Re: [Elecraft] Field Day rig experience

[WILLIE BABER]

Since it is meant for public consumption, maybe Wayne won't mind that I 
reproduce this, that Wes also cited (from the Elecraft website), written by 
Wayne, N6KR:  Maybe we can agree that Wayne and Elecraft ought to know.  And so 
end of thread.
---

What "Roofing Filter" means to Elecraft

There's been so much discussion about this topic that I'd thought I'd better 
try to clarify why we used the term when discussing the K3S.
A "Roofing filter" is simply a filter in the radio's first IF through which all 
signals must pass before they will be "seen" by later receiver stages. The 
narrower this filter is, the less exposure later stages will have. Thus a 
"narrow" roofing filter is desirable -- but "narrow" is relative, as I'll 
explain. 

The term "roofing filter" has most often been used in relation to triple- or 
quadruple-conversion receivers. Such receivers have an  IF above the highest RF 
band covered; it's typically something in the range of 30 to 70 MHz or higher. 
But "roofing" as a term should be interpreted as "protective," not "high in 
frequency." A roofing filter protects later stages, including amplifiers, 
mixers, narrower filters, and DSP subsystems, just as the roof on your house 
keeps rain out of all of the rooms. But a roofing filter can be equally at home 
at a low first IF, if that is how the radio is designed. It still provides the 
same protective function.

When we released the K2 in 1999, we never described our 1st IF crystal filters 
as roofing filters. We had only one IF, so the receiver model was simpler; 
there were no narrow filters at later stages that required protection.

But now, we find that the term is in widespread use. Average hams now think of 
roofing filter bandwidths as the standard of comparison between receivers. This 
is why manufacturers have jumped through hoops to try to provide the narrowest 
possible roofing filters. Many operators have an understanding (justified) that 
a roofing filter that is wider than the communications bandwidth will not best 
protect the receiver's later stages. So the term now seems appropriate to use 
even in a radio such as the K2, K3S, or Orion, all of which use low-frequency 
IFs (5 to 9 MHz).

In recent years, the roofing filter has become the centerpiece of receiver 
redesign:
Suppose that manufacturer "A" initially designed their receiver to use a 15- or 
20-kHz roofing filter. Yes, this allows the receiver to handle NBFM and other 
wide modulation modes; it may also be selected to constrain the signal 
bandwidth ahead of a noise blanker or spectrum scope. But it comes at a price. 
If you're using CW mode, you'll have much narrower filters selected at the 
radio's 2nd and 3rd IFs. Yet the 1st IF roofing filter allows a broad swath of 
signals into the earlier stages. You don't need this energy in your passband. 
It can cause trouble.

Manufacturer "A," realizing they have a problem with dynamic range at close 
spacing, then announces that they've had a breakthrough: they can now offer a 
6-kHz, or more recently 3-kHz roofing filter. This will certainly improve the 
situation for SSB and AM operation, but it still opens the barn door in CW or 
DATA modes, because the bandwidth is a factor of 10 wider than needed for 
communications.  

So why don't they offer much narrower roofing filters that can be switched in 
for CW and data modes, or at times when adjacent-channel SSB QRM is very high? 
It's because they can't make filters any narrower at such a high IF.

Enter the "down-conversion" rig (K2, K3S, Orion, etc.). By converting to a low 
first IF, the designer can easily create narrow filters that are compatible 
with the required communications bandwidth. This is why we are offering filters 
with bandwidths as low as 200 Hz.

And yes, these are still "roofing" filters, because they limit exposure 
(bandwidth), thus protecting later stages (in the K3S case, the IF amp, 2nd 
mixer, and DSP).

73,
Wayne
N6KR

CWops #1085
CWA Advisor levels II and III
http://cwops.org/


On Thu, 6/14/18, K9MA  wrote:

 Subject: Re: [Elecraft] Field Day rig experience
 To: elecraft@mailman.qth.net
 Date: Thursday, June 14, 2018, 8:28 PM
 
 There are at least two excellent
 reasons for the narrow crystal filters 
 in
 the first IF of the K3(s).  (Wayne can correct me if
 I'm wrong.)  
 One, of course, is to
 reject the image of the second IF.  However, the 
 dynamic range of the ADC in the second IF, by
 itself, just isn't enough 
 to provide
 the 140 or so dB we need.  The combination of the ADC/DSP
 and 
 the crystal filter does the trick, even
 though 8 MHz crystal filters 
 aren't all
 that great.  As I recall, there were some earlier DSP only
 
 receivers, but their dynamic range was
 poor. Crystal filters are 
 expensive, but
 until we 

Re: [Elecraft] Field Day rig experience

[Wes Stewart]

Okay, I'll give up, we'll just have to agree to disagree.

On 6/14/2018 6:33 PM, WILLIE BABER wrote:

Wes,

"A "Roofing filter" is simply a filter in the radio's first IF through which all signals must pass before they 
will be "seen" by later receiver stages. The narrower this filter is, the less exposure later stages will have. Thus a 
"narrow" roofing filter is desirable -- but "narrow" is relative, as I'll explain."

What Elecraft said (above) is exactly what I said.  Moreover, Elecraft's 
explanation is required because the term roofing filter is now applied to 
up-conversion in multiple conversion radios (with relatively wide first I-F 
filters compared to what is achievable at a low first I-F) which is what the 
term initially sought to rebuff in the first place, also my point.

73, Will, wj9b

CWops #1085
CWA Advisor levels II and III
http://cwops.org/


On Thu, 6/14/18, Wes Stewart  wrote:

  Subject: Re: [Elecraft] Field Day rig experience
  To: elecraft@mailman.qth.net
  Date: Thursday, June 14, 2018, 4:47 PM
  
  Will,
  
  First of all I have said before and will repeat

  it, I detest the term "roofing
  filter."  That said, by the generally
  accepted definition, you are wrong. See
  Elecraft's take on this:
  
  http://www.elecraft.com/K3/Roofing_Filters.htm
  
  If you will think in

  Wayne's terms, the post-mixer filter is a
  "protective"
  filter, not a
  mode-specific filter.  So the question becomes, how much
  
  protection is necessary?  In

  Elecraft's case, quite a lot, IMHO.  With its QRP
  DNA, Elecraft uses post crystal filter
  circuitry that minimizes current
  consumption.  The trade off for this is the
  need for a bank of pricey crystal
  filters
  to limit the frequencies that the circuitry is exposed
  to.
  
  Now what if the

  subsequent circuitry doesn't require this much
  protection
  because it is more robust?  We
  now have direct-sampling radios that can digitize
  a whole ham band with good performance. If the
  BW was limited to 10-15 kHz in an
  up
  conversion configuration they should be even better.  The
  limitation now
  becomes LO phase noise, but
  newer synthesizer designs overcome that obstacle.
  Another thing to note is that IMD in crystal
  filters is reported to be inversely
  proportional to BW. So a wider filter might
  actually be better from that
  perspective.
  Some Elecraft filters exhibit passive IMD BTW.
  
  Wes  N7WS
  
  On 6/14/2018 8:01 AM, WILLIE BABER wrote:

  > Hello Wes,
  >
  > I took a look.  Both designs are using
  the idea of "roofing filter" to refer to
  up-conversion radios similar to the use of up-conversion
  3khz filters as roofing filters in Icom radios.
  >
  > "Roofing
  filter" (a mode specific filter after the first mixer
  including narrow cw filters) only makes sense in the
  context  of the history of superhet design and in
  particular the use of one broad 15 khz first I-F (so that
  all modes may pass through it) typical of all Japanese
  radios until recently.  Calling a 45 mhz filter at the
  first I-F a "roofing filter" as noted in the info
  you sent entirely misses the point of what roofing filter
  means.  Or, to put it another way, all Ten-Tec radios had
  roofing filters in them (and were ssb and cw only) well
  before the term roofing filter was coined!  Which is why an
  Omni C will out perform any wide (15 khz) first I-F Japanese
  radio, even those built well after the 1980 vintage Omni
  C.
  >
  > Unless mode
  specific up-conversion crystal filters can be made and as
  narrow as 200 hz (this is possible with down-conversion)
  then "roofing filter" and up conversion
  doesn't make sense historically or in reality.
  >
  > Actually, Icom says
  that did it with 1.2khz filter at 64 mhz in the Icom 7851,
  though I'm not convinced the filter is that narrow, and
  1.2khz is far from the 200hz filter that my K3 has in it
  (however, the placement of this filter is why the 7851 is
  among the best radios in Sherwood's chart, on cw).
  >
  > It is possible to
  make very narrow and precise crystal filters as narrow as
  the 200 hz inexpensively, and this is the point of having
  multiple roofing filters at the first I-F.  So, this is the
  origin of the term roofing filter---in comparison to the
  barn-door up conversion first I-F.
  >
  > 73, Will, wj9b
  >
  > CWops #1085
  > CWA
  Advisor levels II and III
  > http://cwops.org/
  >
  >
  
  > On Wed, 6/13/18, Wes Stewart
  wrote:
  >
  >   Subject:
  Re: [Elecraft] Field Day rig experience
  >   To:elecraft@mailman.qth.net
  >   Date: Wednesday, June 13, 2018, 3:08
  PM
  >
  >
  Certainly not to disparage the
  >   K3(S)
  architecture (I have two of them) there is
 

Re: [Elecraft] Field Day rig experience

[K9MA]

There are at least two excellent reasons for the narrow crystal filters 
in the first IF of the K3(s).  (Wayne can correct me if I'm wrong.)  
One, of course, is to reject the image of the second IF.  However, the 
dynamic range of the ADC in the second IF, by itself, just isn't enough 
to provide the 140 or so dB we need.  The combination of the ADC/DSP and 
the crystal filter does the trick, even though 8 MHz crystal filters 
aren't all that great.  As I recall, there were some earlier DSP only 
receivers, but their dynamic range was poor. Crystal filters are 
expensive, but until we have fast ADC's linear to at least 24 bits, 
they're necessary to get that kind of dynamic range.


I've often wondered if any other communication system requires the close 
in dynamic range we do.  Why would anyone design a system that allowed 
signals 2 kHz apart to differ in strength by 140 dB?


73,
Scott K9MA




On 6/14/2018 20:33, WILLIE BABER wrote:

Wes,

"A "Roofing filter" is simply a filter in the radio's first IF through which all signals must pass before they 
will be "seen" by later receiver stages. The narrower this filter is, the less exposure later stages will have. Thus a 
"narrow" roofing filter is desirable -- but "narrow" is relative, as I'll explain."

What Elecraft said (above) is exactly what I said.  Moreover, Elecraft's 
explanation is required because the term roofing filter is now applied to 
up-conversion in multiple conversion radios (with relatively wide first I-F 
filters compared to what is achievable at a low first I-F) which is what the 
term initially sought to rebuff in the first place, also my point.

73, Will, wj9b

CWops #1085
CWA Advisor levels II and III
http://cwops.org/


On Thu, 6/14/18, Wes Stewart  wrote:

  Subject: Re: [Elecraft] Field Day rig experience
  To: elecraft@mailman.qth.net
  Date: Thursday, June 14, 2018, 4:47 PM
  
  Will,
  
  First of all I have said before and will repeat

  it, I detest the term "roofing
  filter."  That said, by the generally
  accepted definition, you are wrong. See
  Elecraft's take on this:
  
  http://www.elecraft.com/K3/Roofing_Filters.htm
  
  If you will think in

  Wayne's terms, the post-mixer filter is a
  "protective"
  filter, not a
  mode-specific filter.  So the question becomes, how much
  
  protection is necessary?  In

  Elecraft's case, quite a lot, IMHO.  With its QRP
  DNA, Elecraft uses post crystal filter
  circuitry that minimizes current
  consumption.  The trade off for this is the
  need for a bank of pricey crystal
  filters
  to limit the frequencies that the circuitry is exposed
  to.
  
  Now what if the

  subsequent circuitry doesn't require this much
  protection
  because it is more robust?  We
  now have direct-sampling radios that can digitize
  a whole ham band with good performance. If the
  BW was limited to 10-15 kHz in an
  up
  conversion configuration they should be even better.  The
  limitation now
  becomes LO phase noise, but
  newer synthesizer designs overcome that obstacle.
  Another thing to note is that IMD in crystal
  filters is reported to be inversely
  proportional to BW. So a wider filter might
  actually be better from that
  perspective.
  Some Elecraft filters exhibit passive IMD BTW.
  
  Wes  N7WS
  
  On 6/14/2018 8:01 AM, WILLIE BABER wrote:

  > Hello Wes,
  >
  > I took a look.  Both designs are using
  the idea of "roofing filter" to refer to
  up-conversion radios similar to the use of up-conversion
  3khz filters as roofing filters in Icom radios.
  >
  > "Roofing
  filter" (a mode specific filter after the first mixer
  including narrow cw filters) only makes sense in the
  context  of the history of superhet design and in
  particular the use of one broad 15 khz first I-F (so that
  all modes may pass through it) typical of all Japanese
  radios until recently.  Calling a 45 mhz filter at the
  first I-F a "roofing filter" as noted in the info
  you sent entirely misses the point of what roofing filter
  means.  Or, to put it another way, all Ten-Tec radios had
  roofing filters in them (and were ssb and cw only) well
  before the term roofing filter was coined!  Which is why an
  Omni C will out perform any wide (15 khz) first I-F Japanese
  radio, even those built well after the 1980 vintage Omni
  C.
  >
  > Unless mode
  specific up-conversion crystal filters can be made and as
  narrow as 200 hz (this is possible with down-conversion)
  then "roofing filter" and up conversion
  doesn't make sense historically or in reality.
  >
  > Actually, Icom says
  that did it with 1.2khz filter at 64 mhz in the Icom 7851,
  though I'm not convinced the filter is that narrow, and
  1.2khz is far from the 200hz filter that my K3 has in it
  (however, the placement of this filter is why the 7851 i

Re: [Elecraft] Field Day rig experience

[WILLIE BABER]

Wes,

"A "Roofing filter" is simply a filter in the radio's first IF through which 
all signals must pass before they will be "seen" by later receiver stages. The 
narrower this filter is, the less exposure later stages will have. Thus a 
"narrow" roofing filter is desirable -- but "narrow" is relative, as I'll 
explain."

What Elecraft said (above) is exactly what I said.  Moreover, Elecraft's 
explanation is required because the term roofing filter is now applied to 
up-conversion in multiple conversion radios (with relatively wide first I-F 
filters compared to what is achievable at a low first I-F) which is what the 
term initially sought to rebuff in the first place, also my point.

73, Will, wj9b

CWops #1085
CWA Advisor levels II and III
http://cwops.org/

----
On Thu, 6/14/18, Wes Stewart  wrote:

 Subject: Re: [Elecraft] Field Day rig experience
 To: elecraft@mailman.qth.net
 Date: Thursday, June 14, 2018, 4:47 PM
 
 Will,
 
 First of all I have said before and will repeat
 it, I detest the term "roofing 
 filter."  That said, by the generally
 accepted definition, you are wrong. See 
 Elecraft's take on this:
 
 http://www.elecraft.com/K3/Roofing_Filters.htm
 
 If you will think in
 Wayne's terms, the post-mixer filter is a
 "protective" 
 filter, not a
 mode-specific filter.  So the question becomes, how much
 
 protection is necessary?  In
 Elecraft's case, quite a lot, IMHO.  With its QRP 
 DNA, Elecraft uses post crystal filter
 circuitry that minimizes current 
 consumption.  The trade off for this is the
 need for a bank of pricey crystal 
 filters
 to limit the frequencies that the circuitry is exposed
 to.
 
 Now what if the
 subsequent circuitry doesn't require this much
 protection 
 because it is more robust?  We
 now have direct-sampling radios that can digitize 
 a whole ham band with good performance. If the
 BW was limited to 10-15 kHz in an 
 up
 conversion configuration they should be even better.  The
 limitation now 
 becomes LO phase noise, but
 newer synthesizer designs overcome that obstacle.  
 Another thing to note is that IMD in crystal
 filters is reported to be inversely 
 proportional to BW. So a wider filter might
 actually be better from that 
 perspective. 
 Some Elecraft filters exhibit passive IMD BTW.
 
 Wes  N7WS
 
 On 6/14/2018 8:01 AM, WILLIE BABER wrote:
 > Hello Wes,
 >
 > I took a look.  Both designs are using
 the idea of "roofing filter" to refer to
 up-conversion radios similar to the use of up-conversion
 3khz filters as roofing filters in Icom radios.
 >
 > "Roofing
 filter" (a mode specific filter after the first mixer
 including narrow cw filters) only makes sense in the
 context  of the history of superhet design and in
 particular the use of one broad 15 khz first I-F (so that
 all modes may pass through it) typical of all Japanese
 radios until recently.  Calling a 45 mhz filter at the
 first I-F a "roofing filter" as noted in the info
 you sent entirely misses the point of what roofing filter
 means.  Or, to put it another way, all Ten-Tec radios had
 roofing filters in them (and were ssb and cw only) well
 before the term roofing filter was coined!  Which is why an
 Omni C will out perform any wide (15 khz) first I-F Japanese
 radio, even those built well after the 1980 vintage Omni
 C.
 >
 > Unless mode
 specific up-conversion crystal filters can be made and as
 narrow as 200 hz (this is possible with down-conversion)
 then "roofing filter" and up conversion
 doesn't make sense historically or in reality.
 >
 > Actually, Icom says
 that did it with 1.2khz filter at 64 mhz in the Icom 7851,
 though I'm not convinced the filter is that narrow, and
 1.2khz is far from the 200hz filter that my K3 has in it
 (however, the placement of this filter is why the 7851 is
 among the best radios in Sherwood's chart, on cw).
 >
 > It is possible to
 make very narrow and precise crystal filters as narrow as
 the 200 hz inexpensively, and this is the point of having
 multiple roofing filters at the first I-F.  So, this is the
 origin of the term roofing filter---in comparison to the
 barn-door up conversion first I-F.
 >
 > 73, Will, wj9b
 >
 > CWops #1085
 > CWA
 Advisor levels II and III
 > http://cwops.org/
 >
 >
 
 > On Wed, 6/13/18, Wes Stewart 
 wrote:
 >
 >   Subject:
 Re: [Elecraft] Field Day rig experience
 >   To:elecraft@mailman.qth.net
 >   Date: Wednesday, June 13, 2018, 3:08
 PM
 >   
 >  
 Certainly not to disparage the
 >   K3(S)
 architecture (I have two of them) there is
 >   nothing inherently wrong with an
 up-conversion
 >   receiver, if modern
 hardware is used.
 >   
 >   See:https://martein.home.xs4all.nl/pa3ake/hmode/g3sbi_intro.html
 >   
 >   

Re: [Elecraft] Field Day rig experience

[Wes Stewart]

Will,

First of all I have said before and will repeat it, I detest the term "roofing 
filter."  That said, by the generally accepted definition, you are wrong. See 
Elecraft's take on this:


http://www.elecraft.com/K3/Roofing_Filters.htm

If you will think in Wayne's terms, the post-mixer filter is a "protective" 
filter, not a mode-specific filter.  So the question becomes, how much 
protection is necessary?  In Elecraft's case, quite a lot, IMHO.  With its QRP 
DNA, Elecraft uses post crystal filter circuitry that minimizes current 
consumption.  The trade off for this is the need for a bank of pricey crystal 
filters to limit the frequencies that the circuitry is exposed to.


Now what if the subsequent circuitry doesn't require this much protection 
because it is more robust?  We now have direct-sampling radios that can digitize 
a whole ham band with good performance. If the BW was limited to 10-15 kHz in an 
up conversion configuration they should be even better.  The limitation now 
becomes LO phase noise, but newer synthesizer designs overcome that obstacle.  
Another thing to note is that IMD in crystal filters is reported to be inversely 
proportional to BW. So a wider filter might actually be better from that 
perspective.  Some Elecraft filters exhibit passive IMD BTW.


Wes  N7WS

On 6/14/2018 8:01 AM, WILLIE BABER wrote:

Hello Wes,

I took a look.  Both designs are using the idea of "roofing filter" to refer to 
up-conversion radios similar to the use of up-conversion 3khz filters as roofing filters 
in Icom radios.

"Roofing filter" (a mode specific filter after the first mixer including narrow cw 
filters) only makes sense in the context  of the history of superhet design and in particular the 
use of one broad 15 khz first I-F (so that all modes may pass through it) typical of all Japanese 
radios until recently.  Calling a 45 mhz filter at the first I-F a "roofing filter" as 
noted in the info you sent entirely misses the point of what roofing filter means.  Or, to put it 
another way, all Ten-Tec radios had roofing filters in them (and were ssb and cw only) well before 
the term roofing filter was coined!  Which is why an Omni C will out perform any wide (15 khz) 
first I-F Japanese radio, even those built well after the 1980 vintage Omni C.

Unless mode specific up-conversion crystal filters can be made and as narrow as 200 hz 
(this is possible with down-conversion) then "roofing filter" and up conversion 
doesn't make sense historically or in reality.

Actually, Icom says that did it with 1.2khz filter at 64 mhz in the Icom 7851, 
though I'm not convinced the filter is that narrow, and 1.2khz is far from the 
200hz filter that my K3 has in it (however, the placement of this filter is why 
the 7851 is among the best radios in Sherwood's chart, on cw).

It is possible to make very narrow and precise crystal filters as narrow as the 
200 hz inexpensively, and this is the point of having multiple roofing filters 
at the first I-F.  So, this is the origin of the term roofing filter---in 
comparison to the barn-door up conversion first I-F.

73, Will, wj9b

CWops #1085
CWA Advisor levels II and III
http://cwops.org/

--------
On Wed, 6/13/18, Wes Stewart  wrote:

  Subject: Re: [Elecraft] Field Day rig experience
  To:elecraft@mailman.qth.net
  Date: Wednesday, June 13, 2018, 3:08 PM
  
  Certainly not to disparage the

  K3(S) architecture (I have two of them) there is
  nothing inherently wrong with an up-conversion
  receiver, if modern hardware is used.
  
  See:https://martein.home.xs4all.nl/pa3ake/hmode/g3sbi_intro.html
  
  and my friend Cornell's,

  Star-10 transceiver.
  https://pdfs.semanticscholar.org/eb33/5c12858779a653d9b9b93ca20120aebb7616.pdf
  
  Wes  N7WS
  
  
    On 6/13/2018 11:38 AM, WILLIE BABER

  wrote:
  > Robert is talking about the
  crystal filters, also known as roofing filters now-days,
  that are typically placed after the first mixer (I
  mistakenly typed "ahead" but I meant
  "after" as Robert notes), though there is a post
  amp and NB before these filters in K2 and K3.
  >
  > The idea is that a
  crystal filter right after the first mixer gives high
  dynamic range because high selectivity comes before the
  receiver has developed stages of gain that otherwise could
  cause blocking or IMD, especially when selectivity is
  postponed to the second mixer while ignoring gain
  distribution in prior stages of the receiver.  This basic
  idea was popularized in Solid State Design for the Radio
  Amateur, and it was applied to Ten-Tec radios for decades
  (at a 9 mhz I-F).
  >
  >
  Roofing filter gets defined in relationship to Japanese
  radios that had up conversion 15 khz filters at the first
  I-F, and generally lower dynamic range as a result, (but you
  got all modes, general coverage, and optional crystal
  filters at

Re: [Elecraft] Field Day rig experience

[Terry Hart G3VFO via Elecraft]

Hi Guys.

For what it's worth, I find it interesting how the term "Roofing filter" has 
changed a bit over time and with different 'ownership'. 

Personally, I first came across the term in around 1966 as a junior design 
engineer working on the Redifon R550 series of HF receivers. I understood then 
that the term "roof" referred to the "top of the house" filter used to provide 
the first measure of protection against adjacent unwanted signals.

These and other similar HF receivers used an up-conversion architecture, and 
the R550/551 employed a first IF at 38 MHz with the local oscillator running 38 
to 68 MHz.  The bandwidth of this filter, which followed the first mixer, was 
around 15 KHz as I recall. The second IF was at 1.4 MHz (or 1.6 MHz in other 
similar designs) and featured a number of selectable crystal filters typically 
providing close-in band-widths from around 200Hz to 12 KHz.  Employing a first 
IF above 30 MHz shifts the first image into the VHF spectrum and allows the use 
of a 30 MHz low pass filter in the front end, with sub-octave band pass filters 
to provide a measure of front-end selectivity.  We would have loved to provide 
close-in selectivity at the first IF frequency and so avoid a down-conversion 
to the second IF, but achieving the required passband /stopband characteristics 
just was (is) not possible at 38 MHz.  However, decent close in selectivity 
(passband and stopband) can be provided with cr
 ystal filters at around 9 MHz or thereabouts, and many of the earlier purely 
analogue designs of amateur equipment took advantage of this, including TenTec. 
 I do not personally view this particular application as a roofing filter as is 
not protecting further stages of selectivity.t it All now ancient 
history...things have moved on a bit since then! Can anyone trace the term 
further back in time?

However, It seems to me that the term "roofing filter" still makes perfectly 
good sense in the context of the K3 design, with the selectable crystal filters 
providing the maximum possible (mode dependent) selectivity protection in front 
of the final IF, even if that is now implemented using DSP techniques! 

Terry
G3VFO
-Original Message-
From: elecraft-boun...@mailman.qth.net  On 
Behalf Of WILLIE BABER
Sent: 14 June 2018 16:02
To: elecraft@mailman.qth.net; Wes Stewart 
Subject: Re: [Elecraft] Field Day rig experience

Hello Wes,

I took a look.  Both designs are using the idea of "roofing filter" to refer to 
up-conversion radios similar to the use of up-conversion 3khz filters as 
roofing filters in Icom radios.

"Roofing filter" (a mode specific filter after the first mixer including narrow 
cw filters) only makes sense in the context  of the history of superhet design 
and in particular the use of one broad 15 khz first I-F (so that all modes may 
pass through it) typical of all Japanese radios until recently.  Calling a 45 
mhz filter at the first I-F a "roofing filter" as noted in the info you sent 
entirely misses the point of what roofing filter means.  Or, to put it another 
way, all Ten-Tec radios had roofing filters in them (and were ssb and cw only) 
well before the term roofing filter was coined!  Which is why an Omni C will 
out perform any wide (15 khz) first I-F Japanese radio, even those built well 
after the 1980 vintage Omni C.

Unless mode specific up-conversion crystal filters can be made and as narrow as 
200 hz (this is possible with down-conversion) then "roofing filter" and up 
conversion doesn't make sense historically or in reality.  

Actually, Icom says that did it with 1.2khz filter at 64 mhz in the Icom 7851, 
though I'm not convinced the filter is that narrow, and 1.2khz is far from the 
200hz filter that my K3 has in it (however, the placement of this filter is why 
the 7851 is among the best radios in Sherwood's chart, on cw).

It is possible to make very narrow and precise crystal filters as narrow as the 
200 hz inexpensively, and this is the point of having multiple roofing filters 
at the first I-F.  So, this is the origin of the term roofing filter---in 
comparison to the barn-door up conversion first I-F.

73, Will, wj9b

CWops #1085
CWA Advisor levels II and III
http://cwops.org/

--------------------
On Wed, 6/13/18, Wes Stewart  wrote:

 Subject: Re: [Elecraft] Field Day rig experience
 To: elecraft@mailman.qth.net
 Date: Wednesday, June 13, 2018, 3:08 PM
 
 Certainly not to disparage the
 K3(S) architecture (I have two of them) there is  nothing inherently wrong 
with an up-conversion  receiver, if modern hardware is used.
 
 See: https://martein.home.xs4all.nl/pa3ake/hmode/g3sbi_intro.html
 
 and my friend Cornell's,
 Star-10 transceiver. 
 https://pdfs.semanticscholar.org/eb33/5c12858779a653d9b9b93ca20120aebb7616.pdf
 
 Wes  N7WS
 
 
   On 6/13/2018 11:38 AM, WILLIE BABER
 wrote:
 > Robert is talking about the
 crystal

Re: [Elecraft] Field Day rig experience

[WILLIE BABER]

Hello Wes,

I took a look.  Both designs are using the idea of "roofing filter" to refer to 
up-conversion radios similar to the use of up-conversion 3khz filters as 
roofing filters in Icom radios.

"Roofing filter" (a mode specific filter after the first mixer including narrow 
cw filters) only makes sense in the context  of the history of superhet design 
and in particular the use of one broad 15 khz first I-F (so that all modes may 
pass through it) typical of all Japanese radios until recently.  Calling a 45 
mhz filter at the first I-F a "roofing filter" as noted in the info you sent 
entirely misses the point of what roofing filter means.  Or, to put it another 
way, all Ten-Tec radios had roofing filters in them (and were ssb and cw only) 
well before the term roofing filter was coined!  Which is why an Omni C will 
out perform any wide (15 khz) first I-F Japanese radio, even those built well 
after the 1980 vintage Omni C.

Unless mode specific up-conversion crystal filters can be made and as narrow as 
200 hz (this is possible with down-conversion) then "roofing filter" and up 
conversion doesn't make sense historically or in reality.  

Actually, Icom says that did it with 1.2khz filter at 64 mhz in the Icom 7851, 
though I'm not convinced the filter is that narrow, and 1.2khz is far from the 
200hz filter that my K3 has in it (however, the placement of this filter is why 
the 7851 is among the best radios in Sherwood's chart, on cw).

It is possible to make very narrow and precise crystal filters as narrow as the 
200 hz inexpensively, and this is the point of having multiple roofing filters 
at the first I-F.  So, this is the origin of the term roofing filter---in 
comparison to the barn-door up conversion first I-F.

73, Will, wj9b

CWops #1085
CWA Advisor levels II and III
http://cwops.org/


On Wed, 6/13/18, Wes Stewart  wrote:

 Subject: Re: [Elecraft] Field Day rig experience
 To: elecraft@mailman.qth.net
 Date: Wednesday, June 13, 2018, 3:08 PM
 
 Certainly not to disparage the
 K3(S) architecture (I have two of them) there is 
 nothing inherently wrong with an up-conversion
 receiver, if modern hardware is used.
 
 See: https://martein.home.xs4all.nl/pa3ake/hmode/g3sbi_intro.html
 
 and my friend Cornell's,
 Star-10 transceiver. 
 https://pdfs.semanticscholar.org/eb33/5c12858779a653d9b9b93ca20120aebb7616.pdf
 
 Wes  N7WS
 
 
   On 6/13/2018 11:38 AM, WILLIE BABER
 wrote:
 > Robert is talking about the
 crystal filters, also known as roofing filters now-days,
 that are typically placed after the first mixer (I
 mistakenly typed "ahead" but I meant
 "after" as Robert notes), though there is a post
 amp and NB before these filters in K2 and K3.
 >
 > The idea is that a
 crystal filter right after the first mixer gives high
 dynamic range because high selectivity comes before the
 receiver has developed stages of gain that otherwise could
 cause blocking or IMD, especially when selectivity is
 postponed to the second mixer while ignoring gain
 distribution in prior stages of the receiver.  This basic
 idea was popularized in Solid State Design for the Radio
 Amateur, and it was applied to Ten-Tec radios for decades
 (at a 9 mhz I-F).
 >
 >
 Roofing filter gets defined in relationship to Japanese
 radios that had up conversion 15 khz filters at the first
 I-F, and generally lower dynamic range as a result, (but you
 got all modes, general coverage, and optional crystal
 filters at the second I-F).
 >
 > Good for everyone radios but with
 lower dynamic range and phase noise from the early
 synthesizers.  This is why Ten-Tec radios were so popular
 among contesters, especially Omni V and VI (modified with a
 narrow cw filter at the first I-F).
 >
 > 73, Will, wj9b
 >
 
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Re: [Elecraft] Field Day rig experience

[Wes Stewart]

Certainly not to disparage the K3(S) architecture (I have two of them) there is 
nothing inherently wrong with an up-conversion receiver, if modern hardware is used.


See: https://martein.home.xs4all.nl/pa3ake/hmode/g3sbi_intro.html

and my friend Cornell's, Star-10 transceiver. 
https://pdfs.semanticscholar.org/eb33/5c12858779a653d9b9b93ca20120aebb7616.pdf


Wes  N7WS


 On 6/13/2018 11:38 AM, WILLIE BABER wrote:

Robert is talking about the crystal filters, also known as roofing filters now-days, that are 
typically placed after the first mixer (I mistakenly typed "ahead" but I meant 
"after" as Robert notes), though there is a post amp and NB before these filters in K2 
and K3.

The idea is that a crystal filter right after the first mixer gives high 
dynamic range because high selectivity comes before the receiver has developed 
stages of gain that otherwise could cause blocking or IMD, especially when 
selectivity is postponed to the second mixer while ignoring gain distribution 
in prior stages of the receiver.  This basic idea was popularized in Solid 
State Design for the Radio Amateur, and it was applied to Ten-Tec radios for 
decades (at a 9 mhz I-F).

Roofing filter gets defined in relationship to Japanese radios that had up 
conversion 15 khz filters at the first I-F, and generally lower dynamic range 
as a result, (but you got all modes, general coverage, and optional crystal 
filters at the second I-F).

Good for everyone radios but with lower dynamic range and phase noise from 
the early synthesizers.  This is why Ten-Tec radios were so popular among 
contesters, especially Omni V and VI (modified with a narrow cw filter at the 
first I-F).

73, Will, wj9b



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Re: [Elecraft] Field Day rig experience

[Wayne Burdick]

Exactly right, Will. In the K3/K3S, we have a very strong mixer and post amp 
followed by crystal filters at the first I.F., 8.215 MHz. Since the IF and ADC 
are down-stream from these filters, they are very well protected from 
out-of-band signals.

Our crystal filters are manufactured to very tight tolerances and as a result, 
provide consistently high dynamic range.

The P3 panadapter gets its signal ahead of the crystal filters so it can 
display a wide spectrum. It is in effect a direct-sampling SDR in its own 
right. 

The beauty of having the panadapter’s receiver chain (P3) fully separate from 
the demodulation receive chain (K3) is that demodulation remains unaffected (up 
to very signal levels) even if the panadapter has to separately reduce its own 
gain. “Pure” SDRs (IC7300, IC7610, Flex) don’t have this luxury; everything 
runs from the same wideband ADC, without narrowband protection via crystal 
filters.

Another K3/K3S advantage is in its very narrow ham-band RF filters. These are 
positioned ahead of the P3 pickoff point, benefitting both the panadapter and 
demodulation channels.

73,
Wayne
N6KR



> On Jun 13, 2018, at 11:38 AM, WILLIE BABER  wrote:
> 
> Robert is talking about the crystal filters, also known as roofing filters 
> now-days, that are typically placed after the first mixer (I mistakenly typed 
> "ahead" but I meant "after" as Robert notes), though there is a post amp and 
> NB before these filters in K2 and K3.  
> 
> The idea is that a crystal filter right after the first mixer gives high 
> dynamic range because high selectivity comes before the receiver has 
> developed stages of gain that otherwise could cause blocking or IMD, 
> especially when selectivity is postponed to the second mixer while ignoring 
> gain distribution in prior stages of the receiver.  This basic idea was 
> popularized in Solid State Design for the Radio Amateur, and it was applied 
> to Ten-Tec radios for decades (at a 9 mhz I-F).
> 
> Roofing filter gets defined in relationship to Japanese radios that had up 
> conversion 15 khz filters at the first I-F, and generally lower dynamic range 
> as a result, (but you got all modes, general coverage, and optional crystal 
> filters at the second I-F). 
> 
> Good for everyone radios but with lower dynamic range and phase noise 
> from the early synthesizers.  This is why Ten-Tec radios were so popular 
> among contesters, especially Omni V and VI (modified with a narrow cw filter 
> at the first I-F).
> 
> 73, Will, wj9b
> 
> 
> 
> CWops #1085
> CWA Advisor levels II and III
> http://cwops.org/
> 
> --------
> On Wed, 6/13/18, Jim Brown  wrote:
> 
> Subject: Re: [Elecraft] Field Day rig experience
> To: elecraft@mailman.qth.net
> Date: Wednesday, June 13, 2018, 10:36 AM
> 
> On 6/12/2018 4:50 PM, Robert G
> Strickland wrote:
>> A small nit...
> perhaps my ignorance... but, I think that the roofing 
>> filter [by whatever name] comes after the
> first mixer, at the 
>> so-called IF
> frequency.
> 
> A month or so
> ago, as part of a project to measure input Z of receivers
> 
> and preamps, I measured the 2nd RX of my K3
> as 50 ohms and with a 
> bandpass filter
> between the antenna input and the 50 ohm load. Clearly, 
> in the K3, there is a "per band"
> bandpass filter ahead of the first RF 
> stage.
> 
> 73, Jim
> K9YC
> 
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Re: [Elecraft] Field Day rig experience

[WILLIE BABER]

Robert is talking about the crystal filters, also known as roofing filters 
now-days, that are typically placed after the first mixer (I mistakenly typed 
"ahead" but I meant "after" as Robert notes), though there is a post amp and NB 
before these filters in K2 and K3.  

The idea is that a crystal filter right after the first mixer gives high 
dynamic range because high selectivity comes before the receiver has developed 
stages of gain that otherwise could cause blocking or IMD, especially when 
selectivity is postponed to the second mixer while ignoring gain distribution 
in prior stages of the receiver.  This basic idea was popularized in Solid 
State Design for the Radio Amateur, and it was applied to Ten-Tec radios for 
decades (at a 9 mhz I-F).

Roofing filter gets defined in relationship to Japanese radios that had up 
conversion 15 khz filters at the first I-F, and generally lower dynamic range 
as a result, (but you got all modes, general coverage, and optional crystal 
filters at the second I-F). 

Good for everyone radios but with lower dynamic range and phase noise from 
the early synthesizers.  This is why Ten-Tec radios were so popular among 
contesters, especially Omni V and VI (modified with a narrow cw filter at the 
first I-F).

73, Will, wj9b



CWops #1085
CWA Advisor levels II and III
http://cwops.org/


On Wed, 6/13/18, Jim Brown  wrote:

 Subject: Re: [Elecraft] Field Day rig experience
 To: elecraft@mailman.qth.net
 Date: Wednesday, June 13, 2018, 10:36 AM
 
 On 6/12/2018 4:50 PM, Robert G
 Strickland wrote:
 > A small nit...
 perhaps my ignorance... but, I think that the roofing 
 > filter [by whatever name] comes after the
 first mixer, at the 
 > so-called IF
 frequency.
 
 A month or so
 ago, as part of a project to measure input Z of receivers
 
 and preamps, I measured the 2nd RX of my K3
 as 50 ohms and with a 
 bandpass filter
 between the antenna input and the 50 ohm load. Clearly, 
 in the K3, there is a "per band"
 bandpass filter ahead of the first RF 
 stage.
 
 73, Jim
 K9YC
 
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Re: [Elecraft] Field Day rig experience

[Jim Brown]

On 6/12/2018 4:50 PM, Robert G Strickland wrote:
A small nit... perhaps my ignorance... but, I think that the roofing 
filter [by whatever name] comes after the first mixer, at the 
so-called IF frequency.


A month or so ago, as part of a project to measure input Z of receivers 
and preamps, I measured the 2nd RX of my K3 as 50 ohms and with a 
bandpass filter between the antenna input and the 50 ohm load. Clearly, 
in the K3, there is a "per band" bandpass filter ahead of the first RF 
stage.


73, Jim K9YC

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Re: [Elecraft] Field Day rig experience

[Robert G Strickland]

Will...

A small nit... perhaps my ignorance... but, I think that the roofing 
filter [by whatever name] comes after the first mixer, at the so-called 
IF frequency. Your points are well made. I think the far out SDR's speak 
more to what can conceivably be done versus what's the design approach 
that best meets a broad range of desirable receiver parameters. Elecraft 
seems to have found the sweet spot in the battle of trade offs.


...robert

On 6/12/2018 15:49, WILLIE BABER wrote:

More then one so2r operator has noted that the 7300 will overload in an so2r 
situation so that you cannot clearly hear on 7300 when the other radio is 
transmitting (yes, on a different band).  Since the 7610 doesn't have a 
front-end either, I imagine that it will do the same.  Sherwood himself notes 
that using the SDR radio (i.e, without a superhet front-end) means reducing 
gain to limit ADC overload, but he has also suggested that blocking dynamic 
range is over-rated.  Generally this is true, dynamic range is over-rated if 
you are using one radio.  However, blocking isn't over-rated in a field day 
situation (more than one radio) or if you have a neighboring op running high 
power, or in legal-limit multi-op situations (with antennas relatively close to 
each other), or in legal-limit so2r.

Reducing sensitivity works to prevent ADC overload on the lower bands where 
sensitivity is not needed in the first place but on 15m through 6m one can use 
the sensitivity.  While SDR radios have their advantages, some of the 
advantages of superhet radios still exist today, namely, that a so-called 
roofing filter front-end (which is just a mode-specific filter ahead of the 
first mixer) will deliver outstanding blocking AND as much sensitivity as 
required (compared to SDR).

I don't see any way around this fact (at least not yet) and you can see the 
difference in the Sherwood numbers.

73, Will, wj9b

CWops #1085
CWA Advisor levels II and III
http://cwops.org/


On Sat, 6/9/18, Wayne Burdick  wrote:

  Subject: Re: [Elecraft] Field Day rig experience
  To: "Bill" 
  Cc: "Elecraft Reflector" 
  Date: Saturday, June 9, 2018, 10:34 AM


  > On Jun 9,
  2018, at 5:24 AM, Bill 
  wrote:
  >
  > Along the
  line (lightly discussed under "K3- AF Knob") of
  what rigs are used for dxpeditions and Field Day..  How
  do the new technology ICOMs (7300 and 7610) do under the
  "several rigs on the same band" conditions? The
  size, weight, and cost factor is inviting for the 7300 -
  BUT!!! Is it up to the job? Close to up to the job? Or,
  better left home during these events?


  Hi Bill,

  Hopefully you’ll get some responses to this
  question from those with direct experience. But looking at
  it theoretically: both the 7300 and 7610 are direct-sampling
  radios with about 25-30 dB less blocking dynamic range than
  the K3 or K3S. On Field Day this could have a definite
  impact when using multiple transmitters on the same band, or
  even on different bands, depending on antenna spacing and
  power level used.

  Dynamic
  range of all of these radios is quantified in the receiver
  performance table at www.sherweng.com, specifically the
  fifth column (“100 kHz Blocking”).

  Wayne



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--
Robert G Strickland, PhD ABPH - KE2WY
rc...@verizon.net.usa
Syracuse, New York, USA
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Re: [Elecraft] Field Day rig experience

[WILLIE BABER]

More then one so2r operator has noted that the 7300 will overload in an so2r 
situation so that you cannot clearly hear on 7300 when the other radio is 
transmitting (yes, on a different band).  Since the 7610 doesn't have a 
front-end either, I imagine that it will do the same.  Sherwood himself notes 
that using the SDR radio (i.e, without a superhet front-end) means reducing 
gain to limit ADC overload, but he has also suggested that blocking dynamic 
range is over-rated.  Generally this is true, dynamic range is over-rated if 
you are using one radio.  However, blocking isn't over-rated in a field day 
situation (more than one radio) or if you have a neighboring op running high 
power, or in legal-limit multi-op situations (with antennas relatively close to 
each other), or in legal-limit so2r.

Reducing sensitivity works to prevent ADC overload on the lower bands where 
sensitivity is not needed in the first place but on 15m through 6m one can use 
the sensitivity.  While SDR radios have their advantages, some of the 
advantages of superhet radios still exist today, namely, that a so-called 
roofing filter front-end (which is just a mode-specific filter ahead of the 
first mixer) will deliver outstanding blocking AND as much sensitivity as 
required (compared to SDR).

I don't see any way around this fact (at least not yet) and you can see the 
difference in the Sherwood numbers.

73, Will, wj9b

CWops #1085
CWA Advisor levels II and III
http://cwops.org/


On Sat, 6/9/18, Wayne Burdick  wrote:

 Subject: Re: [Elecraft] Field Day rig experience
 To: "Bill" 
 Cc: "Elecraft Reflector" 
 Date: Saturday, June 9, 2018, 10:34 AM
 
 
 > On Jun 9,
 2018, at 5:24 AM, Bill 
 wrote:
 > 
 > Along the
 line (lightly discussed under "K3- AF Knob") of
 what rigs are used for dxpeditions and Field Day..  How
 do the new technology ICOMs (7300 and 7610) do under the
 "several rigs on the same band" conditions? The
 size, weight, and cost factor is inviting for the 7300 -
 BUT!!! Is it up to the job? Close to up to the job? Or,
 better left home during these events?
 
 
 Hi Bill,
 
 Hopefully you’ll get some responses to this
 question from those with direct experience. But looking at
 it theoretically: both the 7300 and 7610 are direct-sampling
 radios with about 25-30 dB less blocking dynamic range than
 the K3 or K3S. On Field Day this could have a definite
 impact when using multiple transmitters on the same band, or
 even on different bands, depending on antenna spacing and
 power level used. 
 
 Dynamic
 range of all of these radios is quantified in the receiver
 performance table at www.sherweng.com, specifically the
 fifth column (“100 kHz Blocking”).
 
 Wayne
 
 
 
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Re: [Elecraft] Field Day rig experience

[Jim Brown]

On 6/10/2018 3:46 PM, Al Lorona wrote:

If you do take the icom, at 3.5A receive current drain you'd better take two 
extra batteries, too.


And don't overlook the HUGE KX2 and KX3 advantage of only 150 mA battery 
drain on receive, as compared to about 1A for a single RX K3/K3S.


73, Jim K9YC

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Re: [Elecraft] Field Day rig experience

[Wayne Burdick]

Yes. The K3 is intended to be operable from a battery or solar panel, and it’s 
receive-mode current drain is about 1 amp (a little higher with the sub 
receiver turned on).

73,
Wayne
N6KR




> On Jun 10, 2018, at 3:46 PM, Al Lorona  wrote:
> 
> If you do take the icom, at 3.5A receive current drain you'd better take two 
> extra batteries, too.
> 
> Al  W6LX
> 
> 
> 
>>> Take the K3 , leave the IC-7610 at home. It’s to darn heavy to lug around. 
>>> (19 lbs )
> 
> 
>>> NS2N
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Re: [Elecraft] Field Day rig experience

[Al Lorona]

If you do take the icom, at 3.5A receive current drain you'd better take two 
extra batteries, too.

Al  W6LX



>> Take the K3 , leave the IC-7610 at home. It’s to darn heavy to lug around. 
>> (19 lbs )


>>NS2N
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Re: [Elecraft] Field Day rig experience

[Wayne Burdick]

The K3S has exceptionally low TX phase noise and high RMDR. Both are due to the 
new synth. The rest of the signal chain is also very clean. 

You have to get this right on both RX and TX to optimize for close-proximity, 
multi-transmitter operation (e.g. Field Day, DXpeditions, and big contest 
stations). 

73,
Wayne
N6KR


http://www.elecraft.com

> On Jun 10, 2018, at 12:55 PM, David Gilbert  wrote:
> 
> 
> I couldn't find any data on transmit phase noise on the Sherwood web site 
> either, and I searched all over for it.
> 
> Dave   AB7E
> 
> 
> 
>> On 6/10/2018 11:17 AM, Jim Brown wrote:
>>> On 6/9/2018 12:54 PM, K9MA wrote:
 On 6/9/2018 14:52, David Gilbert wrote:
 I think another major concern for closely positioned rigs would be 
 transmitted phase noise, and of course that doesn't show up in the 
 Sherwood charts. 
>>> 
>>> Yes, it does! 
>> 
>> All I've ever seen from Rob is RX phase noise. Can you provide a link to TX 
>> phase noise?  The TX phase noise data I've published came from ARRL Labs.
>> 
>> 73, Jim K9YC
> 
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Re: [Elecraft] Field Day rig experience

[Ian White]

>I think the LO phase noise should be pretty close.

Perhaps it *should* be... but some of the worst examples of wideband
transmitted noise are caused by additional amplitude noise in the TX
chain, or by poorly filtered DAC noise in SDR-based transceivers
[1]. These noise sources are additional to the LO noise, and are
present whenever the rig is in TX mode (even without modulation).

That unfounded *belief* that "the LO phase noise should be pretty
close" was precisely the reason why none of the designers paid any
attention to the excess transmitter noise. But the equipment reviews
were equally at fault for failing to draw attention to the problem.


[1] Band Pollution from Amateur Transmitters - SM5BSZ
http://sm5bsz.com/dynrange/dubus313.pdf

73 from Ian GM3SEK

>-Original Message-
>From: elecraft-boun...@mailman.qth.net [mailto:elecraft-
>boun...@mailman.qth.net] On Behalf Of K9MA
>Sent: 10 June 2018 20:14
>To: j...@audiosystemsgroup.com
>Cc: elecraft@mailman.qth.net
>Subject: Re: [Elecraft] Field Day rig experience
>
>I think the LO phase noise should be pretty close.
>
>--
>
>Scott Ellington. K9MA
>
> --- via iPhone
>
>> On Jun 10, 2018, at 1:17 PM, Jim Brown
> wrote:
>>
>>> On 6/9/2018 12:54 PM, K9MA wrote:
>>>> On 6/9/2018 14:52, David Gilbert wrote:
>>>> I think another major concern for closely positioned rigs would
be
>transmitted phase noise, and of course that doesn't show up in the
>Sherwood charts.
>>>
>>> Yes, it does!
>>
>> All I've ever seen from Rob is RX phase noise. Can you provide a
link
>to TX phase noise?  The TX phase noise data I've published came
from
>ARRL Labs.
>>
>> 73, Jim K9YC
>>
>>
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Re: [Elecraft] Field Day rig experience

[David Gilbert]

I couldn't find any data on transmit phase noise on the Sherwood web 
site either, and I searched all over for it.


Dave   AB7E



On 6/10/2018 11:17 AM, Jim Brown wrote:

On 6/9/2018 12:54 PM, K9MA wrote:

On 6/9/2018 14:52, David Gilbert wrote:
I think another major concern for closely positioned rigs would be 
transmitted phase noise, and of course that doesn't show up in the 
Sherwood charts. 


Yes, it does! 


All I've ever seen from Rob is RX phase noise. Can you provide a link 
to TX phase noise?  The TX phase noise data I've published came from 
ARRL Labs.


73, Jim K9YC


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Re: [Elecraft] Field Day rig experience

[K9MA]

I think the LO phase noise should be pretty close. 

--

Scott Ellington. K9MA

 --- via iPhone

> On Jun 10, 2018, at 1:17 PM, Jim Brown  wrote:
> 
>> On 6/9/2018 12:54 PM, K9MA wrote:
>>> On 6/9/2018 14:52, David Gilbert wrote:
>>> I think another major concern for closely positioned rigs would be 
>>> transmitted phase noise, and of course that doesn't show up in the Sherwood 
>>> charts. 
>> 
>> Yes, it does! 
> 
> All I've ever seen from Rob is RX phase noise. Can you provide a link to TX 
> phase noise?  The TX phase noise data I've published came from ARRL Labs.
> 
> 73, Jim K9YC
> 
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Re: [Elecraft] Field Day rig experience

[Jim Brown]

On 6/9/2018 12:54 PM, K9MA wrote:

On 6/9/2018 14:52, David Gilbert wrote:
I think another major concern for closely positioned rigs would be 
transmitted phase noise, and of course that doesn't show up in the 
Sherwood charts. 


Yes, it does! 


All I've ever seen from Rob is RX phase noise. Can you provide a link to 
TX phase noise?  The TX phase noise data I've published came from ARRL Labs.


73, Jim K9YC

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Re: [Elecraft] Field Day rig experience

[Paul Antos]

Take the K3 , leave the IC-7610 at home. It’s to darn heavy to lug around. (19 
lbs )

NS2N

Sent from Mail for Windows 10

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Re: [Elecraft] Field Day rig experience

[Jim Shepherd]

Last year I was running my K3s digital, and I could see the CW operators
and the voice operators on the P3, but never heard them. At one point one
of the CW ops was only 10 KHz away and not interfering with PSK31.

Will be repeating the operation this year, with a 7A station, there will be
lots of other signals from the other radios that are a mix of Y-I-K... I'm
bringing some external bandpass filters for those other stations to use to
protect them from each other.

Look for W7TA at Washoe Lake State Park between Reno and Carson City!

73, Jim W6US
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Re: [Elecraft] Field Day rig experience

[Edward R Cole]

We have used the parking lot of Sky View HS, Soldotna, AK for several 
years.  HS was shutdown about five years ago and located in hills 
south of the *small* city of 7500.  Club has TS450's and run two 
stations 80-10m, 100w under KL7AN.


I usually join them to help setup at 9am with 10am start time.  This 
year I will have my KX3 and KXPA100 installed in my truck, as we head 
out on the road with out 5th wheel trailer after FD weekend heading 
for Ohio (5000miles).  Only have 80m and 20m hamsticks for HF and use 
a half-wave base-loaded 2m whip for 6m.  I might turn on the KX3 to 
checkout close operation at the FD site.


Details of the mobile setup: http://www.kl7uw.com/Mobile.htm

73, Ed - KL7UW
  http://www.kl7uw.com
Dubus-NA Business mail:
  dubus...@gmail.com 


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Re: [Elecraft] Field Day rig experience

[K9MA]

On 6/9/2018 14:52, David Gilbert wrote:
I think another major concern for closely positioned rigs would be 
transmitted phase noise, and of course that doesn't show up in the 
Sherwood  charts. 


Yes, it does!

73,

Scott K9MA

--
Scott  K9MA

k...@sdellington.us

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Re: [Elecraft] Field Day rig experience

[David Gilbert]

I think another major concern for closely positioned rigs would be 
transmitted phase noise, and of course that doesn't show up in the 
Sherwood  charts.  Jim's tests 
(http://audiosystemsgroup.com/TXNoise.pdf) show some large differences 
between various rigs, although the 7300 and 7610 are not specifically 
included (the 7600 is, however).  The K3/S are much cleaner rigs.


73,
Dave   AB7E



On 6/9/2018 9:34 AM, Wayne Burdick wrote:

On Jun 9, 2018, at 5:24 AM, Bill  wrote:

Along the line (lightly discussed under "K3- AF Knob") of what rigs are used for 
dxpeditions and Field Day..  How do the new technology ICOMs (7300 and 7610) do under the 
"several rigs on the same band" conditions? The size, weight, and cost factor is inviting 
for the 7300 - BUT!!! Is it up to the job? Close to up to the job? Or, better left home during 
these events?


Hi Bill,

Hopefully you’ll get some responses to this question from those with direct 
experience. But looking at it theoretically: both the 7300 and 7610 are 
direct-sampling radios with about 25-30 dB less blocking dynamic range than the 
K3 or K3S. On Field Day this could have a definite impact when using multiple 
transmitters on the same band, or even on different bands, depending on antenna 
spacing and power level used.

Dynamic range of all of these radios is quantified in the receiver performance 
table at www.sherweng.com, specifically the fifth column (“100 kHz Blocking”).

Wayne



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Re: [Elecraft] Field Day rig experience

[Rick WA6NHC]

When the 7300 first came out, I took mine to FD for a test, with high 
hopes.  Proximity of antennas was close, on the order of 40 
(tribander)-200' (double double extended Zepp on 40M) separation, power 
output limited to 100 watts.  There was a lack of trees to make more 
space between antennas without exceeding the 1500' limitation (besides, 
the snacks were there).


The 7300 crumpled badly, operation on other bands 'desensed' (for lack 
of an accurate word) the 7300 effectively making it deaf in some cases.  
It didn't matter what band the other stations were operating on, the 
7300 was affected.


No band filters were employed, it was a brutal test as a 'worst case 
scenario'.  The 7300 failed.


The Pro-III the group normally uses, displayed no issues.  No one wanted 
to dis/re-assemble their Elecraft stations from home but I'm sure they'd 
hold up very well or better under the same test.  It wasn't a QRP event, 
so the KX2/3 was not deployed.


However it's limitations, the 7300 does exactly what I intend it to be, 
a cheap light weight radio with 100 watts out that I can take into the 
field, use in the RV or the home shack (since I can control other 
transmitters).  It isn't an 'unworthy' radio, if you don't subject it to 
high RF fields. Eventually, I'll have a second K3 just for the RV but 
for now the 7300 will suffice.


There will be two 7610 on site this year, but I won't be there to 
witness their use.  The Pro-III will be there in case the 7610 doesn't 
hold up.


Rick WA6NHC




On 6/9/2018 9:34 AM, Wayne Burdick wrote:

On Jun 9, 2018, at 5:24 AM, Bill  wrote:

How do the new technology ICOMs (7300 and 7610) do under the "several rigs on the 
same band" conditions? The size, weight, and cost factor is inviting for the 7300 - 
BUT!!! Is it up to the job? Close to up to the job? Or, better left home during these 
events?


Hi Bill,

Hopefully you’ll get some responses to this question from those with direct 
experience. But looking at it theoretically: both the 7300 and 7610 are 
direct-sampling radios with about 25-30 dB less blocking dynamic range than the 
K3 or K3S. On Field Day this could have a definite impact when using multiple 
transmitters on the same band, or even on different bands, depending on antenna 
spacing and power level used.

Dynamic range of all of these radios is quantified in the receiver performance 
table at www.sherweng.com, specifically the fifth column (“100 kHz Blocking”).

Wayne



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Re: [Elecraft] Field Day rig experience

[donovanf]

Hi Wayne, 


Few K3 owners are aware that the K3 has built in transmit/receiver 
bandpass filters for each band. That and very low phase noise and 
exceptional receiver dynamic range are why the K3 is such a superb 
Field Day transceiver. 


At the W3AO Field Day we use four K3 transceivers on 20 meters: 
CW, SSB, Digital and GOTA. N one of the 20 meter operators will be 
aware of the other three transceivers u nless one of the other transceivers 
accidentally lands on the same frequency. 


Is there any published data about the performance of the built in 
bandpass filters? 


tks 


73 
Frank 
W3LPL 

- Original Message -

From: "Wayne Burdick"  
To: "Bill"  
Cc: "Elecraft Reflector"  
Sent: Saturday, June 9, 2018 4:34:53 PM 
Subject: Re: [Elecraft] Field Day rig experience 


> On Jun 9, 2018, at 5:24 AM, Bill  wrote: 
> 
> Along the line (lightly discussed under "K3- AF Knob") of what rigs are used 
> for dxpeditions and Field Day.. How do the new technology ICOMs (7300 and 
> 7610) do under the "several rigs on the same band" conditions? The size, 
> weight, and cost factor is inviting for the 7300 - BUT!!! Is it up to the 
> job? Close to up to the job? Or, better left home during these events? 


Hi Bill, 

Hopefully you’ll get some responses to this question from those with direct 
experience. But looking at it theoretically: both the 7300 and 7610 are 
direct-sampling radios with about 25-30 dB less blocking dynamic range than the 
K3 or K3S. On Field Day this could have a definite impact when using multiple 
transmitters on the same band, or even on different bands, depending on antenna 
spacing and power level used. 

Dynamic range of all of these radios is quantified in the receiver performance 
table at www.sherweng.com, specifically the fifth column (“100 kHz Blocking”). 

Wayne 



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Re: [Elecraft] Field Day rig experience

[Wayne Burdick]

> On Jun 9, 2018, at 5:24 AM, Bill  wrote:
> 
> Along the line (lightly discussed under "K3- AF Knob") of what rigs are used 
> for dxpeditions and Field Day..  How do the new technology ICOMs (7300 
> and 7610) do under the "several rigs on the same band" conditions? The size, 
> weight, and cost factor is inviting for the 7300 - BUT!!! Is it up to the 
> job? Close to up to the job? Or, better left home during these events?


Hi Bill,

Hopefully you’ll get some responses to this question from those with direct 
experience. But looking at it theoretically: both the 7300 and 7610 are 
direct-sampling radios with about 25-30 dB less blocking dynamic range than the 
K3 or K3S. On Field Day this could have a definite impact when using multiple 
transmitters on the same band, or even on different bands, depending on antenna 
spacing and power level used. 

Dynamic range of all of these radios is quantified in the receiver performance 
table at www.sherweng.com, specifically the fifth column (“100 kHz Blocking”).

Wayne



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