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Zero beat WWV

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dave.wilburn

Zero beat WWV

I have setup Spectogram, and have 500 & 600 Hz markers setup. I then
set the K2 to 10000.00, in U mode, and adjust the frequency until I have
either 500 or 600 Hz depending on which minute it is (odd minutes being
a 600 Hz tone and even being a 500 Hz tone, even though this seems
backwards of how it should be).

I then used this zero beat reference, and the procedure on page 101 of
the K2 manual so that I have it down to U or L mode is zero beat at
9999.99.

I notice the calibration on page 101 of the K2 manual says to use U or L
mode. My question, is how much should the offset be when I go to CW
mode? I am trying to track down why my CW RX frequency is so far from
my USB frequency (was 1500 Hz off at one point). I have it better, but I
am sure the issue is with how I did the alignments.
--

David Wilburn
[hidden email]
K4DGW
K2 #5982
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Don Wilhelm-3

Re: Zero beat WWV

Dave,

If you have WWV properly tuned at 9999.99 (when in SSB mode), that is
only 10 Hz off frequency, and is well within the range of error to be
expected with the K2. The digital quantizing error is about 20 Hz.

The K2 always displays the frequency of the carrier - so when tuned
properly to WWV, you will hear (or see on Spectrogram) the tones
demodulated (as you have done), but when switching to CW, you should
hear the carrier at the pitch you have set for the sidetone.

When listening to WWV in CW mode it is easy to mistake one of the tones
they transmit for the carrier. At the times they transmit a 600 Hz
tone, you will be able to hear discrete signals at 9999.40, 10,000.00
and 10,000.60 since it is an AM signal transmitting a 600 Hz tone. (You
can hear one signal at the carrier minus the transmitted tone pitch, the
carrier itself, and another signal at the carrier plus the tone pitch.)
If the CW filter is narrow enough, you will hear each of these signals
as separate signals in the receiver - you must be careful to identify
the actual carrier. Using the wrong one will create a large apparent
error in your dial readout. It is best to tune WWV during the minutes
they do not transmit a tone - tune the carrier to your sidetone pitch
and the dial should read correctly.

Just adjust the CW BFOs so the passband is centered at your chosen
sidetone pitch (using a noise input, NOT a single signal) - and set the
dial calibration in LSB or USB, then believe that the K2 will take care
of the offset for you. On CW, the dial readout will be the carrier
frequency of the station you are listening to and will also be the
frequency you will transmit on.

73,
Don W3FPR

David Wilburn wrote:

> I have setup Spectogram, and have 500 & 600 Hz markers setup. I then
> set the K2 to 10000.00, in U mode, and adjust the frequency until I have
> either 500 or 600 Hz depending on which minute it is (odd minutes being
> a 600 Hz tone and even being a 500 Hz tone, even though this seems
> backwards of how it should be).
>
> I then used this zero beat reference, and the procedure on page 101 of
> the K2 manual so that I have it down to U or L mode is zero beat at
> 9999.99.
>
> I notice the calibration on page 101 of the K2 manual says to use U or L
> mode. My question, is how much should the offset be when I go to CW
> mode? I am trying to track down why my CW RX frequency is so far from
> my USB frequency (was 1500 Hz off at one point). I have it better, but I
> am sure the issue is with how I did the alignments.

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Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
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dave.wilburn

Re: Zero beat WWV

Good stuff Don. Thanks. Yea, the 9999.99, I was not worried about at
all. It is the 1300 Hz I have to wander over to, to get the CW signal
that is bothering me. I am experiencing the same thing with local
signals, I have generated from other radios. I will check out WWV
during the quiet time and see what I find.

As far as "Just adjust the CW BFOs so the passband is centered...", what
are you telling me to do here? I have run through c22 adjustment
(started out at 10000.09 for WWV, and got to 9999.99 using the "Wayne"
method), CAL PLL and CAL FIL (with Spectrogram) at least 3 times.
Should I go back and do the BFO test?

Admittedly, it is possible, even likely, that I am making the same
mistake each time I have run them. I have seen the U and L frequency
readout get better, but not the CW. Additionally, it transmits on the
correct frequency.

David Wilburn
[hidden email]
K4DGW
K2 #5982

Don Wilhelm wrote:

> Dave,
>
> If you have WWV properly tuned at 9999.99 (when in SSB mode), that is
> only 10 Hz off frequency, and is well within the range of error to be
> expected with the K2. The digital quantizing error is about 20 Hz.
>
> The K2 always displays the frequency of the carrier - so when tuned
> properly to WWV, you will hear (or see on Spectrogram) the tones
> demodulated (as you have done), but when switching to CW, you should
> hear the carrier at the pitch you have set for the sidetone.
>
> When listening to WWV in CW mode it is easy to mistake one of the tones
> they transmit for the carrier. At the times they transmit a 600 Hz
> tone, you will be able to hear discrete signals at 9999.40, 10,000.00
> and 10,000.60 since it is an AM signal transmitting a 600 Hz tone. (You
> can hear one signal at the carrier minus the transmitted tone pitch, the
> carrier itself, and another signal at the carrier plus the tone pitch.)
> If the CW filter is narrow enough, you will hear each of these signals
> as separate signals in the receiver - you must be careful to identify
> the actual carrier. Using the wrong one will create a large apparent
> error in your dial readout. It is best to tune WWV during the minutes
> they do not transmit a tone - tune the carrier to your sidetone pitch
> and the dial should read correctly.
>
> Just adjust the CW BFOs so the passband is centered at your chosen
> sidetone pitch (using a noise input, NOT a single signal) - and set the
> dial calibration in LSB or USB, then believe that the K2 will take care
> of the offset for you. On CW, the dial readout will be the carrier
> frequency of the station you are listening to and will also be the
> frequency you will transmit on.
>
> 73,
> Don W3FPR
>
> David Wilburn wrote:
>> I have setup Spectogram, and have 500 & 600 Hz markers setup. I then
>> set the K2 to 10000.00, in U mode, and adjust the frequency until I
>> have either 500 or 600 Hz depending on which minute it is (odd minutes
>> being a 600 Hz tone and even being a 500 Hz tone, even though this
>> seems backwards of how it should be).
>>
>> I then used this zero beat reference, and the procedure on page 101 of
>> the K2 manual so that I have it down to U or L mode is zero beat at
>> 9999.99.
>>
>> I notice the calibration on page 101 of the K2 manual says to use U or
>> L mode. My question, is how much should the offset be when I go to CW
>> mode? I am trying to track down why my CW RX frequency is so far from
>> my USB frequency (was 1500 Hz off at one point). I have it better, but
>> I am sure the issue is with how I did the alignments.
>

Don Wilhelm-3

Re: Zero beat WWV

Dave,

Maybe now I understand where your problem is - I suggest you proceed as
follows:

First, adjust the filters so the passbands for all the filters you will
use are positioned properly. Use Spectrogram and a noise input to the
K2 to see where the passbands are positioned. This is the initial
adjustment of the filters - you are looking only to position the
passband at this point.

Then adjust the 4 MHz oscillator (C22) accurately. Do that as follows:
1) Tune in WWV correctly in LSB or USB mode (ignore the dial reading)
2) Enter CAL FCTR and alternate the counter probe between TP1 and TP2 -
if the low order digits are not the same, adust C22 until they are the
same. Do not change C22 from that setting unless you start all over again.

Put the probe into TP1, switch to 40 meters and run CAL PLL.

When CAL PLL has finished, put the probe in TP2 and enter CAL FIL.
There is no need to reposition the passbands since you have already done
that, but you need to force the K2 to write new BFO values into the
EEPROM - so proceed as follows:
1) Set the mode to LSB FL1 and tap the BAND- button. You should see
FL1t nnn (where nnn is some number) in the display.
2) Note the number in the display and change it to the next number (up
or down), then set it back to the original number.
3) Tap the XFIL button to move to LSB FL2 - change its number and change
it back.
4) Tap XFIL again to move to FL3 and do the same thing - repeat for FL4
and then return to FL1.
5) Tap the MODE button to change to USB and repeat steps 2 thru 4 above.
6) do the same thing for CW, CWr, and if you have RTTY turned on, do the
same for RTTY and RTTYr.

When you have done those steps (in order) then exit the menu, switch to
10 MHz, tune WWV in LSB mode again to check your work - the frequency
displayed should be within 20 Hz of 10,000.00 - if it is not, start over
at the 4 MHz reference adjustment to refine that setting and follow
through the steps again.

If WWV does tune correctly in LSB mode, switch to CW mode and you should
hear the WWV carrier appear at the audio frequency that you have set for
the sidetone pitch. If that is true, your K2 is properly calibrated.

The adjustment of C22 will do nothing during normal operation of the K2.
The 4 MHz oscillator can drift all over the map and you will not notice
any change. The K2 does not dynamically use the reference oscillator
for frequency determination in normal operation. However, it does have
to be accurate before doing the CAL PLL or the CAL FIL procedures,
because it IS used during those procedures to determine the frequency of
whichever point the probe is connected to - the resulting frequency
values are then written into EEPROM and the EEPROM values are used
afterward to determine the frequency readout.

73,
Don W3FPR

David Wilburn wrote:

> Good stuff Don. Thanks. Yea, the 9999.99, I was not worried about at
> all. It is the 1300 Hz I have to wander over to, to get the CW signal
> that is bothering me. I am experiencing the same thing with local
> signals, I have generated from other radios. I will check out WWV
> during the quiet time and see what I find.
>
> As far as "Just adjust the CW BFOs so the passband is centered...", what
> are you telling me to do here? I have run through c22 adjustment
> (started out at 10000.09 for WWV, and got to 9999.99 using the "Wayne"
> method), CAL PLL and CAL FIL (with Spectrogram) at least 3 times. Should
> I go back and do the BFO test?
>
> Admittedly, it is possible, even likely, that I am making the same
> mistake each time I have run them. I have seen the U and L frequency
> readout get better, but not the CW. Additionally, it transmits on the
> correct frequency.
>
> David Wilburn
> [hidden email]
> K4DGW
> K2 #5982
>