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K3 to IC-7800 Comparison?

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W5GAI

K3 to IC-7800 Comparison?

If anyone has done a K3 to IC-7800 comparison, please reply direct to me
with your assessment.
Thanks,
Skip W5GAI
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Jim Brown-10

Re: K3 to IC-7800 Comparison?

On Sat,9/12/2015 2:12 PM, Skip Cameron wrote:
> If anyone has done a K3 to IC-7800 comparison, please reply direct to me
> with your assessment.

I've never seen a 7800, so no experience. However, ARRL and Rob Sherwood
have. Rob's data is on his webpage. It concentrates on receiver
performance. I've gathered ARRL Lab test data for a selected bunch of
modern rigs and published it in a form making it easier to compare the
rigs as TRANSMITTERS. My report is at http://k9yc.com/TXNoise.pdf

The original K3 is MUCH cleaner on CW than the 7800. Also, the original
K3 has about 15 dB less phase noise than the 7800, which matters a lot
on Field Day and at a multi-TX contest station. The new synth board
reduces both TX and RX phase noise quite a bit (I've heard numbers in
the range of 10 dB).

I haven't seen ARRL Lab tests of the new K3S or a K3 with the new synth
board, but I suspect both will turn out to be at the head of the pack
for TX cleanliness. Yes, I know about Pure Signal -- NR0V is my neighbor.

73, Jim K9YC
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Dr. William J. Schmidt, II

Re: K3 to IC-7800 Comparison?

In reply to this post by W5GAI

I have two of each. What do you want to know?

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

Owner - Operator
Big Signal Ranch - K9ZC
Staunton, Illinois

Owner - Operator
Villa Grand Piton - J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com

email: [hidden email]

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Skip
Cameron
Sent: Saturday, September 12, 2015 4:13 PM
To: [hidden email]
Subject: [Elecraft] K3 to IC-7800 Comparison?

If anyone has done a K3 to IC-7800 comparison, please reply direct to me
with your assessment.
Thanks,
Skip W5GAI
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Bill-3

Re: K3 to IC-7800 Comparison?

Every now and then I will think of how many dollars I have tied up in my
K-Line and how it is way overkill for what I do. Then I read some of
this type of thread - and I am again convinced that I spent wisely.

Over 55 years on the air and the K-Line beats everything I have ever had
- no contest.

But, these threads are sure interesting to read.

Bill W2BLC K3-Line

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Elecraft mailing list

Re: K3 to IC-7800 Comparison?

You guys are right, the Elecraft radio are great. But I have lots of radios from many manufacturers, current stuff, and Elecraft will have to keep on there toes to stay up there.

Sent from my iPad

> On Sep 12, 2015, at 4:57 PM, Bill <[hidden email]> wrote:
>
> Every now and then I will think of how many dollars I have tied up in my K-Line and how it is way overkill for what I do. Then I read some of this type of thread - and I am again convinced that I spent wisely.
>
> Over 55 years on the air and the K-Line beats everything I have ever had - no contest.
>
> But, these threads are sure interesting to read.
>
> Bill W2BLC K3-Line
>
> ______________________________________________________________
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Wes (N7WS)

Re: K3 to IC-7800 Comparison?

In reply to this post by Jim Brown-10

I'd like a comparison with the IC-7851. https://www.youtube.com/watch?v=-sVpoPJKgo8

On 9/12/2015 2:31 PM, Jim Brown wrote:

> On Sat,9/12/2015 2:12 PM, Skip Cameron wrote:
>> If anyone has done a K3 to IC-7800 comparison, please reply direct to me
>> with your assessment.
>
> I've never seen a 7800, so no experience. However, ARRL and Rob Sherwood have.
> Rob's data is on his webpage. It concentrates on receiver performance. I've
> gathered ARRL Lab test data for a selected bunch of modern rigs and published
> it in a form making it easier to compare the rigs as TRANSMITTERS. My report
> is at http://k9yc.com/TXNoise.pdf
>
> The original K3 is MUCH cleaner on CW than the 7800. Also, the original K3 has
> about 15 dB less phase noise than the 7800, which matters a lot on Field Day
> and at a multi-TX contest station. The new synth board reduces both TX and RX
> phase noise quite a bit (I've heard numbers in the range of 10 dB).
>
> I haven't seen ARRL Lab tests of the new K3S or a K3 with the new synth board,
> but I suspect both will turn out to be at the head of the pack for TX
> cleanliness. Yes, I know about Pure Signal -- NR0V is my neighbor.
>
> 73, Jim K9YC
> _

Jim Brown-10

Re: K3 to IC-7800 Comparison?

In reply to this post by W5GAI

On Sat,9/12/2015 2:12 PM, Skip Cameron wrote:
> If anyone has done a K3 to IC-7800 comparison,

Here's another VERY interesting set of RX measurements. The Noise Power
Ratio (NPR), is essentially a measure of how broadband noise and QRM
outside the passband show up inside the passband. It combines the
effects of phase noise and various forms of non-linearity in the RX
system. First study the methodology, then the data. Big numbers are
better. :)

http://www.ab4oj.com/test/docs/npr_test.pdf

The guy who did this work is Adam Farson, VA7OJ, AB4OJ, an EE retired
from a career in telecom, now living in Vancouver, BC. He spoke to our
local ham club last weekend, and his presentation was quite interesting.
Several of us had dinner with him. He seems quite genuine, no horses in
the race, his objectives seem to be the same as Rob Sherwood and my own
-- to put mfrs feet to the fire to improve the receive performance and
signal quality of the stuff they sell us. :)

There's an important caveat to his work. The NPR measurements require
very sophisticated band-stop filters in his instrumentation setup, and
based on the filters he has been able to source, that limits the
frequency range where he can do his measurements. An example is in the
footnote for the Flex-6700, which has no preselector for the range where
he had to do his measurements, which may have caused that radio to
measure worse than it would on the ham bands.

73, Jim K9YC
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Joe Subich, W4TV-4

Re: K3 to IC-7800 Comparison?

On 9/13/2015 2:10 AM, Jim Brown wrote:
> He seems quite genuine, no horses in the race, his objectives seem to
> be the same as Rob Sherwood and my own -- to put mfrs feet to the
> fire to improve the receive performance and signal quality of the
> stuff they sell us. :)

Adam is an out an out Icom evangelist - not exactly unbiased.

> An example is in the footnote for the Flex-6700, which has no
> preselector for the range where he had to do his measurements, which
> may have caused that radio to measure worse than it would on the ham
> bands.

On the other hand Adam limits noise power for direct sampling SDR
designs to a lower level than used with traditional up/down conversion
transceivers. The lower noise power input gives the direct sampling
designs an unfair advantage be ignoring strong signal environments.

73,

... Joe, W4TV

On 9/13/2015 2:10 AM, Jim Brown wrote:

> On Sat,9/12/2015 2:12 PM, Skip Cameron wrote:
>> If anyone has done a K3 to IC-7800 comparison,
>
> Here's another VERY interesting set of RX measurements. The Noise Power
> Ratio (NPR), is essentially a measure of how broadband noise and QRM
> outside the passband show up inside the passband. It combines the
> effects of phase noise and various forms of non-linearity in the RX
> system. First study the methodology, then the data. Big numbers are
> better. :)
>
> http://www.ab4oj.com/test/docs/npr_test.pdf
>
> The guy who did this work is Adam Farson, VA7OJ, AB4OJ, an EE retired
> from a career in telecom, now living in Vancouver, BC. He spoke to our
> local ham club last weekend, and his presentation was quite interesting.
> Several of us had dinner with him. He seems quite genuine, no horses in
> the race, his objectives seem to be the same as Rob Sherwood and my own
> -- to put mfrs feet to the fire to improve the receive performance and
> signal quality of the stuff they sell us. :)
>
> There's an important caveat to his work. The NPR measurements require
> very sophisticated band-stop filters in his instrumentation setup, and
> based on the filters he has been able to source, that limits the
> frequency range where he can do his measurements. An example is in the
> footnote for the Flex-6700, which has no preselector for the range where
> he had to do his measurements, which may have caused that radio to
> measure worse than it would on the ham bands.
>
> 73, Jim K9YC
> ______________________________________________________________
> 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]
>

Chester Alderman

Re: K3 to IC-7800 Comparison?

I certainly agree with Joe about Adam! I've never heard such prejudicial
explanations trying to justify Icom's innocence for final transistor
failures in the IC-7700's. He took all reports of final failures and said he
was going to forward them to Icom, but very few of us ever believed he
actually forwarded any information to Icom from IC-7700 users about the
failures. And IF did, there was never any response from Japan.
I sold my IC-7700, not because the finals failed, but because the threat of
failure was there every time I turned that radio ON.

73,
Tom - W4BQF

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Joe
Subich, W4TV
Sent: Sunday, September 13, 2015 8:09 AM
To: [hidden email]
Subject: Re: [Elecraft] K3 to IC-7800 Comparison?

On 9/13/2015 2:10 AM, Jim Brown wrote:
> He seems quite genuine, no horses in the race, his objectives seem to
> be the same as Rob Sherwood and my own -- to put mfrs feet to the fire
> to improve the receive performance and signal quality of the stuff
> they sell us. :)

Adam is an out an out Icom evangelist - not exactly unbiased.

> An example is in the footnote for the Flex-6700, which has no
> preselector for the range where he had to do his measurements, which
> may have caused that radio to measure worse than it would on the ham
> bands.

On the other hand Adam limits noise power for direct sampling SDR designs to
a lower level than used with traditional up/down conversion transceivers.
The lower noise power input gives the direct sampling designs an unfair
advantage be ignoring strong signal environments.

73,

... Joe, W4TV

On 9/13/2015 2:10 AM, Jim Brown wrote:

> On Sat,9/12/2015 2:12 PM, Skip Cameron wrote:
>> If anyone has done a K3 to IC-7800 comparison,
>
> Here's another VERY interesting set of RX measurements. The Noise
> Power Ratio (NPR), is essentially a measure of how broadband noise and
> QRM outside the passband show up inside the passband. It combines the
> effects of phase noise and various forms of non-linearity in the RX
> system. First study the methodology, then the data. Big numbers are
> better. :)
>
> http://www.ab4oj.com/test/docs/npr_test.pdf
>
> The guy who did this work is Adam Farson, VA7OJ, AB4OJ, an EE retired
> from a career in telecom, now living in Vancouver, BC. He spoke to our
> local ham club last weekend, and his presentation was quite interesting.
> Several of us had dinner with him. He seems quite genuine, no horses
> in the race, his objectives seem to be the same as Rob Sherwood and my
> own
> -- to put mfrs feet to the fire to improve the receive performance and
> signal quality of the stuff they sell us. :)
>
> There's an important caveat to his work. The NPR measurements require
> very sophisticated band-stop filters in his instrumentation setup, and
> based on the filters he has been able to source, that limits the
> frequency range where he can do his measurements. An example is in the
> footnote for the Flex-6700, which has no preselector for the range
> where he had to do his measurements, which may have caused that radio
> to measure worse than it would on the ham bands.
>
> 73, Jim K9YC
> ______________________________________________________________
> 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]
>

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Phil Wheeler-2

Re: K3 to IC-7800 Comparison?

Tom,

This is pretty off-topic, but not all
vendors/manufacturers operate like that. I had a
Canon camera which had known problems so that I
didn't use it much due to "the threat of failure
was there every time I turned that radio[camera]
ON". So I bought a new camera, a later Canon
model, to replace it. Well I turned on the old one
to compare the image quality (IQ), and it failed!
Sent it to Canon and they fixed it (may have
replaced) and I had it back in a week -- at no
cost, even though it was out of warranty. Turns
out it was a known manufacturing defect -- which
the IC-7700 sounds like. End of story is that I
preferred the old camera's IQ so returned the new
one :-)

I wish more manufacturers operated that way. In
ham radio, Elecraft is the one I am most confident
would (but none of my Elecraft gear has ever
failed, even better!).

73, Phil W7OX

On 9/13/15 8:01 AM, Chester Alderman wrote:

> I certainly agree with Joe about Adam! I've never heard such prejudicial
> explanations trying to justify Icom's innocence for final transistor
> failures in the IC-7700's. He took all reports of final failures and said he
> was going to forward them to Icom, but very few of us ever believed he
> actually forwarded any information to Icom from IC-7700 users about the
> failures. And IF did, there was never any response from Japan.
> I sold my IC-7700, not because the finals failed, but because the threat of
> failure was there every time I turned that radio ON.
>
> 73,
> Tom - W4BQF
>
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of Joe
> Subich, W4TV
> Sent: Sunday, September 13, 2015 8:09 AM
> To: [hidden email]
> Subject: Re: [Elecraft] K3 to IC-7800 Comparison?
>
> On 9/13/2015 2:10 AM, Jim Brown wrote:
>> He seems quite genuine, no horses in the race, his objectives seem to
>> be the same as Rob Sherwood and my own -- to put mfrs feet to the fire
>> to improve the receive performance and signal quality of the stuff
>> they sell us. :)
> Adam is an out an out Icom evangelist - not exactly unbiased.
>
>> An example is in the footnote for the Flex-6700, which has no
>> preselector for the range where he had to do his measurements, which
>> may have caused that radio to measure worse than it would on the ham
>> bands.
> On the other hand Adam limits noise power for direct sampling SDR designs to
> a lower level than used with traditional up/down conversion transceivers.
> The lower noise power input gives the direct sampling designs an unfair
> advantage be ignoring strong signal environments.
>
> 73,
>
> ... Joe, W4TV

alorona

Re: K3 to IC-7800 Comparison?

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

Adam has always been very dismissive publicly of the K3 architecture. However, I would hope that his personal opinion does not in any way influence the results of his testing.
Al W6LX

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Adam Farson

Re: K3 to IC-7800 Comparison?

In reply to this post by W5GAI

For Jim K9YC:

Hi Jim,

Many thanks for the post on my presentations at the club meeting on Saturday
September 5.

To quote:

"There's an important caveat to his work. The NPR measurements require

very sophisticated band-stop filters in his instrumentation setup, and

based on the filters he has been able to source, that limits the

frequency range where he can do his measurements. An example is in the

footnote for the Flex-6700, which has no preselector for the range where

he had to do his measurements, which may have caused that radio to

measure worse than it would on the ham bands."

The instrumentation I use for NPR testing is re-purposed telecom test
equipment, as described in my Web article and also in my article in QEX for
March/April 2015. I rely on the surplus market for the test sets, and also
for the filter pairs (bandstop and bandpass). The bandstop filters typically
have 95 dB stopband attenuation and ~ 3 kHz stopband width.

A number of these filters are on (or near) amateur bands, e.g. 1940, 3886,
5340, 7600 and 11700 kHz. The first filter pair I acquired was on 5340 kHz,
so all the test data in my web article are on this frequency (which is in
the 60m band). The Flex-6700 does not have a preselector for this band, so
the noise loading will hit the front end and the ADC harder. This will
degrade the NPR reading by a few dB, but it will show how the receiver
behaves if heavily loaded on a band for which no preselector is fitted.

As I picked up additional filters, the number of frequencies on which I run
the test has steadily increased. Links to multi-frequency NPR data for
various radios (including the K3 with KSYN3A) are on my website:

http://www.ab4oj.com/test/main.html#NPR

It was a pleasure meeting you guys over the Labour Day weekend.

73, Adam VA7OJ/AB4OJ

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Johnny Siu

K3 to IC-7800 Comparison?

Hello Adam,
From reading of your NPR chart, could I understand that apart from IC7851, the K3 (with new KSYN3A installed) is the second best in terms of NPR test?
73
Johnny VR2XMC
寄件人︰ Adam Farson <[hidden email]>
收件人︰ Elecraft List <[hidden email]>
傳送日期︰ 2015年09月14日 (週一) 2:51 PM
主題︰ Re: [Elecraft] K3 to IC-7800 Comparison?

For Jim K9YC:

Hi Jim,

Many thanks for the post on my presentations at the club meeting on Saturday
September 5.

To quote:

"There's an important caveat to his work. The NPR measurements require

very sophisticated band-stop filters in his instrumentation setup, and

based on the filters he has been able to source, that limits the

frequency range where he can do his measurements. An example is in the

footnote for the Flex-6700, which has no preselector for the range where

he had to do his measurements, which may have caused that radio to

measure worse than it would on the ham bands."

The instrumentation I use for NPR testing is re-purposed telecom test
equipment, as described in my Web article and also in my article in QEX for
March/April 2015. I rely on the surplus market for the test sets, and also
for the filter pairs (bandstop and bandpass). The bandstop filters typically
have 95 dB stopband attenuation and ~ 3 kHz stopband width.

A number of these filters are on (or near) amateur bands, e.g. 1940, 3886,
5340, 7600 and 11700 kHz. The first filter pair I acquired was on 5340 kHz,
so all the test data in my web article are on this frequency (which is in
the 60m band). The Flex-6700 does not have a preselector for this band, so
the noise loading will hit the front end and the ADC harder. This will
degrade the NPR reading by a few dB, but it will show how the receiver
behaves if heavily loaded on a band for which no preselector is fitted.

As I picked up additional filters, the number of frequencies on which I run
the test has steadily increased. Links to multi-frequency NPR data for
various radios (including the K3 with KSYN3A) are on my website:

http://www.ab4oj.com/test/main.html#NPR

It was a pleasure meeting you guys over the Labour Day weekend.

73, Adam VA7OJ/AB4OJ

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Adam Farson

Re: K3 to IC-7800 Comparison?

Hi Johnny,

The K3 with the KSYN3A is in a closely-packed cluster of radios which score highest in the NPR test. Its exact ranking depends on which test frequency is being compared. The differences are very slight, mostly within a couple of dB.

In practice, I regard an NPR value of 80 dB or higher as excellent.

73, Adam VA7OJ/AB4OJ

From: Johnny Siu [mailto:[hidden email]]
Sent: 14-Sep-15 00:54
To: Adam Farson; Elecraft List
Subject: K3 to IC-7800 Comparison?

Hello Adam,

From reading of your NPR chart, could I understand that apart from IC7851, the K3 (with new KSYN3A installed) is the second best in terms of NPR test?

73

Johnny VR2XMC

_____

寄件人︰ Adam Farson <[hidden email]>
收件人︰ Elecraft List <[hidden email]>
傳送日期︰ 2015年09月14日 (週一) 2:51 PM
主題︰ Re: [Elecraft] K3 to IC-7800 Comparison?

For Jim K9YC:

Hi Jim,

Many thanks for the post on my presentations at the club meeting on Saturday
September 5.

To quote:

"There's an important caveat to his work. The NPR measurements require

very sophisticated band-stop filters in his instrumentation setup, and

based on the filters he has been able to source, that limits the

frequency range where he can do his measurements. An example is in the

footnote for the Flex-6700, which has no preselector for the range where

he had to do his measurements, which may have caused that radio to

measure worse than it would on the ham bands."

The instrumentation I use for NPR testing is re-purposed telecom test
equipment, as described in my Web article and also in my article in QEX for
March/April 2015. I rely on the surplus market for the test sets, and also
for the filter pairs (bandstop and bandpass). The bandstop filters typically
have 95 dB stopband attenuation and ~ 3 kHz stopband width.

A number of these filters are on (or near) amateur bands, e.g. 1940, 3886,
5340, 7600 and 11700 kHz. The first filter pair I acquired was on 5340 kHz,
so all the test data in my web article are on this frequency (which is in
the 60m band). The Flex-6700 does not have a preselector for this band, so
the noise loading will hit the front end and the ADC harder. This will
degrade the NPR reading by a few dB, but it will show how the receiver
behaves if heavily loaded on a band for which no preselector is fitted.

As I picked up additional filters, the number of frequencies on which I run
the test has steadily increased. Links to multi-frequency NPR data for
various radios (including the K3 with KSYN3A) are on my website:

http://www.ab4oj.com/test/main.html#NPR <http://www.ab4oj.com/test/main.html#NPR>

It was a pleasure meeting you guys over the Labour Day weekend.

73, Adam VA7OJ/AB4OJ

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Jim Brown-10

Re: K3 to IC-7800 Comparison?

In reply to this post by Adam Farson

On Sun,9/13/2015 11:51 PM, Adam Farson wrote:
> For Jim K9YC:

Hi Adam,

Thanks for the description of your work. Could you take the time to
respond to recent posts by W4TV and W4BQF in this thread?

73, Jim

= = = = =

Adam is an out an out Icom evangelist - not exactly unbiased.

> An example is in the footnote for the Flex-6700, which has no
> preselector for the range where he had to do his measurements, which
> may have caused that radio to measure worse than it would on the ham
> bands.

On the other hand Adam limits noise power for direct sampling SDR
designs to a lower level than used with traditional up/down conversion
transceivers. The lower noise power input gives the direct sampling
designs an unfair advantage be ignoring strong signal environments.

73,

... Joe, W4TV

I certainly agree with Joe about Adam! I've never heard such prejudicial
explanations trying to justify Icom's innocence for final transistor
failures in the IC-7700's. He took all reports of final failures and said he
was going to forward them to Icom, but very few of us ever believed he
actually forwarded any information to Icom from IC-7700 users about the
failures. And IF did, there was never any response from Japan.
I sold my IC-7700, not because the finals failed, but because the threat of
failure was there every time I turned that radio ON.

73,
Tom - W4BQF

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Adam Farson

Re: K3 to IC-7800 Comparison?

In reply to this post by W5GAI

For Joe, W4TV:

To quote: "On the other hand Adam limits noise power for direct sampling SDR
designs to a lower level than used with traditional up/down conversion
transceivers. The lower noise power input gives the direct sampling
designs an unfair advantage be ignoring strong signal environments."

As explained in my web article (and also in my QEX article), the optimum
noise loading points for an ADC and a conventional receiver are different.
In the conventional receiver, optimum noise loading is reached when the
noise power induced in the IF passband within the notch (idle-channel noise)
is equal to the DUT's intrinsic thermal noise power in the same bandwidth.
At this point, the DUT's audio output rises by 3 dB.

Walt Kester of ADI states in ADI Tutorial MT-005 that the optimum noise
loading point for an ADC is where the device's quantisation noise equals the
noise generated by clipping, i.e. the noise loading is run right up to clip
level or 0 dBFS. I use -1 dBFS as my optimum noise loading point, to ensure
that no clipping takes place during the test. In fact, when an ADC is driven
to clip level, it crashes, thus invalidating any tests attempted above clip
level.

I do not compare NPR test data for direct-sampling receivers directly with
data for conventional receivers. The benchmark I use for direct-sampling
receivers is the theoretical value of NPR for the ADC in use; this can be
calculated using the procedure presented in MT-005 and described in my
articles. The closer the measured NPR value is to the theoretical one, the
better the front end will perform under heavy loading. A large drop in NPR
(10 dB or more) as compared to the theoretical value indicates an anomaly
such as passive IMD in the preselector or IMD in an active stage ahead of
the ADC.

For a conventional receiver, the closer the NPR figure is to the bandstop
filter's stopband attenuation, the better the receiver (at least from the
NPR standpoint). I do not use NPR as the sole criterion for receiver
selection; my intent in adapting this test method to HF receivers is to
provide the test engineer with an additional test tool for evaluating a
receiver's behaviour on a band packed with extremely strong signals.

Along these same lines, it is virtually impossible to correlate certain
narrow-band test results for a direct-sampling receiver with those for a
conventional receiver, as the familiar traditional test metrics (DR3, IP3,
blocking gain compression) are completely meaningless in the context of an
ADC. Phase noise (RMDR) is still very much a valid parameter, but RMDR in a
direct-sampling receiver is usually very high as the ADC clock is the only
major source of phase noise. (ADC aperture jitter is a minor phase noise
source.) Of course MDS is valid for both receiver types. I have proposed,
and myself use a front-end IMD test method in which I measure the absolute
power of the IMD3 products at 2 kHz spacing over a range of input power
levels, and draw a chart. I then draw lines across the chart at the typical
ITU-R urban and rural band noise levels. If the IMD product is below the
site band noise level, it is inaudible and can thus be disregarded. I term
this test IFSS (interference-free signal strength) and use it exclusively in
my direct-sampling SDR test suite.

Ultimately, the decision as to whether to acquire a direct-sampling SDR or a
conventional transceiver comes down to the operator's personal operating
preferences.

73, Adam VA7OJ/AB4OJ

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Lu Romero - W4LT

Re: K3 to IC-7800 Comparison?

In reply to this post by W5GAI

All:

OK, I will jump in on this one. It's close to my heart.

My closest local ham friends are IC-7800 owners. All 5 of them. All of
them have larger and taller antennas than I do. I can hear everything they
hear and, though I'm at a 500w transmitter disadvantage viz their kilowatt
amplifiers, I can and do work everything they work with my K3.

My local club (Tampa Amateur Radio Club) is a 100% Icom facility with a
7700, two 7600'ds, one 746Pro and a 7100 in their HF "studios" (more like
"cubicles": there are 6 of them - one is reserved for "classic" AM rigs)

I operated SS SSB two years in succession (2010 and 2011) at our clubhouse
SOABLP using identical antennas (a C31XR at 108 feet, a EF240 at 118 feet, a
C19X at 70 feet and a 80m Dipole at 90 ft). In 2010 I used the club 7700.
The receiver sounded really crunchy, much like my former TS850. Lots or
crackly splatter, lots of adjacent desense. I use that rig often, so I know
how to drive it. It is never pleasant to use that rig in heavy QRM contest
conditions. The same can be said for the 7600'ds. The 746 and the 7100 are
worse by a long shot to the 7700.

The following year, I brought my K3 to the club and operated SS using the
club's identical antenna complement. Not once did I hear any crunching in
the receiver, no splatter mess and no desense. The contest was much more
pleasant on the ears and all signals were much easier to copy on the K3 than
on the 7700 receiver.

I love using the 7700, but not in a serious contesting environment. It
reminds me of my old TS850. But I still love to use it! The reason is the
tactile feel of the 7700 and, a bit less by the same token, the 7600'ds
feels like that too. While the K3 layout is fine and very workable, the
controls on the Icoms are just so incredibly smooth! The "feeling of
Luxury" is exuded by the 7700'ds tactile feedback from its controls. As a
NY friend says "It feels like buttah!". It's a hard concept to explain, but
the feel of the Icom controls is really special. My K3 feels OK, just not as
"silky" as the 7700'd.

Kind of like cars. Drive a Lexus SC430 for show, and a Lotus Elise for go.
Two sports cars for different priorities.

If you are into luxury feel, "free" logo'd leather jackets, and 70lb
transceivers that "feel like buttah", the 78/7700'ds are a great choice. If
you are into well behaved receivers, high operational performance in a
compact, under 10lb lightweight package, the choice is obvious.

Takes all kinds to make a world! I have my priorities, you have yours.

Lu - W4LT

K-Line

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Jim Brown-10

Re: K3 to IC-7800 Comparison?

In reply to this post by Adam Farson

On Mon,9/14/2015 10:10 AM, Adam Farson wrote:
> As explained in my web article (and also in my QEX article), the optimum
> noise loading points for an ADC and a conventional receiver are different.
> In the conventional receiver, optimum noise loading is reached when the
> noise power induced in the IF passband within the notch (idle-channel noise)
> is equal to the DUT's intrinsic thermal noise power in the same bandwidth.
> At this point, the DUT's audio output rises by 3 dB.

I strongly disagree, Adam. If the test is designed to show response of
the receiver to a lot of strong signals such as are present in a
contesting or DX pileup environment, or as are present in a
multi-transmitter site, the signal level should be consistent with that
environment, NOT with the design of the receiver. In other words, if the
input of the RX would be overloaded by those strong signals, the test
should show it. This does (at least) two things -- it lets buyers know
which radios perform best in this environment, and it also puts the
manufacturer's feet to the fire to make the RX better. And this matters
no matter what the architecture of the RX. It would also, for example,
clearly show the difference between an RX with a preselector (or other
selectivity) in front of the input and one without.

And finally, if you choose to test at a reduced signal level to stay
below overload, the report should clearly state by how many dB the test
signal had to be reduced.

I do appreciate your work and your dedication, but to be of value, it
must be consistent with real world conditions, and it must expose the
real differences between radios.

73, Jim K9YC

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Vic Rosenthal

Re: K3 to IC-7800 Comparison?

In reply to this post by Lu Romero - W4LT

I bought a K2 the year it came out and I have one of the first K3s. I still hate the tap/hold interface. I paid what I feel was an obscene amount of money for a set of heavy, machined VFO knobs to replace the stock ones. I wish the K3 had more room for controls, so there would be less overloading of functions.

But all this pales into insignificance when I dial down the selectivity and pick out the weak one in the midst of the pounding 20-over signals from nearby EU stations. And then there is the improvement in copy from diversity reception!

Everyone has different interests. Mine is to work DX on CW. Satisfaction doesn't come from a comfortable interface, but rather from achieving one's goals. The K3 is simply the best tool available to do that.

Vic 4X6GP/K2VCO

> On Sep 14, 2015, at 10:51 PM, Luis V. Romero <[hidden email]> wrote:
>
> All:
>
>
>
> OK, I will jump in on this one. It's close to my heart.
>
>
>
> My closest local ham friends are IC-7800 owners. All 5 of them. All of
> them have larger and taller antennas than I do. I can hear everything they
> hear and, though I'm at a 500w transmitter disadvantage viz their kilowatt
> amplifiers, I can and do work everything they work with my K3.
>
>
>
> My local club (Tampa Amateur Radio Club) is a 100% Icom facility with a
> 7700, two 7600'ds, one 746Pro and a 7100 in their HF "studios" (more like
> "cubicles": there are 6 of them - one is reserved for "classic" AM rigs)
>
>
>
> I operated SS SSB two years in succession (2010 and 2011) at our clubhouse
> SOABLP using identical antennas (a C31XR at 108 feet, a EF240 at 118 feet, a
> C19X at 70 feet and a 80m Dipole at 90 ft). In 2010 I used the club 7700.
> The receiver sounded really crunchy, much like my former TS850. Lots or
> crackly splatter, lots of adjacent desense. I use that rig often, so I know
> how to drive it. It is never pleasant to use that rig in heavy QRM contest
> conditions. The same can be said for the 7600'ds. The 746 and the 7100 are
> worse by a long shot to the 7700.
>
>
>
> The following year, I brought my K3 to the club and operated SS using the
> club's identical antenna complement. Not once did I hear any crunching in
> the receiver, no splatter mess and no desense. The contest was much more
> pleasant on the ears and all signals were much easier to copy on the K3 than
> on the 7700 receiver.
>
>
>
> I love using the 7700, but not in a serious contesting environment. It
> reminds me of my old TS850. But I still love to use it! The reason is the
> tactile feel of the 7700 and, a bit less by the same token, the 7600'ds
> feels like that too. While the K3 layout is fine and very workable, the
> controls on the Icoms are just so incredibly smooth! The "feeling of
> Luxury" is exuded by the 7700'ds tactile feedback from its controls. As a
> NY friend says "It feels like buttah!". It's a hard concept to explain, but
> the feel of the Icom controls is really special. My K3 feels OK, just not as
> "silky" as the 7700'd.
>
>
>
> Kind of like cars. Drive a Lexus SC430 for show, and a Lotus Elise for go.
> Two sports cars for different priorities.
>
>
>
> If you are into luxury feel, "free" logo'd leather jackets, and 70lb
> transceivers that "feel like buttah", the 78/7700'ds are a great choice. If
> you are into well behaved receivers, high operational performance in a
> compact, under 10lb lightweight package, the choice is obvious.
>
>
>
> Takes all kinds to make a world! I have my priorities, you have yours.
>
>
>
> Lu - W4LT
>
> K-Line
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> 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 Bolit

Re: K3 to IC-7800 Comparison?

In reply to this post by W5GAI

Adam,

Please confirm what roofing filter was used for your test on the K3.
Tnx
JimW6AIM

.

-------- Original message --------
From: Adam Farson <[hidden email]>
Date: 9/14/2015 3:14 AM (GMT-06:00)
To: 'Johnny Siu' <[hidden email]>
Cc: Elecraft List <[hidden email]>
Subject: Re: [Elecraft] K3 to IC-7800 Comparison?

Hi Johnny,

The K3 with the KSYN3A is in a closely-packed cluster of radios which score highest in the NPR test. Its exact ranking depends on which test frequency is being compared. The differences are very slight, mostly within a couple of dB.

In practice, I regard an NPR value of 80 dB or higher as excellent.

73, Adam VA7OJ/AB4OJ

From: Johnny Siu [mailto:[hidden email]]
Sent: 14-Sep-15 00:54
To: Adam Farson; Elecraft List
Subject: K3 to IC-7800 Comparison?

Hello Adam,

From reading of your NPR chart, could I understand that apart from IC7851, the K3 (with new KSYN3A installed) is the second best in terms of NPR test?

73

Johnny VR2XMC

_____

寄件人︰ Adam Farson <[hidden email]>
收件人︰ Elecraft List <[hidden email]>
傳送日期︰ 2015年09月14日 (週一) 2:51 PM
主題︰ Re: [Elecraft] K3 to IC-7800 Comparison?

For Jim K9YC:

Hi Jim,

Many thanks for the post on my presentations at the club meeting on Saturday
September 5.

To quote:

"There's an important caveat to his work. The NPR measurements require

very sophisticated band-stop filters in his instrumentation setup, and

based on the filters he has been able to source, that limits the

frequency range where he can do his measurements. An example is in the

footnote for the Flex-6700, which has no preselector for the range where

he had to do his measurements, which may have caused that radio to

measure worse than it would on the ham bands."

The instrumentation I use for NPR testing is re-purposed telecom test
equipment, as described in my Web article and also in my article in QEX for
March/April 2015. I rely on the surplus market for the test sets, and also
for the filter pairs (bandstop and bandpass). The bandstop filters typically
have 95 dB stopband attenuation and ~ 3 kHz stopband width.

A number of these filters are on (or near) amateur bands, e.g. 1940, 3886,
5340, 7600 and 11700 kHz. The first filter pair I acquired was on 5340 kHz,
so all the test data in my web article are on this frequency (which is in
the 60m band). The Flex-6700 does not have a preselector for this band, so
the noise loading will hit the front end and the ADC harder. This will
degrade the NPR reading by a few dB, but it will show how the receiver
behaves if heavily loaded on a band for which no preselector is fitted.

As I picked up additional filters, the number of frequencies on which I run
the test has steadily increased. Links to multi-frequency NPR data for
various radios (including the K3 with KSYN3A) are on my website:

http://www.ab4oj.com/test/main.html#NPR <http://www.ab4oj.com/test/main.html#NPR>

It was a pleasure meeting you guys over the Labour Day weekend.

73, Adam VA7OJ/AB4OJ

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