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Observation on new Synthesizers for K3

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NK7Z

Observation on new Synthesizers for K3

Hello,

I had what I believe to be a unique opportunity to test the new
synthesizer in a high signal level environment, under some controlled
conditions.

K7OLN lives about 750 feet from me, and we both have static antenna
setups, and because he is running WSPR K7OLN also has static power
levels for these tests.

The three test states are as follows:

1. The first P3 capture is K7OLN's K3, using the old synthesizer, as
received on my K3 using an old synthesizer.

2. The second P3 capture is of K7OLN, using the same equipment on both
ends, save the new synthesizer on my rig only, and received on my K3.

3. The third P3 capture is after K7OLN upgraded his K3 to the new
synthesizer, with both radios using the new synthesizer.

I have a personal Wiki, and have published the data there at:

http://nk7z.net/wiki/elecraft-k3-macros/elecraft-k3-xlr-to-radio/elecraft-k3-new-synthesizer/

Not scientific, but close... As can be seen the new synthesizers make a
BIG difference. Bigger than I would have thought! THANK YOU
ELECRAFT!

K7OLN's purchase of a K3, (I want my Hat Elecraft!), made it such that
both he and I can operate on the same band, in the same segment, as
close as 10 to 15 KHz away from each other and not even know the other
station is there, save the HUGE spike in the P3, (which is supposed to
be there), all while at KW power levels for both of us.

--
Thanks and 73's,
For equipment, and software setups and reviews see:
www.nk7z.net

For MixW support see;
http://groups.yahoo.com/neo/groups/mixw/info
For Dopplergram information see:
http://groups.yahoo.com/neo/groups/dopplergram/info
For MM-SSTV see:
http://groups.yahoo.com/neo/groups/MM-SSTV/info

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Don Wilhelm-4

Re: Observation on new Synthesizers for K3

David and all,

Eric's words at his early morning presentation at FDIM (Dayton) were
that the improvement surprised everyone at Elecraft - the results were
much better than expected. So all K3 owners can benefit from that part
of the K3S development.

73,
Don W3FPR

On 7/7/2015 6:32 PM, David Cole wrote:
> Not scientific, but close... As can be seen the new synthesizers make a
> BIG difference. Bigger than I would have thought! THANK YOU
> ELECRAFT!
>
>

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rclark01

Re: Observation on new Synthesizers for K3

Interesting reading. What does the synthesizer actually do? How is the new one better than the old one?

NJ4J

Robert W. Clark
Executive Director
Center for Personnel Development In CTE
Temple University
Philadelphia, Pa

> On Jul 7, 2015, at 6:56 PM, Don Wilhelm <[hidden email]> wrote:
>
> David and all,
>
> Eric's words at his early morning presentation at FDIM (Dayton) were that the improvement surprised everyone at Elecraft - the results were much better than expected. So all K3 owners can benefit from that part of the K3S development.
>
> 73,
> Don W3FPR
>
>> On 7/7/2015 6:32 PM, David Cole wrote:
>> Not scientific, but close... As can be seen the new synthesizers make a
>> BIG difference. Bigger than I would have thought! THANK YOU
>> ELECRAFT!
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
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>
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NK7Z

Re: Observation on new Synthesizers for K3

Hi,
I would be interested in a detailed explanation as to why things are
tighter with the new synths, as opposed to the old ones as well...
--
Thanks and 73's,
For equipment, and software setups and reviews see:
www.nk7z.net

For MixW support see;
http://groups.yahoo.com/neo/groups/mixw/info
For Dopplergram information see:
http://groups.yahoo.com/neo/groups/dopplergram/info
For MM-SSTV see:
http://groups.yahoo.com/neo/groups/MM-SSTV/info

On Wed, 2015-07-08 at 00:31 -0400, Robert Clark wrote:

> Interesting reading. What does the synthesizer actually do? How is the new one better than the old one?
>
> NJ4J
>
> Robert W. Clark
> Executive Director
> Center for Personnel Development In CTE
> Temple University
> Philadelphia, Pa
>
> > On Jul 7, 2015, at 6:56 PM, Don Wilhelm <[hidden email]> wrote:
> >
> > David and all,
> >
> > Eric's words at his early morning presentation at FDIM (Dayton) were that the improvement surprised everyone at Elecraft - the results were much better than expected. So all K3 owners can benefit from that part of the K3S development.
> >
> > 73,
> > Don W3FPR
> >
> >> On 7/7/2015 6:32 PM, David Cole wrote:
> >> Not scientific, but close... As can be seen the new synthesizers make a
> >> BIG difference. Bigger than I would have thought! THANK YOU
> >> ELECRAFT!
> >
> > ______________________________________________________________
> > 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
> > Message delivered to [hidden email]
> ______________________________________________________________
> Elecraft mailing list
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alorona

Re: Observation on new Synthesizers for K3

We like to think that a VFO exists only at one frequency -- the frequency on the receiver display.
But in reality every VFO has width, and it occupies not only it's nominal frequency but is "smeared" both lower and higher in frequency, too. This is because of the phase noise of the synthesizer or VFO.
Because of the smearing effect of this phase noise, received signals can also appear wider than they are. The noise floor on either side rises in direct proportion to the synthesizer's phase noise. Dave's screenshots of the P3 spectrograms show this smearing clearly.
An oscillator with less phase noise looks more like that ideal picture we all have in our heads -- of a signal that's infinitely narrow. In the third of Dave's screenshots you can see how the new synths are closer to an ideal oscillator-- the CW signal's width on the spectrogram is much narrower.
If a signal has lower noise sidebands (whether the sidebands are generated in the transmitter or the receiver... each of them has a synthesizer) then you can enjoy less interference from an adjacent signal. You will also *cause* less interference to your neighbors on the band.
I have no idea of the design of the new synths, but in general to design a synthesizer with low phase noise you have to start with very low noise devices, pay really careful attention to the parts of the phase-locked loop like the Q, feedback, the numeric dithering, the loop filter and various other aspects of the circuit. It's a real art. It appears from Dave's observations that there is a significant and measurable difference.

Al W6LX

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Don Wilhelm-4

Re: Observation on new Synthesizers for K3

In reply to this post by rclark01

Robert,

There is a significant reduction in phase noise.
That means you can work closer to the frequency of another station
without him interfering with the station you are trying to copy.
On transmit, it means your signal is more 'pure' and the sideband
'clutter' on your signal is significantly reduced.
Those parameters are important in contest operating and when working in
a pileup.

73,
Don W3FPR

On 7/8/2015 12:31 AM, Robert Clark wrote:
> Interesting reading. What does the synthesizer actually do? How is the new one better than the old one?
>
>

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NK7Z

Re: Observation on new Synthesizers for K3

In reply to this post by alorona

Al,

Let me pose a set of conditions, and see if I understand this...

Is the smearing caused mostly by the phase noise sidebands, as a
resultant of phase flicker?

i.e. If the phase noise were reduced on a transmitting VFO, then the
smearing would also be reduced, because the sidebands would no longer
reflect the wide band phase noise, as-- well-- sidebands? Is this
correct?

If so, then does that mean that as a station gets stronger, one picks up
more of the phase noise, (a function of how far from center one is), and
that is why a signal gets wider as it gets stronger?

It occurs to me that the the the RX VFO phase noise would be less
influencing, (on phase noise sidebands), than the transmit VFO phase
noise... Is that correct?

If so, then that would explain why the largest change occurred when
K7OLN got his new synthesizer, as opposed to me getting my new
synthesizer, as shown in the difference between photos 2 and 3.

Is my understanding correct?

--
Thanks and 73's,
For equipment, and software setups and reviews see:
www.nk7z.net

For MixW support see;
http://groups.yahoo.com/neo/groups/mixw/info
For Dopplergram information see:
http://groups.yahoo.com/neo/groups/dopplergram/info
For MM-SSTV see:
http://groups.yahoo.com/neo/groups/MM-SSTV/info

On Wed, 2015-07-08 at 05:14 +0000, Al Lorona wrote:

> We like to think that a VFO exists only at one frequency -- the
> frequency on the receiver display.
>
>
> But in reality every VFO has width, and it occupies not only it's
> nominal frequency but is "smeared" both lower and higher in frequency,
> too. This is because of the phase noise of the synthesizer or VFO.
>
>
> Because of the smearing effect of this phase noise, received signals
> can also appear wider than they are. The noise floor on either side
> rises in direct proportion to the synthesizer's phase noise. Dave's
> screenshots of the P3 spectrograms show this smearing clearly.
>
>
> An oscillator with less phase noise looks more like that ideal picture
> we all have in our heads -- of a signal that's infinitely narrow. In
> the third of Dave's screenshots you can see how the new synths are
> closer to an ideal oscillator-- the CW signal's width on the
> spectrogram is much narrower.
>
>
> If a signal has lower noise sidebands (whether the sidebands are
> generated in the transmitter or the receiver... each of them has a
> synthesizer) then you can enjoy less interference from an adjacent
> signal. You will also *cause* less interference to your neighbors on
> the band.
>
>
> I have no idea of the design of the new synths, but in general to
> design a synthesizer with low phase noise you have to start with very
> low noise devices, pay really careful attention to the parts of the
> phase-locked loop like the Q, feedback, the numeric dithering, the
> loop filter and various other aspects of the circuit. It's a real art.
> It appears from Dave's observations that there is a significant and
> measurable difference.
>
>
>
>
> Al W6LX
>
>
>
>

Guy Olinger K2AV

Re: Observation on new Synthesizers for K3

Hi, Dave.

Well, there is one thing you did not do. A fourth condition, which would
be difficult, a lot more work given what you were doing. That would be
changing his syn first and noting the difference. It might be that the TX
change first would create a different middle picture in the series. But I
doubt it...

These are not linear additive behaviors, and explaining noise reduction
from various sources is often very complex. The appearance in the
*frequency span* of the heavy continuous noise is cut in half in the middle
picture and then cut in half again in the third. That would appear that the
combining is a multiplicative function. The difference at a given frequency
would then be completely a child of the shape of the noise curve, rendering
the reduction at some frequencies as an "effectiveness" measure pretty
meaningless.

Noting that the heavy noise bandwidth is halved and then halved again
presents a better assessment. By that measure the changes are equally
effective.

73, Guy

On Wed, Jul 8, 2015 at 9:02 AM, David Cole <[hidden email]> wrote:

> Al,
>
> Let me pose a set of conditions, and see if I understand this...
>
> Is the smearing caused mostly by the phase noise sidebands, as a
> resultant of phase flicker?
>
> i.e. If the phase noise were reduced on a transmitting VFO, then the
> smearing would also be reduced, because the sidebands would no longer
> reflect the wide band phase noise, as-- well-- sidebands? Is this
> correct?
>
> If so, then does that mean that as a station gets stronger, one picks up
> more of the phase noise, (a function of how far from center one is), and
> that is why a signal gets wider as it gets stronger?
>
> It occurs to me that the the the RX VFO phase noise would be less
> influencing, (on phase noise sidebands), than the transmit VFO phase
> noise... Is that correct?
>
> If so, then that would explain why the largest change occurred when
> K7OLN got his new synthesizer, as opposed to me getting my new
> synthesizer, as shown in the difference between photos 2 and 3.
>
> Is my understanding correct?
>
> --
> Thanks and 73's,
> For equipment, and software setups and reviews see:
> www.nk7z.net
>
> For MixW support see;
> http://groups.yahoo.com/neo/groups/mixw/info
> For Dopplergram information see:
> http://groups.yahoo.com/neo/groups/dopplergram/info
> For MM-SSTV see:
> http://groups.yahoo.com/neo/groups/MM-SSTV/info
>
>
> On Wed, 2015-07-08 at 05:14 +0000, Al Lorona wrote:
> > We like to think that a VFO exists only at one frequency -- the
> > frequency on the receiver display.
> >
> >
> > But in reality every VFO has width, and it occupies not only it's
> > nominal frequency but is "smeared" both lower and higher in frequency,
> > too. This is because of the phase noise of the synthesizer or VFO.
> >
> >
> > Because of the smearing effect of this phase noise, received signals
> > can also appear wider than they are. The noise floor on either side
> > rises in direct proportion to the synthesizer's phase noise. Dave's
> > screenshots of the P3 spectrograms show this smearing clearly.
> >
> >
> > An oscillator with less phase noise looks more like that ideal picture
> > we all have in our heads -- of a signal that's infinitely narrow. In
> > the third of Dave's screenshots you can see how the new synths are
> > closer to an ideal oscillator-- the CW signal's width on the
> > spectrogram is much narrower.
> >
> >
> > If a signal has lower noise sidebands (whether the sidebands are
> > generated in the transmitter or the receiver... each of them has a
> > synthesizer) then you can enjoy less interference from an adjacent
> > signal. You will also *cause* less interference to your neighbors on
> > the band.
> >
> >
> > I have no idea of the design of the new synths, but in general to
> > design a synthesizer with low phase noise you have to start with very
> > low noise devices, pay really careful attention to the parts of the
> > phase-locked loop like the Q, feedback, the numeric dithering, the
> > loop filter and various other aspects of the circuit. It's a real art.
> > It appears from Dave's observations that there is a significant and
> > measurable difference.
> >
> >
> >
> >
> > Al W6LX
> >
> >
> >
> >
>
> ______________________________________________________________
> 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
> Message delivered to [hidden email]
>

NK7Z

Re: Observation on new Synthesizers for K3

Hi,
Thanks, I need to think about this a bit prior to commenting on it. :)
--
Thanks and 73's,
For equipment, and software setups and reviews see:
www.nk7z.net

For MixW support see;
http://groups.yahoo.com/neo/groups/mixw/info
For Dopplergram information see:
http://groups.yahoo.com/neo/groups/dopplergram/info
For MM-SSTV see:
http://groups.yahoo.com/neo/groups/MM-SSTV/info

On Wed, 2015-07-08 at 10:20 -0400, Guy Olinger K2AV wrote:

> Hi, Dave.
>
>
> Well, there is one thing you did not do. A fourth condition, which
> would be difficult, a lot more work given what you were doing. That
> would be changing his syn first and noting the difference. It might be
> that the TX change first would create a different middle picture in
> the series. But I doubt it...
>
>
> These are not linear additive behaviors, and explaining noise
> reduction from various sources is often very complex. The appearance
> in the *frequency span* of the heavy continuous noise is cut in half
> in the middle picture and then cut in half again in the third. That
> would appear that the combining is a multiplicative function. The
> difference at a given frequency would then be completely a child of
> the shape of the noise curve, rendering the reduction at some
> frequencies as an "effectiveness" measure pretty meaningless.
>
>
> Noting that the heavy noise bandwidth is halved and then halved again
> presents a better assessment. By that measure the changes are equally
> effective.
>
>
> 73, Guy
>
> On Wed, Jul 8, 2015 at 9:02 AM, David Cole <[hidden email]> wrote:
> Al,
>
> Let me pose a set of conditions, and see if I understand
> this...
>
> Is the smearing caused mostly by the phase noise sidebands, as
> a
> resultant of phase flicker?
>
> i.e. If the phase noise were reduced on a transmitting VFO,
> then the
> smearing would also be reduced, because the sidebands would no
> longer
> reflect the wide band phase noise, as-- well-- sidebands? Is
> this
> correct?
>
> If so, then does that mean that as a station gets stronger,
> one picks up
> more of the phase noise, (a function of how far from center
> one is), and
> that is why a signal gets wider as it gets stronger?
>
> It occurs to me that the the the RX VFO phase noise would be
> less
> influencing, (on phase noise sidebands), than the transmit VFO
> phase
> noise... Is that correct?
>
> If so, then that would explain why the largest change occurred
> when
> K7OLN got his new synthesizer, as opposed to me getting my new
> synthesizer, as shown in the difference between photos 2 and
> 3.
>
> Is my understanding correct?
>
> --
> Thanks and 73's,
> For equipment, and software setups and reviews see:
> www.nk7z.net
>
> For MixW support see;
> http://groups.yahoo.com/neo/groups/mixw/info
> For Dopplergram information see:
> http://groups.yahoo.com/neo/groups/dopplergram/info
> For MM-SSTV see:
> http://groups.yahoo.com/neo/groups/MM-SSTV/info
>
>
> On Wed, 2015-07-08 at 05:14 +0000, Al Lorona wrote:
> > We like to think that a VFO exists only at one frequency --
> the
> > frequency on the receiver display.
> >
> >
> > But in reality every VFO has width, and it occupies not only
> it's
> > nominal frequency but is "smeared" both lower and higher in
> frequency,
> > too. This is because of the phase noise of the synthesizer
> or VFO.
> >
> >
> > Because of the smearing effect of this phase noise, received
> signals
> > can also appear wider than they are. The noise floor on
> either side
> > rises in direct proportion to the synthesizer's phase noise.
> Dave's
> > screenshots of the P3 spectrograms show this smearing
> clearly.
> >
> >
> > An oscillator with less phase noise looks more like that
> ideal picture
> > we all have in our heads -- of a signal that's infinitely
> narrow. In
> > the third of Dave's screenshots you can see how the new
> synths are
> > closer to an ideal oscillator-- the CW signal's width on the
> > spectrogram is much narrower.
> >
> >
> > If a signal has lower noise sidebands (whether the sidebands
> are
> > generated in the transmitter or the receiver... each of them
> has a
> > synthesizer) then you can enjoy less interference from an
> adjacent
> > signal. You will also *cause* less interference to your
> neighbors on
> > the band.
> >
> >
> > I have no idea of the design of the new synths, but in
> general to
> > design a synthesizer with low phase noise you have to start
> with very
> > low noise devices, pay really careful attention to the parts
> of the
> > phase-locked loop like the Q, feedback, the numeric
> dithering, the
> > loop filter and various other aspects of the circuit. It's a
> real art.
> > It appears from Dave's observations that there is a
> significant and
> > measurable difference.
> >
> >
> >
> >
> > Al W6LX
> >
> >
> >
> >
>
> ______________________________________________________________
> 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
> Message delivered to [hidden email]
>
>
>

Alan Bloom

Re: Observation on new Synthesizers for K3

In reply to this post by NK7Z

On 07/08/2015 06:02 AM, David Cole wrote:
>
> It occurs to me that the the the RX VFO phase noise would be less
> influencing, (on phase noise sidebands), than the transmit VFO phase
> noise... Is that correct?
>
> If so, then that would explain why the largest change occurred when
> K7OLN got his new synthesizer, as opposed to me getting my new
> synthesizer, as shown in the difference between photos 2 and 3.
>

I believe the TX and RX phase noise have an equal effect on the
interference.

Let's say the phase noise of the new synthesizer is 10 dB better than
the old at a particular offset frequency. That is, 1/10 the power.

If you replace one synthesizer (RX or TX) then the total phase noise is
reduced by a factor (1 + 1/10) / (1 + 1) = 0.55 or -2.6 dB.

If you replace both synthesizers, then the total phase noise is reduced
by a factor (1/10 + 1/10) / (1 + 1) = -10 dB.

I don't think it makes any difference which synthesizer is changed first.

Alan N1AL
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Alan Bloom

Re: Observation on new Synthesizers for K3

By the way, a corollary to this is that it doesn't help much to improve
the phase noise of your radio if your neighbor's radio is dirty.

Alan N1AL

On 07/08/2015 08:45 AM, Alan wrote:

> On 07/08/2015 06:02 AM, David Cole wrote:
>>
>> It occurs to me that the the the RX VFO phase noise would be less
>> influencing, (on phase noise sidebands), than the transmit VFO phase
>> noise... Is that correct?
>>
>> If so, then that would explain why the largest change occurred when
>> K7OLN got his new synthesizer, as opposed to me getting my new
>> synthesizer, as shown in the difference between photos 2 and 3.
>>
>
> I believe the TX and RX phase noise have an equal effect on the
> interference.
>
> Let's say the phase noise of the new synthesizer is 10 dB better than
> the old at a particular offset frequency. That is, 1/10 the power.
>
> If you replace one synthesizer (RX or TX) then the total phase noise is
> reduced by a factor (1 + 1/10) / (1 + 1) = 0.55 or -2.6 dB.
>
> If you replace both synthesizers, then the total phase noise is reduced
> by a factor (1/10 + 1/10) / (1 + 1) = -10 dB.
>
> I don't think it makes any difference which synthesizer is changed first.
>
> Alan N1AL
> ______________________________________________________________
> 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
> Message delivered to [hidden email]
>

Jim Brown-10

Re: Observation on new Synthesizers for K3

On Wed,7/8/2015 9:04 AM, Alan wrote:
> By the way, a corollary to this is that it doesn't help much to
> improve the phase noise of your radio if your neighbor's radio is dirty.

I can testify to that! My neighbor 8 miles away runs an IC7600. Real POS.

73, Jim K9YC
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NK7Z

Re: Observation on new Synthesizers for K3

My most active neighbor, (I have 5 hams in less than 1/2 mile from me),
runs an Icom 706MKII G, that is a real POS if I have ever seen one...

It takes out most of the band when he is on, and running 100W, as
opposed to the K7OLN's K3, (750 feet form me), when running a KW and I
am able to operate 10-15 KHz away from the K3 at K7OLNs place.

The images at:
http://nk7z.net/wiki/elecraft-k3-macros/elecraft-k3-xlr-to-radio/elecraft-k3-new-synthesizer/
tell the story of why I got my K3...
--
Thanks and 73's,
For equipment, and software setups and reviews see:
www.nk7z.net

For MixW support see;
http://groups.yahoo.com/neo/groups/mixw/info
For Dopplergram information see:
http://groups.yahoo.com/neo/groups/dopplergram/info
For MM-SSTV see:
http://groups.yahoo.com/neo/groups/MM-SSTV/info

On Wed, 2015-07-08 at 09:34 -0700, Jim Brown wrote:

> On Wed,7/8/2015 9:04 AM, Alan wrote:
> > By the way, a corollary to this is that it doesn't help much to
> > improve the phase noise of your radio if your neighbor's radio is dirty.
>
> I can testify to that! My neighbor 8 miles away runs an IC7600. Real POS.
>
> 73, Jim K9YC
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alorona

Re: Observation on new Synthesizers for K3

In reply to this post by NK7Z

I think that once your receiver's phase noise is about 1/10 (-10 dB) of the incoming transmitted signal's phase noise, the incoming will dominate and you'll no longer see an improvement no matter what you do to the receiver. (This is a famous rule-of-thumb we use in any measurement.) From the anecdotal reports we're reading here, the K3 has probably reached that point as compared to many other rigs, especially if they're close by.
Al W6LX

If so, then does that mean that as a station gets stronger, one picks up
more of the phase noise, (a function of how far from center one is), and
that is why a signal gets wider as it gets stronger?

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Mike Harris-9

Re: Observation on new Synthesizers for K3

In reply to this post by Alan Bloom

I have a neighbour approximately 300 metres away who causes significant
noise QRM on the next two bands LF, S3-5. Less so if I'm working a
higher higher band which I assume is due to cut-off of the TX BPFs in
both the transceiver and the linear.

The transceiver in question is an FTDX5000.

Regards,

Mike VP8NO

On 08/07/2015 13:08, Walter Underwood wrote:
> It would help a lot when your neighbor is not transmitting or transmitting on a different band. Plus, it is courteous to transmit a cleaner signal.
>
> wunder
> K6WRU
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Martin Sole (HS0ZED)

Re: Observation on new Synthesizers for K3

The solution is becoming clear. We all need to buy our near neighbours
shiny new K3S's.
Costly maybe but what price for some RF sanity.

Cheers
Martin, HS0ZED

Who has no obvious nearby hams :)

On 08/07/2015 20:28, Mike Harris wrote:

> I have a neighbour approximately 300 metres away who causes
> significant noise QRM on the next two bands LF, S3-5. Less so if I'm
> working a higher higher band which I assume is due to cut-off of the
> TX BPFs in both the transceiver and the linear.
>
> The transceiver in question is an FTDX5000.
>
> Regards,
>
> Mike VP8NO
>
> On 08/07/2015 13:08, Walter Underwood wrote:
>> It would help a lot when your neighbor is not transmitting or
>> transmitting on a different band. Plus, it is courteous to transmit a
>> cleaner signal.
>>
>> wunder
>> K6WRU
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>

Edward R Cole

Re: Observation on new Synthesizers for K3

In reply to this post by NK7Z

Phase noise in oscillators is a subject much discussed amongst
microwave hams and eme'rs who are trying to obtain optimum reception.

It is not totally agreed but much thought is that MDS is lowered by
having low phase-noise (even in a completely quiet band (no adjacent
signals). Thinking is that phase noise *somehow* combines with
antenna noise and internal amplifier noise (NF) to limit MDS. W1GHZ
has recently been *playing* with VCXO's in place of PLL's and states
that he is seeing a 2-dB reduction in MDS level as a result. The
voltage-controlled xtal oscillator takes advantage of the better
phase noise of the xtal osc. Many PLL use a VCO which is wide
frequency in range which is much harder to design for low phase noise
(Wayne and co. can probably tell us a whole bunch about that).

This is probably of no concern on LF/MW/HF/6m due to the much higher
sky noise being the limit on MDS from new equipment (K3 MDS -140 to
-145 dBm on 6m). My 2m-eme station MDS is about -155 dBm without
adding antenna gain (21.3 dBi). MDS does not add in the effect of
antenna gain or sky noise. It is also referred to as Trx (receiving
system noise temperature). This stuff is not in the normal HFers
vocabulary...my apologies.

But I am excited to learn of the improved Synth for the K3s and upgrade for K3.

73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[hidden email]

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Greg Troxel-2

Re: Observation on new Synthesizers for K3

In reply to this post by NK7Z

David Cole <[hidden email]> writes:

> It occurs to me that the the the RX VFO phase noise would be less
> influencing, (on phase noise sidebands), than the transmit VFO phase
> noise... Is that correct?
>
> If so, then that would explain why the largest change occurred when
> K7OLN got his new synthesizer, as opposed to me getting my new
> synthesizer, as shown in the difference between photos 2 and 3.
>
> Is my understanding correct?

In an ideal system, the receiver sees the convolution of the transmit
signal, as conveyed by the antennas and progagation and the receiver's
LO. So for the most part, I think TX and RX phase noise hurt equally
(when viewed in dBc/Hz at some separation). Of course, RX phase noise
is under one's control, and TX is imposed on others, so from that
viewpoint TX phase noise is more like crossing the yellow line than
hitting a tree yourself.

From the measurements I've seen, I don't think it's a fair assumption
that transmit and receive phase noise in a given rig is the same. The
K3 (with original synth) has a transmitter which is relatively cleaner
than RX reciprocal mixing, according to:

http://www.sm5bsz.com/dynrange/dubus313.pdf

But in many radios (including the KX3), that article says that the
transmitter is worse than the receiver.

Also see:

http://k9yc.com/TXNoise.pdf

which focuses on lab measurements of transmitters, disconnected from
receiver issues. Presumably the spectrum analyzers are good enough that
they're not an issue, but I wonder if that's really true given the
levels we're talking about.

I think QST reviews should give some measurement of joint TX/RX noise.
Perhaps the isolation required so that with one instance of a
transceiver at 100W, the 2nd instance receiving at 100 kHz separations
(perhaps for 2/10/50/100/200 kHz) ees some particular absolute level of
noise, picking some level that is about 10 dBo worse than typical MDS.
This is trying to capture "what happens when you have two of Rig X at
Field Day in the same band", or the 300m neighbor situation.

73 de n1dam
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Jim Brown-10

Re: Observation on new Synthesizers for K3

In reply to this post by Mike Harris-9

On Wed,7/8/2015 10:28 AM, Mike Harris wrote:
> The transceiver in question is an FTDX5000.

According to FCC measurments, it's one of the worst of the expensive
modern rigs for CW bandwidth. BUT -- Yaesu issued a firmware update last
fall, and my before/after measurements of a N6TA's FTDX5000 showed a
significant improvement.

73, Jim K9YC
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W1KSZ

Re: Observation on new Synthesizers for K3

So you are saying the FTDX-5KMP is no longer one of the worst ???
Where does it stack up today, in your opinion ??

73, Dick, W1KSZ

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Jim
Brown
Sent: Wednesday, July 08, 2015 6:43 PM
To: [hidden email]
Subject: Re: [Elecraft] Observation on new Synthesizers for K3

On Wed,7/8/2015 10:28 AM, Mike Harris wrote:
> The transceiver in question is an FTDX5000.

According to FCC measurments, it's one of the worst of the expensive modern
rigs for CW bandwidth. BUT -- Yaesu issued a firmware update last fall, and
my before/after measurements of a N6TA's FTDX5000 showed a significant
improvement.

73, Jim K9YC
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