Sherwood's receiver performance table updated

[Joe Subich, W4TV-4]

Thanks for the link, Buck.  I had not checked Adam's site since the
7300 became generally available.

Adam adds a lot to the discussion.  The 7300 is actually a "hybrid"
DSR ... direct down conversion being used to drive the SDR "back end"
typical of Icom's current generation of transceivers.  In essence,
the direct sampling front end replaces the traditional analog up-
conversion front end and is responsible for a much "cleaner" (less
phase noise, etc.) transceiver.  The selectivity, AGC and features
are derived from the 36 KHz DSP "back end".

All in all very smart design as it leverages Icom's experience and
design costs.  It also explains the lack of dual receive as that
would have required a second, frequency agile "IF DSP" or complete
receiver chain like the KRX3.

73,

    ... Joe, W4TV


On 4/27/2016 8:28 AM, Buck via Elecraft wrote:

> Very comprehensive review of the 7300 explaining how it handles ADC
> overload at
>
> http://www.ab4oj.com/icom/ic7300/7300notes.pdf
>
> K4ia
> Buck
> Honor Roll 335
> 8BDXCC
>

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[Elecraft mailing list]

My thoughts on the IC-7300 after using it for several days:

1. The tuner is a lot more capable than 3:1. Much better than older Icoms.

2. Achieving correct viewing angle can almost always be corrected by a
little Shop 101.

3. The height of the display is limited to the size of the screen and
that by the size of the radio. That said - the screen is a wonder of
organization of things needed to control a complex system

4. Two antenna ports, video output, receive only antenna port are all
the things you will see in the next step-up model

5. Touch screens allow a hierarchical and updateable organization of
functions and properties - this is a fundamental principle of user
interface design

6. Sit down with say a TS-590SG (Same basic price) and operate for an
hour.  Then repeat with IC-7300.  You'll instantly see a 20th century
user interface and a 21st century user interface. The IC-7300 will blow
you a way.  So much information at your fingertips.  The IC-7300 is a
wonderful example of how 21st century technology pervades everything.
(Get used to it)

Fortunately, I have two separate operating positions.  The K-Line
occupies my main position.  Stocking the second position is always fun.  
Been through K2 (best), TS-450, IC-746, TS-590SG, FTdx-1200 (Nice rig)
and now the IC-7300.  The 7300 leaves all the other entry level radios
in the dust.  It has placed a strong stack in the ground of
technological advancement and will be the pivotal product for the next
10 to 20 years.  Just like the K2 was when it hit the market.  Even more
like the K3 which was *truly* a pivotal product.

Doug -- K0DXV

>
>
>
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[Elecraft mailing list]

> On Apr 27, 2016, at 9:31 AM, Joe Subich, W4TV <[hidden email]> wrote

> Adam adds a lot to the discussion.  The 7300 is actually a "hybrid"
> DSR ... direct down conversion being used to drive the SDR "back end"
> typical of Icom's current generation of transceivers.  In essence,
> the direct sampling front end replaces the traditional analog up-
> conversion front end and is responsible for a much "cleaner" (less
> phase noise, etc.) transceiver.  The selectivity, AGC and features
> are derived from the 36 KHz DSP "back end".



Joe, I know this thread was closed earlier today, but I just wanted to clarify that the IC-7300 is a "pure" direct-sampling SDR. The architecture that you described is more in line with direct-conversion SDRs such as the KX3.
I also asked myself why ICOM did not go the extra mile and provided more than one receiver on the IC-7300 since the whole spectrum is available on a direct-sampling SDR. The only reason that occurred to me is that its FPGA is not big enough to handled/process the stream of data arriving from the ADC that is necessary to produce more than one of receiver (slices).

73,
Robert-KP4Y/W4

Sent from my iPhone

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[k6mrmagnet]

“P.S. I don't subscribe to the notion that quality coax runs of < 150 feet
make it "ok" to have the ATU in the shack while operating an antenna on
multiple bands....what technical evidence of that posit do you have to
share????”

Jim:

Google “transmission line bounce diagram”. This is a simple concept easily proven by mathematics.

On a practical level, this is the concept behind the use of open wire feed lines. It’s been done for decades. The type of feed line does not change the theory.

Ken K6MR






From: Jim Rodenkirch<mailto:[hidden email]>
Sent: Wednesday, April 27, 2016 06:21
To: [hidden email]<mailto:[hidden email]>
Subject: Re: [Elecraft] Sherwood's receiver performance table updated

"It all depends" is/was the premise for my reply, Don.

 If new and old hams don't understand the potential problems with long runs
of coax to/from an antenna they want to operate on multiple bands and an ATU
in the shack they will be surprised at how inefficient their system is.

P.S. I don't subscribe to the notion that quality coax runs of < 150 feet
make it "ok" to have the ATU in the shack while operating an antenna on
multiple bands....what technical evidence of that posit do you have to
share????

Note 1: I had a 43' vertical with top loading wires in a NORD-style config
with my external ATU at the base of the vertical and 120' of coax back to
the shack ---- never saw a VSWR delta of more than .2 between what was
"seen" at the input to the tuner and what was "seen" at the xmtr while
operating on 160 through 20 meters.



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[Jim Brown-10]

Loss in a feedline due to mismatch can easily be computed by several
means if the antenna feedpoint impedance and the feedline loss vs.
frequency and length are known. Those means include:

TLW, a simple Windoze program by N6BV, retired editor of the ARRL
Antenna Book, and included on the CDROM that comes with the Antenna Book.

ZPlots, an Excel spreadsheet by Dan, AC6LA.

TLA, a simple Windoze program by AC6LA. Both of Dan's programs are
freeware, google his call to find his website.

SimSmith, an excellent freeware Smith Chart program by AE6TY. It runs in
Java, so is cross platform.

Data to plug into these programs can be exported from EZNEC and other
antenna modeling programs. Data for real antennas can be measured using
good quality vector impedance analyzers (they must provide R + jX, or Z
and the phase angle of Z).

If used correctly, all of these programs will provide correct answers.
That can be a big IF -- it's the old GIGO (garbage in, garbage out) rule.

It IS, for example, good engineering practice to use a low loss line
that is mismatched to an antenna with a tuner in the shack IF the line
is short enough, and the line loss is low enough.  Phil Salas, AD5X,
published a method for doing exactly this, using 50 ft or so of 1/2-in
hard line to feed a 43 ft vertical.

The technique of using high impedance open wire line to feed a dipole of
random length is another example, but I consider it no longer good
engineering practice because it is not practical to choke it to reject
receive noise. Off-center fed antennas have the same problem, no matter
how they are fed. A major advantage of coax-fed, resonant antennas is
that they CAN be choked.

73, Jim K9YC

On Wed,4/27/2016 8:36 AM, Ken K6MR wrote:

> “P.S. I don't subscribe to the notion that quality coax runs of < 150 feet
> make it "ok" to have the ATU in the shack while operating an antenna on
> multiple bands....what technical evidence of that posit do you have to
> share????”
>
> Jim:
>
> Google “transmission line bounce diagram”. This is a simple concept easily proven by mathematics.
>
> On a practical level, this is the concept behind the use of open wire feed lines. It’s been done for decades. The type of feed line does not change the theory.
>
> Ken K6MR
>
>
>
>
>
>
> From: Jim Rodenkirch<mailto:[hidden email]>
> Sent: Wednesday, April 27, 2016 06:21
> To: [hidden email]<mailto:[hidden email]>
> Subject: Re: [Elecraft] Sherwood's receiver performance table updated
>
> "It all depends" is/was the premise for my reply, Don.
>
>   If new and old hams don't understand the potential problems with long runs
> of coax to/from an antenna they want to operate on multiple bands and an ATU
> in the shack they will be surprised at how inefficient their system is.
>
> P.S. I don't subscribe to the notion that quality coax runs of < 150 feet
> make it "ok" to have the ATU in the shack while operating an antenna on
> multiple bands....what technical evidence of that posit do you have to
> share????
>
> Note 1: I had a 43' vertical with top loading wires in a NORD-style config
> with my external ATU at the base of the vertical and 120' of coax back to
> the shack ---- never saw a VSWR delta of more than .2 between what was
> "seen" at the input to the tuner and what was "seen" at the xmtr while
> operating on 160 through 20 meters.
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/Sherwood-s-receiver-performance-table-updated-tp7616652p7616802.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
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[Jim Rodenkirch]

CONTENTS DELETED

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[Elecraft mailing list]

    RE:  “P.S. I don't subscribe to the notion that quality coax runs of < 150 feetmake it "ok" to have the ATU in the shack while operating an antenna on
multiple bands....what technical evidence of that posit do you have to
share????”

The best source is "Reflections" by Walter Maxwell, W2DU, originally published as a series of articles in QST (difficult to read due to the poor scans) and then published by ARRL as a book.  The latest edition is "Reflections III" published by CQ Communications, but currently sold out.

If you really want to understand what is happening on a transmission line, how an ATU works, etc., then this is the book you should read.  Be warned, though, it is NOT an "easy read", but more of a "great study".  It requires a lot of thought and re-reading to absorb, but is well worth the effort.


    Mark,
ars:  KE6BB


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[Jim Rodenkirch]

CONTENTS DELETED

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[k6mrmagnet]

But the theory works whether you have open wire line or coax: the additional loss due to SWR on the feedline is only a function of the matched feedline loss. There is a good graph in ON4UNs book (and probably others) that shows the additional loss caused by SWR vs. matched line loss. For example, a 5:1 SWR on a line with 0.5 dB matched loss results in an additional 0.6 dB of loss. The type of feedline is immaterial.  Is 0.6 dB worth installing a tuner at the antenna given the added complexity? Maybe. Maybe not. It’s all a matter of $/dB.

Ken K6MR



From: James Rodenkirch<mailto:[hidden email]>
Sent: Wednesday, April 27, 2016 09:38
To: Ken K6MR<mailto:[hidden email]>; [hidden email]<mailto:[hidden email]>
Subject: Re: [Elecraft] Sherwood's receiver performance table updated

It is not "the principle behind the use of open  wire feed line," Ken IF, I place an antenna auto tuner at the base of, for instance, a vertical and feed the tuner with low loss coax....


I understand the use of open wire feed line and an ATU prior to attaching to the xmtr....BUT...see above - works as well, if not better 'cuz I don't have to worry about the open wire feed line running too close to metal objects...



________________________________
From: Ken K6MR <[hidden email]>
Sent: Wednesday, April 27, 2016 9:36 AM
To: Jim Rodenkirch; [hidden email]
Subject: RE: [Elecraft] Sherwood's receiver performance table updated


"P.S. I don't subscribe to the notion that quality coax runs of < 150 feet
make it "ok" to have the ATU in the shack while operating an antenna on
multiple bands....what technical evidence of that posit do you have to
share????"



Jim:



Google "transmission line bounce diagram". This is a simple concept easily proven by mathematics.



On a practical level, this is the concept behind the use of open wire feed lines. It's been done for decades. The type of feed line does not change the theory.



Ken K6MR












From: Jim Rodenkirch<mailto:[hidden email]>
Sent: Wednesday, April 27, 2016 06:21
To: [hidden email]<mailto:[hidden email]>
Subject: Re: [Elecraft] Sherwood's receiver performance table updated



"It all depends" is/was the premise for my reply, Don.

 If new and old hams don't understand the potential problems with long runs
of coax to/from an antenna they want to operate on multiple bands and an ATU
in the shack they will be surprised at how inefficient their system is.

P.S. I don't subscribe to the notion that quality coax runs of < 150 feet
make it "ok" to have the ATU in the shack while operating an antenna on
multiple bands....what technical evidence of that posit do you have to
share????

Note 1: I had a 43' vertical with top loading wires in a NORD-style config
with my external ATU at the base of the vertical and 120' of coax back to
the shack ---- never saw a VSWR delta of more than .2 between what was
"seen" at the input to the tuner and what was "seen" at the xmtr while
operating on 160 through 20 meters.



--
View this message in context: http://elecraft.365791.n2.nabble.com/Sherwood-s-receiver-performance-table-updated-tp7616652p7616802.html
Sent from the Elecraft mailing list archive at Nabble.com.
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[Jim Rodenkirch]

CONTENTS DELETED

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[Jim Rodenkirch]

CONTENTS DELETED

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[k6mrmagnet]

No problem. Yes, open wire line has its own problems. I was reacting to your note regarding using short runs of coax operated at high SWR. There is nothing inherently inefficient about doing so. Like any design it’s easy to run the numbers to determine what the actual losses are. Many times they are just too small to worry about. Especially in the case of verticals, the ground losses will be far higher unless you invest in an excellent radial/ground shield underneath it. The tuner can’t help that.

Ken K6MR



From: James Rodenkirch<mailto:[hidden email]>
Sent: Wednesday, April 27, 2016 11:01
To: Ken K6MR<mailto:[hidden email]>; [hidden email]<mailto:[hidden email]>
Subject: Re: [Elecraft] Sherwood's receiver performance table updated

Did not mean to sound argumentative, Ken.....apologize if it came out that way....I am "involved" in this discussion becuz' of Don's initial post about new hams not understanding the advantageous aspects of open wire feed line....


________________________________
From: James Rodenkirch
Sent: Wednesday, April 27, 2016 10:38 AM
To: Ken K6MR; [hidden email]
Subject: Re: [Elecraft] Sherwood's receiver performance table updated


It is not "the principle behind the use of open  wire feed line," Ken IF, I place an antenna auto tuner at the base of, for instance, a vertical and feed the tuner with low loss coax....


I understand the use of open wire feed line and an ATU prior to attaching to the xmtr....BUT...see above - works as well, if not better 'cuz I don't have to worry about the open wire feed line running too close to metal objects...



________________________________
From: Ken K6MR <[hidden email]>
Sent: Wednesday, April 27, 2016 9:36 AM
To: Jim Rodenkirch; [hidden email]
Subject: RE: [Elecraft] Sherwood's receiver performance table updated


"P.S. I don't subscribe to the notion that quality coax runs of < 150 feet
make it "ok" to have the ATU in the shack while operating an antenna on
multiple bands....what technical evidence of that posit do you have to
share????"



Jim:



Google "transmission line bounce diagram". This is a simple concept easily proven by mathematics.



On a practical level, this is the concept behind the use of open wire feed lines. It's been done for decades. The type of feed line does not change the theory.



Ken K6MR












From: Jim Rodenkirch<mailto:[hidden email]>
Sent: Wednesday, April 27, 2016 06:21
To: [hidden email]<mailto:[hidden email]>
Subject: Re: [Elecraft] Sherwood's receiver performance table updated



"It all depends" is/was the premise for my reply, Don.

 If new and old hams don't understand the potential problems with long runs
of coax to/from an antenna they want to operate on multiple bands and an ATU
in the shack they will be surprised at how inefficient their system is.

P.S. I don't subscribe to the notion that quality coax runs of < 150 feet
make it "ok" to have the ATU in the shack while operating an antenna on
multiple bands....what technical evidence of that posit do you have to
share????

Note 1: I had a 43' vertical with top loading wires in a NORD-style config
with my external ATU at the base of the vertical and 120' of coax back to
the shack ---- never saw a VSWR delta of more than .2 between what was
"seen" at the input to the tuner and what was "seen" at the xmtr while
operating on 160 through 20 meters.



--
View this message in context: http://elecraft.365791.n2.nabble.com/Sherwood-s-receiver-performance-table-updated-tp7616652p7616802.html
Sent from the Elecraft mailing list archive at Nabble.com.
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[Jim Rodenkirch]

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[Phil Wheeler-2]

But this discussion seems to have evolved into
something difficult to relate to the thread title.
You might want to change the title!

Phil W7OX

On 4/27/16 10:25 AM, James Rodenkirch wrote:

> Wow....lots of good stuff emanating from this discussion - tnx to all for participating....
>
> For Jerry - there are other reasons for employing an ATU in the shack - e.g., using open wire line feed line from the antenna back to the xmtr.
>
> _____________________________________
> From: Jerry <[hidden email]>
> Sent: Wednesday, April 27, 2016 10:10 AM
> To: Ken K6MR
> Cc: Jim Rodenkirch; [hidden email]
> Subject: Re: [Elecraft] Sherwood's receiver performance table updated
>
> I always thought the ATU in the shack was specifically to allow operation where there's an impedance mismatch (not necessarily non-resonant) specifically to protect solid state equipment from the high voltages that can be present.
>
> Obviously an antenna system can be resonant and still not match impedance of the feed line and/or Radio.
>
> Sent from my iPad
>
>> On Apr 27, 2016, at 11:36 AM, Ken K6MR <[hidden email]> wrote:
>>
>> “P.S. I don't subscribe to the notion that quality coax runs of < 150 feet
>> make it "ok" to have the ATU in the shack while operating an antenna on
>> multiple bands....what technical evidence of that posit do you have to
>> share????”
>>
>> Jim:
>>
>> Google “transmission line bounce diagram”. This is a simple concept easily proven by mathematics.
>>
>> On a practical level, this is the concept behind the use of open wire feed lines. It’s been done for decades. The type of feed line does not change the theory.
>>
>> Ken K6MR
>>
>>
>>
>>
>>
>>
>> From: Jim Rodenkirch<mailto:[hidden email]>
>> Sent: Wednesday, April 27, 2016 06:21
>> To: [hidden email]<mailto:[hidden email]>
>> Subject: Re: [Elecraft] Sherwood's receiver performance table updated
>>
>> "It all depends" is/was the premise for my reply, Don.
>>
>> If new and old hams don't understand the potential problems with long runs
>> of coax to/from an antenna they want to operate on multiple bands and an ATU
>> in the shack they will be surprised at how inefficient their system is.
>>
>> P.S. I don't subscribe to the notion that quality coax runs of < 150 feet
>> make it "ok" to have the ATU in the shack while operating an antenna on
>> multiple bands....what technical evidence of that posit do you have to
>> share????
>>
>> Note 1: I had a 43' vertical with top loading wires in a NORD-style config
>> with my external ATU at the base of the vertical and 120' of coax back to
>> the shack ---- never saw a VSWR delta of more than .2 between what was
>> "seen" at the input to the tuner and what was "seen" at the xmtr while
>> operating on 160 through 20 meters.

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[Lynn W. Taylor, WB6UUT]

Please.

I'm always interested in antennas, since I need to figure something out
here in the not distant future.

Laboratory measurements not so much, and the touch-screen debate is a
religious argument.

73 -- Lynn

On 4/27/2016 11:25 AM, Phil Wheeler wrote:
> But this discussion seems to have evolved into something difficult to
> relate to the thread title. You might want to change the title!


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[Eric Swartz - WA6HHQ]

Especially since the prior thread under this name has been closed.
73
Eric
Moderator
/elecraft.com/

On 4/27/2016 11:25 AM, Phil Wheeler wrote:

> But this discussion seems to have evolved into something difficult to relate
> to the thread title. You might want to change the title!
>
> Phil W7OX
>
> On 4/27/16 10:25 AM, James Rodenkirch wrote:
>> Wow....lots of good stuff emanating from this discussion - tnx to all for
>> participating....
>>
>> For Jerry - there are other reasons for employing an ATU in the shack - e.g.,
>> using open wire line feed line from the antenna back to the xmtr.
>>

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[Hank Garretson]

On Wed, Apr 27, 2016 at 3:26 PM, Jim Brown <[hidden email]>
wrote:

Could you rebuild that rotary dipole as a fan?  A 40/20 fan would also give
> you 15. It's worth spending some time with EZNEC. Did you see the great
> work that W6SX did to multi-band his wires?  He showed it at an NCCC
> meeting. Dunno if it's online, but it's worth chasing down.
>

http://tinyurl.com/grbzufx

73,

Hank, W6SX
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[Jim Brown-10]

Actually, Walt Maxwell is NOT the best source -- there are fundamental
errors in it, which is why ARRL no longer publishes it.

73, Jim K9YC

On Wed,4/27/2016 9:58 AM, Mark, ars: KE6BB wrote:

>
> The best source is "Reflections" by Walter Maxwell, W2DU, originally
> published as a series of articles in QST (difficult to read due to the
> poor scans) and then published by ARRL as a book.  The latest edition
> is "Reflections III" published by CQ Communications, but currently
> sold out.
>
>
>
> If you really want to understand what is happening on a transmission
> line, how an ATU works, etc., then this is the book you should read.
>  Be warned, though, it is NOT an "easy read", but more of a "great
> study".  It requires a lot of thought and re-reading to absorb, but is
> well worth the effort.
>
>
>
> Mark,
>
>
> ars: KE6BB
>

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[Wes Stewart-2]

Where are the errors?

On 4/27/2016 3:40 PM, Jim Brown wrote:
> Actually, Walt Maxwell is NOT the best source -- there are fundamental errors
> in it, which is why ARRL no longer publishes it.
>
> 73, Jim K9YC

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[Josh Fiden]

If you mention "conjugate match" expect fireworks...

73,
Josh W6XU

On 4/27/2016 10:32 PM, Wes wrote:
> Where are the errors?
>
> On 4/27/2016 3:40 PM, Jim Brown wrote:
>> Actually, Walt Maxwell is NOT the best source -- there are
>> fundamental errors in it, which is why ARRL no longer publishes it.
>>
>> 73, Jim K9YC
>

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