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- Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card
Re: Open HPSDR Hermes (14 bit ADC, EP3C25) Transceiver Card
OK, please refresh my mind what you mean by "clean".
It certainly appears to be sending something much closer to pure
signal concentrated within its intended bandwidth than most other
transmitters. I also understand that it is not as good as it can
be with full active predistortion. Both might generate increased
noise at some significant separation from the intended signal
frequency. I am not sure of the mechanism by which this would take
toggle quoted messageShow quoted text
As an ornery critter there is nothing I would sit down and declare
"clean" without a definition of "clean". I guess I am asking for
your definition of the term or even of the term "clean enough".
On 20220225 01:13:11, Conrad, PA5Y
I KNOW for a fact that the IC7300 is not
clean. Please provide me some evidence to the contrary. I have
measurements with a R&S FSWP Signal analyser out to a 1MHz
BW. You guys are looking in an SSB BW which is fine unless you
happen to be 130kHz away, then you will hear plenty of
splatter from the IC7300. I tested the IC-7300 as a result of
hearing this on 50MHz. In other words the lab tests were
driven by on air experience.
You are spreading misleading and incorrect
On Wed, Feb 23, 2022 at 12:24 PM, Max
I just think if we follow good design and
signal chain management that superb, clean signals can also
be generated without the need for PS, that's all.
I disagree. My signal is my signature. Audio clarity is
admittedly important but what matters most to me is a
splatter-free signal, and in that regard nothing comes close
to what PS can produce. As I stated earlier, even the best
Class A amplifiers only have -40dB splatter. PS starts at -60db and often pushes
-70dB. That means that PS reduces splatter to less than 1%
(and at times only 1/10 of 1%) of what even the best
traditional equipment can produce.
I also agree with Simon that the 7300 (and also the 7610 for
that matter) produces an extremely sharp-edged signal with
unarguably less splatter than is achievable with any other
non-ANAN radio. It was explained to me by Ray N5LAX that the
reason those radios are so clean splatter-wise is because ICOM
embedded an algorithm into the firmware that functions very
similarly to PS in the sense that it corrects for
non-linearity in the PA, but it is a fixed-value (i.e.,
static) correction only, not a real-time self-adjusting
correction value such as is employed by PS. NOTE: I have not
been able to verify that info, but that is what was told to me
over-the-air by Ray when I commented that I had no idea how
the 7300 could produce such a clean, sharp-edged signal. So
I'm repeating it here.
IMO it's unwise and short-sighted to summarily dismiss the
game-changing value that PS brings to the hobby. Its benefits
are so unarguable that I (and Rob Sherwood) often wonder why
the big-name radios don't offer it as a standard feature. It's
free, so utilize it for goodness sake!
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