The Keysite picture was showing
the spurs from a Hermes at 28.4 MHz with a 192kHz
sample rate using the V1 firmware. it has nothing to
do with the IC7300.
I have spare time now so I will
repost the image of the IC-7300.
IC-7300 is at 30W output on 28.2
MHz with offsets from 10Hz to 1MHz, Blue trace is
PN, Black trace is AM noise, Green trace is
composite noise. This uses the FSWP which can
measure AM noise and PN simultaneously.
Then I will go away for a while.
Looking at the Keysight picture
you posted it's hard to tell the characteristics of
the peaks that appear beside the (was it?) 28.4 MHz
signal. (The screen notation of 390 kHz is
confusing. That is the marker's offset?)
It appears like the 7300 is using a digital
frequency synthesizer with way too few bits to make
a good signal. If I got a rig that bad I think I'd
have some stern words with ICOM about it. While it
might be marginally legal it is unethical to sell
something that bad. (And at 100W I thought the limit
was -70 dB in the US.
Hi, no it is actually 5
different IC7300s tested by 3 different people,
including Rob Sherwood. if you have time you can
see the plots and some other data that I posted
earlier just do a search. I’m in my lunch break or
I would do it for you.
Yes my TX IS that good but it
is easier for me because I use 0dBm transverter
drives at 28Mhz and transverters with high quality
Xtal local oscillators. The 0dBm from either my
K3S or TS-890S is very good indeed. IMD3 from both
is better than -50dBc.
On 144 MHz, PN noise at 1kHz
separation is -144dBc/Hz and close to 156dBc/Hz at
10kHz. This is with the LO PLL active, free
running it is a little better. Composite noise is
the same as in this case it is PN dominated. IM3
is -38dBc but more importantly the 7th
and 9th orders are better than -80dBc.
This is achieved by using tetrode finals on all
432 and 1296 are of course
worse as the LOs are multiplied from Xtals in the
VHF region. However my TX is some 40dB better than
an IC-9700 at 1.3GHz at 10kHz separation.
Only 50MHz is a little worse
due to my TS-890S PA linearity but with the noise
on 6m being higher it is acceptable. When I am on
FT8 where linearity does not matter it is superb.
But who cares we are all on the same ‘channel’.
I suspect your specification is
still beyond the state of the art. Is your
transmitter that good?
It sounds like the 7300 is cleaner than average
close in but has some issues fairly far out. That
is a little surprising. I wonder if the "IP+"
technology is simply RF feedback to linearize the
transmitter stages such as is seen in the old
Collins kW SSB amplifiers. I can see that having
an issue that depends on the charteristics of the
feedback loop. But those are strange
I take it the noise peaks are broadband, right? Do
they depend on the transmit frequency in any way?
It sounds very much like there is a defect in a
specific radio near you. Is that the case or are
hams measuring this in general? If this affects
all the 7300s then the FPGA code will probably
have to be reworked to fix the bug. I kinda wish I
had one and a nice lab with lots of pertinent test
equipment. I doubt Keysight and ICOM would set me
up to do it. (It'd be better for them to set up a
tiger team of their engineers with the equipment
needed to suppress this possible bug.)
On 20220225 01:55:45, Conrad,
By clean I mean - can I hear
anything of sufficient magnitude to disturb the
noise floor anywhere in band, and hence inhibit
my ability to receive signals close to the noise
floor. The noise floor in a semi-rural location
on 28, 50 and 70MHz is not particularly low so I
do not feel that this is unreasonable. The
biggest problem with the IC7300 is the AM noise
bump at 20kHz and 130kHz which is only 60dB down
on the carrier when running at 30W on 28MHz.
This power level is typical when driving an
amplifier. When modulated with an SSB signal
this occupies a considerable amount of
bandwidth. The close in PN -s only -120dBc/Hz
at 1kHz and -130dBc/Hz at 10kHz. The composite
noise is -115kHz at 10kHz, this is not what I
would consider clean, even close in. The K3S(
and a few others) is far better in this respect
although the PA has quite poor linearity,
especially on 6m.
The Hermes will do a much
better job with any decent PA, even without pure
signal. There are some spurs @ -65dBc which
improve with a higher sample rate. I have not
checked these with the V2 firmware but I will do
immediately I receive my Hermes from Apache.
I do not think that a
transceiver at the IC-7300 price point has fixed
pre-distortion. As you quite correctly say
keeping it under control over temperature and
voltage variation would be difficult. Also Icom
would almost certainly have mentioned it in
their advertising. What the IC7300 does well is
manage audio overshoots by using a ‘look ahead’
algorithm. This is maybe where the impression of
it having a clean TX comes from.
I think that the problem here
is that so many transceivers are quite bad, so I
can just about accept that the IC-7300 is less
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
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
On 20220225 01:13:11,
Conrad, PA5Y wrote:
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
You are spreading
misleading and incorrect information.
On Wed, Feb 23, 2022 at
12:24 PM, Max wrote:
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!