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Receivers?

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Scott Gillen ZL1CHM

Receivers?

Can anyone compare the receivers in the KX3 versus K3 versus K2? Is there a significant difference? I am considering the KX3.

73
Scott

N0HOK / ZL1CHM
Auckland New Zealandx

Sent from my iPhone
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Phil Wheeler-2

Re: Receivers?

Scott,

I agree with all that Ron says -- and have the K2,
K3 and KX3 .. and like them all.

Re "I am considering the KX3": The one caveat I
would add, and others can expand on (or disagree
with) this, is that if you operate in a dense ham
environment like Field Day or with other nearby
hams operating on the same bands the
direct-conversion KX3 will not be as good as the
two superhets because you may have more difficulty
hearing weaker signals with those strong, nearby
signals at adjacent frequencies.

In Auckland this may or may not be an issue for
you -- but as I recall 70% or so of New Zealand's
population is in the Auckland area.

73, Phil W7OX

On 12/11/15 1:40 PM, Ron D'Eau Claire wrote:

> Scott, the three rigs use different design formats:
>
> The K3 and K2 and conventional superhetrodyne formats with an Intermediate
> Frequency in the H.F. range and crystal filters to set the passband. The K2
> has an adjustable crystal filter and the K3 uses fixed crystal filter
> bandwidths. The basic K2 bandwidth is established by the crystal filter
> while the K3 adds an adjustable DSP filter after the crystal filter. (The K2
> has an optional audio DSP for enhanced filtering.)
>
> Although you will often see Elecraft rig owners refer to "roofing filters"
> the Elecraft rigs avoid them, using an I.F. in the H.F. range instead that
> avoids a lot of the compromises involved in up-converting to a first I.F. in
> the VHF range with a VHF "roofing filter" to set the initial selectivity.
>
> The KX3 is quite different. It is a high-performance direct conversion
> receiver using phasing to suppress the unwanted sideband followed by
> filtering of the resulting audio.
>
> I'm a casual, mostly QRP operator who avoids pile-ups (and so contests) and
> enjoy all three. If I had to settle on one or the other I'd probably take
> the KX3 as my first choice because of its small size, the "transparent"
> sound of a direct conversion format and options such as the PX3 panadapter.
> My second choice would be my trusty and ever dependable 15 year old K2
> simply because I'm basically an "analog" sort of guy. But I have no
> complaints about the K3/K3S. I'm sure others who enjoy busting "pileups"
> will have more to offer about the advantages of the K3/K3S.
>
> For detailed test comparisons check out the results published by Sherwood
> Engineering on their web site:
>
> http://www.sherweng.com/table.html
>
>
>
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of Scott
> Gillen ZL1CHM
> Sent: Friday, December 11, 2015 1:09 PM
> To: [hidden email]
> Subject: [Elecraft] Receivers?
>
> Can anyone compare the receivers in the KX3 versus K3 versus K2? Is there a
> significant difference? I am considering the KX3.
>
> 73
> Scott
>
> N0HOK / ZL1CHM
> Auckland New Zealand
>
>

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Barry K3NDM

Re: Receivers?

Phil,
I will take the given opportunity to disagree. Our Field Day
operation uses all KX3s, QRP, That accounts for 3AB + a GOTA station.
There have been times when we found one of our GOTA ops on the same band
and in the same portion of the band. What we have found is that if the
other radio is not in the same part of the band, you may not even know
he is there. However, you know he's there. If he is far enough away,
you could work through him. There is one caveat. We do have our antennas
really spread out. Our GOTA antenna(s) can be any where from 200'-400'
away depending on which of our many antennas are being used at the time.
And secondly, all of our radios are using the 8 KHz offset. I was amazed
at the demonstration the first time it happened. I would say that the
KX3 can handle any intelligently crowed environment.

73,
Barry
K3NDM

------ Original Message ------
From: "Phil Wheeler" <[hidden email]>
To: [hidden email]
Sent: 12/11/2015 6:23:11 PM
Subject: Re: [Elecraft] Receivers?

>Scott,
>
>I agree with all that Ron says -- and have the K2, K3 and KX3 .. and
>like them all.
>
>Re "I am considering the KX3": The one caveat I would add, and others
>can expand on (or disagree with) this, is that if you operate in a
>dense ham environment like Field Day or with other nearby hams
>operating on the same bands the direct-conversion KX3 will not be as
>good as the two superhets because you may have more difficulty hearing
>weaker signals with those strong, nearby signals at adjacent
>frequencies.
>
>In Auckland this may or may not be an issue for you -- but as I recall
>70% or so of New Zealand's population is in the Auckland area.
>
>73, Phil W7OX
>
>On 12/11/15 1:40 PM, Ron D'Eau Claire wrote:
>>Scott, the three rigs use different design formats:
>>
>>The K3 and K2 and conventional superhetrodyne formats with an
>>Intermediate
>>Frequency in the H.F. range and crystal filters to set the passband.
>>The K2
>>has an adjustable crystal filter and the K3 uses fixed crystal filter
>>bandwidths. The basic K2 bandwidth is established by the crystal
>>filter
>>while the K3 adds an adjustable DSP filter after the crystal filter.
>>(The K2
>>has an optional audio DSP for enhanced filtering.)
>>
>>Although you will often see Elecraft rig owners refer to "roofing
>>filters"
>>the Elecraft rigs avoid them, using an I.F. in the H.F. range instead
>>that
>>avoids a lot of the compromises involved in up-converting to a first
>>I.F. in
>>the VHF range with a VHF "roofing filter" to set the initial
>>selectivity.
>>
>>The KX3 is quite different. It is a high-performance direct conversion
>>receiver using phasing to suppress the unwanted sideband followed by
>>filtering of the resulting audio.
>>
>>I'm a casual, mostly QRP operator who avoids pile-ups (and so
>>contests) and
>>enjoy all three. If I had to settle on one or the other I'd probably
>>take
>>the KX3 as my first choice because of its small size, the
>>"transparent"
>>sound of a direct conversion format and options such as the PX3
>>panadapter.
>>My second choice would be my trusty and ever dependable 15 year old K2
>>simply because I'm basically an "analog" sort of guy. But I have no
>>complaints about the K3/K3S. I'm sure others who enjoy busting
>>"pileups"
>>will have more to offer about the advantages of the K3/K3S.
>>
>>For detailed test comparisons check out the results published by
>>Sherwood
>>Engineering on their web site:
>>
>>http://www.sherweng.com/table.html
>>
>>
>>
>>
>>-----Original Message-----
>>From: Elecraft [mailto:[hidden email]] On Behalf Of
>>Scott
>>Gillen ZL1CHM
>>Sent: Friday, December 11, 2015 1:09 PM
>>To: [hidden email]
>>Subject: [Elecraft] Receivers?
>>
>>Can anyone compare the receivers in the KX3 versus K3 versus K2? Is
>>there a
>>significant difference? I am considering the KX3.
>>
>>73
>>Scott
>>
>>N0HOK / ZL1CHM
>>Auckland New Zealand
>>
>>
>
>______________________________________________________________
>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]

Barry K3NDM

Re: Receivers?

In reply to this post by Scott Gillen ZL1CHM

Dave,
You are so correct. I didn't re-read what I wrote after I did a few
edits.

This is what I was trying to say. If another station is on the same
band, you may not know he is there if he is operating in another
portion of the band. However, if he is in the same portion and far
enough away, you will know he is there, but you may be able work through
him. Hopefully, this reads better. But, remember I said we keep our
antennas as far apart as we can and we operate QRP.

73,
Barry
K3NDM

------ Original Message ------
From: "dave" <[hidden email]>
To: "Barry LaZar" <[hidden email]>
Sent: 12/11/2015 7:10:54 PM
Subject: Re: [Elecraft] Receivers?

>Barry,
>
>Re-read your note carefully. It doesn't make sense. You first say you
>will not know he is there, then you say you will know he is there but
>you can work through him? What does that mean?
>
>73 de dave
>ab9ca/4
>
>
>
>On 12/11/15 5:49 PM, Barry LaZar wrote:
>>Phil,
>> I will take the given opportunity to disagree. Our Field Day
>>operation uses all KX3s, QRP, That accounts for 3AB + a GOTA station.
>>There have been times when we found one of our GOTA ops on the same
>>band and in the same portion of the band. What we have found is that
>>if the other radio is not in the same part of the band, you may not
>>even know he is there. However, you know he's there. If he is far
>>enough away, you could work through him. There is one caveat. We do
>>have our antennas really spread out. Our GOTA antenna(s) can be any
>>where from 200'-400' away depending on which of our many antennas are
>>being used at the time. And secondly, all of our radios are using the
>>8 KHz offset. I was amazed at the demonstration the first time it
>>happened. I would say that the KX3 can handle any intelligently crowed
>>environment.
>>
>>73,
>>Barry
>>K3NDM
>>
>>------ Original Message ------
>>From: "Phil Wheeler" <[hidden email]>
>>To: [hidden email]
>>Sent: 12/11/2015 6:23:11 PM
>>Subject: Re: [Elecraft] Receivers?
>>
>>>Scott,
>>>
>>>I agree with all that Ron says -- and have the K2, K3 and KX3 .. and
>>>like them all.
>>>
>>>Re "I am considering the KX3": The one caveat I would add, and
>>>others can expand on (or disagree with) this, is that if you operate
>>>in a dense ham environment like Field Day or with other nearby hams
>>>operating on the same bands the direct-conversion KX3 will not be as
>>>good as the two superhets because you may have more difficulty
>>>hearing weaker signals with those strong, nearby signals at adjacent
>>>frequencies.
>>>
>>>In Auckland this may or may not be an issue for you -- but as I
>>>recall 70% or so of New Zealand's population is in the Auckland area.
>>>
>>>73, Phil W7OX
>>>
>>>On 12/11/15 1:40 PM, Ron D'Eau Claire wrote:
>>>>Scott, the three rigs use different design formats:
>>>>
>>>>The K3 and K2 and conventional superhetrodyne formats with an
>>>>Intermediate
>>>>Frequency in the H.F. range and crystal filters to set the
>>>>passband. The K2
>>>>has an adjustable crystal filter and the K3 uses fixed crystal
>>>>filter
>>>>bandwidths. The basic K2 bandwidth is established by the crystal
>>>>filter
>>>>while the K3 adds an adjustable DSP filter after the crystal
>>>>filter. (The K2
>>>>has an optional audio DSP for enhanced filtering.)
>>>>
>>>>Although you will often see Elecraft rig owners refer to "roofing
>>>>filters"
>>>>the Elecraft rigs avoid them, using an I.F. in the H.F. range
>>>>instead that
>>>>avoids a lot of the compromises involved in up-converting to a
>>>>first I.F. in
>>>>the VHF range with a VHF "roofing filter" to set the initial
>>>>selectivity.
>>>>
>>>>The KX3 is quite different. It is a high-performance direct
>>>>conversion
>>>>receiver using phasing to suppress the unwanted sideband followed by
>>>>filtering of the resulting audio.
>>>>
>>>>I'm a casual, mostly QRP operator who avoids pile-ups (and so
>>>>contests) and
>>>>enjoy all three. If I had to settle on one or the other I'd
>>>>probably take
>>>>the KX3 as my first choice because of its small size, the
>>>>"transparent"
>>>>sound of a direct conversion format and options such as the PX3
>>>>panadapter.
>>>>My second choice would be my trusty and ever dependable 15 year old
>>>>K2
>>>>simply because I'm basically an "analog" sort of guy. But I have no
>>>>complaints about the K3/K3S. I'm sure others who enjoy busting
>>>>"pileups"
>>>>will have more to offer about the advantages of the K3/K3S.
>>>>
>>>>For detailed test comparisons check out the results published by
>>>>Sherwood
>>>>Engineering on their web site:
>>>>
>>>>http://www.sherweng.com/table.html
>>>>
>>>>
>>>>
>>>>
>>>>-----Original Message-----
>>>>From: Elecraft [mailto:[hidden email]] On Behalf
>>>>Of Scott
>>>>Gillen ZL1CHM
>>>>Sent: Friday, December 11, 2015 1:09 PM
>>>>To: [hidden email]
>>>>Subject: [Elecraft] Receivers?
>>>>
>>>>Can anyone compare the receivers in the KX3 versus K3 versus K2?
>>>>Is there a
>>>>significant difference? I am considering the KX3.
>>>>
>>>>73
>>>>Scott
>>>>
>>>>N0HOK / ZL1CHM
>>>>Auckland New Zealand
>>>>
>>>>
>>>
>>>______________________________________________________________
>>>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
>>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]
>>

Bill Frantz

Re: Receivers?

In reply to this post by Scott Gillen ZL1CHM

I have both a K3 and a KX3 and have used a K2. The principle
reason I would consider buying a K2 is for the joy of assembling
the kit.

When I compare the KX3 and the K3, I think of the KX3 as being
about 90% of the K3, but many options are standard on the KX3
but extra cost on the K3. (Note that the K3S is the same as the
K3 in these examples.) Examples include:

The digital voice recorder -- standard on the KX3. Separate
board for the K3. Two memories on the KX3 and 4 on the K3.

Dual Watch on the KX3 is a good example of the 90%. The same
functionality is available on the K3 with the subreceiver. The
difference between the two receive frequencies is limited on the
KX3 while the K3 subreceiver is a separate receiver and can
receive on different bands. Also, the dual watch needs to have
wide enough bandwidth to cover both frequencies which can raise
the received noise level.

General coverage: Standard on KX3, needs additional filter board
on K3.

High stability local oscillator: Optional board for K3.
Calibration procedure for KX3. (I suspect the K3's solution is
more stable.)

100W amplifer: Internal on K3. A separate unit on the KX3.

The KX3 is a heck of a good value, and portable too.

73 Bill AE6JV

On 12/12/15 at 1:09 PM, [hidden email] (Scott Gillen
ZL1CHM) wrote:

>Can anyone compare the receivers in the KX3 versus K3 versus
>K2? Is there a significant difference? I am considering the KX3.

---------------------------------------------------------------------------
Bill Frantz | "I wish there was a knob on the TV to turn
up the
408-356-8506 | intelligence. There's a knob called
"brightness", but
www.pwpconsult.com | it doesn't work. -- Gallagher

______________________________________________________________
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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]

Phil Wheeler-2

Re: Receivers?

In reply to this post by Barry K3NDM

Barry,

You said "Our Field Day operation uses all KX3s,
QRP ... ". Well that's a tad different than if
you have some 500 W stations nearby operating near
your frequency. And that is more typical of the
situation I described. So rather than disagree
you provided the exception that proves the rule :-)

And "the KX3 can handle any intelligently crowded
environment": Would that all our bands were
"intelligently crowded"!

73, Phil W7OX

On 12/11/15 3:49 PM, Barry LaZar wrote:

> Phil,
> I will take the given opportunity to
> disagree. Our Field Day operation uses all KX3s,
> QRP, That accounts for 3AB + a GOTA station.
> There have been times when we found one of our
> GOTA ops on the same band and in the same
> portion of the band. What we have found is that
> if the other radio is not in the same part of
> the band, you may not even know he is there.
> However, you know he's there. If he is far
> enough away, you could work through him. There
> is one caveat. We do have our antennas really
> spread out. Our GOTA antenna(s) can be any where
> from 200'-400' away depending on which of our
> many antennas are being used at the time. And
> secondly, all of our radios are using the 8 KHz
> offset. I was amazed at the demonstration the
> first time it happened. I would say that the KX3
> can handle any intelligently crowed environment.
>
> 73,
> Barry
> K3NDM
>
> ------ Original Message ------
> From: "Phil Wheeler" <[hidden email]>
> To: [hidden email]
> Sent: 12/11/2015 6:23:11 PM
> Subject: Re: [Elecraft] Receivers?
>
>> Scott,
>>
>> I agree with all that Ron says -- and have the
>> K2, K3 and KX3 .. and like them all.
>>
>> Re "I am considering the KX3": The one caveat I
>> would add, and others can expand on (or
>> disagree with) this, is that if you operate in
>> a dense ham environment like Field Day or with
>> other nearby hams operating on the same bands
>> the direct-conversion KX3 will not be as good
>> as the two superhets because you may have more
>> difficulty hearing weaker signals with those
>> strong, nearby signals at adjacent frequencies.
>>
>> In Auckland this may or may not be an issue for
>> you -- but as I recall 70% or so of New
>> Zealand's population is in the Auckland area.
>>
>> 73, Phil W7OX
>>
>> On 12/11/15 1:40 PM, Ron D'Eau Claire wrote:
>>> Scott, the three rigs use different design
>>> formats:
>>>
>>> The K3 and K2 and conventional superhetrodyne
>>> formats with an Intermediate
>>> Frequency in the H.F. range and crystal
>>> filters to set the passband. The K2
>>> has an adjustable crystal filter and the K3
>>> uses fixed crystal filter
>>> bandwidths. The basic K2 bandwidth is
>>> established by the crystal filter
>>> while the K3 adds an adjustable DSP filter
>>> after the crystal filter. (The K2
>>> has an optional audio DSP for enhanced
>>> filtering.)
>>>
>>> Although you will often see Elecraft rig
>>> owners refer to "roofing filters"
>>> the Elecraft rigs avoid them, using an I.F. in
>>> the H.F. range instead that
>>> avoids a lot of the compromises involved in
>>> up-converting to a first I.F. in
>>> the VHF range with a VHF "roofing filter" to
>>> set the initial selectivity.
>>>
>>> The KX3 is quite different. It is a
>>> high-performance direct conversion
>>> receiver using phasing to suppress the
>>> unwanted sideband followed by
>>> filtering of the resulting audio.
>>>
>>> I'm a casual, mostly QRP operator who avoids
>>> pile-ups (and so contests) and
>>> enjoy all three. If I had to settle on one or
>>> the other I'd probably take
>>> the KX3 as my first choice because of its
>>> small size, the "transparent"
>>> sound of a direct conversion format and
>>> options such as the PX3 panadapter.
>>> My second choice would be my trusty and ever
>>> dependable 15 year old K2
>>> simply because I'm basically an "analog" sort
>>> of guy. But I have no
>>> complaints about the K3/K3S. I'm sure others
>>> who enjoy busting "pileups"
>>> will have more to offer about the advantages
>>> of the K3/K3S.
>>>
>>> For detailed test comparisons check out the
>>> results published by Sherwood
>>> Engineering on their web site:
>>>
>>> http://www.sherweng.com/table.html
>>>
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: Elecraft
>>> [mailto:[hidden email]] On
>>> Behalf Of Scott
>>> Gillen ZL1CHM
>>> Sent: Friday, December 11, 2015 1:09 PM
>>> To: [hidden email]
>>> Subject: [Elecraft] Receivers?
>>>
>>> Can anyone compare the receivers in the KX3
>>> versus K3 versus K2? Is there a
>>> significant difference? I am considering the
>>> KX3.
>>>
>>> 73
>>> Scott
>>>
>>> N0HOK / ZL1CHM
>>> Auckland New Zealand

Scott Gillen ZL1CHM

Re: Receivers?

In reply to this post by Bill Frantz

Thanks Bill your description is really helpful. Thanks for taking the time to send tha info along.

73
Scott
N0HOK / ZL1CHM
Auckland New Zealandx

Sent from my iPhone

On 12/12/2015, at 3:25 PM, Bill Frantz <[hidden email]> wrote:

> I have both a K3 and a KX3 and have used a K2. The principle reason I would consider buying a K2 is for the joy of assembling the kit.
>
> When I compare the KX3 and the K3, I think of the KX3 as being about 90% of the K3, but many options are standard on the KX3 but extra cost on the K3. (Note that the K3S is the same as the K3 in these examples.) Examples include:
>
> The digital voice recorder -- standard on the KX3. Separate board for the K3. Two memories on the KX3 and 4 on the K3.
>
> Dual Watch on the KX3 is a good example of the 90%. The same functionality is available on the K3 with the subreceiver. The difference between the two receive frequencies is limited on the KX3 while the K3 subreceiver is a separate receiver and can receive on different bands. Also, the dual watch needs to have wide enough bandwidth to cover both frequencies which can raise the received noise level.
>
> General coverage: Standard on KX3, needs additional filter board on K3.
>
> High stability local oscillator: Optional board for K3. Calibration procedure for KX3. (I suspect the K3's solution is more stable.)
>
> 100W amplifer: Internal on K3. A separate unit on the KX3.
>
> The KX3 is a heck of a good value, and portable too.
>
> 73 Bill AE6JV
>
> On 12/12/15 at 1:09 PM, [hidden email] (Scott Gillen ZL1CHM) wrote:
>
>> Can anyone compare the receivers in the KX3 versus K3 versus K2? Is there a significant difference? I am considering the KX3.
>
> ---------------------------------------------------------------------------
> Bill Frantz | "I wish there was a knob on the TV to turn up the
> 408-356-8506 | intelligence. There's a knob called "brightness", but
> www.pwpconsult.com | it doesn't work. -- Gallagher
>
>

David Woolley (E.L)

Re: Receivers?

In reply to this post by Scott Gillen ZL1CHM

I don't think these descriptions are accurate, particularly the K2
versus K3 one.

The K2 is a fairly conventional, single conversion, analogue design. As
stated, it uses the crystal filter for primary selectivity. It
typically has up to two crystal filter options, one hard wired, and the
other as an integral part of the SSB adapter. The hard wired one is
adjustable, and the SSB one is fixed. The filters are constructed by
the final assembler, from individual crystals. Although there is a DSP
option, it works purely on the audio.

The K3 and K3X are software defined radios (SDRs) of the non-direct
sampling variety. I use SDR in the technical sense, not in the amateur
radio community sense; the latter requires the digital processing to be
performed on a PC. This means they have an analogue front end with at
least one analogue mixer, but the final processing is done digitally.

The K3 has a double conversion superhet architecture, with an HF first
IF and an extremely low second one. There is a selectable crystal
filter (using commercial sub-assemblies) in the first IF, which provides
coarse selectivity. The final IF processing is digital. There is a
quadrature path starting from the second mixer, analogue at that stage.
Combined with digital processing, this creates an analogue of a
phasing design receiver to suppress the final IF image, rather than the
audio image. As the signal continues in quadrature, the digital
processing may also act analogously to a phasing receiver to do the
final conversion and audio image stripping, but it may be that the
internal logic is more complex than that - the fine details are a trade
secret, although they may or may not have release information about that
part of it.

The K3 also does digital processing on the recovered audio, but this is
done within the same digital processor as the final IF processing.

The K3X, for CW at least, implements a hybrid analogue/SDR direct
conversion, phasing design. For SSB it may do the same, but it is also
possible that it actually implements a final passband centre at 0Hz, and
then does a final frequency shift to move the centre of the passband to
the correct audio frequency (i.e. they could have implemented it as a
single conversion architecture). Selectivity is provided entirely by
digital processing.

For both the K2 and K3, first mixer image rejection is provided by a
combination of band pass filters, optimised for each band, and a low
pass filter, also optimised for the band. For the KX3, the image is the
one removed by the phasing, although there is also analogue band and low
pass filtering - I'm not sure whether this is switched, or there is a
single, compromise, filter.

Block diagrams for all three are fairly easy to find. I have the K2, so
did that from memory, but the K3 one is at
<http://www.qsl.net/wb4kdi/Elecraft/K3/K3_Block.png> and the KX3 at
<http://www.elecraft.com/manual/KX3%20Manual%20Block%20Diagram.pdf>.
There are likely other places, including a better K3 image.

--
David Woolley
Owner K2 06123

On 11/12/15 21:40, Ron D'Eau Claire wrote:
> The K3 and K2 and conventional superhetrodyne formats with an Intermediate
> Frequency in the H.F. range and crystal filters to set the passband. The K2
> has an adjustable crystal filter and the K3 uses fixed crystal filter
> bandwidths. The basic K2 bandwidth is established by the crystal filter
> while the K3 adds an adjustable DSP filter after the crystal filter. (The K2
> has an optional audio DSP for enhanced filtering.)

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Hajo Dezelski

Re: Receivers?

Hi,

the block diagram of the K2 can be found in the owners manual page 148.
http://www.elecraft.com/manual/E740001_K2%20Owner's%20Manual%20Rev%20I.pdf

73 de Hajo DL1SDZ

Gruss
Hajo

---
Cela est bien dit, mais il faut cultiver notre jardin.

On Sat, Dec 12, 2015 at 12:55 PM, David Woolley <[hidden email]>
wrote:

> I don't think these descriptions are accurate, particularly the K2 versus
> K3 one.
>
> The K2 is a fairly conventional, single conversion, analogue design. As
> stated, it uses the crystal filter for primary selectivity. It typically
> has up to two crystal filter options, one hard wired, and the other as an
> integral part of the SSB adapter. The hard wired one is adjustable, and
> the SSB one is fixed. The filters are constructed by the final assembler,
> from individual crystals. Although there is a DSP option, it works purely
> on the audio.
>
> The K3 and K3X are software defined radios (SDRs) of the non-direct
> sampling variety. I use SDR in the technical sense, not in the amateur
> radio community sense; the latter requires the digital processing to be
> performed on a PC. This means they have an analogue front end with at
> least one analogue mixer, but the final processing is done digitally.
>
> The K3 has a double conversion superhet architecture, with an HF first IF
> and an extremely low second one. There is a selectable crystal filter
> (using commercial sub-assemblies) in the first IF, which provides coarse
> selectivity. The final IF processing is digital. There is a quadrature
> path starting from the second mixer, analogue at that stage. Combined with
> digital processing, this creates an analogue of a phasing design receiver
> to suppress the final IF image, rather than the audio image. As the signal
> continues in quadrature, the digital processing may also act analogously to
> a phasing receiver to do the final conversion and audio image stripping,
> but it may be that the internal logic is more complex than that - the fine
> details are a trade secret, although they may or may not have release
> information about that part of it.
>
> The K3 also does digital processing on the recovered audio, but this is
> done within the same digital processor as the final IF processing.
>
> The K3X, for CW at least, implements a hybrid analogue/SDR direct
> conversion, phasing design. For SSB it may do the same, but it is also
> possible that it actually implements a final passband centre at 0Hz, and
> then does a final frequency shift to move the centre of the passband to the
> correct audio frequency (i.e. they could have implemented it as a single
> conversion architecture). Selectivity is provided entirely by digital
> processing.
>
> For both the K2 and K3, first mixer image rejection is provided by a
> combination of band pass filters, optimised for each band, and a low pass
> filter, also optimised for the band. For the KX3, the image is the one
> removed by the phasing, although there is also analogue band and low pass
> filtering - I'm not sure whether this is switched, or there is a single,
> compromise, filter.
>
> Block diagrams for all three are fairly easy to find. I have the K2, so
> did that from memory, but the K3 one is at <
> http://www.qsl.net/wb4kdi/Elecraft/K3/K3_Block.png> and the KX3 at <
> http://www.elecraft.com/manual/KX3%20Manual%20Block%20Diagram.pdf>. There
> are likely other places, including a better K3 image.
>
> --
> David Woolley
> Owner K2 06123
>
> On 11/12/15 21:40, Ron D'Eau Claire wrote:
>
>> The K3 and K2 and conventional superhetrodyne formats with an Intermediate
>> Frequency in the H.F. range and crystal filters to set the passband. The
>> K2
>> has an adjustable crystal filter and the K3 uses fixed crystal filter
>> bandwidths. The basic K2 bandwidth is established by the crystal filter
>> while the K3 adds an adjustable DSP filter after the crystal filter. (The
>> K2
>> has an optional audio DSP for enhanced filtering.)
>>
>
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>

Brian Hunt

Re: Receivers?

In reply to this post by Scott Gillen ZL1CHM

This has been an excellent discussion but I'm surprised there hasn't been a reference to Rob Sherwood's chart which has a quantitative comparison of the three receivers. Here it is: http://www.sherweng.com/table.html

73,
Brian, K0DTJ
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Phil Wheeler-2

Re: Receivers?

I believe Ron had that at the tail end of his very
first reply, Brian.

Phil

On 12/12/15 7:21 AM, Brian Hunt wrote:
> This has been an excellent discussion but I'm surprised there hasn't been a reference to Rob Sherwood's chart which has a quantitative comparison of the three receivers. Here it is: http://www.sherweng.com/table.html
>
> 73,
> Brian, K0DTJ

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Barry K3NDM

Re: Receivers?

In reply to this post by Phil Wheeler-2

Phil,
I am using Field Day as a worst case scenario. I can't think of any
situation that is worse than have a collection of radios operating in
close proximity, to include their antennas. QRP operation does offer
the least challenges, but it still does have its problems. At the other
end, the serious QRO stations like W3LPL all take special precautions in
field layout and they use bandpass filters. However, I think you know
all that.

We don't have Frank's acreage to operate. We have to live within 2
acres for everything, but the KX3s do allow us to be less than
absolutely rigorous in our operation. We chose what we do because it
allows us to operate without the need to use bandpass filtering and the
need to model our site so that everything will work. I suspect strongly
we could operate at the 100 what level and still make no changes to our
site or operation except that we would need to be careful to have only
one transmitter on a band at a time, better band management.

One could argue the definition of the term intelligently crowed.
However, I was thinking that for a co-site operation no two transmitters
would be in the same portion of the same band. I may have a bit clumsy
with the my definition on this one.

Bottom line: my original point is that the KX3 does survive quite
nicely in what I would call an RF hostile environment. Will it wilt when
things get really crazy? Yes, it will along with every other radio.

73,
Barry
K3NDM

------ Original Message ------
From: "Phil Wheeler" <[hidden email]>
To: "Elecraft Reflector" <[hidden email]>
Sent: 12/12/2015 3:18:43 AM
Subject: Re: [Elecraft] Receivers?

>Barry,
>
>You said "Our Field Day operation uses all KX3s, QRP ... ". Well
>that's a tad different than if you have some 500 W stations nearby
>operating near your frequency. And that is more typical of the
>situation I described. So rather than disagree you provided the
>exception that proves the rule :-)
>
>And "the KX3 can handle any intelligently crowded environment": Would
>that all our bands were "intelligently crowded"!
>
>73, Phil W7OX
>
>On 12/11/15 3:49 PM, Barry LaZar wrote:
>>Phil,
>> I will take the given opportunity to disagree. Our Field Day
>>operation uses all KX3s, QRP, That accounts for 3AB + a GOTA station.
>>There have been times when we found one of our GOTA ops on the same
>>band and in the same portion of the band. What we have found is that
>>if the other radio is not in the same part of the band, you may not
>>even know he is there. However, you know he's there. If he is far
>>enough away, you could work through him. There is one caveat. We do
>>have our antennas really spread out. Our GOTA antenna(s) can be any
>>where from 200'-400' away depending on which of our many antennas are
>>being used at the time. And secondly, all of our radios are using the
>>8 KHz offset. I was amazed at the demonstration the first time it
>>happened. I would say that the KX3 can handle any intelligently crowed
>>environment.
>>
>>73,
>>Barry
>>K3NDM
>>
>>------ Original Message ------
>>From: "Phil Wheeler" <[hidden email]>
>>To: [hidden email]
>>Sent: 12/11/2015 6:23:11 PM
>>Subject: Re: [Elecraft] Receivers?
>>
>>>Scott,
>>>
>>>I agree with all that Ron says -- and have the K2, K3 and KX3 .. and
>>>like them all.
>>>
>>>Re "I am considering the KX3": The one caveat I would add, and others
>>>can expand on (or disagree with) this, is that if you operate in a
>>>dense ham environment like Field Day or with other nearby hams
>>>operating on the same bands the direct-conversion KX3 will not be as
>>>good as the two superhets because you may have more difficulty
>>>hearing weaker signals with those strong, nearby signals at adjacent
>>>frequencies.
>>>
>>>In Auckland this may or may not be an issue for you -- but as I
>>>recall 70% or so of New Zealand's population is in the Auckland area.
>>>
>>>73, Phil W7OX
>>>
>>>On 12/11/15 1:40 PM, Ron D'Eau Claire wrote:
>>>>Scott, the three rigs use different design formats:
>>>>
>>>>The K3 and K2 and conventional superhetrodyne formats with an
>>>>Intermediate
>>>>Frequency in the H.F. range and crystal filters to set the passband.
>>>>The K2
>>>>has an adjustable crystal filter and the K3 uses fixed crystal
>>>>filter
>>>>bandwidths. The basic K2 bandwidth is established by the crystal
>>>>filter
>>>>while the K3 adds an adjustable DSP filter after the crystal filter.
>>>>(The K2
>>>>has an optional audio DSP for enhanced filtering.)
>>>>
>>>>Although you will often see Elecraft rig owners refer to "roofing
>>>>filters"
>>>>the Elecraft rigs avoid them, using an I.F. in the H.F. range
>>>>instead that
>>>>avoids a lot of the compromises involved in up-converting to a first
>>>>I.F. in
>>>>the VHF range with a VHF "roofing filter" to set the initial
>>>>selectivity.
>>>>
>>>>The KX3 is quite different. It is a high-performance direct
>>>>conversion
>>>>receiver using phasing to suppress the unwanted sideband followed by
>>>>filtering of the resulting audio.
>>>>
>>>>I'm a casual, mostly QRP operator who avoids pile-ups (and so
>>>>contests) and
>>>>enjoy all three. If I had to settle on one or the other I'd probably
>>>>take
>>>>the KX3 as my first choice because of its small size, the
>>>>"transparent"
>>>>sound of a direct conversion format and options such as the PX3
>>>>panadapter.
>>>>My second choice would be my trusty and ever dependable 15 year old
>>>>K2
>>>>simply because I'm basically an "analog" sort of guy. But I have no
>>>>complaints about the K3/K3S. I'm sure others who enjoy busting
>>>>"pileups"
>>>>will have more to offer about the advantages of the K3/K3S.
>>>>
>>>>For detailed test comparisons check out the results published by
>>>>Sherwood
>>>>Engineering on their web site:
>>>>
>>>>http://www.sherweng.com/table.html
>>>>
>>>>
>>>>
>>>>
>>>>-----Original Message-----
>>>>From: Elecraft [mailto:[hidden email]] On Behalf
>>>>Of Scott
>>>>Gillen ZL1CHM
>>>>Sent: Friday, December 11, 2015 1:09 PM
>>>>To: [hidden email]
>>>>Subject: [Elecraft] Receivers?
>>>>
>>>>Can anyone compare the receivers in the KX3 versus K3 versus K2? Is
>>>>there a
>>>>significant difference? I am considering the KX3.
>>>>
>>>>73
>>>>Scott
>>>>
>>>>N0HOK / ZL1CHM
>>>>Auckland New Zealand
>
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vk2rq

Re: Receivers?

In reply to this post by David Woolley (E.L)

In the K3 schematic, I don’t see any quadrature path starting from the second mixer in the RX path — the two signals lines coming out of that 2nd RX mixer are a balanced (differential) output, not in-phase and quadrature signals. On the TX side, the DSP seems to produce I&Q outputs, but it seems the I signal is not used for anything and only the Q signal is used as an input to the TX mixer.

This is in contrast to the KX3 where there are I&Q signals used between true quadrature mixers and the DSP. The IF of the KX3 can be 0Hz (direct conversion), 8KHz (single conversion), or as you point out, in the case of SSB weaver demodulation the 0Hz mark can be placed in the centre of the signal passband, then the I/Q signals are passed through the optional roofing low pass filter before being unfolded/shifted in the DSP.

--
73 de Matt VK2RQ

On 12 décembre 2015 at 10:55:59 PM, David Woolley ([hidden email]) wrote:

I don't think these descriptions are accurate, particularly the K2
versus K3 one.

The K3 has a double conversion superhet architecture, with an HF first
IF and an extremely low second one. There is a selectable crystal
filter (using commercial sub-assemblies) in the first IF, which provides
coarse selectivity. The final IF processing is digital. There is a
quadrature path starting from the second mixer, analogue at that stage.
Combined with digital processing, this creates an analogue of a
phasing design receiver to suppress the final IF image, rather than the
audio image. As the signal continues in quadrature, the digital
processing may also act analogously to a phasing receiver to do the
final conversion and audio image stripping, but it may be that the
internal logic is more complex than that - the fine details are a trade
secret, although they may or may not have release information about that
part of it.

The K3X, for CW at least, implements a hybrid analogue/SDR direct
conversion, phasing design. For SSB it may do the same, but it is also
possible that it actually implements a final passband centre at 0Hz, and
then does a final frequency shift to move the centre of the passband to
the correct audio frequency (i.e. they could have implemented it as a
single conversion architecture). Selectivity is provided entirely by
digital processing.
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Brian Hunt

Re: Receivers?

In reply to this post by Brian Hunt

Sorry guys, my bad. Comes from reading email on an iPod. 😄
Brian, K0DTJ

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Don Wilhelm-4

Re: Receivers?

In reply to this post by vk2rq

Matt,

You will not see analog I/Q signals in the K3 - the 2nd mixer's 15kHz
output feeds an Analog to Digital converter and the I and Q signals only
exist in the digital realm.
In transmit, the same thing happens in reverse - the mixer sees the 15
kHz output of a DAC.

73,
Don W3FPR

On 12/12/2015 2:10 PM, Matt Maguire wrote:

> In the K3 schematic, I don’t see any quadrature path starting from the second mixer in the RX path — the two signals lines coming out of that 2nd RX mixer are a balanced (differential) output, not in-phase and quadrature signals. On the TX side, the DSP seems to produce I&Q outputs, but it seems the I signal is not used for anything and only the Q signal is used as an input to the TX mixer.
>
> This is in contrast to the KX3 where there are I&Q signals used between true quadrature mixers and the DSP. The IF of the KX3 can be 0Hz (direct conversion), 8KHz (single conversion), or as you point out, in the case of SSB weaver demodulation the 0Hz mark can be placed in the centre of the signal passband, then the I/Q signals are passed through the optional roofing low pass filter before being unfolded/shifted in the DSP.
>
> --
> 73 de Matt VK2RQ
>
> On 12 décembre 2015 at 10:55:59 PM, David Woolley ([hidden email]) wrote:
>
> I don't think these descriptions are accurate, particularly the K2
> versus K3 one.
>
> The K3 has a double conversion superhet architecture, with an HF first
> IF and an extremely low second one. There is a selectable crystal
> filter (using commercial sub-assemblies) in the first IF, which provides
> coarse selectivity. The final IF processing is digital. There is a
> quadrature path starting from the second mixer, analogue at that stage.
> Combined with digital processing, this creates an analogue of a
> phasing design receiver to suppress the final IF image, rather than the
> audio image. As the signal continues in quadrature, the digital
> processing may also act analogously to a phasing receiver to do the
> final conversion and audio image stripping, but it may be that the
> internal logic is more complex than that - the fine details are a trade
> secret, although they may or may not have release information about that
> part of it.
>
> The K3X, for CW at least, implements a hybrid analogue/SDR direct
> conversion, phasing design. For SSB it may do the same, but it is also
> possible that it actually implements a final passband centre at 0Hz, and
> then does a final frequency shift to move the centre of the passband to
> the correct audio frequency (i.e. they could have implemented it as a
> single conversion architecture). Selectivity is provided entirely by
> digital processing.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

Bill Frantz

Re: Receivers?

In reply to this post by Barry K3NDM

The West Valley Amateur Radio Association (WVARA) Field Day
operation, using the K6EI call, has been using a mixture of
mostly K3s with some K2s and KX3s. We run QRP and last year
entered as 11AB. We have very little difficulty with mutual
interference, even when we are running SSB, digital, and CW on
the same band.

The only extra filters we use are in conjunction with a
triplexer which lets use one tribander on 10M, 15m, and 20M at
the same time.

We have been quite successful with the approach for many years
as can be seen from the field day results.

This year, we took our operation to Sierra County for the
California QSO Party. There we ran 2 K3s and a KX3, all at 100
watts. We kept the SSB stations on separate bands. The worst
interference problem we had was when our batteries got low and
we got a lot of IMD in our signals. That caused interference
between our stations. Replacing the batteries with freshly
charged batteries cured the problem.

73 Bill AE6JV

On 12/12/15 at 9:58 AM, [hidden email] (Barry LaZar) wrote:

>I am using Field Day as a worst case scenario. I can't think of
>any situation that is worse than have a collection of radios
>operating in close proximity, to include their antennas. QRP
>operation does offer the least challenges, but it still does
>have its problems. At the other end, the serious QRO stations
>like W3LPL all take special precautions in field layout and
>they use bandpass filters. However, I think you know all that.
-----------------------------------------------------------------------
Bill Frantz | "The only thing we have to | Periwinkle
(408)356-8506 | fear is fear itself." - FDR | 16345
Englewood Ave
www.pwpconsult.com | Inaugural address, 3/4/1933 | Los Gatos,
CA 95032

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