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K3s/FT8 Audio Question

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Richard-6

K3s/FT8 Audio Question

The Elecraft K3s manual states over and over that the RF gain should always be wide open. I had been running it at about 12 o'clock on FT8 for some time before this was brought to my attention. I supposed that 100% RF gain could possibly show me weak stations I’d not seen before, so I’m trying it.

In order to keep the Audio Input to WSJT FT8 at a reasonable level (nominally 40dB: noise only) with the K3s RF gain wide open I have to run the SignaLink’s RX way down near full CCW. Very touchy and hard to adjust. SignaLink’s JP2 jumper is NOT connected. I do NOT use AGC, nor do I wish to.

Oh, this is a Mac so the USB Audio Codec input has no level adjustment.

Any suggestions as to what I might do to get SignaLink’s RX back to about 12 o’clock where it used to be?

Please reply to [hidden email]

Cheers!

Richard Kunc - W4KBX
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Bill Frantz

Re: K3s/FT8 Audio Question

There is no reason to always run RF gain at maximum. Otherwise
there wouldn't be a control.

I have always set up FT8 with the gains about 12 o'clock and
adjusted the RF gain so the signal strength meter in wsjt-x is
about 60 to 70. This adjustment gives the maximum level for the
weak signals without overloading the analog to digital
converter. The whole idea is to get every stage in the RF and AF
chains in their linear range.

Sometimes when trying to copy a weak CW or SSB signal, dropping
the RF gain so the band noise is barely audible will help.

73 Bill AE6JV

On 10/30/19 at 8:24 PM, [hidden email] (Richard) wrote:

>The Elecraft K3s manual states over and over that the RF gain
>should always be wide open. I had been running it at about 12
>o'clock on FT8 for some time before this was brought to my
>attention. I supposed that 100% RF gain could possibly show me
>weak stations I’d not seen before, so I’m trying it.
>
>In order to keep the Audio Input to WSJT FT8 at a reasonable
>level (nominally 40dB: noise only) with the K3s RF gain wide
>open I have to run the SignaLink’s RX way down near full CCW.
>Very touchy and hard to adjust. SignaLink’s JP2 jumper is
>NOT connected. I do NOT use AGC, nor do I wish to.
>
>Oh, this is a Mac so the USB Audio Codec input has no level adjustment.
>
>Any suggestions as to what I might do to get SignaLink’s RX
>back to about 12 o’clock where it used to be?
>
>Please reply to [hidden email]
>
>Cheers!
>
>Richard Kunc - W4KBX

-----------------------------------------------------------------------
Bill Frantz | When an old person dies, a | Periwinkle
(408)356-8506 | library burns. - Joe McGawon | 16345
Englewood Ave
www.pwpconsult.com | Irish Ethnographer | Los Gatos,
CA 95032

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Bob McGraw - K4TAX

Re: K3s/FT8 Audio Question

In reply to this post by Richard-6

You can reduce the LIN OUT level via the Config menu in the radio.
Normal is 010. I would back that value down.

I use Windows 10 thus I have full control of all levels via the
computer.   Also I use the USB connection between the radio and computer
and do not need a Signalink.

I can't say I agree that RF Gain should always be at maximum, nor do I
agree that AGC should be OFF. I know that information in the WSJT-X
Help file indicated to turn AGC off.    I know is I've been operating
my K3S for 3 years now, I use the RF Gain as needed to set the receiver
for optimum performance based on no signal band noise.    And I run the
AGC on Fast with a RX BW of 2.7kHz and don't experience any issues from
strong stations.   I think the key is setting the RF Gain and ATTN to
values to allow the no signal band noise to be about 10 dB above the
noise floor of the receiver.

73

Bob, K4TAX

On 10/30/2019 7:24 PM, Richard wrote:

> The Elecraft K3s manual states over and over that the RF gain should always be wide open. I had been running it at about 12 o'clock on FT8 for some time before this was brought to my attention. I supposed that 100% RF gain could possibly show me weak stations I’d not seen before, so I’m trying it.
>
> In order to keep the Audio Input to WSJT FT8 at a reasonable level (nominally 40dB: noise only) with the K3s RF gain wide open I have to run the SignaLink’s RX way down near full CCW. Very touchy and hard to adjust. SignaLink’s JP2 jumper is NOT connected. I do NOT use AGC, nor do I wish to.
>
> Oh, this is a Mac so the USB Audio Codec input has no level adjustment.
>
> Any suggestions as to what I might do to get SignaLink’s RX back to about 12 o’clock where it used to be?
>
> Please reply to [hidden email]
>
> Cheers!
>
> Richard Kunc - W4KBX
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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Bob McGraw - K4TAX

Optimum Receiver Performance

In reply to this post by Bill Frantz

In writing this, I do so, saying that I find the method to be excellent
and reliable and repeatable with regard to HF radio receiver operation
for all modes.

In general it seems that hams have the more incorrect notion or idea
where more gain is needed to hear a weak signal. To some degree in
certain conditions that is true, but not understanding the why and the
how can actually lead to worst receiver performance issues. In my
communications with Rob Sherwood, {Sherwood Engineering, Inc.} both
face to face and in writing, I've learned that most if not many hams use
too much RF Gain with their receivers. All legacy receivers are
typically designed for 10 meters, thus attenuation is desirable on the
lower HF bands. I've adopted this recommend practice and I'm amazed at
the weak signals that I would often miss hearing that I now can hear and
pull out of the noise.

If the no signal band noise is reading upscale on your S meter, add some
attenuation and/or reduce the RF Gain. There is no point in the noise
running the AGC.   You would like the no signal band noise to be about
10 dB above the noise floor of the receiver.

If the receiver noise floor is 10 dB below band noise, the receiver is
contributing less than 0.5 dB of the total noise. Thus more gain means
more receiver noise.    So how does all of this work?    As an example;
the value taken from the manufactures specifications we find the
receiver noise floor to be -130 dBm. Therefore, the target of 10 dB
above the receiver noise floor for the no signal band noise would be
-120 dBm.   Band noise, by band, varies as much as 30 dB over the bands
160M - 10M.    In a noisy urban environment it is anybody's guess at to
you band noise level. The point being, you must adjust receiver gain,
and attenuation based on your antenna and your location to attain be
best results.   It will most assuredly be different for each band and
antenna to antenna.    And with directional antennas, some directions
are noisier than others.

Here's how one is able to determine band noise.   On a clear frequency
for that band and with the chosen antenna, with no attenuation, no
preamp and RF gain a maximum, observe the S meter value.   For our
example; lets say the S meter reads S-5 on no signal band noise. This
is equivalent to -97 dBm.   There are charts readily available to
convert S units to dBm. {see ARRL Handbook} We accept the standard of
6 dB per S unit.   Now for the math; our target of 10 dB above receiver
noise floor is -120 dBm and our band noise is -97 dBm. The difference
is 23 dB. This says we need to use some value of attenuation, example 15
dB, and 8 dB of RF gain reduction for a total of 23 dB. This then
places the band noise at 10 dB above the noise floor of the receiver.
Depending on your receiver, you may have different values of attenuation
choices.   Also we must realize with directional antennas that band
noise will likely vary with direction. Usually worst case and best case
conditions must be observed in order to resolve a nominal value.

As to the method for adjusting RF Gain, most receivers' S meter will
move up scale as RF Gain is reduced. At 6 dB per S unit, reducing the
RF Gain such that the receiver S meter indicates 3 S units would be
equivalent of 18 dB.   This is easily seen when the receiver is
connected to a dummy load.

Another way to assure you have this correct is to connect an AC
voltmeter, one that reads dB to the audio output of the receiver. Adjust
the receiver gain such that the meter reads -10 db when the receiver is
on a dummy load. Then connect the antenna. If the noise goes up 3 dB
that says the the receiver is contributing 1/2 of the noise. If you can
barely hear your antenna connect, you will need more RF Gain or less
attenuation.

As to the use of the receiver preamp, again that is some amount of gain
added to the receiver chain and must be considered accordingly. As a
rule, the preamp should only be engaged on the higher bands, 6M and 10M
and to a lesser extent on other bands. Also one must take into
consideration of the noise floor of the receiver with the preamp engaged.

For further study on the subject, visit Sherwood Engineering for one of
his papers, videos, or PowerPoint presentations for Contest
University. Look under the heading of "Presentations, Tips and How to,
and White Papers" . http://www.sherweng.com/

73

Bob, K4TAX

On 10/30/2019 7:33 PM, Bill Frantz wrote:

> There is no reason to always run RF gain at maximum. Otherwise there
> wouldn't be a control.
>
> I have always set up FT8 with the gains about 12 o'clock and adjusted
> the RF gain so the signal strength meter in wsjt-x is about 60 to 70.
> This adjustment gives the maximum level for the weak signals without
> overloading the analog to digital converter. The whole idea is to get
> every stage in the RF and AF chains in their linear range.
>
> Sometimes when trying to copy a weak CW or SSB signal, dropping the RF
> gain so the band noise is barely audible will help.
>
> 73 Bill AE6JV
>
>

David Olean

Re: Optimum Receiver Performance

I just had a graphic demonstration of the fact Bob mentioned when I was
just rebuilding an old R-390 receiver a few weeks ago. I was pleased
that I saw an AM sensitivity (30% modulation in a 4 khz BW) of 0.49
microvolts for a 10 dB S/N ratio at 26 MHz. I then realized that I had
the IF gain (an internal pot) set way too high. I re adjusted it to drop
the gain and saw 0.28 microvolts in a 4 kHz BW and 0.14 microvolts in a
2 kHz BW . More isn't always better.

Dave K1WHS

On 10/31/2019 1:03 AM, Bob McGraw K4TAX wrote:

> In writing this, I do so, saying that I find the method to be
> excellent and reliable and repeatable with regard to HF radio receiver
> operation for all modes.
>
> In general it seems that hams have the more incorrect notion or idea
> where more gain is needed to hear a weak signal. To some degree in
> certain conditions that is true, but not understanding the why and the
> how can actually lead to worst receiver performance issues. In my
> communications with Rob Sherwood, {Sherwood Engineering, Inc.} both
> face to face and in writing, I've learned that most if not many hams
> use too much RF Gain with their receivers. All legacy receivers are
> typically designed for 10 meters, thus attenuation is desirable on the
> lower HF bands. I've adopted this recommend practice and I'm amazed at
> the weak signals that I would often miss hearing that I now can hear
> and pull out of the noise.
>
> If the no signal band noise is reading upscale on your S meter, add
> some attenuation and/or reduce the RF Gain. There is no point in the
> noise running the AGC.   You would like the no signal band noise to be
> about 10 dB above the noise floor of the receiver.
>
> If the receiver noise floor is 10 dB below band noise, the receiver is
> contributing less than 0.5 dB of the total noise. Thus more gain means
> more receiver noise.    So how does all of this work?    As an
> example; the value taken from the manufactures specifications we find
> the receiver noise floor to be -130 dBm. Therefore, the target of 10
> dB above the receiver noise floor for the no signal band noise would
> be -120 dBm.   Band noise, by band, varies as much as 30 dB over the
> bands 160M - 10M.    In a noisy urban environment it is anybody's
> guess at to you band noise level. The point being, you must adjust
> receiver gain, and attenuation based on your antenna and your location
> to attain be best results.   It will most assuredly be different for
> each band and antenna to antenna.    And with directional antennas,
> some directions are noisier than others.
>
> Here's how one is able to determine band noise.   On a clear frequency
> for that band and with the chosen antenna, with no attenuation, no
> preamp and RF gain a maximum, observe the S meter value.   For our
> example; lets say the S meter reads S-5 on no signal band noise. This
> is equivalent to -97 dBm.   There are charts readily available to
> convert S units to dBm. {see ARRL Handbook} We accept the standard
> of 6 dB per S unit.   Now for the math; our target of 10 dB above
> receiver noise floor is -120 dBm and our band noise is -97 dBm. The
> difference is 23 dB. This says we need to use some value of
> attenuation, example 15 dB, and 8 dB of RF gain reduction for a total
> of 23 dB. This then places the band noise at 10 dB above the noise
> floor of the receiver. Depending on your receiver, you may have
> different values of attenuation choices.   Also we must realize with
> directional antennas that band noise will likely vary with direction.
> Usually worst case and best case conditions must be observed in order
> to resolve a nominal value.
>
> As to the method for adjusting RF Gain, most receivers' S meter will
> move up scale as RF Gain is reduced. At 6 dB per S unit, reducing the
> RF Gain such that the receiver S meter indicates 3 S units would be
> equivalent of 18 dB.   This is easily seen when the receiver is
> connected to a dummy load.
>
> Another way to assure you have this correct is to connect an AC
> voltmeter, one that reads dB to the audio output of the receiver.
> Adjust the receiver gain such that the meter reads -10 db when the
> receiver is on a dummy load. Then connect the antenna. If the noise
> goes up 3 dB that says the the receiver is contributing 1/2 of the
> noise. If you can barely hear your antenna connect, you will need
> more RF Gain or less attenuation.
>
> As to the use of the receiver preamp, again that is some amount of
> gain added to the receiver chain and must be considered accordingly.
> As a rule, the preamp should only be engaged on the higher bands, 6M
> and 10M and to a lesser extent on other bands. Also one must take into
> consideration of the noise floor of the receiver with the preamp engaged.
>
> For further study on the subject, visit Sherwood Engineering for one
> of his papers, videos, or PowerPoint presentations for Contest
> University. Look under the heading of "Presentations, Tips and How
> to, and White Papers" . http://www.sherweng.com/
>
> 73
>
> Bob, K4TAX
>
>
> On 10/30/2019 7:33 PM, Bill Frantz wrote:
>> There is no reason to always run RF gain at maximum. Otherwise there
>> wouldn't be a control.
>>
>> I have always set up FT8 with the gains about 12 o'clock and adjusted
>> the RF gain so the signal strength meter in wsjt-x is about 60 to 70.
>> This adjustment gives the maximum level for the weak signals without
>> overloading the analog to digital converter. The whole idea is to get
>> every stage in the RF and AF chains in their linear range.
>>
>> Sometimes when trying to copy a weak CW or SSB signal, dropping the
>> RF gain so the band noise is barely audible will help.
>>
>> 73 Bill AE6JV
>>
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

Gwen Patton

Re: K3s/FT8 Audio Question

In reply to this post by Bob McGraw - K4TAX

I found an article a while back that extolled the virtue of running with
the volume all the way up, but the RF gain down. That way, you don't
amplify the noise along with the signal, if the signal is sticking up out
of the noise at all. It works pretty well! I'd get so frustrated trying to
keep the RF gain high and adjust the volume up and down, trying to pick out
a weak signal. The hash was always so hard to isolate the signal from, no
matter how much I diddled the filters. But running with volume high and
adjusting volume with the RF gain appears to work a lot better. I get far
better performance on my KX3 doing that!

Here's the article:
https://www.hamradioqrp.com/2015/08/copying-weak-cw-signals-counter.html

73,
Gwen, NG3P

On Wed, Oct 30, 2019 at 8:50 PM Bob McGraw K4TAX <[hidden email]>
wrote:

> You can reduce the LIN OUT level via the Config menu in the radio.
> Normal is 010. I would back that value down.
>
> I use Windows 10 thus I have full control of all levels via the
> computer. Also I use the USB connection between the radio and computer
> and do not need a Signalink.
>
> I can't say I agree that RF Gain should always be at maximum, nor do I
> agree that AGC should be OFF. I know that information in the WSJT-X
> Help file indicated to turn AGC off. I know is I've been operating
> my K3S for 3 years now, I use the RF Gain as needed to set the receiver
> for optimum performance based on no signal band noise. And I run the
> AGC on Fast with a RX BW of 2.7kHz and don't experience any issues from
> strong stations. I think the key is setting the RF Gain and ATTN to
> values to allow the no signal band noise to be about 10 dB above the
> noise floor of the receiver.
>
> 73
>
> Bob, K4TAX
>
> On 10/30/2019 7:24 PM, Richard wrote:
> > The Elecraft K3s manual states over and over that the RF gain should
> always be wide open. I had been running it at about 12 o'clock on FT8 for
> some time before this was brought to my attention. I supposed that 100% RF
> gain could possibly show me weak stations I’d not seen before, so I’m
> trying it.
> >
> > In order to keep the Audio Input to WSJT FT8 at a reasonable level
> (nominally 40dB: noise only) with the K3s RF gain wide open I have to run
> the SignaLink’s RX way down near full CCW. Very touchy and hard to adjust.
> SignaLink’s JP2 jumper is NOT connected. I do NOT use AGC, nor do I wish
> to.
> >
> > Oh, this is a Mac so the USB Audio Codec input has no level adjustment.
> >
> > Any suggestions as to what I might do to get SignaLink’s RX back to
> about 12 o’clock where it used to be?
> >
> > Please reply to [hidden email]
> >
> > Cheers!
> >
> > Richard Kunc - W4KBX
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to [hidden email]
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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