"Caveat Lector" bravely wrote to "All" (21 Feb 05 17:42:40)
--- on the heady topic of " Are there multi-tone AF generators?"

CL From: "Caveat Lector"
CL Xref: aeinews rec.radio.amateur.homebrew:2292


CL "Asimov" wrote in
CL message g...
"Caveat Lector" bravely wrote to "All" (21 Feb 05 09:36:46)
--- on the heady topic of " Are there multi-tone AF generators?"

CL From: "Caveat Lector"
CL Xref: aeinews rec.radio.amateur.homebrew:2274

CL Just FYI -- the Kenwood Station Monitor SM-230 provides a two tone
CL output for testing

A piano even does semi-tones... 10 at a time, 11 if you use your nose!

A*s*i*m*o*v

... Hanging: Early form of bungee jumping practiced in the old west.

CL Great device (piano) for checking transmitters
CL In the off chance you or others don't know
CL 2-tone IMD testing was the original topic --- see URL:
CL http://www.w8ji.com/transmitter_splatter.htm

I wrote that facetiously but I was really hinting of using a pc
soundcard. A sound card can produce very pure sinewaves from its FM
generator IC and most can play many dozens of notes at a time.

A*s*i*m*o*v

.... ...on the other hand, you also have 5 fingers.

On Monday, 21 Feb 2005 16:00:56 -500, "Asimov"
wrote:

"Insert 2 audio signals into the MIC Connector
1.9kHz at 3mV
1.3kHz at 3mV

A piano even does semi-tones... 10 at a time, 11 if you use your nose!

With some kind of PC, search for a program that can generate multiple
tones (e.g. some electronic instrument imitations) or use two programs
capable of generating a sine wave and mix them together with the PC's
audio mixer and run the combined signal to the sound card output and
to an audio amplifier.

The hardest part is getting some kind of calibrated output level.

One way of doing this with very simple test gear would be to put a low
impedance 40 dB attenuator between the audio amplifier and the mic
input.

Using a single 50 or 60 Hz sine tone from the sound card and a DVM at
the amplifier output, adjust the amplifier output voltage to 300
mVrms, the microphone input will now be 3 mVrms. It is important to
use 50/60 Hz, since a typical DVM frequency response would be quite
bad at 1.3 or 1.9 kHz.

Now turn the 1.3 and 1.9 kHz tones on and make the transmitter
adjustments.

Paul OH3LWR

On Mon, 21 Feb 2005 17:55:14 -0500, Gary Schafer wrote:
On 21 Feb 2005 17:27:34 GMT, Allodoxaphobia
wrote:

On Sun, 20 Feb 2005 20:49:50 -0800, Sparky wrote:
The transmitter alignment instructions for my Icom 751A tranceiver
calls for a 2 tone input during the alignment process....

"Insert 2 audio signals into the MIC Connector
1.9kHz at 3mV
1.3kHz at 3mV

Are there AF generators out ther that will generate more than one
tone? The units I am seeing seem to generate just one tone (or at
least the used stuff out ther that I could afford)

Yep. To add to the other reponses, there are two-tone audio
generators used for two-tone control testing of commercial gear.
I've got one from my dad's estate that does two-tone-sequential
with adjustable duration for each tone, and two-tone-combined, and
single-tone. Thumbwheel freq(s) select from 100 cps to 9.999 kcs.
Pot adjustable tone durations (and delays), and levels.
It's probably 15-20 years old: Automated Industrial Electroncis
Corp., Model 2TSG-1.

They must show up on eBay from time-to-time. Google claims several
'hits' there -- but a search on eBay at this time shows none.

That two tone generator is only two sequential tones. It will not
produce two tones at the same time. It is also pretty much of a square
wave coming out of it too. No good for ssb testing.
It was made for pager testing.
73
Gary K4FMX

Right you are!! My apologies!
I just fired it up and verified: 2-tone, combined is _not_ an option.

(Damn! The older I get - the more wrong stuff I remember...)

One way to 'fix' a square wave is to push it through one or more
audio transformers.

73
Jonesy
--
| Marvin L Jones | jonz | W3DHJ | linux
| Gunnison, Colorado | @ | Jonesy | OS/2 __
| 7,703' -- 2,345m | config.com | DM68mn SK

On 22 Feb 2005 17:23:11 GMT, Allodoxaphobia
wrote:

On Mon, 21 Feb 2005 17:55:14 -0500, Gary Schafer wrote:
On 21 Feb 2005 17:27:34 GMT, Allodoxaphobia
wrote:

On Sun, 20 Feb 2005 20:49:50 -0800, Sparky wrote:
The transmitter alignment instructions for my Icom 751A tranceiver
calls for a 2 tone input during the alignment process....

"Insert 2 audio signals into the MIC Connector
1.9kHz at 3mV
1.3kHz at 3mV

Are there AF generators out ther that will generate more than one
tone? The units I am seeing seem to generate just one tone (or at
least the used stuff out ther that I could afford)

Yep. To add to the other reponses, there are two-tone audio
generators used for two-tone control testing of commercial gear.
I've got one from my dad's estate that does two-tone-sequential
with adjustable duration for each tone, and two-tone-combined, and
single-tone. Thumbwheel freq(s) select from 100 cps to 9.999 kcs.
Pot adjustable tone durations (and delays), and levels.
It's probably 15-20 years old: Automated Industrial Electroncis
Corp., Model 2TSG-1.

They must show up on eBay from time-to-time. Google claims several
'hits' there -- but a search on eBay at this time shows none.

That two tone generator is only two sequential tones. It will not
produce two tones at the same time. It is also pretty much of a square
wave coming out of it too. No good for ssb testing.
It was made for pager testing.
73
Gary K4FMX

Right you are!! My apologies!
I just fired it up and verified: 2-tone, combined is _not_ an option.

(Damn! The older I get - the more wrong stuff I remember...)

One way to 'fix' a square wave is to push it through one or more
audio transformers.

73
Jonesy


Automated Industrial Electronics had an option where you could tie two
of those boxes together and generate two tones at once if I remember
right. Pretty rare though.

They did also make a specific two tone generator box for ssb. They did
have a pretty good sine wave out. You probably won't see many around
though.

73
Gary K4FMX

I wonder what kind of unit ICOM would use when they got to this step
in the transmitter alignment for my 751A when they are suppossed to
use the 2 tones... I emailed them, I'll post back what they say.
Mike AB7RU


Automated Industrial Electronics had an option where you could tie two
of those boxes together and generate two tones at once if I remember
right. Pretty rare though.

They did also make a specific two tone generator box for ssb. They did
have a pretty good sine wave out. You probably won't see many around
though.

73
Gary K4FMX

From: Paul Keinanen on Tues, Feb 22 2005 12:04 am:

On Monday, 21 Feb 2005 16:00:56 -500, "Asimov"
wrote:

"Insert 2 audio signals into the MIC Connector
1.9kHz at 3mV
1.3kHz at 3mV

A piano even does semi-tones... 10 at a time, 11 if you use your
nose!

With some kind of PC, search for a program that can generate multiple
tones (e.g. some electronic instrument imitations) or use two programs
capable of generating a sine wave and mix them together with the PC's
audio mixer and run the combined signal to the sound card output and
to an audio amplifier.

The hardest part is getting some kind of calibrated output level.

Paul, I don't want to sound critical here, but this newsgroup is
about "homebrew." In that light, I'd suggest a simple quad
op-amp circuited as two phase-shift oscillators (pick the AF
desired) out of two of the op-amps in the quad package, use
the third as a resistive summing mixer. The summing mixer
will have a low output impedance capable of driving anything
from low-Z to high-Z. Almost any quad op-amp IC will work
if their open-loop frequency response unity gain is at least
1 MHz (which is to say just about all of them). Use whatever
DC supply is handy (within the op-amp supply ranges).

The fourth op-amp in the package is either spare or can be
made into a preamp with its output mixing in the summing
mixer. Basic op-amp circuits and how to calculate them
are mature subjects and found in many texts and on the
Internet.

I doubt there is a "typical" DVM (of the handheld variety)
that cannot reach into AF with calibration, made anywhere.
Checking the DVM specs is a must if it is unknown. Even
the ultra-cheap oscilloscopes have response beyond AF.
[I had one of the original Heathkit model O-1 'scopes
made from a kit a half century ago, reached 50 KHz+
before rolling off 3 db in response...gave it away a decade
ago... :-) ]

"Hard to get a calibrated output?" I'll disagree if using the
simple single-IC generator I've described in general. A
phase-shift oscillator uses an R-C network which can be
configured as a low-pass filter (R in series, C in shunt).
Many textbooks have easy formulas for parts values. The
AF R-C filter loss is a known quantity at 180 degree phase
shift for oscillatory feedback...combine that with an op-amp
gain set by resistor feedback (the DVM can check the
resistance values rather accurately) and the output sine
voltage will be constant. The summing mixer output can
have a gain of unity if desired, or any value needed. The
output into a microphone input can be done with a one-
or two-stage resistive voltage divider (depending on parts
values available). The ohmmeter part of a DVM can
check the resistor values and the level into the
microphone input can be calculated on paper.

No computer with sound card needed. Just a little
perf-board assembly (if quick assembly desired),
may be battery powered or by a cheap series
regulator IC from a cheap wall-wart. The op-amps
insure low distortion at AF from all the negative
feedback setting the closed-loop gains low. Output
AF voltage stability will be good if the DC supply is
stable.

For those that don't want to go through the hassle of
calculating anything, use a DTMF assembly from a
junked telephone (of the North American variety, haven't
checked other world regions). They automatically
generate two simultaneous audio tones out of a choice
of 8 frequencies; four frequencies in a "low band," four
in a "high band" the "bands" on either side of about
1 KHz.

If I remember correctly from a project of three decades
ago, the Bell System specifications required a fairly
pure sine for each of the tones selected. Don't have
the specs now. As I recall, the early Western Electric
telephone sets used only two transistors for DTMF
generation so a homebuilt two-tone generator is NOT
difficult to make from scratch.



retired (from regular hours) electronic engineer person

I can't imagine what they want a two tone signal for in alignment.
Maybe to set the alc level?

To do much else with it you also need a spectrum analyzer.

73
Gary K4FMX

On Tue, 22 Feb 2005 10:32:18 -0800, AB7RU
wrote:

I wonder what kind of unit ICOM would use when they got to this step
in the transmitter alignment for my 751A when they are suppossed to
use the 2 tones... I emailed them, I'll post back what they say.
Mike AB7RU


Automated Industrial Electronics had an option where you could tie two
of those boxes together and generate two tones at once if I remember
right. Pretty rare though.

They did also make a specific two tone generator box for ssb. They did
have a pretty good sine wave out. You probably won't see many around
though.

73
Gary K4FMX

It is a standard transmitter test for IMD determination
See URL:
http://rfdesign.com/mag/radio_twotone_imd_measurement/

--
Caveat Lector (Reader Beware)
Help The New Hams
Someone Helped You
Or did You Forget That ?



"Gary Schafer" wrote in message
...
I can't imagine what they want a two tone signal for in alignment.
Maybe to set the alc level?

On 22 Feb 2005 15:42:00 -0800, wrote:

Paul, I don't want to sound critical here, but this newsgroup is
about "homebrew." In that light, I'd suggest a simple quad
op-amp circuited as two phase-shift oscillators (pick the AF
desired) out of two of the op-amps in the quad package, use
the third as a resistive summing mixer.

Did I miss something or are you suggesting using a Wien bridge circuit
as an audio oscillator ? How should the amplitude be stabilised in
order to get nearly a sine wave output ?

While I guess that quite a few radio amateurs with professional
background in electronics are following this newsgroup, do not forget
that most young radio amateurs (with limited test equipments) are much
more used to playing with computer programming and computer hardware
than working with circuit design.

Both the traditional approach as well as some more day to day approach
is required, in order to make amateur radio a viable hobby even in the
future.

Paul OH3LWR

Yes I know it is a standard IMD test. :) That is why I asked what
they were doing with two tones without a spectrum analyzer.

You left out the last part of my post.
"To do much else with it you also need a spectrum analyzer."


73
Gary K4FMX

On Tue, 22 Feb 2005 16:51:08 -0800, "Caveat Lector"
wrote:

It is a standard transmitter test for IMD determination
See URL:
http://rfdesign.com/mag/radio_twotone_imd_measurement/

--
Caveat Lector (Reader Beware)
Help The New Hams
Someone Helped You
Or did You Forget That ?



"Gary Schafer" wrote in message
.. .
I can't imagine what they want a two tone signal for in alignment.
Maybe to set the alc level?