On Sun,4/9/2017 8:24 PM, Steve Wright wrote:
Surely most multi-band yagi's, 1/4y verticals, plain ol' dipoles, and
any other competitive HF antenna that you would WANT to poke some
horsepower into is gonna have <1.5:1 SWR?
At one frequency, perhaps. But it takes some real tricks (good ones) to
get a dipole apparent SWR (as read at the transmitter) under 2:1 for 400
kHz of 80/75. Ditto for 160M.
Maybe you alligators want to
tune up your half size g5rv on 160M or similar?
It's almost as baffling as the fixation with IMD..
IMD is a VERY big deal if you care about not making a mess on the band
when you transmit. IMD ==> wide clicks on CW and splatter on SSB. If you
read FCC Rules, it says that we must use the minimum bandwidth required
for the mode of transmission. Since Elecraft introduced their P3
spectrum display (almost a lab quality instrument, by the way), I'm
repeatedly disgusted (and QRMed) by many of the dirty signals I hear/see.
A disgustingly large number of SSB signals have almost as much splatter
in the bandwidth of their suppressed sideband, and an equal amount above
where the sideband filter in the rig cuts off. That's ALL IMD, much of
it in the amps, but some in the rigs themselves. Causes include the
output device driving a mismatch, overdriving the amp, driving the amp
at full output of the rig and letting ALC throttle it back, and even IMD
produced in the rig itself through bad design of "processing" that
includes the RF chain. W4TV has written about this.
K6XX taught me that a mis-tuned amp (or a solid state amp working into a
mismatch load) produces a lot more clicks and splatter than one that is
properly tuned. We're both serious contesters, and when I moved in 3
miles S of him, he made damn sure that I knew how to tune my Titan amps.
Bob is an engineer working at Elecraft, where he works as a production
engineer. As a result, we can work with 500 Hz of each other on CW at
legal limit and hear the other as simply another strong signal, and
easily work fairly weak signals. We're both running tube amps.
Isn't the goal to get on the air, work some DX and bend some jealous locals'
S-meters?
I'm and old fart, and when I was young, I was taught that with rights,
we have responsibilities. We have the right under FCC Rules and our
license to run big power to big antennas, but we also have the
responsibility to keep our signal CLEAN.
Cmon people.. Make a resonant antenna already!
I'm a VERY strong believer on that score. All of my TX antennas (about a
dozen) are resonant.
On a separate topic, sort of -- the amp sold for use with the 6700 Flex
can run SO2R. For those who don't contest, that means there are two
radios on different bands, and one radio is always calling CQ while the
other is listening. Or, when things get slow, dueling CQs. Think about
this with RTTY -- it could be damn near solid keydown at the end of a
contest when you've worked almost everyone. The Flex 6700 is set up so
that that single radio can function as two complete receivers, and
transmitters than can be switched between two outputs. If a single amp
like the one announced does SO2R, it's going to see a duty cycle that
approaches twice that of an amp connected to only one of those outputs.
As to CCS and ICAS -- it's been a long time since I've looked at the
definition, but CCS clearly means that you turn the transmitter on and
it stays on 24/7. Think broadcast, or a repeater that stays up for very
long periods. As I recall, ICAS means intermittent commercial and
amateur service. But I could be wrong. And these ratings are for the
output devices, which when I was knowing about it, were hollow state.
73, Jim K9YC
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