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BFO resets itself after cal fil (K2)

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Erik Linder-2

BFO resets itself after cal fil (K2)

Hi all,

I decided to recalibrate the filters in my K2 because I noticed a small
RX-TX frequency difference which made it hard to use my NUE-PSK.

But I didn't get the calibration working...

I enter filter calibration menu. I select FL1 in open-mode. I adjust (in
RX) the BFO and watch the audio move on the waterfall (change pitch). All
seems 100% OK.
Then I press XFIL to save the value. (the freq-probe is in TP2 - duoble
checked).
When I then return to FL1 the pitch is back where it was from the start.

I first thaught that the value did not get saved, but after re-checking the
BFO-D/A value it has been saved.
I then tried to measure U8 pin 16 to see if the control voltage is changing
- yes it is.
The voltage changes when I change the BFO-D/A value in cal filter. The
value I choose will be saved and I can measure the same voltage when I
return to FL1.

But the BFO keeps resetting itself no matter what value I choose in cal
filter. The most strange thing is that the BFO changes as long as I am in
cal filter menu, it resets itself when I change filter (saving the value)

I had the SSB option in, but in the troubleshooting I removed it. The
behavior is still the same with or without the SSB option plugged in.

So... Can anyone give me a clue what's going on here?

Tnx in advance and 73 de SM0RVV
./Erik
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Don Wilhelm-4

Re: BFO resets itself after cal fil (K2)

Erik,

Do you see the BFO frequency flashed on the display when you exit? If
so, you are verifying that the value is being saved.

Fact, the DAC resolution in the K2 is about 20 Hz. If the difference is
less than 20 Hz, it my be a situation you have to live with - you have
reached the limit.

Are you using SSB or the RTTY filter set? If so, there should be no
difference in the VFO between RX and TX. If you are listening with a
filter other than FL1, then yes the BFO will be switched to FL1 for TX.
If your goal is no difference between TX and RX, then you will have to
RX with FL1

If you use an RX filter different than FL1, you will have to unlock TX
and RX in your software to keep from "walking the band". Most packages
allow that - I don't know about the NUE-PSK, but II would think that is
a required condition.

73,
Don W3FPR

On 4/29/2012 3:28 PM, Erik Linder wrote:

> Hi all,
>
> I decided to recalibrate the filters in my K2 because I noticed a small
> RX-TX frequency difference which made it hard to use my NUE-PSK.
>
> But I didn't get the calibration working...
>
> I enter filter calibration menu. I select FL1 in open-mode. I adjust (in
> RX) the BFO and watch the audio move on the waterfall (change pitch). All
> seems 100% OK.
> Then I press XFIL to save the value. (the freq-probe is in TP2 - duoble
> checked).
> When I then return to FL1 the pitch is back where it was from the start.
>
> I first thaught that the value did not get saved, but after re-checking the
> BFO-D/A value it has been saved.
> I then tried to measure U8 pin 16 to see if the control voltage is changing
> - yes it is.
> The voltage changes when I change the BFO-D/A value in cal filter. The
> value I choose will be saved and I can measure the same voltage when I
> return to FL1.
>
> But the BFO keeps resetting itself no matter what value I choose in cal
> filter. The most strange thing is that the BFO changes as long as I am in
> cal filter menu, it resets itself when I change filter (saving the value)
>
> I had the SSB option in, but in the troubleshooting I removed it. The
> behavior is still the same with or without the SSB option plugged in.
>
> So... Can anyone give me a clue what's going on here?
>
> Tnx in advance and 73 de SM0RVV
> ./Erik
> ______________________________________________________________
> 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
>

______________________________________________________________
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Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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Erik Linder-2

Re: BFO resets itself after cal fil (K2)

Don, tnx for the answer.

Yes, the difference was small. Tnx for the info about 20 Hz, then I now the
limitation of the construction.

Yes I can use the FL1 (open) as both TX and RX (well of course TX is alway
using FL1). But if I want something more narrow I like to use FL2 - FL4.
And now I know that I can get in 20 or so Hz if I work hard enough. :-)

But the main problem here is that I cannot adjust my filters at all right
now. :-(
I can move the BFO (change the pitch) as long as I am in cal fil but as
soon as I save the filter and return to listen the pitch has changed to
"default". The BFO-value _has_ changed, it _has_ been saved. (I see the
display showing BFO freq for a short time).
But still - the pitch is where it was before I changed the BFO-value.

And I have changed it much - like 50 to 100 units. USB, LSB, CW - the mode
does no difference.

So:
Received pitch of the signal transmitted from my 2:nd TRX: 1500 Hz
The BFO value is (lets say) 128
I change the BFO value too 100
I hear (and see on the waterfall) that the pitch is changing.
I press XFIL (to save)
Display shows BFO freq for a short time.
I press XFIL a couple of times to "get round" to FL1 again.
The pitch has now jumped back to 1500
The BFO-value is at it's saved 100

I can now lower the BFO value once more and when I come around the pitch
will be 1500 and the BFO is saved with the new value.

Isn't it suppose to work like:
Change the BFO to get the correct pitch
Save
Return to the filter and the pitch is where you programmed it to be.

73 de SM0RVV
./Erik

2012/4/29 Don Wilhelm <[hidden email]>

> Erik,
>
> Do you see the BFO frequency flashed on the display when you exit? If so,
> you are verifying that the value is being saved.
>
> Fact, the DAC resolution in the K2 is about 20 Hz. If the difference is
> less than 20 Hz, it my be a situation you have to live with - you have
> reached the limit.
>
> Are you using SSB or the RTTY filter set? If so, there should be no
> difference in the VFO between RX and TX. If you are listening with a
> filter other than FL1, then yes the BFO will be switched to FL1 for TX. If
> your goal is no difference between TX and RX, then you will have to RX with
> FL1
>
> If you use an RX filter different than FL1, you will have to unlock TX and
> RX in your software to keep from "walking the band". Most packages allow
> that - I don't know about the NUE-PSK, but II would think that is a
> required condition.
>
> 73,
> Don W3FPR
>
>
> On 4/29/2012 3:28 PM, Erik Linder wrote:
>
>> Hi all,
>>
>> I decided to recalibrate the filters in my K2 because I noticed a small
>> RX-TX frequency difference which made it hard to use my NUE-PSK.
>>
>> But I didn't get the calibration working...
>>
>> I enter filter calibration menu. I select FL1 in open-mode. I adjust (in
>> RX) the BFO and watch the audio move on the waterfall (change pitch). All
>> seems 100% OK.
>> Then I press XFIL to save the value. (the freq-probe is in TP2 - duoble
>> checked).
>> When I then return to FL1 the pitch is back where it was from the start.
>>
>> I first thaught that the value did not get saved, but after re-checking
>> the
>> BFO-D/A value it has been saved.
>> I then tried to measure U8 pin 16 to see if the control voltage is
>> changing
>> - yes it is.
>> The voltage changes when I change the BFO-D/A value in cal filter. The
>> value I choose will be saved and I can measure the same voltage when I
>> return to FL1.
>>
>> But the BFO keeps resetting itself no matter what value I choose in cal
>> filter. The most strange thing is that the BFO changes as long as I am in
>> cal filter menu, it resets itself when I change filter (saving the value)
>>
>> I had the SSB option in, but in the troubleshooting I removed it. The
>> behavior is still the same with or without the SSB option plugged in.
>>
>> So... Can anyone give me a clue what's going on here?
>>
>> Tnx in advance and 73 de SM0RVV
>> ./Erik
>> ______________________________**______________________________**__
>> Elecraft mailing list
>> Home: http://mailman.qth.net/**mailman/listinfo/elecraft<http://mailman.qth.net/mailman/listinfo/elecraft>
>> Help: http://mailman.qth.net/mmfaq.**htm<http://mailman.qth.net/mmfaq.htm>
>> Post: mailto:[hidden email].**net <[hidden email]>
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
>>

Don Wilhelm-4

Re: BFO resets itself after cal fil (K2)

Erik,

The K2 will preserve the pitch when the BFO is changed. Of course, if
you move the BFO enough, the signal will no longer be inside the passband.

You must move the VFO to change the pitch, just changing the BFO will
not do it. The filter passband edges will change, but the pitch of a
tuned signal will not. That is why it is important to use a broadband
noise generator (often band noise will do) and some type of audio
spectrum analyzer (I use Spectrogram) to view the shape of the passband
- you can see when it is centered at your target pitch. Use no signals
in the passband when changing the filters, having signals present will
only confuse your view of the passband shape and positioning.

If you need Spectrogram, you can find it on my website www.w3fpr.com -
look near the bottom of the opening page.

73,
Don W3FPR

On 4/29/2012 4:40 PM, Erik Linder wrote:

> Don, tnx for the answer.
>
> Yes, the difference was small. Tnx for the info about 20 Hz, then I now the
> limitation of the construction.
>
> Yes I can use the FL1 (open) as both TX and RX (well of course TX is alway
> using FL1). But if I want something more narrow I like to use FL2 - FL4.
> And now I know that I can get in 20 or so Hz if I work hard enough. :-)
>
> But the main problem here is that I cannot adjust my filters at all right
> now. :-(
> I can move the BFO (change the pitch) as long as I am in cal fil but as
> soon as I save the filter and return to listen the pitch has changed to
> "default". The BFO-value _has_ changed, it _has_ been saved. (I see the
> display showing BFO freq for a short time).
> But still - the pitch is where it was before I changed the BFO-value.
>
> And I have changed it much - like 50 to 100 units. USB, LSB, CW - the mode
> does no difference.
>
> So:
> Received pitch of the signal transmitted from my 2:nd TRX: 1500 Hz
> The BFO value is (lets say) 128
> I change the BFO value too 100
> I hear (and see on the waterfall) that the pitch is changing.
> I press XFIL (to save)
> Display shows BFO freq for a short time.
> I press XFIL a couple of times to "get round" to FL1 again.
> The pitch has now jumped back to 1500
> The BFO-value is at it's saved 100
>
> I can now lower the BFO value once more and when I come around the pitch
> will be 1500 and the BFO is saved with the new value.
>
> Isn't it suppose to work like:
> Change the BFO to get the correct pitch
> Save
> Return to the filter and the pitch is where you programmed it to be.
>

Erik Linder-2

Re: BFO resets itself after cal fil (K2)

Aha! Then I did not fully understand the inner workings of the K2.
I just looked att the schematics and noticed the BFO and the mixer. Out of
that I made the conclution that the BFO value must change the pitch.

So what you are saying is:
During filter setup, it is normal for the pitch to change but when I press
XFIL the save-routine inside the K2 is compensating for the change and
restores the pitch to its original position?
Is that correct?

Which in practice means that I cannot adjust the pitch manually (like on an
old radio), it's up to the K2 routine to set the pitch.

./Erik

2012/4/29 Don Wilhelm <[hidden email]>

> Erik,
>
> The K2 will preserve the pitch when the BFO is changed. Of course, if
> you move the BFO enough, the signal will no longer be inside the passband.
>
> You must move the VFO to change the pitch, just changing the BFO will
> not do it. The filter passband edges will change, but the pitch of a
> tuned signal will not. That is why it is important to use a broadband
> noise generator (often band noise will do) and some type of audio
> spectrum analyzer (I use Spectrogram) to view the shape of the passband
> - you can see when it is centered at your target pitch. Use no signals
> in the passband when changing the filters, having signals present will
> only confuse your view of the passband shape and positioning.
>
> If you need Spectrogram, you can find it on my website www.w3fpr.com -
> look near the bottom of the opening page.
>
> 73,
> Don W3FPR
>
>
> On 4/29/2012 4:40 PM, Erik Linder wrote:
> > Don, tnx for the answer.
> >
> > Yes, the difference was small. Tnx for the info about 20 Hz, then I now
> the
> > limitation of the construction.
> >
> > Yes I can use the FL1 (open) as both TX and RX (well of course TX is
> alway
> > using FL1). But if I want something more narrow I like to use FL2 - FL4.
> > And now I know that I can get in 20 or so Hz if I work hard enough. :-)
> >
> > But the main problem here is that I cannot adjust my filters at all right
> > now. :-(
> > I can move the BFO (change the pitch) as long as I am in cal fil but as
> > soon as I save the filter and return to listen the pitch has changed to
> > "default". The BFO-value _has_ changed, it _has_ been saved. (I see the
> > display showing BFO freq for a short time).
> > But still - the pitch is where it was before I changed the BFO-value.
> >
> > And I have changed it much - like 50 to 100 units. USB, LSB, CW - the
> mode
> > does no difference.
> >
> > So:
> > Received pitch of the signal transmitted from my 2:nd TRX: 1500 Hz
> > The BFO value is (lets say) 128
> > I change the BFO value too 100
> > I hear (and see on the waterfall) that the pitch is changing.
> > I press XFIL (to save)
> > Display shows BFO freq for a short time.
> > I press XFIL a couple of times to "get round" to FL1 again.
> > The pitch has now jumped back to 1500
> > The BFO-value is at it's saved 100
> >
> > I can now lower the BFO value once more and when I come around the pitch
> > will be 1500 and the BFO is saved with the new value.
> >
> > Isn't it suppose to work like:
> > Change the BFO to get the correct pitch
> > Save
> > Return to the filter and the pitch is where you programmed it to be.
> >
> ______________________________________________________________
> 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
>

Don Wilhelm-4

Re: BFO resets itself after cal fil (K2)

Erik,

Yes, that is why you cannot use a single signal (tone) when aligning the
filters.
The use of a broadband noise source and an audio spectrum analyzer
application running on the computer soundcard will make K2 filter setup
easy and uncomplicated.

73,
Don W3FPR

On 4/30/2012 2:49 AM, Erik Linder wrote:

> Aha! Then I did not fully understand the inner workings of the K2.
> I just looked att the schematics and noticed the BFO and the mixer. Out of
> that I made the conclution that the BFO value must change the pitch.
>
> So what you are saying is:
> During filter setup, it is normal for the pitch to change but when I press
> XFIL the save-routine inside the K2 is compensating for the change and
> restores the pitch to its original position?
> Is that correct?
>
> Which in practice means that I cannot adjust the pitch manually (like on an
> old radio), it's up to the K2 routine to set the pitch.
>
> ./Erik
>
> 2012/4/29 Don Wilhelm<[hidden email]>
>
>> Erik,
>>
>> The K2 will preserve the pitch when the BFO is changed. Of course, if
>> you move the BFO enough, the signal will no longer be inside the passband.
>>
>> You must move the VFO to change the pitch, just changing the BFO will
>> not do it. The filter passband edges will change, but the pitch of a
>> tuned signal will not. That is why it is important to use a broadband
>> noise generator (often band noise will do) and some type of audio
>> spectrum analyzer (I use Spectrogram) to view the shape of the passband
>> - you can see when it is centered at your target pitch. Use no signals
>> in the passband when changing the filters, having signals present will
>> only confuse your view of the passband shape and positioning.
>>
>> If you need Spectrogram, you can find it on my website www.w3fpr.com -
>> look near the bottom of the opening page.
>>
>> 73,
>> Don W3FPR
>>
>>
>> On 4/29/2012 4:40 PM, Erik Linder wrote:
>>> Don, tnx for the answer.
>>>
>>> Yes, the difference was small. Tnx for the info about 20 Hz, then I now
>> the
>>> limitation of the construction.
>>>
>>> Yes I can use the FL1 (open) as both TX and RX (well of course TX is
>> alway
>>> using FL1). But if I want something more narrow I like to use FL2 - FL4.
>>> And now I know that I can get in 20 or so Hz if I work hard enough. :-)
>>>
>>> But the main problem here is that I cannot adjust my filters at all right
>>> now. :-(
>>> I can move the BFO (change the pitch) as long as I am in cal fil but as
>>> soon as I save the filter and return to listen the pitch has changed to
>>> "default". The BFO-value _has_ changed, it _has_ been saved. (I see the
>>> display showing BFO freq for a short time).
>>> But still - the pitch is where it was before I changed the BFO-value.
>>>
>>> And I have changed it much - like 50 to 100 units. USB, LSB, CW - the
>> mode
>>> does no difference.
>>>
>>> So:
>>> Received pitch of the signal transmitted from my 2:nd TRX: 1500 Hz
>>> The BFO value is (lets say) 128
>>> I change the BFO value too 100
>>> I hear (and see on the waterfall) that the pitch is changing.
>>> I press XFIL (to save)
>>> Display shows BFO freq for a short time.
>>> I press XFIL a couple of times to "get round" to FL1 again.
>>> The pitch has now jumped back to 1500
>>> The BFO-value is at it's saved 100
>>>
>>> I can now lower the BFO value once more and when I come around the pitch
>>> will be 1500 and the BFO is saved with the new value.
>>>
>>> Isn't it suppose to work like:
>>> Change the BFO to get the correct pitch
>>> Save
>>> Return to the filter and the pitch is where you programmed it to be.
>>>
>> ______________________________________________________________
>> 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
>>
> ______________________________________________________________
> 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
>

Erik Linder-2

Re: BFO resets itself after cal fil (K2)

Thank you for the help.
Despite owning the K2 since 2005 its not until now I start to understand
it. :$ :-)

Thanks again and best 73 de SM0RVV
./Erik
Den 30 apr 2012 13:04 skrev "Don Wilhelm" <[hidden email]>:

> Erik,
>
> Yes, that is why you cannot use a single signal (tone) when aligning the
> filters.
> The use of a broadband noise source and an audio spectrum analyzer
> application running on the computer soundcard will make K2 filter setup
> easy and uncomplicated.
>
> 73,
> Don W3FPR
>
> On 4/30/2012 2:49 AM, Erik Linder wrote:
>
>> Aha! Then I did not fully understand the inner workings of the K2.
>> I just looked att the schematics and noticed the BFO and the mixer. Out of
>> that I made the conclution that the BFO value must change the pitch.
>>
>> So what you are saying is:
>> During filter setup, it is normal for the pitch to change but when I press
>> XFIL the save-routine inside the K2 is compensating for the change and
>> restores the pitch to its original position?
>> Is that correct?
>>
>> Which in practice means that I cannot adjust the pitch manually (like on
>> an
>> old radio), it's up to the K2 routine to set the pitch.
>>
>> ./Erik
>>
>> 2012/4/29 Don Wilhelm<[hidden email]>
>>
>> Erik,
>>>
>>> The K2 will preserve the pitch when the BFO is changed. Of course, if
>>> you move the BFO enough, the signal will no longer be inside the
>>> passband.
>>>
>>> You must move the VFO to change the pitch, just changing the BFO will
>>> not do it. The filter passband edges will change, but the pitch of a
>>> tuned signal will not. That is why it is important to use a broadband
>>> noise generator (often band noise will do) and some type of audio
>>> spectrum analyzer (I use Spectrogram) to view the shape of the passband
>>> - you can see when it is centered at your target pitch. Use no signals
>>> in the passband when changing the filters, having signals present will
>>> only confuse your view of the passband shape and positioning.
>>>
>>> If you need Spectrogram, you can find it on my website www.w3fpr.com -
>>> look near the bottom of the opening page.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>>
>>> On 4/29/2012 4:40 PM, Erik Linder wrote:
>>>
>>>> Don, tnx for the answer.
>>>>
>>>> Yes, the difference was small. Tnx for the info about 20 Hz, then I now
>>>>
>>> the
>>>
>>>> limitation of the construction.
>>>>
>>>> Yes I can use the FL1 (open) as both TX and RX (well of course TX is
>>>>
>>> alway
>>>
>>>> using FL1). But if I want something more narrow I like to use FL2 - FL4.
>>>> And now I know that I can get in 20 or so Hz if I work hard enough. :-)
>>>>
>>>> But the main problem here is that I cannot adjust my filters at all
>>>> right
>>>> now. :-(
>>>> I can move the BFO (change the pitch) as long as I am in cal fil but as
>>>> soon as I save the filter and return to listen the pitch has changed to
>>>> "default". The BFO-value _has_ changed, it _has_ been saved. (I see the
>>>> display showing BFO freq for a short time).
>>>> But still - the pitch is where it was before I changed the BFO-value.
>>>>
>>>> And I have changed it much - like 50 to 100 units. USB, LSB, CW - the
>>>>
>>> mode
>>>
>>>> does no difference.
>>>>
>>>> So:
>>>> Received pitch of the signal transmitted from my 2:nd TRX: 1500 Hz
>>>> The BFO value is (lets say) 128
>>>> I change the BFO value too 100
>>>> I hear (and see on the waterfall) that the pitch is changing.
>>>> I press XFIL (to save)
>>>> Display shows BFO freq for a short time.
>>>> I press XFIL a couple of times to "get round" to FL1 again.
>>>> The pitch has now jumped back to 1500
>>>> The BFO-value is at it's saved 100
>>>>
>>>> I can now lower the BFO value once more and when I come around the pitch
>>>> will be 1500 and the BFO is saved with the new value.
>>>>
>>>> Isn't it suppose to work like:
>>>> Change the BFO to get the correct pitch
>>>> Save
>>>> Return to the filter and the pitch is where you programmed it to be.
>>>>
>>>> ______________________________**______________________________**__
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/**mailman/listinfo/elecraft<http://mailman.qth.net/mailman/listinfo/elecraft>
>>> Help: http://mailman.qth.net/mmfaq.**htm<http://mailman.qth.net/mmfaq.htm>
>>> Post: mailto:[hidden email].**net <[hidden email]>
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>>
>>> ______________________________**______________________________**__
>> Elecraft mailing list
>> Home: http://mailman.qth.net/**mailman/listinfo/elecraft<http://mailman.qth.net/mailman/listinfo/elecraft>
>> Help: http://mailman.qth.net/mmfaq.**htm<http://mailman.qth.net/mmfaq.htm>
>> Post: mailto:[hidden email].**net <[hidden email]>
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
>>