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WSJT-X Frequency Anomaly

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Richard-6

WSJT-X Frequency Anomaly

After working a friend on 10 meters with FT8 I phoned and asked him why he always stayed up high at 2454 Hz. He said WSJT-X said he was dead on 2500 Hz.

I asked him what it said my frequency was. He said it was 1048 Hz; my WSJT-X said I was dead on 1000 Hz. We did more testing at other frequencies and on other bands and found similar discrepancies.

We involved a third station and compared three ways. The results were the same: no agreement anywhere.

The radios were my K3s, a TS-990s, and a high-end Yaesu. All of us were using WSJT-X 2.0.0. None of us had RIT or XIT in use.

What’s the deal? Is there a way to calibrate the software so the frequency shown by WSJT-X is the frequency upon which we are actually transmitting or receiving?

Please keep in mind that none of us is a Paul Horowitz, but neither are we Gomer Pyle… somewhere in between.

Cheers.
Richard - W4KBX
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Rick WA6NHC-2

Re: WSJT-X Frequency Anomaly

The obvious first places to look are the calibrations of each radio. My
K3 (always one, has the TCXO option) stays within a cycle or two and I
can 'net' it to within about a quarter cycle (using the WOW method).
Who ever answers on the tone freq I use in FT8 (actually kind of rude
because multiple callers cause a mess, use an offset) is typically
within one cycle of what I've selected, so it's not a common issue.

I'd venture proper calibration hasn't been done within that group.

If no one else has done that, your mileage WILL vary. This is the most
likely reason since phone folks tend to tolerate frequency variations
easier than other modes.

The other place is to make sure that the XIT (or second VFO) is not engaged.

Rick NHC

On 1/18/2019 8:54 AM, Richard wrote:

> After working a friend on 10 meters with FT8 I phoned and asked him why he always stayed up high at 2454 Hz. He said WSJT-X said he was dead on 2500 Hz.
>
> I asked him what it said my frequency was. He said it was 1048 Hz; my WSJT-X said I was dead on 1000 Hz. We did more testing at other frequencies and on other bands and found similar discrepancies.
>
> We involved a third station and compared three ways. The results were the same: no agreement anywhere.
>
> The radios were my K3s, a TS-990s, and a high-end Yaesu. All of us were using WSJT-X 2.0.0. None of us had RIT or XIT in use.
>
> What’s the deal? Is there a way to calibrate the software so the frequency shown by WSJT-X is the frequency upon which we are actually transmitting or receiving?
>
> Please keep in mind that none of us is a Paul Horowitz, but neither are we Gomer Pyle… somewhere in between.
>
> Cheers.
> Richard - W4KBX
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Don Wilhelm

Re: WSJT-X Frequency Anomaly

Note that in the two cases mentioned, you reported 47 +/-1 Hz difference.

That is not much and can easily be attributed to a difference in the
calibration of the radio or the audio frequency accuracy of the soundcards.

73,
Don W3FPR

On 1/18/2019 12:07 PM, Rick WA6NHC wrote:

> On 1/18/2019 8:54 AM, Richard wrote:
>> After working a friend on 10 meters with FT8 I phoned and asked him
>> why he always stayed up high at 2454 Hz. He said WSJT-X said he was
>> dead on 2500 Hz.
>>
>> I asked him what it said my frequency was. He said it was 1048 Hz; my
>> WSJT-X said I was dead on 1000 Hz. We did more testing at other
>> frequencies and on other bands and found similar discrepancies.
>>
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Bob McGraw - K4TAX

Re: WSJT-X Frequency Anomaly

There is a Freq Cal mode in WSJT-X. I suggest if the radio or sound
card is in question, run this mode and determine the results. Bet
you'll be surprised at the inaccuracy of the digital readout on a radio
and or soundcard. I was!

73

Bob, K4TAX

On 1/18/2019 3:23 PM, Don Wilhelm wrote:

> Note that in the two cases mentioned, you reported 47 +/-1 Hz difference.
>
> That is not much and can easily be attributed to a difference in the
> calibration of the radio or the audio frequency accuracy of the
> soundcards.
>
> 73,
> Don W3FPR
>
> On 1/18/2019 12:07 PM, Rick WA6NHC wrote:
>
>> On 1/18/2019 8:54 AM, Richard wrote:
>>> After working a friend on 10 meters with FT8 I phoned and asked him
>>> why he always stayed up high at 2454 Hz. He said WSJT-X said he was
>>> dead on 2500 Hz.
>>>
>>> I asked him what it said my frequency was. He said it was 1048 Hz;
>>> my WSJT-X said I was dead on 1000 Hz. We did more testing at other
>>> frequencies and on other bands and found similar discrepancies.
>>>
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>

Elecraft mailing list

Re: WSJT-X Frequency Anomaly

In reply to this post by Don Wilhelm

Do a sanity check by listening to WWV. That will tell you if your
various radios are telling frequency lies or not.

The thing to be aware of is that the reference oscillators in the
respective radios will drift. There is a method using WWV in the K3
manual to check and adjust the REF CAL error.

Regards,

Mike VP8NO

On 18/01/2019 18:23, Don Wilhelm wrote:

> Note that in the two cases mentioned, you reported 47 +/-1 Hz difference.
>
> That is not much and can easily be attributed to a difference in the
> calibration of the radio or the audio frequency accuracy of the soundcards.
>
> 73,
> Don W3FPR
>
> On 1/18/2019 12:07 PM, Rick WA6NHC wrote:
>
>> On 1/18/2019 8:54 AM, Richard wrote:
>>> After working a friend on 10 meters with FT8 I phoned and asked him
>>> why he always stayed up high at 2454 Hz. He said WSJT-X said he was
>>> dead on 2500 Hz.
>>>
>>> I asked him what it said my frequency was. He said it was 1048 Hz; my
>>> WSJT-X said I was dead on 1000 Hz. We did more testing at other
>>> frequencies and on other bands and found similar discrepancies.
>>>
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> Please help support this email list: http://www.qsl.net/donate.html
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>

Bob McGraw - K4TAX

Re: WSJT-X Frequency Anomaly

One easy method is place the radio on the CW mode. Time to one of the WWV frequencies. Press the SPOT to activate the function. Any difference between the WWV frequency and the readout is the error.

Bob, K4TAX

Sent from my iPhone

> On Jan 18, 2019, at 4:42 PM, Mike Harris via Elecraft <[hidden email]> wrote:
>
> Do a sanity check by listening to WWV. That will tell you if your various radios are telling frequency lies or not.
>
> The thing to be aware of is that the reference oscillators in the respective radios will drift. There is a method using WWV in the K3 manual to check and adjust the REF CAL error.
>
> Regards,
>
> Mike VP8NO
>
>> On 18/01/2019 18:23, Don Wilhelm wrote:
>> Note that in the two cases mentioned, you reported 47 +/-1 Hz difference.
>> That is not much and can easily be attributed to a difference in the calibration of the radio or the audio frequency accuracy of the soundcards.
>> 73,
>> Don W3FPR
>>> On 1/18/2019 12:07 PM, Rick WA6NHC wrote:
>>>> On 1/18/2019 8:54 AM, Richard wrote:
>>>> After working a friend on 10 meters with FT8 I phoned and asked him why he always stayed up high at 2454 Hz. He said WSJT-X said he was dead on 2500 Hz.
>>>>
>>>> I asked him what it said my frequency was. He said it was 1048 Hz; my WSJT-X said I was dead on 1000 Hz. We did more testing at other frequencies and on other bands and found similar discrepancies.
>>>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>> Please help support this email list: http://www.qsl.net/donate.html
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>

Don Wilhelm

Re: WSJT-X Frequency Anomaly

One subtle point is to make certain in CW mode that you have tuned WWV
to the carrier frequency and not to one of the transmitted tones.
You also must tune to the audio pitch you have set for your sidetone.
That is why SPOT is so important.

Listen for the WOW-WOW-WOW of the beat note between WWV and your SPOT
frequency. Tune the VFO until the WOW-WOW-WOW slows to a stop if
possible - then look at the frequency. If it does not have a string of
zeros to the right side, adjust the K3 Reference Oscillator as indicated
in the manual Calibration Procedures - Use Method 2.

I mention this because I have encountered many hams who do not know what
zero-beat is.

73,
Don W3FPR

On 1/18/2019 6:15 PM, Bob McGraw K4TAX wrote:
> One easy method is place the radio on the CW mode. Time to one of the WWV frequencies. Press the SPOT to activate the function. Any difference between the WWV frequency and the readout is the error.
>
> Bob, K4TAX
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