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Noisy K3 receiver

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Bill K9YEQ

Re: Noisy K3 receiver

Don,

I tried your settings and wow. I love the radio. I am not sure it is
working well. I am on 75 and what a difference. I do have to turn up the
audio a bit because signals are fading, but at least the static noise from
the radio is greatly reduced and it does behave more like the venerable K2
which I still have and love.

73,

Bill
K9YEQ
K2 #35; KX1 #35; K3 #1744; mini mods
ATS-3B

-----Original Message-----
From: Don Wilhelm [mailto:[hidden email]]
Sent: Friday, December 18, 2009 5:09 PM
To: Bill K9YEQ
Cc: [hidden email]; 'Arie Kleingeld PA3A'; 'Elecraft - K3'
Subject: Re: [Elecraft] Noisy K3 receiver

Yes, AGC can do that. At all settings the AGC will do its job, but if
the settings are agressive, when there is no strong signal, the receiver
goes to full gain and any noise becomes loud - the K3 will try to make
the noise as loud as the signal you were previously listening to.

I personally think the default AGC settings are too agressive, but that
is only my opinion - I like my K2 AGC (despite Wayne's preference for
the default settings).

73,
Don W3FPR

Bill K9YEQ wrote:
> Don & all,
>
> I was also besieged with noise. I changed my settings which I acquired,
not
> sure because the memory is failing :-), and tried your minimum
settings...
> my GOSH, a whole new world. I will test further, but so far on a very
> "noisey" 75, the radio quited right down. We forget about all the
internal
> settings. I do not yet have the DsP upgrade but will once the 144m mod
> becomes available so there is only one entrance into the radio to
accomplish

> the upgrades.
>
>
> 73,
>
> Bill
> K9YEQ
> K2 #35; KX1 #35; K3 #1744; mini mods
> ATS-3B
>
>
> -----Original Message-----
> ........................................
> The only way I can get my K3 to have almmost as much noise with the
> antenna removed as it has with the antenna connected is to set the AGC
> Threshold to its minimum value (002). My AGC Threshold is normally set
> at 008. As a side-point, I set my AGC SLP at 002 because that produces
> a response similar to that of the K2 which I liked - weak signals sound
> weaker, strong signals stronger and I can judge that without reference
> to the S-meter.
>
> If you wish to try some other tests, let me know and I will try to help.
>
> 73,
> Don W3FPR
>
>
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n7ws

Re: Noisy K3 receiver

In reply to this post by Geoffrey Mackenzie-Kennedy

I concur completely.

Regards,

Wes

--- On Fri, 12/18/09, Geoffrey Mackenzie-Kennedy <[hidden email]> wrote:

From: Geoffrey Mackenzie-Kennedy <[hidden email]>
Subject: Re: [Elecraft] Noisy K3 receiver
To: "Wes Stewart" <[hidden email]>
Cc: "Elecraft Discussion List" <[hidden email]>
Date: Friday, December 18, 2009, 4:25 PM

Wes Stewart, N7WS, wrote on Friday December 18, 2009 at 4:43 PM:

<snip>

> We have DXpeditions operating on some chunk of coral that are running wireless networks between stations and uploading their logbooks in near real-time to the Internet via satellite yet their operators > are still "riding the RF gain control". Something is wrong with this picture.

Wes,

What is wrong IMHO is that many if not most commercial receivers designed for the amateur market are designed with too much gain ahead of their roofing filter, followed by a small dynamic range IF "system" - not a good mix which requires several roofing filters of various bandwidths, and in some cases multiple loop AGC systems. A multi loop AGC scheme can cause "noise problems" if any "see-sawing" between the AGC loops takes place as the result of overshoot in any one loop, for example, certainly if the loop time constants are incorrect. No wonder then that "riding the RF gain" is required in some cases.

One approach used in the design of high performance downconversion superhets is always to use negative gain ahead of the roofing filter, followed by a low noise large IMDDR3 IF system, with minimnal required AGC applied using "electronic attenuators", not current starvation of an amplifier, to protect the "weakest link", be it the DSP's ADC if used or an audio amp. The HF noise figure of such a receiver without preamp is typically 9 to 10 db.

When using these high performance receivers it is not necessary to "ride the RF gain control" when digging out weak signals in the presence of QRM.

73,
Geoff
GM4ESD

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Ian Maude

Re: Noisy K3 receiver

In reply to this post by Ralph Parker

Hi all,
I have been following this thread with interest. My experience is that my
K3 seems noisy at home where my ambient RF noise floor can be anything up to
s9 at times with the amount of RF producing electrical junk all around me.
However, when I use it at a 'quiet' location such as our DXpedition to the
Isle of Jura or our contest site, the RX is extremely quiet. This leads me
to believe that I am simply suffering from a RX with a *lot* of gain. At
home, I simply turn down the RF gain and it is amazing how quickly the noise
lowers significantly! There is only about 30dB of isolation between antenna
1 and antenna 2 off the tuner which does not help the noise floor and as
such I have simply stopped putting an antenna in ant2 for HF, I only have my
6m log periodic in there.
I think in a lot of ways we are chasing our tails here.

73 Ian

--
Ian J Maude, G0VGS
SysOp GB7MBC & HB9DRV-9 DX Clusters
Member RSGB, GQRP 9838, FISTS 14077 | K3 #455
http://www.amateurradiotraining.org
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Richard Squire - HB9ANM

Re: Noisy K3 receiver

I'll second that, Ian! I'm lucky to live in quite, rural QTH with no computers around except my own...
So the K3's inherent white/pink or whatever colour noise is certainly something that can be put up with, as in ANY other DSP rig. Wonder why this topic suddenly pops up - and seems to be relevant to so many after 2 years... causing such a "noise floor" on the reflector! I listened to FT2Ks, Orions, ... then purchased the K3. I must have had some good reasons.
73

Ian Maude wrote

Hi all,
I have been following this thread with interest. My experience is that my
K3 seems noisy at home where my ambient RF noise floor can be anything up to
s9 at times with the amount of RF producing electrical junk all around me.
However, when I use it at a 'quiet' location such as our DXpedition to the
Isle of Jura or our contest site, the RX is extremely quiet. This leads me
to believe that I am simply suffering from a RX with a *lot* of gain. At
home, I simply turn down the RF gain and it is amazing how quickly the noise
lowers significantly! There is only about 30dB of isolation between antenna
1 and antenna 2 off the tuner which does not help the noise floor and as
such I have simply stopped putting an antenna in ant2 for HF, I only have my
6m log periodic in there.
I think in a lot of ways we are chasing our tails here.

73 Ian

--
Ian J Maude, G0VGS
SysOp GB7MBC & HB9DRV-9 DX Clusters
Member RSGB, GQRP 9838, FISTS 14077 | K3 #455
http://www.amateurradiotraining.org
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Richard - HB9ANM

PD2R

Re: Noisy K3 receiver

Correct me if I'm wrong Richard, but are you saying that "the noise",
whatever color it may be, is something we all have to put up with? And since
2 years have past, we have lost the right to say anything about it?

There are a lot off people who find this topic very helpful. You obviously
do not and consider it "noise floor". As far as I can tell, nobody is
twisting your arm and makes you read this topic so don't read it if it
bothers you that much.

I hope that with the help of this topic on the reflector, I too am able to
set my K3 correctly for my circumstances so I too can enjoy noise free
reception.

Thank you for your contribution.

2009/12/19 Richard Squire - HB9ANM <[hidden email]>

>
> I'll second that, Ian! I'm lucky to live in quite, rural QTH with no
> computers around except my own...
> So the K3's inherent white/pink or whatever colour noise is certainly
> something that can be put up with, as in ANY other DSP rig. Wonder why this
> topic suddenly pops up - and seems to be relevant to so many after 2
> years... causing such a "noise floor" on the reflector! I listened to
> FT2Ks,
> Orions, ... then purchased the K3. I must have had some good reasons.
> 73
>
>
>

Maarten, PD2R
Member of the PI4DX contest group
www.pi4dx.com

Elecraft K3 nr:1849

pd0psb

Re: Noisy K3 receiver

I think what people experience (perceive) is not a noisy receiver.
If it were K3's MDS would have to be much worse than other radios :-)

It is a combination of the K3's sound character and AGC character.
-The "color" of noise defines its annoyance factor.
-The AGC setting define how much signals and noise are seperated (how signals "jump" out of the noise or drown in it)

Fortunately both are throroughly adjustable in the K3.

Wouldn't it be a good idea if Elecraft would gather and mediate information from users about sets they perceive as pleasant sounding radios.
I'm quite sure Elecraft could come up with a few setting templates that mimic a certain FT/TS/TT radio if that's what users would like, but it takes time to just sit down and compare A to B.
The K3 is highly configurable but many seem to get lost because they don't know how to translate a specific "sound" in AGC/EQ settings, which is quite a task with all variables available.

73'
Paul
PD0PSB

Correct me if I'm wrong Richard, but are you saying that "the noise",
whatever color it may be, is something we all have to put up with? And since
2 years have past, we have lost the right to say anything about it?

Richard Squire - HB9ANM

Re: Noisy K3 receiver

In reply to this post by PD2R

Hi Maarten. It is a fact that DSP receivers tend to have a somewhat higher noise floor. I am certainly not suggesting anybody lost his rights to talk about it. But what puzzles me is why this topic now suddenly pops up more two years after the first K3s appeared in the ham community? There must be some good reason why nobody raised the subject before... Until someone sparked a tsunami of comments!

PD2R wrote

Correct me if I'm wrong Richard, but are you saying that "the noise",
whatever color it may be, is something we all have to put up with? And since
2 years have past, we have lost the right to say anything about it?

Richard - HB9ANM

Richard Ferch

Re: Noisy K3 receiver

In reply to this post by Ralph Parker

HB9ANM wrote:
> what puzzles me is why this topic now suddenly pops up more
> two years after the first K3s appeared in the ham community? There must be
> some good reason why nobody raised the subject before... Until someone
> sparked a tsunami of comments!

Possibly because the problem might exist in only a small percentage of
K3s. For example, my main RX is quiet, but my sub-RX is noisy. Two K3
receivers in the same box with the same settings and firmware, different
audio performance. Maybe the main receivers in the K3s whose owners
complain about noise have the same problem as my sub-RX, whatever that
problem may happen to be.

73,
Rich VE3KI
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Don Wilhelm-4

Re: Noisy K3 receiver

In reply to this post by Ian Maude

Ian,

You are quite correct - the K3 does have a LOT of gain. It is capable
of bringing the level of even a small amount of band noise up to a large
amount of audio output.

While AGC *can* accomplish that task, it will not be active when there
are pauses in the speech or between CW characters (or words), so the AGC
will return the K3 to full gain. You are correct in reducing the RF
Gain to the point where the band noise is reduced. I trust you are also
using the attenuator and have the preamp off because these are stages
prior to the mixer and will have a greater impact on the band noise
reduction than the RF Gain which operates at the IF.

For those who have noisy reception, do a trial at a spot in each HF band
where there are no signals present - first turn off the preamp, and then
if noise is still present and bothersome, turn on the attenuator, then
lastly reduce the RF Gain.

For the majority of those objecting to the K3 noise level, I do not
believe that the K3 is generating the noise (there may be exceptions
where the K3 has a fault), but it is faithfully demodulating the entire
passband contents, whether that be noise or signal. With enough gain
combined with an aggressive AGC, the noise will be heard when there are
no signals present. The *cure* is to alter either the receiver gain or
alter the AGC behavior (or both). The K3 has reserve gain for those
times when it is required, but must be "tamed" a bit in many cases. My
analogy is a sports car with a powerful engine - one does not operate
that sports car all the time with the "pedal to the metal".

73,
Don W3FPR

Ian Maude wrote:

> Hi all,
> I have been following this thread with interest. My experience is that my
> K3 seems noisy at home where my ambient RF noise floor can be anything up to
> s9 at times with the amount of RF producing electrical junk all around me.
> However, when I use it at a 'quiet' location such as our DXpedition to the
> Isle of Jura or our contest site, the RX is extremely quiet. This leads me
> to believe that I am simply suffering from a RX with a *lot* of gain. At
> home, I simply turn down the RF gain and it is amazing how quickly the noise
> lowers significantly! There is only about 30dB of isolation between antenna
> 1 and antenna 2 off the tuner which does not help the noise floor and as
> such I have simply stopped putting an antenna in ant2 for HF, I only have my
> 6m log periodic in there.
> I think in a lot of ways we are chasing our tails here.
>
> 73 Ian
>
>

PD2R

Re: Noisy K3 receiver

In reply to this post by Richard Squire - HB9ANM

Hi Richard,

About I year ago the subject was discussed on the reflector as well. Just
like it does now it then caused a lot of discussion too. If I remember it
correctly Elecraft came up with a firmware release which provided more low
audio response partially because of that discussion on the reflector.
Among others, K8ZOA wrote an article about the different parameters of the
AGC which helped a lot of people to set up the AGC correctly.
It seems to me that now, a year later, that article has dropped to the
background and new users seem to struggle with a correct AGC setting.
It's certainly is not something new, people have mentioned it before and I
like to believe it's still a work in progress.

73, Maarten van Rossum
PD2R

P.s. This is the article I reffered to:
http://www.cliftonlaboratories.com/Documents/Elecraft%20K3%20Transceiver%20AGC%20Parameters%20and%20S-meter.pdf

2009/12/19 Richard Squire - HB9ANM <[hidden email]>

>
> Hi Maarten. It is a fact that DSP receivers tend to have a somewhat higher
> noise floor. I am certainly not suggesting anybody lost his rights to talk
> about it. But what puzzles me is why this topic now suddenly pops up more
> two years after the first K3s appeared in the ham community? There must be
> some good reason why nobody raised the subject before... Until someone
> sparked a tsunami of comments!
>
>
> PD2R wrote:
> >
> > Correct me if I'm wrong Richard, but are you saying that "the noise",
> > whatever color it may be, is something we all have to put up with? And
> > since
> > 2 years have past, we have lost the right to say anything about it?
> >
> >
>
>
> -----
> Richard - HB9ANM
> --
> View this message in context:
> http://n2.nabble.com/Noisy-K3-receiver-tp4184529p4191276.html
> Sent from the [K3] mailing list archive at Nabble.com.
> ______________________________________________________________
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>

Maarten, PD2R
Member of the PI4DX contest group
www.pi4dx.com

Elecraft K3 nr:1849

Jan Erik Holm

Re: Noisy K3 receiver

In reply to this post by Don Wilhelm-4

Well something isn´t right or different from other radios.
There are radios with lower MDS that sounds much quieter then
the K3.
Here we have proposals to turn of preamp and make MDS even
higher. Not logical and state of the art to me.

So again, I know there are receivers with lower MDS then the
K3 that sounds much more quiet.
IMO something is going on but I can´t put my fingers on it
and I don´t have the time to investigate. And believe you
me with the experience I do have in the performance of a
multitude of different radios going back in to the 60´ties
I know what I´m talking about.

It´s been most interesting to read some of the comments,
maybe something can come out of it and things can be fixed.

merry xmas Jim SM2EKM
-----------------------------
Don Wilhelm wrote:

> will return the K3 to full gain. You are correct in reducing the RF
> Gain to the point where the band noise is reduced. I trust you are also
> using the attenuator and have the preamp off because these are stages
> prior to the mixer and will have a greater impact on the band noise
> reduction than the RF Gain which operates at the IF.
>
> For those who have noisy reception, do a trial at a spot in each HF band
> where there are no signals present - first turn off the preamp, and then
> if noise is still present and bothersome, turn on the attenuator, then
> lastly reduce the RF Gain.
>

Don Wilhelm-4

Re: Noisy K3 receiver

In reply to this post by PD2R

Maarten (and all),

There are two separate noise sources to be considered here, and it is
important to separate them. One is the internal receiver noise, and the
second is demodulated noise that comes into the receiver via the antenna
port.

For anyone who suspects that the K3 itself is noisy (because of internal
noise), I encourage those owners to do an MDS measurement. If the
internal noise is excessive, the MDS will be greatly reduced - MDS is
the minimum signal level that can be detected above the receiver noise
floor. The Elecraft XG1 or XG2 is an inexpensive signal generator that
will do the task - and the instructions for measuring MDS are in the
manual. If your K3 is not 'up to par', then that problem can be fixed.

OTOH, if the noise is coming into the receiver on the antenna port,
there is not much that can be done to eliminate it - it is just like any
other "signal" coming in from the antenna.
The K3 does offer tools such as the attenuator and AGC adjustments that
can better handle than noise. Unfortunately, there is not a "one size
fits all" solution because each source of noise is different in its
character and amplitude.

I cannot comment intelligently to those who are comparing the K3 audio
noise output with that of another receiver because I do not have access
to the receivers they are comparing. I can only guess that the
difference may be due to differences in receiver gain, AGC action,
bandpass width, or the shaping of the audio spectrum. Without doing
actual measurements, these variables cannot be quantified.

73,
Don W3FPR

Maarten van Rossum wrote:
> I hope that with the help of this topic on the reflector, I too am able to
> set my K3 correctly for my circumstances so I too can enjoy noise free
> reception.
>
>
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ROBERT CARROLL-4

Re: Noisy K3 receiver

In reply to this post by Jan Erik Holm

I have K3 envy but use an Orion and, as with Van, I have an FT2000 and am a
member of that reflector. Until a death-by-lightning incident I also had an
FT1000MP. One of the frequently heard complaints on the 2000 and sometimes
the Orion reflector is that the Orion is noisy compared to either an MP or
2K. I don't find that to be the case unless I am using too much RF gain
with the Orion but quite a few others dont agree. I recall that in early
runs of the MP there were many complaints about audio hiss, and InRad had a
fix which was a simple audio BW roll-off cap. I suspect Yaesu may have
included a similar change in later MP's and MKV's as those complaints
stopped. The idea was to eliminate any white noise in the phones when the
antenna input was disconnected. That noise was coming from an audio stage. I
am very interested in seeing where the K3 noise thread leads.

73
Bob W2WG

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Jan Erik Holm
Sent: Saturday, December 19, 2009 10:12 AM
Cc: Elecraft List
Subject: Re: [Elecraft] Noisy K3 receiver

Well something isn´t right or different from other radios.
There are radios with lower MDS that sounds much quieter then
the K3.
Here we have proposals to turn of preamp and make MDS even
higher. Not logical and state of the art to me.

So again, I know there are receivers with lower MDS then the
K3 that sounds much more quiet.
IMO something is going on but I can´t put my fingers on it
and I don´t have the time to investigate. And believe you
me with the experience I do have in the performance of a
multitude of different radios going back in to the 60´ties
I know what I´m talking about.

It´s been most interesting to read some of the comments,
maybe something can come out of it and things can be fixed.

merry xmas Jim SM2EKM
-----------------------------
Don Wilhelm wrote:

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Ed Gray W0SD

My K3's Very Quiet

In reply to this post by Don Wilhelm-4

I am listening on 17 meters SSB right now and Europe is coming through
mostly S-7 to S-9 on the TH-11.
I can tune to an open spot in the band or just above the top edge of the
band and my S-meter
has one bar. This is with the pre-amp off. The band width is 2.1 khz.
Even at 2.7 khz I stay at one bar but
to my ear I can hear just a tiny bit more background noise which seems
logical to me. I had the RF gain at maximum
for the test. Obviously if you have some noise backing the RF gain off
is the way to go.

I like to listen with the shift at FC 1.40 rather than 1.50. For me a
little shift is always more
pleasant to listen to. I also always did this with the FT-1000D and
TS-950SDX
that I previously owned.

IMHO what more can you ask for?

When I switch to the dummy load at normal volume I can barely tell the
radio is on. I have zero bars on the S-Meter on
the dummy load.

I did these same checks with #1037, #1096 and #3423 and I can hear no
difference. They are all very quiet! Of course a factor
here is I live in a rural area where man made noise is low! I sure
don't expect my K3 to be quiet if I have man made noise other than
things you can do with the NB, NR, AGC and bandwidth.

It has been my experience over the years to "NOT" use the pre-amp on any
HF radio unless you are out of audio gain. The FT-1000D did not have a
pre-amp and the only place for me it was lacking was 10 meters. For me
I just don't hear more at 10 meters and down with a pre-amp. For me it
just brings the noise up with the signal. The only place I have seen a
big benefit from a pre-amp is above 28 mhz. Obviously the K3 benefits
from a pre-amp on six meters.

Ed W0SD

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Julian, G4ILO

Re: Noisy K3 receiver

In reply to this post by Richard Squire - HB9ANM

I can't say that I was ever completely happy with the audio output of the K3. My father was an audiophile and the K3 reminds me a bit of some of the high-end audio stuff that he used to demonstrate to me. It had remarkable detail and clarity but it also revealed things that perhaps were best hidden and made it, to me, a bit tiring to listen to compared to my own budget stereo system.

On the K3 CW and data signals sound remarkably pure and distortion free and SSB sounds very clean and open. But on headphones particularly and on some speakers other than the internal speaker I do find the K3 tiring to listen to. This may be due to high frequency "artifacts" that some have mentioned, but I have come to the conclusion that it has more to do with the excessive low frequency roll-off in the K3 audio circuits particularly the headphone circuit.

Today, I performed the RF gain calibration procedure, recalibrated the S meter, then experimented with the AGC threshold and slope settings along the lines suggested in this thread. I didn't find it made much difference to the sound of the radio, or even the ability of signals to "pop out" of the noise has been described.

I then made some A/B comparisons between the K3 and my FT-817ND, since that was connected up and available. Listening on headphones, the FT-817ND was definitely the most pleasant of the two radios to listen to, and signals seemed to stand clear of the noise better. I then attempted to record this to make some demo MP3 files via the line audio from both radios. The difference, though still noticeable, was less marked than when listening on headphones.

As my K3 is connected to its own dedicated sound card, I downloaded Spectran and used this to experiment with the effect of filtering on the received audio. You can play the K3 audio into one sound card and play back the output (optionally filtered by Spectran) to the regular one and listen with headphones plugged into the computer. This convinced me that the K3 is certainly capable of producing very high quality audio. I didn't see any sign of high frequency "artifacts" on the display. A low pass filter coming in anywhere from 2.7KHz or higher didn't make much difference to the sound at all. But changing the position of the high pass filter to allow more bass through made a big subjective difference to the sound. More bass made the audio less tiring and more pleasant to listen to.

I have done the KIO3 mod to improve the bass through the line output and the mod on the main board for the speaker output. I still have the original DSP board. Recently I plugged a pair of cheap computer speakers into the rear speaker socket of the K3. Being computer speakers they were powered with a high impedance input so there is less attenuation of low frequencies than when using non-powered 8 ohm speakers. The audio quality was quite pleasant considering the price of the speakers. The audio through headphones plugged into the socket of one of the speakers was also much better than the audio from the same headphones plugged directly into the K3.

I agree with others who have said that more information is needed than just "my K3 is noisy". We need to know what they are listening with, what impedance it is, what audio-related mods have been done.

I personally think that the excessive attenuation of low frequencies in the K3's audio circuits particularly the headphone output is the major factor in many of the complaints that the K3 sounds tiring. I am not convinced that an add-in LPF will have any effect. What I am concerned about - especially in view of the cost of exchanging the DSP board for those outside the US - is whether the improvements in low frequency output are enough.

A lower-cost workaround might be to try some powered computer speakers and use the headphone output on those. Most people will have computer speakers already they can hook up as an experiment, so it would not be difficult to try it.

Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com
* KComm - http://www.g4ilo.com/kcomm.html
* KTune - http://www.g4ilo.com/ktune.html

David Gilbert

Re: Noisy K3 receiver

In reply to this post by Richard Ferch

That's an interesting observation and there is an easy way to check it
out. If you feed the stereo Line Out signal from your K3 into your
sound card while using Spectrogram (a free program) to observe both
channels, you should be able to get a direct comparison of the two
receivers. Spectrogram will even let you take a jpeg snapshot of the
spectrum display. Any chance you might be willing to do that? If you
don't want to mess with it, just record some of the audio as a stereo
file and I'll run it through Spectrogram for you.

Just be sure to have all the same K3 settings (gain, bandwidth, shift,
etc) for both receivers and tune both receivers to similar portions of
the band.

73,
Dave AB7E

Richard Ferch wrote:

> HB9ANM wrote:
>
>> what puzzles me is why this topic now suddenly pops up more
>> two years after the first K3s appeared in the ham community? There must be
>> some good reason why nobody raised the subject before... Until someone
>> sparked a tsunami of comments!
>>
>
> Possibly because the problem might exist in only a small percentage of
> K3s. For example, my main RX is quiet, but my sub-RX is noisy. Two K3
> receivers in the same box with the same settings and firmware, different
> audio performance. Maybe the main receivers in the K3s whose owners
> complain about noise have the same problem as my sub-RX, whatever that
> problem may happen to be.
>
> 73,
> Rich VE3KI
> ________________

drewko

Re: My K3's Very Quiet

In reply to this post by Ed Gray W0SD

Regarding the preamp: MDS measurements show a better (S+N)/N with the
preamp on, approx 4 db improvement in MDS on my K3 on 40m. A similar
improvement is obtained by setting the ATU to BYPASS.

The macro to toggle Preamp+Bypass is SWH19;SWT24; for anyone who wants
to try it. It may be useful for weak signals. You do have to remember
to toggle it (the ATU) back on when you transmit though.

73,
Drew
AF2Z

On Sat, 19 Dec 2009 10:27:16 -0600, Ed W0SD wrote:

>
>It has been my experience over the years to "NOT" use the pre-amp on any
>HF radio unless you are out of audio gain. The FT-1000D did not have a
>pre-amp and the only place for me it was lacking was 10 meters. For me
>I just don't hear more at 10 meters and down with a pre-amp. For me it
>just brings the noise up with the signal. The only place I have seen a
>big benefit from a pre-amp is above 28 mhz. Obviously the K3 benefits
>from a pre-amp on six meters.
>
>Ed W0SD

Re: Noisy K3 receiver

In reply to this post by Don Wilhelm-4

There are two ways to hear noise that comes from the antenna. If you are hearing it while hearing a CW tone, it is strong enough to compete with the signal and about all you can do is narrow the band width or mentally filter it. If the noise is blanked by the key down signal, but you are hearing it in the pauses it can still be annoying and you can still perceive the receiver to be noisy. In the latter case, changes in the AGC, or RF gain can be effective and reduce the annoyance. This is primarily why I like my slope at about 6 instead of 10. But, I am mostly a CW operator with some SSB. I don't operate AM or FM with my K3 which would certainly have different requirements. Also there is a difference in what is appropriate for weak signal operation or strong signal operation. In a contest situation you repidly switch between strong and weak signals so you probably would prefer a compromise setting.
Willis 'Cookie' Cooke
K5EWJ

________________________________
From: Don Wilhelm <[hidden email]>
To: [hidden email]
Sent: Sat, December 19, 2009 9:23:08 AM
Subject: Re: [Elecraft] [K3] Noisy K3 receiver

Maarten (and all),

There are two separate noise sources to be considered here, and it is
important to separate them. One is the internal receiver noise, and the
second is demodulated noise that comes into the receiver via the antenna
port.

For anyone who suspects that the K3 itself is noisy (because of internal
noise), I encourage those owners to do an MDS measurement. If the
internal noise is excessive, the MDS will be greatly reduced - MDS is
the minimum signal level that can be detected above the receiver noise
floor. The Elecraft XG1 or XG2 is an inexpensive signal generator that
will do the task - and the instructions for measuring MDS are in the
manual. If your K3 is not 'up to par', then that problem can be fixed.

OTOH, if the noise is coming into the receiver on the antenna port,
there is not much that can be done to eliminate it - it is just like any
other "signal" coming in from the antenna.
The K3 does offer tools such as the attenuator and AGC adjustments that
can better handle than noise. Unfortunately, there is not a "one size
fits all" solution because each source of noise is different in its
character and amplitude.

I cannot comment intelligently to those who are comparing the K3 audio
noise output with that of another receiver because I do not have access
to the receivers they are comparing. I can only guess that the
difference may be due to differences in receiver gain, AGC action,
bandpass width, or the shaping of the audio spectrum. Without doing
actual measurements, these variables cannot be quantified.

73,
Don W3FPR

Maarten van Rossum wrote:
> I hope that with the help of this topic on the reflector, I too am able to
> set my K3 correctly for my circumstances so I too can enjoy noise free
> reception.
>
>
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Bob Naumann W5OV

Re: Noisy K3 receiver

There's something about Cookie's description of how one can hear noise that
makes me think that perhaps some of these "noisy" K3 comments are due to
having an expectation that is simply not realistic.

I get the impression that the expectation may be that at some point, with a
given signal strength, and enough signal to noise ratio, you will hear no
noise at all. I know this is false - unless you are using FM and the
receiver is locked on that one signal. Even under such a "full quieting"
situation, you can still hear lightning crashes through the FM signal if
they're strong enough.

The only other way that this would happen is if we were removing the noise
using DSP techniques, and re-creating the desired signal absent of the noise
that will always be there. I have tried such DSP stuff, and what remains
does not sound all that good to me, and it needs to be used sparingly.

When we're listening to CW or SSB, the level of the signal is constantly
changing in amplitude from both fading and just from the constant waveform
variance. If the AGC is set to a value (slow) that holds the gain down
during the variances, it will mask the apparent amount of noise that we
hear. Its not gone, but we don't hear it as much. To confirm this just
switch from fast to slow AGC and back to fast on most any receiver and you
will notice this phenomena. The point is that there will be noise within
your pass band regardless of how narrow it may be and how strong the signal
may be that you are listening to.

Am I recognizing an unrealistic expectation by users of the K3 (or most any
receiver) or am I just misinterpreting this comment?

73,

Bob W5OV

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of WILLIS COOKE
Sent: Saturday, December 19, 2009 11:37 AM
To: [hidden email]; Elecraft Reflector
Subject: Re: [Elecraft] [K3] Noisy K3 receiver

There are two ways to hear noise that comes from the antenna. If you are
hearing it while hearing a CW tone, it is strong enough to compete with the
signal and about all you can do is narrow the band width or mentally filter
it. If the noise is blanked by the key down signal, but you are hearing
it in the pauses it can still be annoying and you can still perceive the
receiver to be noisy. In the latter case, changes in the AGC, or RF gain
can be effective and reduce the annoyance. This is primarily why I like my
slope at about 6 instead of 10. But, I am mostly a CW operator with some
SSB. I don't operate AM or FM with my K3 which would certainly have
different requirements. Also there is a difference in what is appropriate
for weak signal operation or strong signal operation. In a contest
situation you repidly switch between strong and weak signals so you probably
would prefer a compromise setting.
Willis 'Cookie' Cooke
K5EWJ

________________________________
From: Don Wilhelm <[hidden email]>
To: [hidden email]
Sent: Sat, December 19, 2009 9:23:08 AM
Subject: Re: [Elecraft] [K3] Noisy K3 receiver

Maarten (and all),

There are two separate noise sources to be considered here, and it is
important to separate them. One is the internal receiver noise, and the
second is demodulated noise that comes into the receiver via the antenna
port.

For anyone who suspects that the K3 itself is noisy (because of internal
noise), I encourage those owners to do an MDS measurement. If the
internal noise is excessive, the MDS will be greatly reduced - MDS is
the minimum signal level that can be detected above the receiver noise
floor. The Elecraft XG1 or XG2 is an inexpensive signal generator that
will do the task - and the instructions for measuring MDS are in the
manual. If your K3 is not 'up to par', then that problem can be fixed.

OTOH, if the noise is coming into the receiver on the antenna port,
there is not much that can be done to eliminate it - it is just like any
other "signal" coming in from the antenna.
The K3 does offer tools such as the attenuator and AGC adjustments that
can better handle than noise. Unfortunately, there is not a "one size
fits all" solution because each source of noise is different in its
character and amplitude.

I cannot comment intelligently to those who are comparing the K3 audio
noise output with that of another receiver because I do not have access
to the receivers they are comparing. I can only guess that the
difference may be due to differences in receiver gain, AGC action,
bandpass width, or the shaping of the audio spectrum. Without doing
actual measurements, these variables cannot be quantified.

73,
Don W3FPR

Maarten van Rossum wrote:
> I hope that with the help of this topic on the reflector, I too am able to
> set my K3 correctly for my circumstances so I too can enjoy noise free
> reception.
>
>
______________________________________________________________
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Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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Jan Erik Holm

Re: My K3's Very Quiet

In reply to this post by drewko

Hmm, interesting, 4 dB MDS improvement and the gain of the
preamp is 15-20 dB i think. Spontaneously this is a lousy
preamp or I had too much too drink during Saturday dinner.

Correction to W0SD:

The FT-1000D DO have a preamp, about20 dB gain. Check the
schematic and you will see. When you turn switch to IPO it
kicks out the preamp. Then turning it further to 6 dB etc etc
you switch in attenuation in 6 dB steps. IMO this was soo stupid,
instead I did modify my FT-1000D NOT to turn off preamp but just
use the atennuation steps. Easy to do, just look at the schematic.
By using the 6 12 18 dB attenuation steps I easily can improve
the IMDDR3 when needed. My modified FT-1000D has about 92 dB
IMDDR3 at a MDS of about 142 dB 2 kHz spacing. Not too shabby,
and I don´t have to "ride the" RF gain. Also I don´t get fatigued by
strange pink or whatever noise.

Soo here we have a radio ( K3 ) with 135 dB MDS and you guys
are going to lower the gain! In my head something is totally
wacky here.

/ Jim SM2EKM
------------------------
drewko wrote:

> Regarding the preamp: MDS measurements show a better (S+N)/N with the
> preamp on, approx 4 db improvement in MDS on my K3 on 40m. A similar
> improvement is obtained by setting the ATU to BYPASS.
>
> The macro to toggle Preamp+Bypass is SWH19;SWT24; for anyone who wants
> to try it. It may be useful for weak signals. You do have to remember
> to toggle it (the ATU) back on when you transmit though.
>
> 73,
> Drew
> AF2Z
>
>
> On Sat, 19 Dec 2009 10:27:16 -0600, Ed W0SD wrote:
>> It has been my experience over the years to "NOT" use the pre-amp on any
>> HF radio unless you are out of audio gain. The FT-1000D did not have a
>> pre-amp and the only place for me it was lacking was 10 meters. For me
>> I just don't hear more at 10 meters and down with a pre-amp. For me it
>> just brings the noise up with the signal. The only place I have seen a
>> big benefit from a pre-amp is above 28 mhz. Obviously the K3 benefits
>>from a pre-amp on six meters.
>> Ed W0SD
>

1234