K2 Crystal Filter Alignment Questions

[Jeff-229]

Hi gang,

I think my K2's crystal filter/BFO alignment (CAL FIL) is messed up, and I
need a bit of guidance...

Should the pitch of the background atmospheric noise change when CW RV is
toggled on and off?  Mine changes greatly, but it seems that it shouldn't,
if all CW RV does is switch sidebands.

Also, I have the KSB2 installed, and the pitch of the atmospheric noise
changes greatly when I switch from USB to LSB or vice versa.  It seems that
this pitch change shouldn't happen, if the crystal filters are aligned
properly.

Finally, and most irritatingly of all, in CW mode, when I switch from filter
FL1 to FL2, the pitch of the received CW signal changes significantly.
However, when I switch from FL2 to FL3, or from FL3 to FL4, no such pitch
change occurs, which is good.

I assume that I inadvertently changed the FL1 BFO setting.  However, I
subsequently tried various settings and couldn't get the pitch of the
received CW note for FL1 to match that of FL2.  What am I doing wrong?
Shouldn't I be able to correct this problem by trial-and-error, without
using Spectrogram?

Unfortunately, I'm not set up to use Spectrogram to align the filters.  The
problem is that I know very little about PC hardware, so I have no idea how
to feed the K2 receiver's audio into my computer, or whether my computer and
sound card are even capable of such a thing.

I'd very much appreciate any advice.

My filters have never been aligned carefully for SSB, but I haven't been too
worried about it, since I work nearly 100% CW.  However, the basic CW
filters, FL1-FL4, were aligned by Gary at Elecraft before I installed the
KSB2, so they were right at one time.  Is the alignment of FL1-FL4 in CW
mode affected by the addition of the KSB2?

My K2 is an older one -- s/n 821 with no rev. B mods, nor any other mods.
The options installed are the KSB2, KAT2, KAF2, KNB2, and KBT2.

Thanks in advance, 73 & 72,
Jeff
WB5GWB
Long Island, NY

p.s.  Here's a trivia question to which I'm curious to know the answer:  Why
is it that the KAT2's relays chatter pleasantly when you turn the K2 on, but
make not a peep when you turn it off?

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[Ingo Meyer DK3RED]

Hello Jeff,

> p.s.  Here's a trivia question to which I'm curious to know the answer:  Why
> is it that the KAT2's relays chatter pleasantly when you turn the K2 on, but
> make not a peep when you turn it off?

The relays are latch types and "memory" the last position without floating current. If you
turn on your K2 the microprozessor switch all relays with the typical "relay chatter" in a
start position. If you switch the K2 off the microprozessor going to sleep - no need to
work with the relays.
--
72/73 de Ingo, DK3RED - Don't forget: the fun is the power!

    [hidden email] - www.dk3red.homepage.t-online.de
      DL-QRP-AG   #824 - www.dl-qrp-ag.de
       QRP ARCI #11295 - www.qrparci.org
         DARC #2360404 - www.darc.de

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[Bill Coleman-2]

On Aug 19, 2006, at 1:52 AM, Jeff wrote:

> Should the pitch of the background atmospheric noise change when CW  
> RV is
> toggled on and off?

If you get it adjusted right, the pitch shouldn't change (or should  
change very little), however the "color" of the noise might shift a  
bit, depending on the bandwidth, due to a bit of asymmetry in the  
bandpass of the filter.

> Also, I have the KSB2 installed, and the pitch of the atmospheric  
> noise
> changes greatly when I switch from USB to LSB or vice versa.

You don't have it adjusted right. The pitch should change very  
little, the color will change a bit because of the asymmetry of the  
filter, but if you get it adjusted correctly you'd hardly notice the  
shift.

> Finally, and most irritatingly of all, in CW mode, when I switch  
> from filter
> FL1 to FL2, the pitch of the received CW signal changes significantly.
> However, when I switch from FL2 to FL3, or from FL3 to FL4, no such  
> pitch
> change occurs, which is good.

The K2 design isn't perfect in this regard, because of the way the  
BFO frequencies are determined - but you should be able to get any  
shift down to a few Hz, if that.

It sounds to me like you don't quite have the filters aligned correctly.

> I assume that I inadvertently changed the FL1 BFO setting.  However, I
> subsequently tried various settings and couldn't get the pitch of the
> received CW note for FL1 to match that of FL2.

Again, because of the quantization of the BFO frequency, you may not  
be able to get all the filters perfectly aligned on the same  
frequency. Close is good.

> Shouldn't I be able to correct this problem by trial-and-error,  
> without
> using Spectrogram?

Yes, I've done this. Try moving a filter one step up or down from  
where Spectrogram thinks it should be. See if it makes things better  
or worse.

> Unfortunately, I'm not set up to use Spectrogram to align the filters.

If you can't use Spectrogram, perhaps you can use another piece of  
software that supports and audio spectrum display. This is really the  
best way to align the K2 filters. (I personally use CocoaModem (a  
MacOS X RTTY / PSK application) to align my K2)

> p.s.  Here's a trivia question to which I'm curious to know the  
> answer:  Why
> is it that the KAT2's relays chatter pleasantly when you turn the  
> K2 on, but
> make not a peep when you turn it off?

Latching relays. They remember their last state and stay there even  
if no power is supplied.

Bill Coleman, AA4LR, PP-ASEL        Mail: [hidden email]
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901

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[Tom Hammond-3]

>On Aug 19, 2006, at 1:52 AM, Jeff wrote:
>
>>Finally, and most irritatingly of all, in CW mode, when I switch
>>from filter FL1 to FL2, the pitch of the received CW signal changes
>>significantly. However, when I switch from FL2 to FL3, or from FL3
>>to FL4, no such pitch change occurs, which is good.
>
>The K2 design isn't perfect in this regard, because of the way the
>BFO frequencies are determined - but you should be able to get any
>shift down to a few Hz, if that.
>
>It sounds to me like you don't quite have the filters aligned correctly.

My guess is that IF the CW note changes SIGNIFICANTLY between FL1 and
FL2, then you probably have the BFO setting on the WRONG SIDE of
filter-center. This is not an uncommon problem. Fortunately, it is
one which can be easily fixed... especially if you are using
Spectrogram and IF you follow the published instructions, BOTH of
which are available FOR FREE at www.n0ss.net.

The important thing is to know which sideband (CW NOR or CW REV)
you're aligning, and then ensuring that the BFO is always positioned
to the proper sideband (either above or below the center frequency of
the filter).

>>Shouldn't I be able to correct this problem by trial-and-error,
>>without using Spectrogram?
>
>Yes, I've done this. Try moving a filter one step up or down from
>where Spectrogram thinks it should be. See if it makes things better
>or worse.

It CAN be corrected by trial & error, but it's a WHALE OF A LOT
EASIER if you do use Spectrogram.

>>Unfortunately, I'm not set up to use Spectrogram to align the filters.

What are the problems to setting up TO use it?

73,

Tom Hammond   N0SS

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[Don Wilhelm-3]

Jeff,

Let me add my 2 cents worth:

First, if you have been attempting to align your filters by trial and error,
you may have the wrong sideband set.

Secondly, a shift of 20 Hz or so is to be expected because of the DAC
resolution - if your shift is any more than 20 Hz, it can be corrected by
proper filter adjustment.

Third, I don't understand why you are shying away from Spectrogram - it is
by far the easiest method of correctly setting the filter passbands.

Forth, If you have been arbitrarily moving the BDO settings 'by ear', it is
quite possible that you have the BFOs set to the wrong sideband.  A good
starting point is the settings in the manual (either the K2 manual or the
KSB2 manual.  Shift the sideband as required from these settings, but do not
go too far - going far from those values will result in the BFO being set to
the incorrect sideband.

I strongly suggest that you download Spectrogram and use that to set your
filters - see the note from Tom Hammond.  Tom's websote contains the last
freeware version of Spectrogram and instructions for setting it up and using
it to align the K2 filters - try it, I assure you that you will not be
disappointed in the results.

73,
Don W3FPR

> -----Original Message-----
>
> On Aug 19, 2006, at 1:52 AM, Jeff wrote:
>
> > Should the pitch of the background atmospheric noise change when CW
> > RV is
> > toggled on and off?
>
> If you get it adjusted right, the pitch shouldn't change (or should
> change very little), however the "color" of the noise might shift a
> bit, depending on the bandwidth, due to a bit of asymmetry in the
> bandpass of the filter.
>
> > Also, I have the KSB2 installed, and the pitch of the atmospheric
> > noise
> > changes greatly when I switch from USB to LSB or vice versa.
>
> You don't have it adjusted right. The pitch should change very
> little, the color will change a bit because of the asymmetry of the
> filter, but if you get it adjusted correctly you'd hardly notice the
> shift.
>
> > Finally, and most irritatingly of all, in CW mode, when I switch
> > from filter
> > FL1 to FL2, the pitch of the received CW signal changes significantly.
> > However, when I switch from FL2 to FL3, or from FL3 to FL4, no such
> > pitch
> > change occurs, which is good.
>
> The K2 design isn't perfect in this regard, because of the way the
> BFO frequencies are determined - but you should be able to get any
> shift down to a few Hz, if that.
>
> It sounds to me like you don't quite have the filters aligned correctly.
>
> > I assume that I inadvertently changed the FL1 BFO setting.  However, I
> > subsequently tried various settings and couldn't get the pitch of the
> > received CW note for FL1 to match that of FL2.
>
> Again, because of the quantization of the BFO frequency, you may not
> be able to get all the filters perfectly aligned on the same
> frequency. Close is good.
>
> > Shouldn't I be able to correct this problem by trial-and-error,
> > without
> > using Spectrogram?
>
> Yes, I've done this. Try moving a filter one step up or down from
> where Spectrogram thinks it should be. See if it makes things better
> or worse.
>
> > Unfortunately, I'm not set up to use Spectrogram to align the filters.
>
> If you can't use Spectrogram, perhaps you can use another piece of
> software that supports and audio spectrum display. This is really the
> best way to align the K2 filters. (I personally use CocoaModem (a
> MacOS X RTTY / PSK application) to align my K2)
>
> > p.s.  Here's a trivia question to which I'm curious to know the
> > answer:  Why
> > is it that the KAT2's relays chatter pleasantly when you turn the
> > K2 on, but
> > make not a peep when you turn it off?
>
> Latching relays. They remember their last state and stay there even
> if no power is supplied.
>
> Bill Coleman, AA4LR, PP-ASEL        Mail: [hidden email]
> Quote: "Not within a thousand years will man ever fly!"
>              -- Wilbur Wright, 1901
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
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>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>
>
> --
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.1.405 / Virus Database: 268.12.3/445 - Release Date: 9/11/2006
>
>

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[Jeff-229]

Don,

Thanks very much for the response.  I actually did get up to speed on
Spectrogram, and I'm very happy with the results.  Now, the CW signal
remains stationary in pitch, and jumps out at me as I invoke successively
tighter filters.  Spectrogram is also fun!

The problem that previously prevented me from using Spectrogram was that I
didn't know that getting the K2's audio into the PC was as simple as running
a cable from the K2's headphone jack to the PC's microphone jack.  Instead,
I envisioned having to have an interface circuit of some kind and wire up a
USB connector.

As a side benefit, now that I have receiver audio going into my computer, my
next project is to figure out how to decode PSK-31 signals.  Cool stuff!

73,
Jeff
WB5GWB

----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "Bill Coleman" <[hidden email]>; "Jeff" <[hidden email]>
Cc: <[hidden email]>
Sent: Sunday, September 17, 2006 12:06 AM
Subject: RE: [Elecraft] K2 Crystal Filter Alignment Questions


> Jeff,
>
> Let me add my 2 cents worth:
>
> First, if you have been attempting to align your filters by trial and
error,

> you may have the wrong sideband set.
>
> Secondly, a shift of 20 Hz or so is to be expected because of the DAC
> resolution - if your shift is any more than 20 Hz, it can be corrected by
> proper filter adjustment.
>
> Third, I don't understand why you are shying away from Spectrogram - it is
> by far the easiest method of correctly setting the filter passbands.
>
> Forth, If you have been arbitrarily moving the BDO settings 'by ear', it

is
> quite possible that you have the BFOs set to the wrong sideband.  A good
> starting point is the settings in the manual (either the K2 manual or the
> KSB2 manual.  Shift the sideband as required from these settings, but do
not
> go too far - going far from those values will result in the BFO being set
to
> the incorrect sideband.
>
> I strongly suggest that you download Spectrogram and use that to set your
> filters - see the note from Tom Hammond.  Tom's websote contains the last
> freeware version of Spectrogram and instructions for setting it up and
using
> it to align the K2 filters - try it, I assure you that you will not be
> disappointed in the results.
>
> 73,
> Don W3FPR

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[Don Wilhelm-3]

Jeff,

If what you want to do right now is just receive PSK31 signals, use the same
cable connection that you used for Spectrogram and run one of the PSK31
programs on your PC (DigiPan and Ham Radio Deluxe are 2 popular freeware
programs - yes there are others).  You may have better luck with the K2
external speaker jack and the soundcard line-in jacks than the headphone
jack and the mic input, but try them both and see what works.

Transmitting gets a bit more complex, but you only need to connect the
soundcard line out to the K2 mic AF input - because the soundcard output is
much greater than the mic input, you will need a resistive divider. Also at
this point, you should consider isolating the lines between the computer and
the K2 - I use transformers salvaged from defunct modems successfully.
While you can change from receive to transmit by manually keying the
transceiver after clicking the mouse, as a further step add automatic
control of the PTT line.  Add an optoisolator to connect the RTS and signal
ground from a computer serial port and drive the K2 PTT line from the output
of the optoisolator.  You could use a simple transistor instead of the
optoisolator, but the transistor does not allow ground isolation, and you
could encounter RF feedback being picked up on the computer chassis and
grounding system, etc., but for simplicity, it is worth a try.

If you are stuck with no serial ports on your computer, a USB to Serial
adapter could be used ahead of the PTT keying circuit.

That is all there is to any PSK31 interface - some of the boxes available
include microphone switching, and audio output switching, but those are
add-on conveniences, the simple interface that I described (2 lines from the
computer preferrably with transformers and an optoisolator for the PTT
activation) is all that is needed for a full interface function, and can be
built for less than $10 if you scrounge the transformers and don't have to
pay much for an enclosure and jacks.

73,
Don W3FPR

> -----Original Message-----
>
> The problem that previously prevented me from using Spectrogram was that I
> didn't know that getting the K2's audio into the PC was as simple
> as running
> a cable from the K2's headphone jack to the PC's microphone jack.
>  Instead,
> I envisioned having to have an interface circuit of some kind and
> wire up a
> USB connector.
>
> As a side benefit, now that I have receiver audio going into my
> computer, my
> next project is to figure out how to decode PSK-31 signals.  Cool stuff!
>
> 73,
> Jeff
> WB5GWB

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[Bill Allen-6]

Just a note:  For those who do not have a serial port available and wish to
use a USB to Serial to converter (for PTT purposes, etc.), the Belkin F5U409
model works terrifically well.  It supports the entire RS232 protocol (not
all converters do) and has LINK, TX, & RX indicator LEDS.  

73, Bill Allen WA5PB





-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Don Wilhelm
Sent: Sunday, September 17, 2006 2:08 PM
To: Jeff; [hidden email]
Cc: [hidden email]
Subject: RE: [Elecraft] K2 Crystal Filter Alignment Questions

Jeff,

If what you want to do right now is just receive PSK31 signals, use the same
cable connection that you used for Spectrogram and run one of the PSK31
programs on your PC (DigiPan and Ham Radio Deluxe are 2 popular freeware
programs - yes there are others).  You may have better luck with the K2
external speaker jack and the soundcard line-in jacks than the headphone
jack and the mic input, but try them both and see what works.

Transmitting gets a bit more complex, but you only need to connect the
soundcard line out to the K2 mic AF input - because the soundcard output is
much greater than the mic input, you will need a resistive divider. Also at
this point, you should consider isolating the lines between the computer and
the K2 - I use transformers salvaged from defunct modems successfully.
While you can change from receive to transmit by manually keying the
transceiver after clicking the mouse, as a further step add automatic
control of the PTT line.  Add an optoisolator to connect the RTS and signal
ground from a computer serial port and drive the K2 PTT line from the output
of the optoisolator.  You could use a simple transistor instead of the
optoisolator, but the transistor does not allow ground isolation, and you
could encounter RF feedback being picked up on the computer chassis and
grounding system, etc., but for simplicity, it is worth a try.

If you are stuck with no serial ports on your computer, a USB to Serial
adapter could be used ahead of the PTT keying circuit.

That is all there is to any PSK31 interface - some of the boxes available
include microphone switching, and audio output switching, but those are
add-on conveniences, the simple interface that I described (2 lines from the
computer preferrably with transformers and an optoisolator for the PTT
activation) is all that is needed for a full interface function, and can be
built for less than $10 if you scrounge the transformers and don't have to
pay much for an enclosure and jacks.

73,
Don W3FPR

> -----Original Message-----
>
> The problem that previously prevented me from using Spectrogram was that I
> didn't know that getting the K2's audio into the PC was as simple
> as running
> a cable from the K2's headphone jack to the PC's microphone jack.
>  Instead,
> I envisioned having to have an interface circuit of some kind and
> wire up a
> USB connector.
>
> As a side benefit, now that I have receiver audio going into my
> computer, my
> next project is to figure out how to decode PSK-31 signals.  Cool stuff!
>
> 73,
> Jeff
> WB5GWB

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--
No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.1.405 / Virus Database: 268.12.4/449 - Release Date: 9/15/2006


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[Don Wilhelm-3]

Bill,

Good info, but if the purpose is only for PSK31 PTT keying, most any adapter
should do the job because it needs only RTS and signal ground, and I can't
imagine any USB to serial adapter that would not include those essential
signals.  I got one that works for $3.99 at TigerDirect.

73,
Don W3FPR

> -----Original Message-----
>
> Just a note:  For those who do not have a serial port available
> and wish to
> use a USB to Serial to converter (for PTT purposes, etc.), the
> Belkin F5U409
> model works terrifically well.  It supports the entire RS232 protocol (not
> all converters do) and has LINK, TX, & RX indicator LEDS.
>
> 73, Bill Allen WA5PB
>
>
>

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