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Old May 2nd 09, 07:52 PM posted to rec.radio.amateur.homebrew
Joerg Joerg is offline
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First recorded activity by RadioBanter: Nov 2006
Posts: 58
Default Frequency doubling: Is bandpass filtering needed?

Joel Koltner wrote:
"mikea" wrote in message
...
HB content: I'm thinking of building one of the little receivers shown
at http://mikea.ath.cx/1-chip-rx.html/, just for hunting QRM.


I like his sentence, "you can do only so much work on a notebook computer with
no reference material around." Wow -- 1997, before ubiquitous high-speed
Internet access (...reference material on pretty much anything you want in
seconds...) in airports was available! And it doesn't even seem that long ago
now!


I don't agree with Steve there. In the early 90's I regularly carried my
trusty old Compaq Contura 410 on longhaul flights. And I sure was glad
it allowed up to 6 hours on a battery charge. Did a lot of schematics,
module specs and so on. Seen many business execs with their high
faluting IBM laptops fold'em because their batteries were at zilch,
grumpily watching me plugging along until 2nd mealtime.

The trick was to place asterisks in the document whenever I could not
complete something because I didn't have the datasheet right there. At
the destination I'd then go from one asterisk to the next and complete
the module spec. Same for new non-lib CAD parts where I didn't have the
pinout, I just placed an asterisk in the schematic. One can get a whole
lot of work done at an airport or during a flight.

Nowadays you can carry tens of thousands of PDF datasheets on the hard
drive of your laptop. Easily the equivalent of a large book shelf full
of databooks.


I suspect taking a radio like that to an airport these days is also going to
get you a lot of close scrutiny going through security... so I like your idea
of using it for QRM hunting.


I was lazy and just bought a Realistic Jetstream pocket radio. $30 or
$40, looks like a normal pocket radio but has regular AM plus airband,
no FM.

--
Regards, Joerg

http://www.analogconsultants.com/