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Determining zero-beat

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Pete Smith N4ZR

Determining zero-beat

I want to use my K3 to calibrate the QS1R receiver used here as part of
the Reverse Beacon Network. For technical reasons, it's desirable to
calibrate the QS1R at as high a frequency as possible, so I wanted to do
so in the 6-meter band. I thought that if I knew how accurate the K3's
frequency display was at 10 MHz WWV, I'd know whether I needed to
compensate for any systematic error when comparing the two up on 6M.

Here's where the problem comes in. AM mode isn't usable for finding
zero-beat, of course. On CW, it appears that the zero-beat frequency is
displayed as 10 MHz minus the "pitch" frequency (which can only be
adjusted down to 300 Hz). I'd like to know the frequency accuracy of
the K3 within 20-30 Hz if possible for this exercise.

How to proceed?

--
73, Pete N4ZR

The World Contest Station Database, updated daily at www.conteststations.com
The Reverse Beacon Network at http://reversebeacon.net, blog at reversebeacon.blogspot.com,
spots at telnet.reversebeacon.net, port 7000

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Guy, K2AV

Re: Determining zero-beat

Set mode to CW. Set width to 200 Hz. Do a HOLD on MON. Set level to
20-25. Tap MON to turn off beat. Tune to 10.000.000. Tap SPOT.
Should hear a beat, albeit a slow one. Advance or retard AF gain to
get the obvious beat. In CONFIG: go to REF CAL. This will have turned
off SPOT. Tap it again. Adjust VFO A to get slowest beat.

With some patience and careful listening this is usually clearly a
specific setting, in my case 49.379.737. You will find that the beat
frequency wavers around due to changing propagation path length so you
have to listen for a while. Having accounted for the variation in
propagation it is quite clear in my case, albeit subtle, that 738 is
too high, and 736 is too low. It is also more clearly heard at some
times of day on a given frequency than others. There are also times
where there is a fast QSB on the signal that can be confusing and you
may just have to wait until the signal steadies. When you have it
spot on, there will be periods of several seconds or more where the
beat does not vary, something which does not happen nearly as much up
or down one Hz on the REF CAL frequency.

After this adjustment it is clear that my K3 is within +/- 0.5 Hz at
10.000000 MHz with no drift, probably within +/- 0.2 Hz though I won't
claim that. I have the KTCXO3-1 option in mine. It may be that a K3
without it may be a bit more cranky, I would imagine so, but I'm not
pulling it out to see :>)

0.5 Hz at 10 will be less than 2.5 Hz at 50, though I don't know the
formula. It's not a straight multiply because of the conversion
scheme. With this adjustment in the menu, the chief contribution of
the KTCXO3-1 is no drift, not an absolute accuracy.

My K3 is way more accurate than they spec, and accurate enough to show
up the propagational variations in the WWV frequencies. I would think
that if you have left it on for a while, and calibrate it before an
"exercise", you can count on it for spot on.

73, Guy.

On Fri, Dec 3, 2010 at 6:09 AM, Pete Smith <[hidden email]> wrote:

> I want to use my K3 to calibrate the QS1R receiver used here as part of
> the Reverse Beacon Network. For technical reasons, it's desirable to
> calibrate the QS1R at as high a frequency as possible, so I wanted to do
> so in the 6-meter band. I thought that if I knew how accurate the K3's
> frequency display was at 10 MHz WWV, I'd know whether I needed to
> compensate for any systematic error when comparing the two up on 6M.
>
> Here's where the problem comes in. AM mode isn't usable for finding
> zero-beat, of course. On CW, it appears that the zero-beat frequency is
> displayed as 10 MHz minus the "pitch" frequency (which can only be
> adjusted down to 300 Hz). I'd like to know the frequency accuracy of
> the K3 within 20-30 Hz if possible for this exercise.
>
> How to proceed?
>
> --
> 73, Pete N4ZR
>
> The World Contest Station Database, updated daily at www.conteststations.com
> The Reverse Beacon Network at http://reversebeacon.net, blog at reversebeacon.blogspot.com,
> spots at telnet.reversebeacon.net, port 7000
>
> ______________________________________________________________
> 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
>

Bill VanAlstyne W5WVO

Re: Determining zero-beat

Just one caveat on this procedure (thanks Guy!) -- make sure you have CWT
turned OFF; otherwise, SPOT will not do what you want it to. (It will
attempt to retune the VFO.)

Bill W5WVO

-----Original Message-----
From: Guy Olinger K2AV
Sent: Friday, December 03, 2010 13:38
To: [hidden email]
Cc: Elecraft List
Subject: Re: [Elecraft] Determining zero-beat

Set mode to CW. Set width to 200 Hz. Do a HOLD on MON. Set level to
20-25. Tap MON to turn off beat. Tune to 10.000.000. Tap SPOT.
Should hear a beat, albeit a slow one. Advance or retard AF gain to
get the obvious beat. In CONFIG: go to REF CAL. This will have turned
off SPOT. Tap it again. Adjust VFO A to get slowest beat.

With some patience and careful listening this is usually clearly a
specific setting, in my case 49.379.737. You will find that the beat
frequency wavers around due to changing propagation path length so you
have to listen for a while. Having accounted for the variation in
propagation it is quite clear in my case, albeit subtle, that 738 is
too high, and 736 is too low. It is also more clearly heard at some
times of day on a given frequency than others. There are also times
where there is a fast QSB on the signal that can be confusing and you
may just have to wait until the signal steadies. When you have it
spot on, there will be periods of several seconds or more where the
beat does not vary, something which does not happen nearly as much up
or down one Hz on the REF CAL frequency.

After this adjustment it is clear that my K3 is within +/- 0.5 Hz at
10.000000 MHz with no drift, probably within +/- 0.2 Hz though I won't
claim that. I have the KTCXO3-1 option in mine. It may be that a K3
without it may be a bit more cranky, I would imagine so, but I'm not
pulling it out to see :>)

0.5 Hz at 10 will be less than 2.5 Hz at 50, though I don't know the
formula. It's not a straight multiply because of the conversion
scheme. With this adjustment in the menu, the chief contribution of
the KTCXO3-1 is no drift, not an absolute accuracy.

My K3 is way more accurate than they spec, and accurate enough to show
up the propagational variations in the WWV frequencies. I would think
that if you have left it on for a while, and calibrate it before an
"exercise", you can count on it for spot on.

73, Guy.

On Fri, Dec 3, 2010 at 6:09 AM, Pete Smith <[hidden email]> wrote:

> I want to use my K3 to calibrate the QS1R receiver used here as part of
> the Reverse Beacon Network. For technical reasons, it's desirable to
> calibrate the QS1R at as high a frequency as possible, so I wanted to do
> so in the 6-meter band. I thought that if I knew how accurate the K3's
> frequency display was at 10 MHz WWV, I'd know whether I needed to
> compensate for any systematic error when comparing the two up on 6M.
>
> Here's where the problem comes in. AM mode isn't usable for finding
> zero-beat, of course. On CW, it appears that the zero-beat frequency is
> displayed as 10 MHz minus the "pitch" frequency (which can only be
> adjusted down to 300 Hz). I'd like to know the frequency accuracy of
> the K3 within 20-30 Hz if possible for this exercise.
>
> How to proceed?
>
> --
> 73, Pete N4ZR
>
> The World Contest Station Database, updated daily at
> www.conteststations.com
> The Reverse Beacon Network at http://reversebeacon.net, blog at
> reversebeacon.blogspot.com,
> spots at telnet.reversebeacon.net, port 7000
>
> ______________________________________________________________
> 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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Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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Please help support this email list: http://www.qsl.net/donate.html

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Guy, K2AV

Re: Determining zero-beat

I guess you can tell I never use CWT :>)

Thanks for the tip. 73, Guy.

On Fri, Dec 3, 2010 at 8:48 AM, Bill VanAlstyne W5WVO
<[hidden email]> wrote:

> Just one caveat on this procedure (thanks Guy!) -- make sure you have CWT
> turned OFF; otherwise, SPOT will not do what you want it to. (It will
> attempt to retune the VFO.)
>
> Bill W5WVO
>
>
> -----Original Message----- From: Guy Olinger K2AV
> Sent: Friday, December 03, 2010 13:38
> To: [hidden email]
> Cc: Elecraft List
> Subject: Re: [Elecraft] Determining zero-beat
>
> Set mode to CW. Set width to 200 Hz. Do a HOLD on MON. Set level to
> 20-25. Tap MON to turn off beat. Tune to 10.000.000. Tap SPOT.
> Should hear a beat, albeit a slow one. Advance or retard AF gain to
> get the obvious beat. In CONFIG: go to REF CAL. This will have turned
> off SPOT. Tap it again. Adjust VFO A to get slowest beat.
>
> With some patience and careful listening this is usually clearly a
> specific setting, in my case 49.379.737. You will find that the beat
> frequency wavers around due to changing propagation path length so you
> have to listen for a while. Having accounted for the variation in
> propagation it is quite clear in my case, albeit subtle, that 738 is
> too high, and 736 is too low. It is also more clearly heard at some
> times of day on a given frequency than others. There are also times
> where there is a fast QSB on the signal that can be confusing and you
> may just have to wait until the signal steadies. When you have it
> spot on, there will be periods of several seconds or more where the
> beat does not vary, something which does not happen nearly as much up
> or down one Hz on the REF CAL frequency.
>
> After this adjustment it is clear that my K3 is within +/- 0.5 Hz at
> 10.000000 MHz with no drift, probably within +/- 0.2 Hz though I won't
> claim that. I have the KTCXO3-1 option in mine. It may be that a K3
> without it may be a bit more cranky, I would imagine so, but I'm not
> pulling it out to see :>)
>
> 0.5 Hz at 10 will be less than 2.5 Hz at 50, though I don't know the
> formula. It's not a straight multiply because of the conversion
> scheme. With this adjustment in the menu, the chief contribution of
> the KTCXO3-1 is no drift, not an absolute accuracy.
>
> My K3 is way more accurate than they spec, and accurate enough to show
> up the propagational variations in the WWV frequencies. I would think
> that if you have left it on for a while, and calibrate it before an
> "exercise", you can count on it for spot on.
>
> 73, Guy.
>
> On Fri, Dec 3, 2010 at 6:09 AM, Pete Smith <[hidden email]> wrote:
>>
>> I want to use my K3 to calibrate the QS1R receiver used here as part of
>> the Reverse Beacon Network. For technical reasons, it's desirable to
>> calibrate the QS1R at as high a frequency as possible, so I wanted to do
>> so in the 6-meter band. I thought that if I knew how accurate the K3's
>> frequency display was at 10 MHz WWV, I'd know whether I needed to
>> compensate for any systematic error when comparing the two up on 6M.
>>
>> Here's where the problem comes in. AM mode isn't usable for finding
>> zero-beat, of course. On CW, it appears that the zero-beat frequency is
>> displayed as 10 MHz minus the "pitch" frequency (which can only be
>> adjusted down to 300 Hz). I'd like to know the frequency accuracy of
>> the K3 within 20-30 Hz if possible for this exercise.
>>
>> How to proceed?
>>
>> --
>> 73, Pete N4ZR
>>
>> The World Contest Station Database, updated daily at
>> www.conteststations.com
>> The Reverse Beacon Network at http://reversebeacon.net, blog at
>> reversebeacon.blogspot.com,
>> spots at telnet.reversebeacon.net, port 7000
>>
>> ______________________________________________________________
>> 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
>
>
>

n7ws

Re: Determining zero-beat

In reply to this post by Pete Smith N4ZR

http://elecraft.365791.n2.nabble.com/Ref-Osc-Cal-Method-4-td2595451.html

--- On Fri, 12/3/10, Pete Smith <[hidden email]> wrote:

> From: Pete Smith <[hidden email]>
> Subject: [Elecraft] Determining zero-beat
> To: "Elecraft List" <[hidden email]>
> Date: Friday, December 3, 2010, 4:09 AM
> I want to use my K3 to calibrate the
> QS1R receiver used here as part of
> the Reverse Beacon Network. For technical reasons,
> it's desirable to
> calibrate the QS1R at as high a frequency as possible, so I
> wanted to do
> so in the 6-meter band. I thought that if I knew how
> accurate the K3's
> frequency display was at 10 MHz WWV, I'd know whether I
> needed to
> compensate for any systematic error when comparing the two
> up on 6M.
>
> Here's where the problem comes in. AM mode isn't
> usable for finding
> zero-beat, of course. On CW, it appears that the
> zero-beat frequency is
> displayed as 10 MHz minus the "pitch" frequency (which can
> only be
> adjusted down to 300 Hz). I'd like to know the
> frequency accuracy of
> the K3 within 20-30 Hz if possible for this exercise.
>
> How to proceed?
>
> --
> 73, Pete N4ZR
>

roncasa

spam/ was hello

In reply to this post by Guy, K2AV

Uh ...
did someone just spammed our reflector??

72
Ron, wb1hga
"how much deeper would the ocean be without sponges"

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Pete Smith N4ZR

Re: Determining zero-beat

In reply to this post by Pete Smith N4ZR

Thanks, guys - that works FB, and my K3 appears to be right on, at least
by ear. Someday maybe I'll try an audio spectrum analyzer, but this
looks good enough.

73, Pete N4ZR

The World Contest Station Database, updated daily at www.conteststations.com
The Reverse Beacon Network at http://reversebeacon.net, blog at reversebeacon.blogspot.com,
spots at telnet.reversebeacon.net, port 7000

______________________________________________________________
Elecraft mailing list
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Guy, K2AV

Re: Determining zero-beat

If you get listening to a stretch of it to see how much "flat beat"
time you get, that's as close as you'll ever get it. Plenty close for
me and then some. 73 Guy.

On Fri, Dec 3, 2010 at 2:02 PM, Pete Smith <[hidden email]> wrote:

> Thanks, guys - that works FB, and my K3 appears to be right on, at least
> by ear. Someday maybe I'll try an audio spectrum analyzer, but this
> looks good enough.
>
> 73, Pete N4ZR
>
> The World Contest Station Database, updated daily at www.conteststations.com
> The Reverse Beacon Network at http://reversebeacon.net, blog at reversebeacon.blogspot.com,
> spots at telnet.reversebeacon.net, port 7000
>
>
>
> ______________________________________________________________
> 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
>

Edward R Cole

Re: Determining zero-beat

In reply to this post by Pete Smith N4ZR

I have the TCXO3-1 (49.380.000) but never bothered to calibrate
it. So out of curiosity, I measured my freq. on the K3 in the tune
mode on 20m and 6m:
Measured on a EIP-538 microwave counter, agrees <1-Hz accuracy with
my rubidium on 10-MHz:
14.205.000 read 14.204.994 (-6Hz)
50.110.000 read 50.109.984 (-16Hz)

73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ 500 KHz - 10-GHz www.kl7uw.com
EME: 144-800*w, 432-100w, 1296-testing*, 3400-winter?
DUBUS Magazine USA Rep [hidden email]
======================================
*temp not in service
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