[Elecraft] OT: Inverter type generators used for FD?
Jim Brown
jim at audiosystemsgroup.com
Fri Jun 30 18:18:54 EDT 2017
On 6/30/2017 12:55 PM, Fred Moore wrote:
> All of my testing was done with places far removed from the mains, that
> is why I need a generator to start with.
Mains power is NOT the only source of noise. Noise from electronic
sources is FAR more common, and we often bring a lot of electronic noise
with us with accessories for our radio gear. That's an important part of
the message in the nccc.cc link.
> The generator I alluded to that was generating extremely high hash, was
> generating it without anything plugged in, not even an extension cord,
> the hash did not diminish when you placed it on a load either, so it was
> NOT common mode. That generator was the Generac Inverter (3 different
> ones) that is competing with the Honda.
Good information, Fred. That tells me that it's terrible layout of
internal wiring and/or circuit board layout. Combined with bad shielding.
> BTW I consulted your web site, and didn't see any references to the how
> far a generator must be kept from the antenna's, Please add a reference
> for all of us so we know when we will have a problem, we may not be able
> to move it without advanced warning of the problems it might cause.
As I've tried to make clear, that depends on the generator, the
antennas, the other noise at the site.
> And I still don't need a common noise choke you designed, so don't think
> I will build one, no matter what the mechanism is.
I'm a firm believer in "if it ain't broke, don't fix it." I try to help
folks understand how things work, how to make them work better, and how
to solve problems when they happen. A choke won't fix the noise from
that Generac, but it can help a LOT with a better designed unit.
Likewise, the original post asked about how others successfully do
multiple radios on the same band, and I outlined the rules/guidelines
that the fundamentals give us, and what's worked for me. I'm pleased to
hear that others have short-cutted one or more of these guidelines and
gotten away with it. But I've heard dozens of horror stories over the
years about the RF mess generated by el-cheapo rigs, especially the 706
and the Y-brand equivalents.
My goals are to be able to work QRP stations and home stations with
lousy antennas. To do that, you've gotta be nutso about killing RX
noise. Do the math -- the difference between S3 and S6 is 15-18 dB,
depending on whose definition of an S-unit you accept. 15 dB is a 32x
power difference, 18 dB is 64x. 15 dB more noise makes a 100W signal
sound like a 3W signal.
Most of us own Elecraft rigs because we want the best. My
recommendations are aimed at making the rest of our stations the best,
and to do so without throwing un-necessary bucks at it.
73, Jim K9YC
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