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IMD and supply voltage

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Charlie T, K3ICH

Re: IMD and supply voltage

Yep, I remember a certain net control op claiming
to put his rig into "war" mode during a weekly
Sunday net when competing with the incessant
"seeque keyontest" encroachment.

He was running a grid driven 4CX-1000A . All he
had to do was drive it so a few milliamps of grid
current showed and like magic, the frequency was
clear.

This was the "street-sweeper" * of radio set-ups
and pretty guaranteed a QRM free frequency for
the net.

Not sayin' I condone such antics, but it WAS
effective.

73, Charlie k3ICH

* Street-Sweeper, a rotary magazine 12 shot, 12
Ga semi-automatic shotgun. Sorta looks like fat
version of the popular Thompson machine gun.

Yes, I understand completely. From a "Real World
Practical" standpoint, if I have a really clean
transmitter with lovely IMD specifications and I
stuff over compressed, highly processed, all
compressor-limiter knobs to the right audio into
it I will get completely unintelligible audio with
wonderful technical specifications and still
bother my neighbors.

And don't forget. Some contesters *WANT* the
scenario you described above.
No sense in sweeping that under the rug!

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Alan Bloom

Re: The Technical Side of Ham Radio

In reply to this post by Jim Brown-10

I have a "Signal Hound" USB-SA-44B, which is a 1 Hz to 4.4 GHz spectrum
analyzer that uses a PC for power and the user interface. It currently
goes for $919. I've been pretty happy with it.

https://signalhound.com/

They also offer an optional USB-TG44A tracking generator for $599, which
I don't have.

Alan N1AL

On 10/30/2015 10:06 AM, Jim Brown wrote:

> Hi Chris,
>
> I have one. It is fine for looking at harmonics and standard IMD tests,
> but the ANAN 10e runs rings around it for spectrum analysis, and for
> $500 less. So does the VNWA for gain measurements, and for half the
> cost. Major limitation is that the frequency resolution isn't nearly
> fine enough to look at occupied bandwidth of ham gear. That's why I've
> been using P3/SVGA to look at ham rigs. Bottom line -- I wouldn't buy it
> again.
>
> 73, Jim K9YC
>
> On Fri,10/30/2015 6:10 AM, Chris Hallinan wrote:
>> Glad you keep posting, I keep learning. Can I ask, off list, what you
>> think of this? It's on my "wish list" at amazon. For my money, it
>> looks pretty good.
>>
>> http://www.amazon.com/dp/B00CLWJA38/ref=wl_it_dp_o_pd_S_ttl
>>
>> 73,
>>
>> K1AY
>> Chris in Punta Gorda, FL
>>

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Edward R Cole

Re: The Technical Side of Ham Radio

In reply to this post by Jim Brown-10

Jim,

Could resist but to reply (keep your sense of humor hat on!):
------------------------------
From: Jim Brown <[hidden email]>
To: [hidden email]
Subject: [Elecraft] The Technical Side of Ham Radio
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=windows-1252; format=flowed

Ham radio is a hobby for those who are willing to learn about how radio
works. To obtain a license, we must pass a test that shows we know the
fundamentals of radio and electronics. Some don't bother to do that, but
instead cram by memorizing answers to a lot multiple guess questions. I
view that as cheating. If they don't know anything when they're done,
that's their own fault.

-------------------------------
Yep, that's how I passed tests in college and got rewarded with a
degree. REAL learning came later on the job.
-------------------------------

Last I looked, ARRL license study material taught the fundamentals of
electronics and radio, and at least a third of the ARRL Handbook is
specifically written for those just beginning to learn it. I'd bet that
the vast majority of those who put us on the moon, and a generation
later a lander on Mars, first learned electronics from the ARRL Handbook!

-------------------------------
There you go again. My Novice at age 14 lead to degrees in math &
engineering and ultimately a job with NASA/JPL where I helped land
the first s/c on Mars: Viking-I on July 4, 1976! The fact it took me
until 1982 to Advanced Class and 2000 to Extra - while holding a 2nd
Class Radiotelephone since 1971 is a bit absurd. <hint it was about CW speed>
-------------------------------

As hams, we are responsible for producing a reasonably clean signal and
operating within the FCC Rules. Operators in other services like CB,
commercial 2-way, and so on are not permitted to modify equipment, but
we are!

-------------------------------
And that is special. Of course hams were among the pioneers of early
radio before there were even kits.
-------------------------------

I also do my best to produce tutorial materials to share what I've
learned. I AM an EE, but I also taught for five years (at DeVry in
Chicago), and my goal has always been to try to make complicated things
easier to understand. Like many OTs on this reflector, I passed my
General exam in my first year of high school, and the Extra exam the
summer after high school. All that study (and on air activity) made me
want to study EE. :)

-------------------------------
At age 8 (1952) I wanted to be a "rocket scientist or space cadet"
(later called astronaut). At age 14 it was clear I was not fit
enough to do that but smart enough to be part of the party (an
engineer). College took a little of the hubris away <smile>
-------------------------------

All of these study materials require STUDY, not casual reading. Some of
the concepts take a while to sink in, and with my work on RFI and
ferrites, took me a LONG time to figure out. It is a combination of my
own research and work with colleagues on the AES Standards Committee's
Working Group on EMC.

I have some nice test gear, but nothing even close to the $100K range --
much of the work I've done on clean transmitters has been with a
P3/SVGA, and I'm planning to increase my measurement capabilities next
year with one of the new under $1K ANAN radios. My VNWA cost $769, with
shipping and a calibration kit.

------------------------------------
Has taken me some time to get a little test equipment - its all old
stuff like my HP141T (same model I used working at Goldstone in mid
1970's). Much is acquired not fully working. Good to have 30+ years
of radio repair experience.
------------------------------------

You don't have to set this stuff up and measure it yourself -- there's
plenty of data on my website you can download and study. There's an
excellent Power Point, mostly by K6XX, an EE at Elecraft, that shows
virtually everything that's been discussed here in the thread on
transmitter distortion. I've posted these links several times. There's a
summary of ARRL measurements on transmitters that makes it easy to
compare them. You and others can learn a lot by downloading and studying
them. I learned a lot by doing the work to prepare them!

-----------------------------------
And thanks to several, like you, who share the "wealth" unlike the
"back stabbing" bunch I used to work with. That is REALLY the
shining example that is ham radio - those who share for free!
-----------------------------------

CAPS added for emphasis. :)

73, Jim K9YC

73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[hidden email]

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Jim Brown-10

Re: The Technical Side of Ham Radio

In reply to this post by Alan Bloom

On Fri,10/30/2015 1:13 PM, Alan wrote:
> I have a "Signal Hound" USB-SA-44B, which is a 1 Hz to 4.4 GHz
> spectrum analyzer that uses a PC for power and the user interface. It
> currently goes for $919. I've been pretty happy with it.
>
> https://signalhound.com/
>
> They also offer an optional USB-TG44A tracking generator for $599,
> which I don't have.

Interesting. What's the dynamic range -- i.e., how much can you display
on-screen?

73, Jim K9YC
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Alan Bloom

Re: The Technical Side of Ham Radio

On 10/30/2015 01:59 PM, Jim Brown wrote:

> On Fri,10/30/2015 1:13 PM, Alan wrote:
>> I have a "Signal Hound" USB-SA-44B, which is a 1 Hz to 4.4 GHz
>> spectrum analyzer that uses a PC for power and the user interface. It
>> currently goes for $919. I've been pretty happy with it.
>>
>> https://signalhound.com/
>>
>> They also offer an optional USB-TG44A tracking generator for $599,
>> which I don't have.
>
> Interesting. What's the dynamic range -- i.e., how much can you display
> on-screen?
>
> 73, Jim K9YC

You can set the dB/div scale for pretty much anything you want. 40
dB/div gives 400 dB display range, but of course that's not useful.

With a -10 dBm signal from an HP 8656B signal generator at 18.116 MHz,
span = 10 kHz and resolution bandwidth = 3.2 Hz, I see that the noise is
a bit less than -110 dBm at the edges (away from the phase noise near
the carrier).

So >100 dB dynamic range with those settings.

With a narrow enough span you can set the RBW all the way down to 0.1
Hz, but at a really slow update rate. (e.g. 37 seconds with 100 Hz span)

One thing I like about this unit is that it covers all the way down to
low audio frequencies (1 Hz), which is rare in a microwave spectrum
analyzer.

Alan N1AL

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Harlan Sherriff

Re: The Technical Side of Ham Radio

In reply to this post by Jim Brown-10

I have the same unit with the tracking gen. Great setup.

Sent from my Verizon Wireless 4G LTE smartphone

-------- Original message --------
From: Alan <[hidden email]>
Date: 10/30/2015 6:21 PM (GMT-05:00)
To: [hidden email]
Subject: Re: [Elecraft] The Technical Side of Ham Radio

On 10/30/2015 01:59 PM, Jim Brown wrote:

Wes (N7WS)

Re: The Technical Side of Ham Radio

In reply to this post by Jim Brown-10

Before springing for this I would suggest reading the RSGB review.

On 10/30/2015 1:59 PM, Jim Brown wrote:

> On Fri,10/30/2015 1:13 PM, Alan wrote:
>> I have a "Signal Hound" USB-SA-44B, which is a 1 Hz to 4.4 GHz spectrum
>> analyzer that uses a PC for power and the user interface. It currently goes
>> for $919. I've been pretty happy with it.
>>
>> https://signalhound.com/
>>
>> They also offer an optional USB-TG44A tracking generator for $599, which I
>> don't have.
>
> Interesting. What's the dynamic range -- i.e., how much can you display
> on-screen?
>
> 73, Jim K9YC

Cortland Richmond-2

Re: The Technical Side of Ham Radio

In reply to this post by Jim Brown-10

On Thu, 29 Oct 2015, at 23:39:56 Jim K9YC wrote:
> I AM an EE, but I also taught for five years (at DeVry in
> Chicago), and my goal has always been to try to make complicated things
> easier to understand.

I've worked in EMC since retiring from the Army in 1983 (was an
avionics instructor there for 4 years myself), and been up and down the
ladder in engineering positions (best paid was 5 years as R&D's EMC
design engineer at Alacatel USA in Petaluma; most interesting a
2-turned-8-months contract in Washington working on AED's). This,
despite never did taking any college engineering courses or getting a
degree. Playing with electronics since I was a kid was a good start, and
21 years in comms and avionics in the Army encouraged troubleshooting
skills and understanding. I still got an occasional contract (a couple
earlier this year) since retiring at GE Aviation; experience teaches
lessons most degree programs don't.

The HPJIE paid for some cool if ancient test equipment; directional
couplers, scopes to monitor RF envelopes counters and SA's to look at
the spectrum as needed (and be sure my local extended band AMBC station
goes to nighttime power on schedule and their coax doesn't arc over again).

The questions might be on the test, but the ANSWERS are wild in the
world, you know?

Cortland
KA5S
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Alan Bloom

Re: The Technical Side of Ham Radio

In reply to this post by Wes (N7WS)

On 10/30/2015 07:56 PM, Wes (N7WS) wrote:
> Before springing for this I would suggest reading the RSGB review.

I found on the Signal Hound web site a copy of a review by G4DDK in
September 2011 RADCOM (Journal of the RSGB). Is that the one you are
referring to?

https://signalhound.com/sigdownloads/SA44B/SA44B-IndependentReview.pdf

The only major complaint he had was that the screen update rate is slow
for wide sweeps. (OK for narrow sweeps) He concluded:

Overall I was very pleased with the performance of the SA44B.
If I didn't already possess a good spectrum analyser I could be
very tempted to buy one of these. The TG44 is perfectly useable and
has excellent frequency coverage.

(The TG44 is the optional tracking generator.)

Alan N1AL

>
> On 10/30/2015 1:59 PM, Jim Brown wrote:
>> On Fri,10/30/2015 1:13 PM, Alan wrote:
>>> I have a "Signal Hound" USB-SA-44B, which is a 1 Hz to 4.4 GHz
>>> spectrum analyzer that uses a PC for power and the user interface.
>>> It currently goes for $919. I've been pretty happy with it.
>>>
>>> https://signalhound.com/
>>>
>>> They also offer an optional USB-TG44A tracking generator for $599,
>>> which I don't have.
>>
>> Interesting. What's the dynamic range -- i.e., how much can you
>> display on-screen?
>>
>> 73, Jim K9YC
>
> ______________________________________________________________
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>

gm3sek

Re: The Technical Side of Ham Radio

In reply to this post by Cortland Richmond-2

>The questions might be on the test, but the ANSWERS are wild in the
>world, you know?
>
>Cortland
>KA5S

Thanks - that's a great quote.

73 from Ian GM3SEK

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Wes (N7WS)

Re: The Technical Side of Ham Radio

In reply to this post by Alan Bloom

That's it.

On 10/30/2015 9:51 PM, Alan wrote:

> On 10/30/2015 07:56 PM, Wes (N7WS) wrote:
>> Before springing for this I would suggest reading the RSGB review.
>
> I found on the Signal Hound web site a copy of a review by G4DDK in September
> 2011 RADCOM (Journal of the RSGB). Is that the one you are referring to?
>
> https://signalhound.com/sigdownloads/SA44B/SA44B-IndependentReview.pdf
>
> The only major complaint he had was that the screen update rate is slow for
> wide sweeps. (OK for narrow sweeps) He concluded:
>
> Overall I was very pleased with the performance of the SA44B.
> If I didn't already possess a good spectrum analyser I could be
> very tempted to buy one of these. The TG44 is perfectly useable and
> has excellent frequency coverage.
>
> (The TG44 is the optional tracking generator.)
>
> Alan N1AL
>

Wes (N7WS)

Re: The Technical Side of Ham Radio

In reply to this post by Wes (N7WS)

I should have added, read the manual too, especially sections 2.2 and 2.3:

http://signalhound.com/sigdownloads/SA44B/SA44B-User-Manual.pdf

This thing has some major limitations that turned me off.

On 10/30/2015 7:56 PM, Wes (N7WS) wrote:

> Before springing for this I would suggest reading the RSGB review.
>
>
> On 10/30/2015 1:59 PM, Jim Brown wrote:
>> On Fri,10/30/2015 1:13 PM, Alan wrote:
>>> I have a "Signal Hound" USB-SA-44B, which is a 1 Hz to 4.4 GHz spectrum
>>> analyzer that uses a PC for power and the user interface. It currently goes
>>> for $919. I've been pretty happy with it.
>>>
>>> https://signalhound.com/
>>>
>>> They also offer an optional USB-TG44A tracking generator for $599, which I
>>> don't have.
>>
>> Interesting. What's the dynamic range -- i.e., how much can you display
>> on-screen?
>>
>> 73, Jim K9YC
>

Lynn W. Taylor, WB6UUT

Re: The Technical Side of Ham Radio

In reply to this post by gm3sek

I'll admit that I passed the Extra test by memorizing the questions and
answers.

The reason: the answers in the wild and the answers on the test did not
always match.

Since I learned a lot of what was in the real world before going for my
Extra, it was a problem.

73 -- Lynn

On 10/31/2015 12:33 AM, Ian White wrote:
>> The questions might be on the test, but the ANSWERS are wild in the
>> >world, you know?
>> >
>> >Cortland
>> >KA5S
> Thanks - that's a great quote.
>
> 73 from Ian GM3SEK

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Alan Bloom

Re: The Technical Side of Ham Radio

In reply to this post by Wes (N7WS)

On 10/31/2015 09:32 AM, Wes (N7WS) wrote:
> I should have added, read the manual too, especially sections 2.2 and 2.3:
>
> http://signalhound.com/sigdownloads/SA44B/SA44B-User-Manual.pdf
>
> This thing has some major limitations that turned me off.

The limitations are due to the fact that it uses software algorithms
rather than hardware for image rejection. Basically it takes two
measurements with different local oscillator frequencies and figures out
which spectral components are real and which are images. It works quite
well. Other than slowing down the sweep speed somewhat (for span > 200
kHz), I have never noticed any effects in normal operation.

The main effect is it doesn't work correctly on transient signals, like
pulse-modulated or swept. If you need to measure one of those you can
always turn off image rejection, at the risk of seeing spurious responses.

Also it can't be used for wideband signals greater than 42 MHz. Maximum
resolution bandwidth is 250 kHz, so you can't demodulate an analog TV
signal (although you can display the spectrum).

But for the types of measurements typically needed for ham radio it acts
just like a conventional spectrum analyzer. I doubt you'd ever notice
the difference.

Alan N1AL

> On 10/30/2015 7:56 PM, Wes (N7WS) wrote:
>> Before springing for this I would suggest reading the RSGB review.
>>
>>
>> On 10/30/2015 1:59 PM, Jim Brown wrote:
>>> On Fri,10/30/2015 1:13 PM, Alan wrote:
>>>> I have a "Signal Hound" USB-SA-44B, which is a 1 Hz to 4.4 GHz
>>>> spectrum analyzer that uses a PC for power and the user interface.
>>>> It currently goes for $919. I've been pretty happy with it.
>>>>
>>>> https://signalhound.com/
>>>>
>>>> They also offer an optional USB-TG44A tracking generator for $599,
>>>> which I don't have.
>>>
>>> Interesting. What's the dynamic range -- i.e., how much can you
>>> display on-screen?
>>>
>>> 73, Jim K9YC
>>

Wes (N7WS)

Re: The Technical Side of Ham Radio

On 10/31/2015 9:56 AM, Alan wrote:
> I doubt you'd ever notice the difference.
>
> Alan N1AL
>
Really? And you know this how?
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Phil Kane-2

Re: The Technical Side of Ham Radio

In reply to this post by Cortland Richmond-2

On 10/30/2015 9:48 PM, CR wrote:

> The questions might be on the test, but the ANSWERS are wild in the
> world, you know?

The answers are right there on the paper in front of you. All you
really have to know is "a", "b", "c", and "d". Just like any other
multiple-guess exam... :)

73 de K2ASP - Phil Kane
Elecraft K2/100 s/n 5402

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon
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Jim Brown-10

Re: The Technical Side of Ham Radio

In reply to this post by Alan Bloom

On Sat,10/31/2015 9:56 AM, Alan wrote:
> The main effect is it doesn't work correctly on transient signals,
> like pulse-modulated or swept.

That suggest that it would not do well measuring a series of dits.

73, Jim K9YC
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Alan Bloom

Re: The Technical Side of Ham Radio

On 10/31/2015 04:44 PM, Jim Brown wrote:
> On Sat,10/31/2015 9:56 AM, Alan wrote:
>> The main effect is it doesn't work correctly on transient signals,
>> like pulse-modulated or swept.
>
> That suggest that it would not do well measuring a series of dits.

It's only an issue with sweeps wider than 200 kHz.

Alan N1AL

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123