K3. RX too sensitive for me

[mikerodgerske5gbc]

I've got a lot of noise which I attribute to a sensitive receiver. If possible I would like to find a way to reduce it somehow maybe artificially. This would go a long way towards increasing my listening pleasure.
My agc dcy is soft. Hold is zero
Pls is nor,slope 10 threshold 8
Agc-f  120. S- 20. I generally keep it on fast.

S meter noise level usually 4-5
If I could use the rf gain to reduce it to s1 or 2 I'd like that. I know the s meter wouldn't be accurate but I'd like it better instead of now showing s9 or so when backing down rf gain. Would changing the s meter mode to ABS allow the meter to do that?

If the filter gain could go below zero I would do that. Maybe that could be implemented?

Ideas?

Sent from my spy ring
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[Jim Brown-10]

> I've got a lot of noise which I attribute to a sensitive receiver.

You may be mistaken about why the noise is loud.  Many of us live in
places where there is a lot of electrical noise. When I lived in
Chicago, my noise level was rarely less than about S6, and often S9.

There are three good ways to reduce the sensitivity of the K3.  First,
turn off the Pre-amp. The preamp should nearly always be off below 20M,  
Second, turn ON the Attenuator. The Attenuator should usually be ON for
80M and 160M.  If you set the meter mode for ABS it will still correctly
read the voltage at the antenna input.

Third, turn down the RF gain.  When those of us with lots of grey hair
started in ham radio, we learned early on that receivers should
generally be run with the AF gain fairly high and to control the
sensitivity with the RF gain. Sadly, that method has fallen into dis-use
as more hams don't bother to sudy the fundamentals of how their radios
work.  Yes, the S-meter is not calibrated when the RF gain is turned
down, but the radio works better that way. :)

73, Jim K9YC
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[wayne burdick]

Hi Mike,

The K3 has a lot of receiver gain. You can reduce it to something more  
like the gain of a K2 by setting CONFIG menu entry AF GAIN to LO. This  
will have no impact on performance.

Have you already tried turning the preamp off? It really isn't needed  
on the bands from 160-20 m unless you have a lossy antenna.

73,
Wayne
N6KR

On May 17, 2011, at 12:45 PM, Mike Rodgers wrote:

> I've got a lot of noise which I attribute to a sensitive receiver.  
> If possible I would like to find a way to reduce it somehow maybe  
> artificially. This would go a long way towards increasing my  
> listening pleasure.
> My agc dcy is soft. Hold is zero
> Pls is nor,slope 10 threshold 8
> Agc-f  120. S- 20. I generally keep it on fast.
>
> S meter noise level usually 4-5
> If I could use the rf gain to reduce it to s1 or 2 I'd like that. I  
> know the s meter wouldn't be accurate but I'd like it better instead  
> of now showing s9 or so when backing down rf gain. Would changing  
> the s meter mode to ABS allow the meter to do that?
>
> If the filter gain could go below zero I would do that. Maybe that  
> could be implemented?
>
> Ideas?
>
> Sent from my spy ring
> ______________________________________________________________
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[VK7JB]

Helpful comments, Jim.
I ride the RF gain control on the K3 to very good effect.  The only problem, as you point out, is that the S-meter won't read signal strength at the antenna with the RF gain wound back.  I have my K3 s-meter set in absolute mode, so using ATT or PRE does not influence the s-meter reading, but using RF gain does.

On my TenTec Eagle, the S-meter reads independently of ATT, PRE AND RF gain control.  I find this very helpful, given that rely on the RF gain control adjustment to give me comfortable listening.  I can then look at the s-meter and give a meaningful report without having to wind up the RF gain.

Is there a way of implementing this on the K3?  Is there any reason why this hasn't been implemented in absolute mode?  Would be great if it could be.

73,
John
VK7JB

[Buck - k4ia]

Riding the RF gain just changes the floor.  An S7 signal will still read
S7.  No?

Buck
k4ia
K3 # 101

On 5/17/2011 7:56 PM, VK7JB wrote:

> Helpful comments, Jim.
> I ride the RF gain control on the K3 to very good effect.  The only problem,
> as you point out, is that the S-meter won't read signal strength at the
> antenna with the RF gain wound back.  I have my K3 s-meter set in absolute
> mode, so using ATT or PRE does not influence the s-meter reading, but using
> RF gain does.
>
> On my TenTec Eagle, the S-meter reads independently of ATT, PRE AND RF gain
> control.  I find this very helpful, given that rely on the RF gain control
> adjustment to give me comfortable listening.  I can then look at the s-meter
> and give a meaningful report without having to wind up the RF gain.
>
> Is there a way of implementing this on the K3?  Is there any reason why this
> hasn't been implemented in absolute mode?  Would be great if it could be.
>
> 73,
> John
> VK7JB
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/K3-RX-too-sensitive-for-me-tp6374861p6375785.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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[Guy, K2AV]

They're not likely to see this, rolling up to Dayton, but rolling the
s-meter up scale as you roll the RF gain back is making a digital
radio behave like an analog radio just to keep from all the complaints
that it's broke because it doesn't act analog.  The designer knows
full well that we tolerate changes very poorly, even changes that are
huge improvements. Remember that the analog S-meter was a voltage on a
bus that controlled gain all over the RX. When you manually reduced
the gain, that changed the resting voltage on that circuit and
"buried" any movement less than that voltage.  Hence the familiar
covering up of voltage changes for signals less than the increased
threshold.

If one has chosen "absolute" s-meter performance which is already
un-analog, it would be nice to see the input level regardless of the
RF gain setting, and perhaps just slow "plink" only the top segment
that would be "covered" with the analog convention.

73, Guy.

On Tue, May 17, 2011 at 11:40 PM, Ron D'Eau Claire <[hidden email]> wrote:

> Sometimes we're just too picky about that "S-Meter". Many years ago (almost
> before my time) a number of receivers had no meter but instead calibrated
> the gain control in S-units (or the S-unit's ancestor, the "R-unit"). If you
> wanted to see how strong the signal was, set the gain for a comfortable
> volume and check the position of the knob. Of course 99% of us reported
> signal strength "by ear" and didn't need a "calibrated" knob, Hi!
>
> I'm not entirely sure today's rigs are an improvement, at least in the area
> of receiver gain control. They are, however, much more "automatic" and with
> that comes limitations. I'm a heavy user of the ATTEN, Preamp and RF gain
> control in any receiver.

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[Stephen G4SJP]

I wholeheartedly agree.  This behaviour has always irked me.

73 Stephen G4SJP

On 18 May 2011 17:27, Guy Olinger K2AV <[hidden email]> wrote:

> They're not likely to see this, rolling up to Dayton, but rolling the
> s-meter up scale as you roll the RF gain back is making a digital
> radio behave like an analog radio just to keep from all the complaints
> that it's broke because it doesn't act analog.  The designer knows
> full well that we tolerate changes very poorly, even changes that are
> huge improvements. Remember that the analog S-meter was a voltage on a
> bus that controlled gain all over the RX. When you manually reduced
> the gain, that changed the resting voltage on that circuit and
> "buried" any movement less than that voltage.  Hence the familiar
> covering up of voltage changes for signals less than the increased
> threshold.
>
> If one has chosen "absolute" s-meter performance which is already
> un-analog, it would be nice to see the input level regardless of the
> RF gain setting, and perhaps just slow "plink" only the top segment
> that would be "covered" with the analog convention.
>
> 73, Guy.
>
> On Tue, May 17, 2011 at 11:40 PM, Ron D'Eau Claire <[hidden email]> wrote:
>> Sometimes we're just too picky about that "S-Meter". Many years ago (almost
>> before my time) a number of receivers had no meter but instead calibrated
>> the gain control in S-units (or the S-unit's ancestor, the "R-unit"). If you
>> wanted to see how strong the signal was, set the gain for a comfortable
>> volume and check the position of the knob. Of course 99% of us reported
>> signal strength "by ear" and didn't need a "calibrated" knob, Hi!
>>
>> I'm not entirely sure today's rigs are an improvement, at least in the area
>> of receiver gain control. They are, however, much more "automatic" and with
>> that comes limitations. I'm a heavy user of the ATTEN, Preamp and RF gain
>> control in any receiver.
> ______________________________________________________________
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[Nate Bargmann]

* On 2011 18 May 16:31 -0500, Ron D'Eau Claire wrote:

> So turning the RF gain down simply fools the receiver into acting as if a
> very strong signal was being received.

Please, could we refrain from using the venacular of "fooling" an
inanimate object when it comes to electronics?  No such thing is
happening.  What is happening is defined by physics and engineering
principles.  Nothing is being "fooled" except the poor amateur who lacks
the technical background and accepts that such tom-foolery of
electronics is possible.

I have yet to find the term "fooled" in technical documentation outside
of amateur radio.  Unfortunately, it's use is too widely and sadly
prevelant in our hobby especially with regard to antenna matching
networks.

This is not personal, just a pet peeve.

73, de Nate N0NB >>

--

"The optimist proclaims that we live in the best of all
possible worlds.  The pessimist fears this is true."

Ham radio, Linux, bikes, and more: http://www.n0nb.us
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[VK7JB]

"If one has chosen "absolute" s-meter performance which is already
un-analog, it would be nice to see the input level regardless of the
RF gain setting, and perhaps just slow "plink" only the top segment
that would be "covered" with the analog convention. "


Exactly my view, Guy.  "Absolute" on the K3 is only partly "Absolute".
My point is that other designers have implemented true "absolute" S-meter
function and it works well.  On my TT Eagle 599, I can ride the RF gain, play with ATT and PRE to my heart's content and still see the input level on the s-meter, uninfluenced by my fiddling.

I'm looking forward to being able to do the same in "absolute mode" on my K3 one day.

73,
John
VK7JB

[Guy, K2AV]

On Wed, May 18, 2011 at 5:29 PM, Ron D'Eau Claire <[hidden email]> wrote:
> Don't forget that the K3 *is* a largely analog radio. The signal path only
> goes digital at the second I.F.
>
> I believe the K3 (and K2) handle manual RF gain control just like any analog
> radio does - they insert an adjustable d-c bias gain control voltage that
> replaces voltage originally created by the received signal.

Well, not so much analog as you think. ALL of the smart stuff is done
digital, including the frequency synthesizers.  NONE of the gain
devices are DIRECTLY controlled from a knob or a switch.  You can
easily verify this with some time in the schematics, which are out in
the open on the Elecraft web site.

The RF and AF gain pots all have a standard voltage on top and the
wipe in the pot is fed to an analog to digital converter (ADC).  The
ADC's now digital advice from those pots is passed to the CPU.
Firmware decides what voltage should be sent to the variable gain IF
stage and can completely ignore the RF and AF pot's numerical advice
if it wants to.  All the audio output devices are FIXED GAIN.  The
conversion from the number stream representing the audio is fixed.
The audio gain pot's numerical advice is interpreted by firmware and
the output of the speakers was a flat multiplication of the number
stream fed to the speaker's digital to analog converter chip (DAC).

There is no RF or AF pot voltage lead off the front panel boards. It's
buried in multiplexing done by the FPU and buried in the number soup
passed to the main CPU.

The PRE and ATT button states have to be interpreted by the CPU to set
an internal state for each of those.  The CPU then sends a state
"message" to a demultiplexer which puts high or low on an output pin
to appropriate lines which throw diode switches which either include
or exclude the preamp and attenuator altogether from the signal path.
This procedure is why such things can be changed from commands coming
in on the CAT connection.

There is a defensive hardware (analog) AGC which will keep the output
of the 15 kHz IF from overranging the last IF's and RX signal ADC with
very loud signals. This is the only conventional analog gain device,
and if PRE and ATT are being used properly, it will infrequently be
used to throttle the variable IF gain.  It has nothing to do with the
menu-driven firmware AGC processing.  Wayne's description of this is
that the main AGC simply assumes that any defensive AGC assertions on
the signal are coming in on the antenna.  And the result is as if
magically no signal coming in ever overranges anything.

A K3 has close to as little analog stuff as is possible, second only
to a Flex which goes digital one step closer to the antenna. But the
Elecraft method saved having a PC with expensive top end audio
devices.  Pretty sound trade-off IMHO.

Yes it does have some analog circuitry in it, but it sure ain't your
daddy's analog radio.

73, Guy.
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[David Gilbert]

Can someone explain for me this recurring fixation on the K3 S-meter?  I
honestly don't understand why it is such a big deal for some folks.  If
you need accurate relative readings, such as when plotting antenna
patterns or something, you just pick some settings and leave them
alone.  Absolute readings are meaningless for signal reports because of
the much greater variability of antennas, feedlines, matching networks,
etc from station to station, and the guy on the other end has no way of
knowing where you fit into that continuum.   What you see on the meter
doesn't really mean anything, and the resolution on the scale isn't very
high anyway.

So what am I missing?  Some kind of misguided peace of mind?

Dave   AB7E



On 5/18/2011 4:50 PM, VK7JB wrote:

> "If one has chosen "absolute" s-meter performance which is already
> un-analog, it would be nice to see the input level regardless of the
> RF gain setting, and perhaps just slow "plink" only the top segment
> that would be "covered" with the analog convention. "
>
>
> Exactly my view, Guy.  "Absolute" on the K3 is only partly "Absolute".
> My point is that other designers have implemented true "absolute" S-meter
> function and it works well.  On my TT Eagle 599, I can ride the RF gain,
> play with ATT and PRE to my heart's content and still see the input level on
> the s-meter, uninfluenced by my fiddling.
>
> I'm looking forward to being able to do the same in "absolute mode" on my K3
> one day.
>
> 73,
> John
> VK7JB
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/K3-RX-too-sensitive-for-me-tp6374861p6380059.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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[VK7JB]

Well, from one perspective this is, of course true.  But this arguement leads to the question, why is an s-meter implemented at all on the K3 then?  If it doesn't really mean anything, why have it?

I'm more interested in exploring other questions.  Having decided it is of value to implement an s-meter on a rig, what are the different ways in which it can enunciate that which is being measured.  How can that be manipulated to best suit the operator?

Interesting discussion.

John
VK7JB


"What you see on the meter
doesn't really mean anything, and the resolution on the scale isn't very
high anyway. "

[AC7AC]

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[AC7AC]

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[Guy, K2AV]

On Wed, May 18, 2011 at 10:33 PM, Ron D'Eau Claire <[hidden email]> wrote:
> Guy, you obviously didn't read my post.
>
> I said the signal path was analog all the way to the second I.F.

Actually I DID read your post.  You said:

"Don't forget that the K3 *is* a largely analog radio."

I quite disagree with "largely", and that is what I was writing about.
 It AIN'T your daddy's analog radio.  It doesn't have an analog
skeleton, it doesn't have an analog heart, it doesn't have analog
controls, and the front panel could be easily remoted across the
internet if Wayne took a mind to do it. It's essential behavior is all
in firmware, not in the analog components.  If anything, it's
minimally analog as necessary.

And the signal path to the second IF is NOT all analog,  It is
composed of a collection of analog pieces which are switched in and
out, shared between RX and TX, directions reversed, by digital
switches controlled by firmware.  Most of the main board is dual use,
and there are dozens of those switching double diodes.  The preamp is
used in some situations in the transmit state.  It's all in plain view
in the schematics.

73, Guy.
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[drewko]

Same here. I haven't discovered any practical use for the s-meter
going to the top of the scale as the gain control is reduced.

73,
Drew
AF2Z


On Wed, 18 May 2011 16:50:41 -0700 (PDT), you wrote:

>
>Exactly my view, Guy.  "Absolute" on the K3 is only partly "Absolute".
>My point is that other designers have implemented true "absolute" S-meter
>function and it works well.  On my TT Eagle 599, I can ride the RF gain,
>play with ATT and PRE to my heart's content and still see the input level on
>the s-meter, uninfluenced by my fiddling.
>
>I'm looking forward to being able to do the same in "absolute mode" on my K3
>one day.
>
>73,
>John
>VK7JB

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