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Data mode and filters

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k6dgw

Re: New K3 is on the way

Just a note on top of Don's advice, the stock, "out-of-the-box" settings
on a new K3 are a great place to start. Basically, you can power it up
and use as is. Your's may not be in the stock configuration, but it has
been in use [?], and I'd recommend playing around with it on the air for
awhile before tweaking anything.

Secondly, when you do decide to tweak, go slow, use it for awhile before
another tweak, and only mess with one thing at a time. The radio is
almost infinitely configurable and some of the changes may not be
immediately obvious. I didn't make this up ... Jim, K9YC, told me when
I was trying to adjust the RX EQ for SSB and failing. I of course was
just moving the settings all over the place and got thoroughly lost.

Fred Cady's book combined with the manual is a winning combo.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
- www.cqp.org

On 5/9/2015 4:28 PM, Don Wilhelm wrote:

> Tom,
>
> Walk through the Cady book and do the exercises, and by the time you get
> to the end, you will know the K3 capabilities and how to operate it very
> well.
>
> If you want a "quick start", take a look at the K3 menu entries in the
> regular K3 manual (they are listed about 2/3 of the way through the
> manual). That will give you an idea of how you can customize the K3 to
> your particular tastes and operating desires. Then equipped with that
> customization information, you can dig deeper into the K3 manual or Cady
> book to tell you how to make the menu changes to your advantage.
>
> 73,
> Don W3FPR
>
> On 5/9/2015 7:14 PM, KF5WBS via Elecraft wrote:
>> I have a new (to me) K3 on the way along with the Cady book. I would
>> really like to get a good start with this rig. Any setup/startup
>> suggestions or experiences from someone who has been there before
>> would be most appreciated,
>>
>> Thanks everyone,
>>
>> Tom KF5WBS

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Bill-3

Re: New K3 is on the way

I will offer a little sage advice for tinkering with setting changes -
KEEP GOOD NOTES! Notes have save my bacon several times when I had to
reinvent the wheel.

Bill W2BLC K-Line

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k6mkf

Re: New K3 is on the way

Also use the Elecraft K3 Utility to update the firmware to the latest production level.

Also, along with your notes, use the K3 Utility to make backups of your K3 configuration along the way.

-- Mike Flowers, K6MKF, NCDXC - "It's about DX!"

> On May 9, 2015, at 6:15 PM, Bill <[hidden email]> wrote:
>
> I will offer a little sage advice for tinkering with setting changes - KEEP GOOD NOTES! Notes have save my bacon several times when I had to reinvent the wheel.
>
> Bill W2BLC K-Line
>
>
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Jim Bolit

Re: Data mode and filters

In reply to this post by Grant Youngman

.

As some have pointed out, getting an email from someone you don't know, stating your signal is wide and not clean, would draw a reaction of "who is this guy"?

Terms such as Cop, Dudley do Right, where is his badge, President of HOA do come up. These types of comments are not surprising, but none the less, disappointing.

It took decades for busy bodies to get it across to mfg.'s that the ham community wanted better receive performance on "close in" signals, but they finally got it.

The weak link in the "system" is now the transmitter. Some may " go outside and find something actually productive to do". Others may bring it to the attention of the ham community in an effort to get the mfg's to fix the poor design of synthesizers and amplifiers

If you have ever tried to work Sweepstakes CW, or the 160 meter CW contest, one would change their tune about "imaginary authority". It is even worse in Europe due to the density of operators, and then when you add in contest conditions, it is VERY difficult to find some elbow room (that should be there) be it for poor designs. It may not be intentional, but I have seen cases where it was CLEARLY intentional

Screen shots, data and math does not lie. The facts are as presented. I see NO reason that a mfg'er shud allow the end user to adjust the CW wave shaping, as Icom, and Yaesu have. People have mentioned that a controlled test, using lab type setups would be more effective than an email. I agree, to a point. The ARRL has been publishing information on the performance of signal purity. If you do not subscribe to QST (a majority of hams are not members), you would have to do a significant amount of research and/or testing that is beyond the scope or capabilities of most ham operators. I challenge people to listen to the CWops Mini-CWT Test on May 14, 2015 at 03:00z to 04:00z (note the date and time is in UTC) and listen on 40m to a relatively packed band. Use a receiver that is better than an SX-28 and you will quickly be able to pick up signals that are full of key clicks, and those that are wide. Having a P3 makes it all the easier to also see these poor xmitters.

Elecraft was asked to have the ability to gain access to the code that performs the wave shaping function in their rigs.

Elecraft declined to offer this, and for a very good reason.

Can you guess what that reason was?

Jim
W6AIM
.

.

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of GRANT YOUNGMAN
Sent: Saturday, May 9, 2015 3:38 PM
To: Elecraft Reflector
Subject: Re: [Elecraft] Data mode and filters

> On May 9, 2015, at 4:50 PM, Matthew Pitts via Elecraft <[hidden email]> wrote:
>
> Phil,
> This is a good idea, … or they deliberately make bad adjustments for whatever reason, and don't want to accept the negative signal reports as fact.
> Matthew PittsN8OHU
>

Look .. some guy you’ve never heard of sends you an email telling you your signal is wide. And sends a screenshot from somewhere. I think it would be the reaction of most people to ask “who is this guy, where is his badge, why is he trolling me, and who the <deleted> does he think he is .. the president of my HOA”? For those of you sending “friendly” emails, to presume that your "fabulous highly educated, K3-whatever-based signal measurement expertise” or the fact that you’re “famous” (real or imagined) as a signal quality control genius in your close-knit group is going to push a concrete block out of the way is assuming too much. After all, the guy receiving the email has a Wizeroo 1000 transceiver and Gozmodics 1500 amp, and .. well … they’re the BEST, and they’re connected together just like they’re supposed to be … and the score is everything anyway, which is why all the knobs are turned all the way up, and if there’s a problem it’s YOUR receiver.

So maybe the fellow sending you the report of how wide your signal is is tuning around on a SX-28(?). After all, your contest score is fine, your sidetone is clean, and NO ONE else told you your signal sucks.

What are you going to think? You’re going to blow the guy off. Of course you will. I would, too — because I MONITOR my signal, and would know one way or the other (it’s amazing the number of hams that don’t own a scope, but that’s another issue).

Sending someone an email after the fact might make a difference in a minuscule number of cases. Teaching someone new to it all how to properly adjust a transmitter/amp will help, too. My cynical view is that an ever increasing number take the “open carry and it’s all about me me” society we increasingly live in into radio — if you think you can gain an advantage by screwing up your signal to <deleted> everyone else … well …the score and potential for celebrity is everything. Or some bit of all of the above. Which is why during the seemingly never ending contests on the weekends, I go outside and find something actually productive to do … :)

Grant NQ5T

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Raymond Sills

Re: New K3 is on the way

In reply to this post by k6mkf

And, don't forget to download the -latest- version of the KX3 Utility,
as appropriate to your computer's OS. The Utility gets updated, too,
and sometimes older versions won't work properly.

Having those periodic backup copies of your rig's configuration can be
a lifesaver. You'll be able to revert to a known working
configuration, should you get "frisky" and try a beta version of a rig
update that does something unpredictable (unlikely, since even beta
versions are often stable and often become the production release
without any changes). Couldn't hurt to put those config files into a
thumb drive or one of the cloud services, like DropBox... just in case
your computer tanks.

73 de Ray
K2ULR
KX3 #211

On May 9, 2015, at 9:22 PM, Mike Flowers wrote:

> Also use the Elecraft K3 Utility to update the firmware to the
> latest production level.
>
> Also, along with your notes, use the K3 Utility to make backups of
> your K3 configuration along the way.
>
> -- Mike Flowers, K6MKF, NCDXC - "It's about DX!"
>
>> On May 9, 2015, at 6:15 PM, Bill <[hidden email]> wrote:
>>
>> I will offer a little sage advice for tinkering with setting
>> changes - KEEP GOOD NOTES! Notes have save my bacon several times
>> when I had to reinvent the wheel.
>>
>> Bill W2BLC K-Line

Elecraft mailing list

Re: Data mode and filters

In reply to this post by Grant Youngman

Grant,
I understand what you're saying, but there are a lot of hams that think that the factory defaults that their particular radio shipped with are just fine when they could be improved with assistance, or they think that if a little adjustment is good, more is better.

Matthew PittsN8OHU

From: GRANT YOUNGMAN <[hidden email]>
To: Elecraft Reflector <[hidden email]>
Sent: Saturday, May 9, 2015 6:37 PM
Subject: Re: [Elecraft] Data mode and filters

> On May 9, 2015, at 4:50 PM, Matthew Pitts via Elecraft <[hidden email]> wrote:
>
> Phil,
> This is a good idea, … or they deliberately make bad adjustments for whatever reason, and don't want to accept the negative signal reports as fact.
> Matthew PittsN8OHU
>

Look .. some guy you’ve never heard of sends you an email telling you your signal is wide. And sends a screenshot from somewhere. I think it would be the reaction of most people to ask “who is this guy, where is his badge, why is he trolling me, and who the <deleted> does he think he is .. the president of my HOA”? For those of you sending “friendly” emails, to presume that your "fabulous highly educated, K3-whatever-based signal measurement expertise” or the fact that you’re “famous” (real or imagined) as a signal quality control genius in your close-knit group is going to push a concrete block out of the way is assuming too much. After all, the guy receiving the email has a Wizeroo 1000 transceiver and Gozmodics 1500 amp, and .. well … they’re the BEST, and they’re connected together just like they’re supposed to be … and the score is everything anyway, which is why all the knobs are turned all the way up, and if there’s a problem it’s YOUR receiver.

So maybe the fellow sending you the report of how wide your signal is is tuning around on a SX-28(?). After all, your contest score is fine, your sidetone is clean, and NO ONE else told you your signal sucks.

What are you going to think? You’re going to blow the guy off. Of course you will. I would, too — because I MONITOR my signal, and would know one way or the other (it’s amazing the number of hams that don’t own a scope, but that’s another issue).

Sending someone an email after the fact might make a difference in a minuscule number of cases. Teaching someone new to it all how to properly adjust a transmitter/amp will help, too. My cynical view is that an ever increasing number take the “open carry and it’s all about me me” society we increasingly live in into radio — if you think you can gain an advantage by screwing up your signal to <deleted> everyone else … well …the score and potential for celebrity is everything. Or some bit of all of the above. Which is why during the seemingly never ending contests on the weekends, I go outside and find something actually productive to do … :)

Grant NQ5T

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k6dgw

Re: Data mode and filters

OTOH, a K3 will play just fine and not incur the wrath of the BW cops
when fired up "right out of the box." In fact, it is wise to use it
some, become familiar with the manual and menus, and have Fred Cady's
book open to the correct page before changing anything. Elecraft has
wisely omitted the menu entry to change the keying waveform found on
some other transceivers in the upper price classes.

If I got an unsolicited email from a stranger telling me something was
wrong with my signal, I doubt I'd panic [the FCC seems to have run out
of "pink slips" several decades ago], but I'd check it out with a
reliable friend just in case. RF into the mic circuit can cause a whole
lot of trouble in an otherwise pristine radio.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
- www.cqp.org

On 5/10/2015 11:22 AM, Matthew Pitts via Elecraft wrote:
> Grant, I understand what you're saying, but there are a lot of hams
> that think that the factory defaults that their particular radio
> shipped with are just fine when they could be improved with
> assistance, or they think that if a little adjustment is good, more
> is better.
>
> Matthew PittsN8OHU
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Bill Frantz

Re: Data mode and filters

I'm with Fred on this one. I want to put out a clean signal. If
someone tells me I'm not, I'll at least investigate it.

When I got my K3, I knew that the designers were a lot more
experienced hams than I was. I used the settings "stock" for a
long time. Most of them are still that way. One of the unsung
advantages of Elecraft radios is that the designers are users.
This is true of some of the other manufacturers as well.

73 Bill AE6JV

73 Bill AE6JV

On 5/10/15 at 1:24 PM, [hidden email] (Fred Jensen) wrote:

>If I got an unsolicited email from a stranger telling me
>something was wrong with my signal, I doubt I'd panic [the FCC
>seems to have run out of "pink slips" several decades ago], but
>I'd check it out with a reliable friend just in case. RF into
>the mic circuit can cause a whole lot of trouble in an
>otherwise pristine radio.
---------------------------------------------------------------------------
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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Kevin Stover

Re: Data mode and filters

In reply to this post by k6dgw

On Sun, 10 May 2015 13:24:53 -0700
Fred Jensen <[hidden email]> wrote:

> OTOH, a K3 will play just fine and not incur the wrath of the BW cops

Notr true at all.
The K3's transmit IMD numbers aren't any better than any other manuafactuirers and probably worse than the 200W rigs because they use 24 or 50V finals.

Elecraft needs to quit messing with the spectacular receiver they built and work on cleaning up the transmitter. If that means dumping the 12V finals for higher voltage cleaner types so be it.

--
R. Kevin Stover
AC0H
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Jim Brown-10

Re: Data mode and filters

On Mon,5/11/2015 5:52 AM, Kevin Stover wrote:
> The K3's transmit IMD numbers aren't any better than any other manuafactuirers and probably worse than the 200W rigs because they use 24 or 50V finals.

That's true ONLY at full power. What matters a LOT more is IMD at the
lower power levels required to drive power amps to legal limit. At
reduced power levels IMD in the K3 is reduced significantly, while the
IMD in the other rigs I've tested do NOT. See K6XX's bench data in

http://k9yc.com/K6XXAmpTalk.pdf

Even more important, IMD is only part of the problem. An equally
important part is the shaping of CW rise and fall times, which is what
excites IMD. The K3's CW bandwidth is the best of all rigs tested by
ARRL. Their closest competitor is the Kenwood TS-590S.

And then there's phase noise -- again, the K3 is in the top 3 rigs, and
the recent synth board upgrade improved it by 5-6 dB.

See ARRL data here. http://k9yc.com/TXNoise.pdf

And here's my measured data for a K3 driving a KPA500 and a Ten Tec
Titan. Note that this includes the combined IMD products of the K3 and
those amps. P3_Spectrum_Measurements.pdf and FTDX5000_Report.pdf

> Elecraft needs to quit messing with the spectacular receiver they built and work on cleaning up the transmitter. If that means dumping the 12V finals for higher voltage cleaner types so be it.

See above.

73, Jim K9YC

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Joe Subich, W4TV-4

Re: Data mode and filters

On 2015-05-11 12:39 PM, Jim Brown wrote:
> That's true ONLY at full power. What matters a LOT more is IMD at
> the lower power levels required to drive power amps to legal limit.
> At reduced power levels IMD in the K3 is reduced significantly, while
> the IMD in the other rigs I've tested do NOT.

Considering that a great many stations operate at the 100 - 150W level
*with no amplifier*, moving to 48V final amplifiers capable of -37 dB
or better IMD is *very* important. Continued insistence on PAs that
operate on a lead-acid battery for home stations at the 100W level
is a blind spot.

At least choose devices that will operate at either 12/24 or 12/48V
and design the transformers so that the PA can operate at 200W with
48 V and 25W at 12V with excellent IMD. Those that refuse to use
reasonable dual voltage power supplies can still limp along with
their back-pack compatible battery supplies but those who prefer to
operate at the traditional 100W "barefoot" level can do so with clean
signals that befit the rest of the K3 design.

73,

... Joe, W4TV

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Jim Brown-10

Re: Data mode and filters

On Mon,5/11/2015 1:50 PM, Joe Subich, W4TV wrote:
> Considering that a great many stations operate at the 100 - 150W level
> *with no amplifier*, moving to 48V final amplifiers capable of -37 dB
> or better IMD is *very* important.

I disagree, only because the signal is 12 dB weaker without the amp. And
even at 100W, the K3 is cleaner than most rigs.

73, Jim K9YC

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Joe Subich, W4TV-4

Re: Data mode and filters

On 2015-05-11 8:55 PM, Jim Brown wrote:
> I disagree, only because the signal is 12 dB weaker without the amp.
> And even at 100W, the K3 is cleaner than most rigs.

The K3 may be cleaner than low end 12V/100W rigs like the Icom 706mkIIg
7000, 7100, Yaesu FT-450/991, etc. but it is certainly *not* as clean as
the other top of the line contest rigs like the Icom 7600/7800,
Yaesu 2000/5000, Kenwood 990, etc. For example, ARRL measured the K3
at -29/-43/-46/-51 dB vs. -32/-49/-52/-54 dB for the Icom 7800 and
-31/-46/-54/-57 dB for the TS-990. That makes the K3 3 to 6 dB *worse*
than other top of the line rigs at rated output.

Again, it's time to get past this silly attachment to PA stages that
can be run from a battery pack and move to higher voltage devices for
lower IMD.

73,

... Joe, W4TV

On 2015-05-11 8:55 PM, Jim Brown wrote:

> On Mon,5/11/2015 1:50 PM, Joe Subich, W4TV wrote:
>> Considering that a great many stations operate at the 100 - 150W level
>> *with no amplifier*, moving to 48V final amplifiers capable of -37 dB
>> or better IMD is *very* important.
>
> I disagree, only because the signal is 12 dB weaker without the amp. And
> even at 100W, the K3 is cleaner than most rigs.
>
> 73, Jim K9YC
>
>
> ______________________________________________________________
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>

Jim Brown-10

Re: Data mode and filters

On Mon,5/11/2015 6:45 PM, Joe Subich, W4TV wrote:
> The K3 may be cleaner than low end 12V/100W rigs like the Icom 706mkIIg
> 7000, 7100, Yaesu FT-450/991, etc. but it is certainly *not* as clean
> as the other top of the line contest rigs like the Icom 7600/7800,
> Yaesu 2000/5000, Kenwood 990, etc. For example, ARRL measured the K3
> at -29/-43/-46/-51 dB vs. -32/-49/-52/-54 dB for the Icom 7800 and
> -31/-46/-54/-57 dB for the TS-990. That makes the K3 3 to 6 dB *worse*
> than other top of the line rigs at rated output.

But Joe, you are fixating on a single specification, which is only one
part of what establishes the cleanliness of a radio. On CW and FSK,
there is the keying waveform, and on all modes there is phase noise. The
K3 rise time for both modes is quite well controlled, so the keying
transients that excite IM in those other radios don't excite IM in the
K3. And phase noise in the K3, even before the new synth boards is close
to the best of any modern radio.

The occupied bandwidth measurements show the SUM of all these
mechanisms. I've been using pink noise for SSB spectrum measurements
because the signal excites IMD in a manner similar to what a voice
would, and I've made measurements with me talking into a live mic.
There's no significant difference between the live mic and the pink noise.

The FTDX5000 report to which I posted a link shows that the K3 and
FTDX5000 have almost the same occupied bandwidth on SSB, but the K3 has
10 dB of signal processing. AND -- my K3 is even narrower because I've
cut everything below about 400 Hz with TXEQ. If you missed the link,
it's on my website.

In many contests, I've got a CQ machine 8 miles from me with a 7600 and
a legal limit amp who regularly wipes out 5-10 kHz on CW, but K6XX, only
3 miles away with a K3 and ancient tube amps is only 700 Hz wide at -50
dBC. The 7600 and 7800 tested quite similarly in bandwidth tests by ARRL.

Six months ago, when I began doing my own measurements with a P3/SVGA,
you insisted that the IMD in a K3 would make a mess of PSK31, so I
measured PSK31 signals. They are in the set of P3 measurements I have
posted here several times, and they clearly show that you were wrong! :)

For those who missed the link, the measurements, as well as a
description of my test setup, are on my website. k9yc.com/publish.htm

73, Jim K9YC

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Joe Subich, W4TV-4

Re: Data mode and filters

Jim,

> But Joe, you are fixating on a single specification, which is only
> one part of what establishes the cleanliness of a radio. On CW and
> FSK, there is the keying waveform, and on all modes there is phase
> noise.

IMD is not an issue with CW or FSK (or JT65/JT9 for that matter) - they
are modes designed to work with saturated (class C) amplifiers. IMD is
a real issue with SSB when you separate out all the other junk caused
by bad ALC, excess IF gain and excess *audio* processing.

The K3 can be 4 to 6 dB *cleaner* than it already is if the proper
approach were taken in the KPA3. Since I don't use an amplifier, I
want the cleanest "exciter power level" possible and it is annoying
that given all the other attention to detail, the K3 has a dirty PA
(IMD comparable to the IC-706mkIIg on my test bench) simply to make
it compatible with a battery pack.

> Six months ago, when I began doing my own measurements with a
> P3/SVGA, you insisted that the IMD in a K3 would make a mess of
> PSK31, so I measured PSK31 signals. They are in the set of P3
> measurements I have posted here several times, and they clearly show
> that you were wrong! :)

Your PSK31 "measurements" are clearly not believable. Look at the
IMD values in most PSK software when the K3 is run at more than 30
to 40 watts *average* power output. You will see the PSK IMD rise
significantly because the KPA3 is going into compression. If you
measure at 100W *instantaneous* peaks (using an oscilloscope and
looking for 70.7 Volts peak RF across 50 Ohms), the average power
in a PSK31 signal (e.g. measured on the K3 Wattmeter or a Bird 43)
will be around 30 Watts then the IMD of the KPA3 (and the rest of
the signal chain) will be acceptable. If you press the K3 to 100
W *average* output in PSK31 the PA will saturate, you will cause
about 4 dB of compression (peak clipping) of the PSK waveform and
PSK IMD will be around -15 dB or worse.

Non-linearities (compression) destroy BPSK and QPSK signals.

73,

... Joe, W4TV

On 2015-05-11 11:12 PM, Jim Brown wrote:

> On Mon,5/11/2015 6:45 PM, Joe Subich, W4TV wrote:
>> The K3 may be cleaner than low end 12V/100W rigs like the Icom 706mkIIg
>> 7000, 7100, Yaesu FT-450/991, etc. but it is certainly *not* as clean
>> as the other top of the line contest rigs like the Icom 7600/7800,
>> Yaesu 2000/5000, Kenwood 990, etc. For example, ARRL measured the K3
>> at -29/-43/-46/-51 dB vs. -32/-49/-52/-54 dB for the Icom 7800 and
>> -31/-46/-54/-57 dB for the TS-990. That makes the K3 3 to 6 dB *worse*
>> than other top of the line rigs at rated output.
>
> But Joe, you are fixating on a single specification, which is only one
> part of what establishes the cleanliness of a radio. On CW and FSK,
> there is the keying waveform, and on all modes there is phase noise. The
> K3 rise time for both modes is quite well controlled, so the keying
> transients that excite IM in those other radios don't excite IM in the
> K3. And phase noise in the K3, even before the new synth boards is close
> to the best of any modern radio.
>
> The occupied bandwidth measurements show the SUM of all these
> mechanisms. I've been using pink noise for SSB spectrum measurements
> because the signal excites IMD in a manner similar to what a voice
> would, and I've made measurements with me talking into a live mic.
> There's no significant difference between the live mic and the pink noise.
>
> The FTDX5000 report to which I posted a link shows that the K3 and
> FTDX5000 have almost the same occupied bandwidth on SSB, but the K3 has
> 10 dB of signal processing. AND -- my K3 is even narrower because I've
> cut everything below about 400 Hz with TXEQ. If you missed the link,
> it's on my website.
>
> In many contests, I've got a CQ machine 8 miles from me with a 7600 and
> a legal limit amp who regularly wipes out 5-10 kHz on CW, but K6XX, only
> 3 miles away with a K3 and ancient tube amps is only 700 Hz wide at -50
> dBC. The 7600 and 7800 tested quite similarly in bandwidth tests by ARRL.
>
> Six months ago, when I began doing my own measurements with a P3/SVGA,
> you insisted that the IMD in a K3 would make a mess of PSK31, so I
> measured PSK31 signals. They are in the set of P3 measurements I have
> posted here several times, and they clearly show that you were wrong! :)
>
> For those who missed the link, the measurements, as well as a
> description of my test setup, are on my website. k9yc.com/publish.htm
>
> 73, Jim K9YC
>
>
>
>
>
>
>
>
>
>
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>
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Jim Brown-10

Re: Data mode and filters

On Mon,5/11/2015 8:39 PM, Joe Subich, W4TV wrote:
> IMD is not an issue with CW or FSK (or JT65/JT9 for that matter) - they
> are modes designed to work with saturated (class C) amplifiers. IMD is
> a real issue with SSB when you separate out all the other junk caused
> by bad ALC, excess IF gain and excess *audio* processing.

Not true, Joe. Both CW and FSK involve 100% modulation of a carrier by
square waves. That's why rise time and shaping of the keying signal
matters. That's what Elecraft changed when they cleaned up their FSK a
year or two ago. That's why some rigs click a lot wider than others.
Compare the keying spectrum with the unkeyed steady carrier.

Further, EVERY component of audio excites IMD, depending on the relative
strength of all of the thousands of components. It is NOT to over
processing audio -- the distortion of excessive processing and
overdriven audio happens at baseband (audio) and in the audio chain.

I don't buy your complaints about my PSK31 measurements. It has never
been my practice to drive amplifiers into saturation.

73, Jim K9YC

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Joe Subich, W4TV-4

Re: Data mode and filters

On 2015-05-12 12:40 AM, Jim Brown wrote:
> Not true, Joe. Both CW and FSK involve 100% modulation of a carrier
> by square waves. That's why rise time and shaping of the keying
> signal matters.

While that is true, using a class C amplifier with properly shaped
CW, FSK or JT65/JT9 will not significantly change the bandwidth of
the signal. Yes, there will be some increased "click" at the top
of the rising edge but the impact will be nowhere near as significant
as an ALC system with severe overshoot driving a PA with only -30 dB
IMD on SSB.

> I don't buy your complaints about my PSK31 measurements. It has never
> been my practice to drive amplifiers into saturation.

If you are measuring 100W average power on PSK31 (anything more than
25 to 40 W depending on data) you are driving the KPA3 into saturation.
If you are not measuring 100W average power in your tests, you are not
fully testing the IMD of the KPA3 (at least as generated by the "all
knobs to the right" class of operators).

The vast majority of amateurs do not have calibrated scopes on the
output of their transmitter/amplifier to keep the instantaneous peak
output below the onset of compression in the final stage of power
amplification.

73,

... Joe, W4TV

On 2015-05-12 12:40 AM, Jim Brown wrote:

> On Mon,5/11/2015 8:39 PM, Joe Subich, W4TV wrote:
>> IMD is not an issue with CW or FSK (or JT65/JT9 for that matter) - they
>> are modes designed to work with saturated (class C) amplifiers. IMD is
>> a real issue with SSB when you separate out all the other junk caused
>> by bad ALC, excess IF gain and excess *audio* processing.
>
> Not true, Joe. Both CW and FSK involve 100% modulation of a carrier by
> square waves. That's why rise time and shaping of the keying signal
> matters. That's what Elecraft changed when they cleaned up their FSK a
> year or two ago. That's why some rigs click a lot wider than others.
> Compare the keying spectrum with the unkeyed steady carrier.
>
> Further, EVERY component of audio excites IMD, depending on the relative
> strength of all of the thousands of components. It is NOT to over
> processing audio -- the distortion of excessive processing and
> overdriven audio happens at baseband (audio) and in the audio chain.
>
> I don't buy your complaints about my PSK31 measurements. It has never
> been my practice to drive amplifiers into saturation.
>
> 73, Jim K9YC
>
>
> ______________________________________________________________
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>

Jim Brown-10

Re: Data mode and filters

On Fri,5/15/2015 9:10 AM, Joe Subich, W4TV wrote:
> The vast majority of amateurs do not have calibrated scopes on the
> output of their transmitter/amplifier to keep the instantaneous peak
> output below the onset of compression in the final stage of power
> amplification.

No, but they/we can put a calibrated peak-reading wattmeter like the
LP-100A in line with the feed to our antennas.

And last I looked, few hams run much power with PSK-31. As both my
measurements and K6XX measurements clearly show, IMD in the K3 drops
significantly below full power.

73, Jim K9YC

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Bill Frantz

Re: Data mode and filters

For what it's worth, I operate PSK a fair bit. I would say that
most operators report using between 25 and 35 watts. (I'm
generally at 5 watts, unless I fuzz out when changing from RTTY
where I seem to need 100W.)

73 Bill AE6JV

On 5/15/15 at 9:44 AM, [hidden email] (Jim Brown) wrote:

>And last I looked, few hams run much power with PSK-31. As both
>my measurements and K6XX measurements clearly show, IMD in the
>K3 drops significantly below full power.
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Joe Subich, W4TV-4

Re: Data mode and filters

In reply to this post by Jim Brown-10

> No, but they/we can put a calibrated peak-reading wattmeter like the
> LP-100A in line with the feed to our antennas.

While a peak reading wattmeter like the LPA-100 is a good step, it
still does not respond to instantaneous peaks. Most "peak reading"
wattmeters will show peak values that vary depending on the PSK31
datastream and never show the true instantaneous peak.

> And last I looked, few hams run much power with PSK-31.

They have to do that or they would be clipping terribly in the final
amplifier stage (or in the transmit IF of some poorly aligned rigs).
They certainly can't push the rigs to 100W as your tests would imply.

73,

... Joe, W4TV

On 2015-05-15 12:44 PM, Jim Brown wrote:

> On Fri,5/15/2015 9:10 AM, Joe Subich, W4TV wrote:
>> The vast majority of amateurs do not have calibrated scopes on the
>> output of their transmitter/amplifier to keep the instantaneous peak
>> output below the onset of compression in the final stage of power
>> amplification.
>
> No, but they/we can put a calibrated peak-reading wattmeter like the
> LP-100A in line with the feed to our antennas.
>
> And last I looked, few hams run much power with PSK-31. As both my
> measurements and K6XX measurements clearly show, IMD in the K3 drops
> significantly below full power.
>
> 73, Jim K9YC
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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