In light of the Sherwood presentation referenced in the thread about K3
audio, I haven't seen much comment on the spectrum analyzer plot of the K3
transmit IMD. Is this still an artifact of the (now fixed) firmware error
mentioned by Eric earlier in this thread?
The K3 firmware used for the
Yes - That firmware fix improved 3rd order TX IMD by 3-5 dB on the worst
case band (12M) and it is better than that on all other bands. We also
made other firmware changes in the gain of various stages to improve TX
IMD. Those changes have been in every firmware release for many months.
One
Hello Lyle,
You said:
There is apparently some confusion about how the K3 ALC works. Just
to help muddy the waters a bit, I'll toss in what little I know about it.
snip
Thanks for doing so. Excellent explanation!
73,
Joe - W1AIU
___
Wes Stewart wrote:
--- Eric Swartz - WA6HHQ, Elecraft
[EMAIL PROTECTED] wrote:
The K3 firmware used for the original QST review did
not turn off the
K3's RF speech compressor clipper even when the
compressor was set to
zero for their TX IMD two tone test. This resulted
in a
If we distort our SSB audio by compression etc, then let's hope that the
sideband filter will limit the bandwidth. (I don't know where the
compression or whatever is done in a K3).
But if the PA distorts the signal even more, there is no filter to limit
this within a few kHz.
So I think the IMD
Arie Kleingeld PA3A wrote:
If we distort our SSB audio by compression etc, then let's hope that the
sideband filter will limit the bandwidth. (I don't know where the
compression or whatever is done in a K3).
But if the PA distorts the signal even more, there is no filter to limit
this
Julian G4ILO wrote:
In any event, ALC
should not have an effect on a laboratory IMD test since the two tones are
not varying in amplitude, unlike a real SSB or PSK signal. So the
laboratory
IMD test bears little relationship to the real world.
Perhaps. In the case of two constant level test
Geoffrey Mackenzie-Kennedy wrote:
Julian G4ILO wrote:
The design of ALC systems is not a casual matter especially when dealing
with human speech, and the points which you raise have to be addressed by
the designer if the ALC might be used improperly. It would appear that ALC
systems
There is apparently some confusion about how the K3 ALC works. Just to
help muddy the waters a bit, I'll toss in what little I know about it.
We recommend setting the Mic (or LINE IN) Gain so you get 5 bars of ALC,
with possibly the 6th bar occasionally flickering, with CMP set to 0.
No,
Hmmm. Your advice to:
...*please* set it to 4 bars in soundcard digital modes...
contradicts the direction given here (in step 7):
http://www.elecraft.com/K3/k3_operating_tips.htm#psk%20audio
viz. You should not see any ALC bars on the K3 display (when set to CMP/ALC)
This always confused me
In a message dated 4/6/2008 3:07:22 P.M. Eastern Daylight Time,
[EMAIL PROTECTED] writes:
Note: For PSK and other operation, you want to set things to the level
where the 5th bar just comes on -- or just doesn't. If you have only 4
bars in digital modes, that's OK. With less than 4, you
The suggested 4 Bar system does seem to work using SSB for the PSK.
Sorry for adding yet more confusion to the mix. I am running firmware
that is in field test and should be released next week. The statement I
made I believe to be true for the firmware I am running. I haven't gone
back
First I want to establish that I'm in the market for a
K3 and will definitely buy one---just as soon as I can
get one 2-3 weeks ARO. (Hint)
I read the digest and I saw the question was raised
about the poor transmit IMD performance of the K3 as
reported in the QST review. If this was addressed
Wes Stewart wrote:
So I humbly propose a new transceiver composite
test. Receiver performance shall be measured by using
two other like transceivers, operating at full output
power, as the signal sources for the measurement(s).
Wes, I understand what you're saying, but IMO this idea doesn't
Well, I've seeming stirred up a hornets' nest, or as
we have in Southern Arizona, an Africanized (killer)
honeybees' nest.
I do stand corrected about a response from Elecraft
regarding this subject that I failed to see.
http://www.mail-archive.com/elecraft@mailman.qth.net/msg50667.html
--- Eric Swartz - WA6HHQ, Elecraft
[EMAIL PROTECTED] wrote:
The K3 firmware used for the original QST review did
not turn off the
K3's RF speech compressor clipper even when the
compressor was set to
zero for their TX IMD two tone test. This resulted
in a significant
increase in
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