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Old May 1st 09, 05:25 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?

Scott wrote:
Joerg wrote:
Harold E. Johnson wrote:
BTW, in the olden days we preferred 3x, 5x per stage. Two 3x stages
would give you 9x. The most brazen ones (not me) did a direct 7x or
even 9x. We just drove transistors in class C real hard.
Or today, many of us just overdrive an untuned MMIC amplifier and
filter out the unwanted harmonics...

Scott
N0EDV

And often have unwanted sometimes unfound parametric oscillations
that have nothing to do with harmonic content.


If a huge drab-green truck stops in front of the house and folks in
fatigues and army boots hop off then the unfound oscillation has been
found ;-)


Listening to all the "crap" on the bands these days, I doubt ANY truck
from the government would ever show up However, that being said, as
hams, we all need to make sure our "house is clean"...now about all that
other "crap"...has anyone else noticed all the interference these days
on 2M from other sources of "spurious junk"??? Examples: I pull up to
gas pumps and the squelch opens on my 2M radio...driving down the
Interstate, I pass semi trucks and get a static burst from the
speaker...Drive through town, listening to 145.19 and get static bursts
(this just happens to be a cable TV frequency...isn't the idea of cable
TV to keep the signals INSIDE the cable?)....


Sure, but when you see how cable "professionals" handle stuff you'd get
the goose bumps. We don't have a cable subscription but a cable box down
the street. Often I see workers in the street and when walking the dogs
next day the lid on the green box is askew. Heck, often they didn't even
slide the lid all the way in, let alone lock it. Being a guy who can't
stand the sight of electronics just rotting and corroding away because
of neglect I always push it back on. Once the lid was completely off, it
rained and water was dripping from all the coaxes. This doesn't exactly
improve shielding effectiveness ;-)

--
Regards, Joerg

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