
> 
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-----------------
"If you can remain calm, you just don't have all the facts"

Dennis Wade
KG6ZI
Carmichael, CA