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FTDX5000 Design Flaw

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John, KI6WX

FTDX5000 Design Flaw

There have been a lot of comments on the reflector about the QST review of
the FTDX5000. However, no one has noted a significant design flaw in the
transmitter that shows up in the review. Refer to Figure 3 that shows the
composite transmitter noise. It shows a noise level of -130 dBc/Hz from 10
kHz to 1 MHz (and probably beyond).

This transmitter when combined with a full power amp could wipe weak signals
in an entire amateur band for anyone living within a few miles of the
transmitter (see the math calculation below). While a number of other
transceivers have this problem, I wouldn't expect a top of the line $6K
radio to have such lousy composite transmit noise.

This problem is created either in the radio's synthesizer or its transmit
amplification chain. The K3 was specifically designed to minimize composite
transmit noise. The K3 QST review showed a transmit noise level of -155
dBc/Hz at a 100 kHz offset. This is 4 S-units less noise than the FTDX5000
at the same offset.

This is not a theoretical calculation. I know of one case of composite
transmit noise where an amateur transmitter wiped out weak signal reception
across an entire ham band in a receiver located several miles away.

-John

KI6WX

CALCULATIONS

Assume that we have a FTDX5000 transmitting CW on 20 meters followed by a
1.5 kW amp. The transmit power is +62 dBm. At a 100 kHz offset, the
transmit noise is -68 dBm/Hz.

Assume that the FTDX5000 transmit output is fed to an isotropic radiator (0
dB gain) on top of a hill and we have a receiver also with an isotropic
antenna in a valley with line of sight to the hill. For directional
antennas, the sum of the antenna gains depends on where they are aimed and
could be greater or less than the 0 dB in this example. For the moment,
we'll place the receiver 1 mile from the transmit antenna.

The path loss between the transmit and receive antennas is 60 dB, which
implies the receive power of the transmit noise will be -128 dBm/Hz. The
normal atmospheric noise on 20 meters is about -144 dBm/Hz, which means that
the transmit noise will be 16 dB greater than the normal background noise.
This noise will be spread across the entire band whenever the FTDX5000 is
transmitting. If it is transmitting CW, the receiver will hear noise
modulated in Morse code. If it is transmitting SSB, the noise will vary
with the voice modulation peaks. The receiver would have to be more than 6
miles away for the noise to drop to background levels.

Another way to look at this problem is how many S-units would the show up in
a 500 Hz receive bandwidth. The total power in the noise is -101 dBm in the
500 Hz bandwidth. S4 is -103 dBm, so the noise would be about a S4 signal
level. Each time you halve the distance to the transmitter, the noise will
increase by 1 S-unit. If you live 1000' from a FTDX5000, you could see a
noise level of S7. You can reduce the noise by using a narrower filter, but
you would have to drop down to a 100 Hz filter to reduce it by 1 S-unit.

This calculation was done with the transmit antenna on top of a hill so we
could use free space radiation to calculate the path loss. If both antennas
are on a flat surface of earth, the path loss will be somewhat greater, but
the exact magnitude requires using antenna radiation software such as NEC-4.

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Joe Subich, W4TV-4

Re: FTDX5000 Design Flaw

>> This transmitter when combined with a full power amp could wipe
>> weak signals in an entire amateur band for anyone living within a
>> few miles of the transmitter (see the math calculation below).
>> While a number of other transceivers have this problem, I wouldn't
>> expect a top of the line $6K radio to have such lousy composite
>> transmit noise.

Why is this not sent to the Editor and Technical Editor or QST as
well as the lead test engineer at the ARRL lab? What was their
response?

If the radio's transmitted phase noise is that bad, Yaesu should be
forced to recall all units currently in the field.

73,

... Joe, W4TV

On 11/20/2010 12:08 AM, John, KI6WX wrote:

> There have been a lot of comments on the reflector about the QST review of
> the FTDX5000. However, no one has noted a significant design flaw in the
> transmitter that shows up in the review. Refer to Figure 3 that shows the
> composite transmitter noise. It shows a noise level of -130 dBc/Hz from 10
> kHz to 1 MHz (and probably beyond).
>
>
>
> This transmitter when combined with a full power amp could wipe weak signals
> in an entire amateur band for anyone living within a few miles of the
> transmitter (see the math calculation below). While a number of other
> transceivers have this problem, I wouldn't expect a top of the line $6K
> radio to have such lousy composite transmit noise.
>
>
>
> This problem is created either in the radio's synthesizer or its transmit
> amplification chain. The K3 was specifically designed to minimize composite
> transmit noise. The K3 QST review showed a transmit noise level of -155
> dBc/Hz at a 100 kHz offset. This is 4 S-units less noise than the FTDX5000
> at the same offset.
>
>
>
> This is not a theoretical calculation. I know of one case of composite
> transmit noise where an amateur transmitter wiped out weak signal reception
> across an entire ham band in a receiver located several miles away.
>
>
>
> -John
>
> KI6WX
>
>
>
>
>
> CALCULATIONS
>
>
>
> Assume that we have a FTDX5000 transmitting CW on 20 meters followed by a
> 1.5 kW amp. The transmit power is +62 dBm. At a 100 kHz offset, the
> transmit noise is -68 dBm/Hz.
>
>
>
> Assume that the FTDX5000 transmit output is fed to an isotropic radiator (0
> dB gain) on top of a hill and we have a receiver also with an isotropic
> antenna in a valley with line of sight to the hill. For directional
> antennas, the sum of the antenna gains depends on where they are aimed and
> could be greater or less than the 0 dB in this example. For the moment,
> we'll place the receiver 1 mile from the transmit antenna.
>
>
>
> The path loss between the transmit and receive antennas is 60 dB, which
> implies the receive power of the transmit noise will be -128 dBm/Hz. The
> normal atmospheric noise on 20 meters is about -144 dBm/Hz, which means that
> the transmit noise will be 16 dB greater than the normal background noise.
> This noise will be spread across the entire band whenever the FTDX5000 is
> transmitting. If it is transmitting CW, the receiver will hear noise
> modulated in Morse code. If it is transmitting SSB, the noise will vary
> with the voice modulation peaks. The receiver would have to be more than 6
> miles away for the noise to drop to background levels.
>
>
>
> Another way to look at this problem is how many S-units would the show up in
> a 500 Hz receive bandwidth. The total power in the noise is -101 dBm in the
> 500 Hz bandwidth. S4 is -103 dBm, so the noise would be about a S4 signal
> level. Each time you halve the distance to the transmitter, the noise will
> increase by 1 S-unit. If you live 1000' from a FTDX5000, you could see a
> noise level of S7. You can reduce the noise by using a narrower filter, but
> you would have to drop down to a 100 Hz filter to reduce it by 1 S-unit.
>
>
>
> This calculation was done with the transmit antenna on top of a hill so we
> could use free space radiation to calculate the path loss. If both antennas
> are on a flat surface of earth, the path loss will be somewhat greater, but
> the exact magnitude requires using antenna radiation software such as NEC-4.
>
>
>
>
>
> ______________________________________________________________
> 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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Bob Cunnings NW8L

Re: FTDX5000 Design Flaw

The FTDX500 wouldn't be the only one, if a -130 dBc composite noise
number defines failure. If you have access to QST reviews, compare:

Flex 5000
FT-2000
Orion II
IC-7700
K3

all of which plot tx composite noise at 100 or 200 W out to 1 Mhz. You
can draw your own conclusions, but the FTDX5000 apparently isn't
exceptional in that regard. The Flex is no better than -120 dBc out
to 1 MHz, the FT-2000 is slightly worse than the FTDX-5000, and the
Orion II is no better than -130 dBc out to 100 kHz. The Icom rigs seem
to do a little better. The K3 performance indeed far surpasses the
others. I could find no comment on these numbers in the reviews.

Bob NW8L

> Why is this not sent to the Editor and Technical Editor or QST as
> well as the lead test engineer at the ARRL lab? What was their
> response?
>
> If the radio's transmitted phase noise is that bad, Yaesu should be
> forced to recall all units currently in the field.
>
>
> 73,
>
> ... Joe, W4TV
>

John, KI6WX

Re: FTDX5000 Design Flaw

The ARRL is aware of this issue. This problem was discussed in my 1988
articles on phase noise in QST (March & April issues). The article notes
that a high phase noise transmitter degrades the performance of a low phase
noise receiver to that of the transmitter. This article started the ARRL
making composite transmit noise measurements.

A strong signal (>S9+50dB) from a transmitter with broadband -130 dBc
composite noise in a 500 Hz bandwidth reduces the receiver's blocking
dynamic range to 103 dB. Most top notch receivers show a blocking dynamic
range of around 140 dB. In this case, the dynamic range is reduced because
the noise floor is increased.

I don't think most hams are aware of the problem. If you have a nearby ham
running high power and your receiver doesn't work well when they are
transmitting, you just assume that the signal is too strong for your
receiver.

This problem is like splatter or key clicks. It doesn't impact the owner of
the transmitter, but instead degrades the receiving environment of those who
live near them. There is little incentive for the owner of the high
composite noise transmitter to improve their equipment.

-John
KI6WX

>
> The FTDX500 wouldn't be the only one, if a -130 dBc composite noise
> number defines failure. If you have access to QST reviews, compare:
>
> Flex 5000
> FT-2000
> Orion II
> IC-7700
> K3
>
> all of which plot tx composite noise at 100 or 200 W out to 1 Mhz. You
> can draw your own conclusions, but the FTDX5000 apparently isn't
> exceptional in that regard. The Flex is no better than -120 dBc out
> to 1 MHz, the FT-2000 is slightly worse than the FTDX-5000, and the
> Orion II is no better than -130 dBc out to 100 kHz. The Icom rigs seem
> to do a little better. The K3 performance indeed far surpasses the
> others. I could find no comment on these numbers in the reviews.
>
> Bob NW8L
>
> > Why is this not sent to the Editor and Technical Editor or QST as
> > well as the lead test engineer at the ARRL lab? What was their
> > response?
> >
> > If the radio's transmitted phase noise is that bad, Yaesu should be
> > forced to recall all units currently in the field.
> >
> >
> > 73,
> >
> > ... Joe, W4TV
> >

Eugene Balinski

Re: FTDX5000 Design Flaw

The phase noise on the original Icom IC-751 (not the "A"
versions) was so bad that it was banned from our
multi-transmitter field day site. Seems it took out a
number of bands when transmitting-.

Gene K1NR

On Sat, 20 Nov 2010 12:48:53 -0800
"John, KI6WX" <[hidden email]> wrote:

> The ARRL is aware of this issue. This problem was
> discussed in my 1988
> articles on phase noise in QST (March & April issues).
> The article notes
> that a high phase noise transmitter degrades the
> performance of a low phase
> noise receiver to that of the transmitter. This article
> started the ARRL
> making composite transmit noise measurements.
>
> A strong signal (>S9+50dB) from a transmitter with
> broadband -130 dBc
> composite noise in a 500 Hz bandwidth reduces the
> receiver's blocking
> dynamic range to 103 dB. Most top notch receivers show a
> blocking dynamic
> range of around 140 dB. In this case, the dynamic range
> is reduced because
> the noise floor is increased.
>
> I don't think most hams are aware of the problem. If you
> have a nearby ham
> running high power and your receiver doesn't work well
> when they are
> transmitting, you just assume that the signal is too
> strong for your
> receiver.
>
> This problem is like splatter or key clicks. It doesn't
> impact the owner of
> the transmitter, but instead degrades the receiving
> environment of those who
> live near them. There is little incentive for the owner
> of the high
> composite noise transmitter to improve their equipment.
>
> -John
> KI6WX
>
> >
> > The FTDX500 wouldn't be the only one, if a -130 dBc
> composite noise
> > number defines failure. If you have access to QST
> reviews, compare:
> >
> > Flex 5000
> > FT-2000
> > Orion II
> > IC-7700
> > K3
> >
> > all of which plot tx composite noise at 100 or 200 W
> out to 1 Mhz. You
> > can draw your own conclusions, but the FTDX5000
> apparently isn't
> > exceptional in that regard. The Flex is no better than
> -120 dBc out
> > to 1 MHz, the FT-2000 is slightly worse than the
> FTDX-5000, and the
> > Orion II is no better than -130 dBc out to 100 kHz. The
> Icom rigs seem
> > to do a little better. The K3 performance indeed far
> surpasses the
> > others. I could find no comment on these numbers in the
> reviews.
> >
> > Bob NW8L
> >
> > > Why is this not sent to the Editor and Technical
> Editor or QST as
> > > well as the lead test engineer at the ARRL lab? What
> was their
> > > response?
> > >
> > > If the radio's transmitted phase noise is that bad,
> Yaesu should be
> > > forced to recall all units currently in the field.
> > >
> > >
> > > 73,
> > >
> > > ... Joe, W4TV
> > >
>
>

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juergen piezo

Re: FTDX5000 Design Flaw

In reply to this post by Joe Subich, W4TV-4

Hi Joe

A recall for Yaesu is the new FT6000! Yaesu's past history with the keyclick debacle makes me believe that a recall of any Yaesu product is very unlikely.

The FT5000 with its tuning birdies, image rejection and now wideband phase
noise problems is fast becoming an expensive lemon.

It is unlikely that the FT5000 will be used in any multi multi station with these phase noise problems. It will also make the FT5000 unusable for VHF contesting with transverters in Europe. Wideband phase noise problems can cause huge problems for line of site VHF contesting. There are VHF radios that are worst than the FT5000, the Icom IC910H is one of them.

73
John

--- On Sat, 11/20/10, Joe Subich, W4TV <[hidden email]> wrote:

> From: Joe Subich, W4TV <[hidden email]>
> Subject: Re: [Elecraft] FTDX5000 Design Flaw
> To: [hidden email]
> Date: Saturday, November 20, 2010, 8:10 AM
>
> >> This transmitter when combined with a full power
> amp could wipe
> >> weak signals in an entire amateur band for anyone
> living within a
> >> few miles of the transmitter (see the math
> calculation below).
> >> While a number of other transceivers have this
> problem, I wouldn't
> >> expect a top of the line $6K radio to have such
> lousy composite
> >> transmit noise.
>
> Why is this not sent to the Editor and Technical Editor or
> QST as
> well as the lead test engineer at the ARRL lab? What
> was their
> response?
>
> If the radio's transmitted phase noise is that bad, Yaesu
> should be
> forced to recall all units currently in the field.
>
> 73,
>
> ... Joe, W4TV
>
>
> On 11/20/2010 12:08 AM, John, KI6WX wrote:
> > There have been a lot of comments on the reflector
> about the QST review of
> > the FTDX5000. However, no one has noted a
> significant design flaw in the
> > transmitter that shows up in the review. Refer
> to Figure 3 that shows the
> > composite transmitter noise. It shows a noise
> level of -130 dBc/Hz from 10
> > kHz to 1 MHz (and probably beyond).
> >
> >
> >
> > This transmitter when combined with a full power amp
> could wipe weak signals
> > in an entire amateur band for anyone living within a
> few miles of the
> > transmitter (see the math calculation below).
> While a number of other
> > transceivers have this problem, I wouldn't expect a
> top of the line $6K
> > radio to have such lousy composite transmit noise.
> >
> >
> >
> > This problem is created either in the radio's
> synthesizer or its transmit
> > amplification chain. The K3 was specifically
> designed to minimize composite
> > transmit noise. The K3 QST review showed a
> transmit noise level of -155
> > dBc/Hz at a 100 kHz offset. This is 4 S-units
> less noise than the FTDX5000
> > at the same offset.
> >
> >
> >
> > This is not a theoretical calculation. I know of
> one case of composite
> > transmit noise where an amateur transmitter wiped out
> weak signal reception
> > across an entire ham band in a receiver located
> several miles away.
> >
> >
> >
> > -John
> >
> > KI6WX
> >
> >
> >
> >
> >
> > CALCULATIONS
> >
> >
> >
> > Assume that we have a FTDX5000 transmitting CW on 20
> meters followed by a
> > 1.5 kW amp. The transmit power is +62 dBm.
> At a 100 kHz offset, the
> > transmit noise is -68 dBm/Hz.
> >
> >
> >
> > Assume that the FTDX5000 transmit output is fed to an
> isotropic radiator (0
> > dB gain) on top of a hill and we have a receiver also
> with an isotropic
> > antenna in a valley with line of sight to the
> hill. For directional
> > antennas, the sum of the antenna gains depends on
> where they are aimed and
> > could be greater or less than the 0 dB in this
> example. For the moment,
> > we'll place the receiver 1 mile from the transmit
> antenna.
> >
> >
> >
> > The path loss between the transmit and receive
> antennas is 60 dB, which
> > implies the receive power of the transmit noise will
> be -128 dBm/Hz. The
> > normal atmospheric noise on 20 meters is about -144
> dBm/Hz, which means that
> > the transmit noise will be 16 dB greater than the
> normal background noise.
> > This noise will be spread across the entire band
> whenever the FTDX5000 is
> > transmitting. If it is transmitting CW, the
> receiver will hear noise
> > modulated in Morse code. If it is transmitting
> SSB, the noise will vary
> > with the voice modulation peaks. The receiver
> would have to be more than 6
> > miles away for the noise to drop to background
> levels.
> >
> >
> >
> > Another way to look at this problem is how many
> S-units would the show up in
> > a 500 Hz receive bandwidth. The total power in
> the noise is -101 dBm in the
> > 500 Hz bandwidth. S4 is -103 dBm, so the noise
> would be about a S4 signal
> > level. Each time you halve the distance to the
> transmitter, the noise will
> > increase by 1 S-unit. If you live 1000' from a
> FTDX5000, you could see a
> > noise level of S7. You can reduce the noise by
> using a narrower filter, but
> > you would have to drop down to a 100 Hz filter to
> reduce it by 1 S-unit.
> >
> >
> >
> > This calculation was done with the transmit antenna on
> top of a hill so we
> > could use free space radiation to calculate the path
> loss. If both antennas
> > are on a flat surface of earth, the path loss will be
> somewhat greater, but
> > the exact magnitude requires using antenna radiation
> software such as NEC-4.
> >
> >
> >
> >
> >
> >
> ______________________________________________________________
> > 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
>

Jim Brown-10

Re: FTDX5000 Design Flaw

In reply to this post by John, KI6WX

On Sat,11/20/2010 12:48 PM, John, KI6WX wrote:
> The ARRL is aware of this issue. This problem was discussed in my 1988
> articles on phase noise in QST (March & April issues). The article notes
> that a high phase noise transmitter degrades the performance of a low phase
> noise receiver to that of the transmitter. This article started the ARRL
> making composite transmit noise measurements.

I've recently added fuel to the fire with an online document plotting
ARRL TX data for multiple radios on the same graphs, making comparison's
easier. I did that by taking data point by point off of ARRL's published
plots, then putting them in my own spreadsheet. I did that for both
keying spectra and phase noise.

Seeing that document, Bob Allison sent me the raw data for the CW keying
spectra for those radios, and I've been processing and plotting that
data. He was not able to provide the phase noise data in electronic
form, so we're stuck with what I am able to eyeball from the published
plots.

You can see an "in-progress" version at k9yc.com/TXNoise.pdf

73, Jim K9YC

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wayne burdick

Re: FTDX5000 Design Flaw

Administrator

Jim,

Thanks for your analysis of transmitted phase and keying noise of various transceivers. I'd like to provide a couple of technical details, and to give credit where it is due.

To achieve the excellent results shown in your paper for the K3, we used a combination of four techniques:

1. A hybrid PLL/DDS synthesizer with a very high C/L ratio VCO: Many of the radios shown in your plots use unfiltered DDS for their VFO, or in the case of PLL designs, VCOs with a much higher C/L ratio than the K3. Both of these design decisions can increase phase noise and dynamic artifacts. To preserve a consistently high C/L ratio, we use up to 128 different C/L combinations as the VCO is band-switched. (This is in contrast to the usual 1, 2, or 3 VCO C/L ranges used in other rigs.) We also used very narrow-band crystal filtering of the DDS output to completely remove any of the usual spurs due to quantization, etc. John Grebenkemper assisted greatly with the synthesizer design.

2. Transmit ALC with long time-constant, pre-calculated power calibration, and virtually no dynamic artifacts: The K3's transmit ALC is, in effect, open-loop in relation to keying waveform rise/fall timing. In other words, we do not apply power corrections over short periods, since this can distort the keying envelope. This is especially noticeable in CW mode but applies to T/R switching in other modes as well.

3. Conversion to a low I.F., with both RX and TX signals running through a narrow crystal filter: This band-limits I.F. noise from early stages (DSP and D-to-A converter) and helps establish a very low transmit noise floor ahead of the main mixer. Even in speech modes, all fast ALC is applied ahead of the crystal filter, which I believe is unique to the K3.

4. Sigmoidal keying waveform applied at the DSP: Our DSP engineer (Lyle Johnson, KK7P) studied the sidebands resulting from various sigmoidal and raise-cosine modulation envelopes. He selected the one that provided the smallest keying bandwidth consistent with rise and fall times of approximately 4 ms.

One clarification. The reason we created the K3's "QRQ mode" was to provide faster full break-in at very high code speeds (up to 100 WPM). The keying dynamics and phase noise are the same with QRQ mode either on or off; they are not "soft" with QRQ mode on. The KPA500 amplifier also switches very fast, so it is fully compatible with either mode.

73,
Wayne
N6KR

On Aug 31, 2014, at 3:40 PM, Jim Brown <[hidden email]> wrote:

> On Sat,11/20/2010 12:48 PM, John, KI6WX wrote:
>> The ARRL is aware of this issue. This problem was discussed in my 1988
>> articles on phase noise in QST (March & April issues). The article notes
>> that a high phase noise transmitter degrades the performance of a low phase
>> noise receiver to that of the transmitter. This article started the ARRL
>> making composite transmit noise measurements.
>
> I've recently added fuel to the fire with an online document plotting ARRL TX data for multiple radios on the same graphs, making comparison's easier. I did that by taking data point by point off of ARRL's published plots, then putting them in my own spreadsheet. I did that for both keying spectra and phase noise.
>
> Seeing that document, Bob Allison sent me the raw data for the CW keying spectra for those radios, and I've been processing and plotting that data. He was not able to provide the phase noise data in electronic form, so we're stuck with what I am able to eyeball from the published plots.
>
> You can see an "in-progress" version at k9yc.com/TXNoise.pdf
>
> 73, Jim K9YC

wayne burdick

Re: FTDX5000 Design Flaw [typo]

Administrator

Typo:

Change "...or in the case of PLL designs, VCOs with a much higher C/L ratio than the K3..."

to "...or in the case of PLL designs, VCOs with a much *lower* C/L ratio than the K3."

Wayne
N6KR

On Aug 31, 2014, at 7:17 PM, Wayne Burdick <[hidden email]> wrote:

> Jim,
>
> Thanks for your analysis of transmitted phase and keying noise of various transceivers. I'd like to provide a couple of technical details, and to give credit where it is due.
>
> To achieve the excellent results shown in your paper for the K3, we used a combination of four techniques:
>
> 1. A hybrid PLL/DDS synthesizer with a very high C/L ratio VCO: Many of the radios shown in your plots use unfiltered DDS for their VFO, or in the case of PLL designs, VCOs with a much higher C/L ratio than the K3. Both of these design decisions can increase phase noise and dynamic artifacts. To preserve a consistently high C/L ratio, we use up to 128 different C/L combinations as the VCO is band-switched. (This is in contrast to the usual 1, 2, or 3 VCO C/L ranges used in other rigs.) We also used very narrow-band crystal filtering of the DDS output to completely remove any of the usual spurs due to quantization, etc. John Grebenkemper assisted greatly with the synthesizer design.

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Wes (N7WS)

Re: FTDX5000 Design Flaw

In reply to this post by Jim Brown-10

This is why that on more than one occasion over the years I've said (only
semi-facetiously) that the two-tone testing of the receiver portion of a
transceiver should be performed using two other like transceiver transmitters,
running rated output power, as the two test tones. When our transmitters are as
pure as HP-8663s then we can go back to using them for receiver testing.

Wes N7WS

On 8/31/2014 3:40 PM, Jim Brown wrote:

> On Sat,11/20/2010 12:48 PM, John, KI6WX wrote:
>> The ARRL is aware of this issue. This problem was discussed in my 1988
>> articles on phase noise in QST (March & April issues). The article notes
>> that a high phase noise transmitter degrades the performance of a low phase
>> noise receiver to that of the transmitter. This article started the ARRL
>> making composite transmit noise measurements.
>
> I've recently added fuel to the fire with an online document plotting ARRL TX
> data for multiple radios on the same graphs, making comparison's easier. I did
> that by taking data point by point off of ARRL's published plots, then putting
> them in my own spreadsheet. I did that for both keying spectra and phase noise.
>
> Seeing that document, Bob Allison sent me the raw data for the CW keying
> spectra for those radios, and I've been processing and plotting that data. He
> was not able to provide the phase noise data in electronic form, so we're
> stuck with what I am able to eyeball from the published plots.
>
> You can see an "in-progress" version at k9yc.com/TXNoise.pdf
>
> 73, Jim K9YC
>

Jim Brown-10

Re: FTDX5000 Design Flaw

In reply to this post by wayne burdick

On Sun,8/31/2014 7:17 PM, Wayne Burdick wrote:
> I'd like to provide a couple of technical details, and to give credit where it is due.

Thanks Wayne. I was aware of some of this, but didn't want to show any
more of your cards than you chose. Your comments will make a fine sidebar.

73, Jim K9YC
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Jim Brown-10

Re: FTDX5000 Design Flaw

In reply to this post by Wes (N7WS)

On Sun,8/31/2014 8:17 PM, Wes (N7WS) wrote:
> This is why that on more than one occasion over the years I've said
> (only semi-facetiously) that the two-tone testing of the receiver
> portion of a transceiver should be performed using two other like
> transceiver transmitters, running rated output power, as the two test
> tones. When our transmitters are as pure as HP-8663s then we can go
> back to using them for receiver testing.
>
> Wes N7WS

Great idea, Wes. I had to read through it twice to get it. :)

73, Jim
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dw-4

Re: FTDX5000 Design Flaw

In reply to this post by John, KI6WX

Super impressed!!!!
Wonderful piece of work Jim!!!
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