Are there multi-tone AF generators?
 

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)
Thanks!

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?

They do exist - I'm in the process of doing some restoration on an old
Singer tone generator which does arbitrary pairs of frequencies.

These days, the easiest way to create a tone combination is usually to
use PC software. Generate two sinewave tones at the two frequencies
you want, with 50% amplitude or less, then mix 'em with the
appropriate relative amplitudes. There's lotsa free software which
will do this - e.g. Audacity on Linux and no doubt many others.

You can then play the mixed file out through your PC sound card, or
burn it to a CD-R and use a portable CD player to reproduce the
sound... whichever is most convenient. In either case, feed the
line-level output signal to a fixed or variable attenuator to get the
voltage level you need.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

A Square Wave is all the harmonics of the fundamental, so a 1.9kHz square
wave will have all the harmonics which will complicate the measurement --

If you take a square wave and filter it you can get a relatively low
distortion fundamental -- it's much easier than you might think -- use an
NE556 dual timer to generate 1.9kHz and 1.3kHz square waves, combine with
10k resistors into an opamp buffer, filter with an MF-10 (now upgraded to
LMF100) switched capacitor low pass filter -- voila.


"Dave Platt" wrote in message
...
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?

They do exist - I'm in the process of doing some restoration on an old
Singer tone generator which does arbitrary pairs of frequencies.

These days, the easiest way to create a tone combination is usually to
use PC software. Generate two sinewave tones at the two frequencies
you want, with 50% amplitude or less, then mix 'em with the
appropriate relative amplitudes. There's lotsa free software which
will do this - e.g. Audacity on Linux and no doubt many others.

You can then play the mixed file out through your PC sound card, or
burn it to a CD-R and use a portable CD player to reproduce the
sound... whichever is most convenient. In either case, feed the
line-level output signal to a fixed or variable attenuator to get the
voltage level you need.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

All the _ODD_ harmonics (including the fundamental as the 1st)
in inverse proportion to their harmonic number.

"John Walton" wrote in message
...
A Square Wave is all the harmonics of the fundamental, so a 1.9kHz square
wave will have all the harmonics which will complicate the measurement --

"John Walton" ) writes:
A Square Wave is all the harmonics of the fundamental, so a 1.9kHz square
wave will have all the harmonics which will complicate the measurement --

If you take a square wave and filter it you can get a relatively low
distortion fundamental -- it's much easier than you might think -- use an
NE556 dual timer to generate 1.9kHz and 1.3kHz square waves, combine with
10k resistors into an opamp buffer, filter with an MF-10 (now upgraded to
LMF100) switched capacitor low pass filter -- voila.

And why not start with a sinewave oscillator in the first place? That's
the way it used to be done, two transistors each making up phase shift
oscillators.

A sqarewave won't complicate measurements, it will downright give
different results. The whole point of two-tone testing is that the
first tone causes a "carrier" out of the SSB transmitter (the single
tone translates to an RF frequency), and the second tone adds modulation.
If the tones aren't pure sinewave, the output of the transmitter will
be radically different.

Michael VE2BVW


"Dave Platt" wrote in message
...
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?

They do exist - I'm in the process of doing some restoration on an old
Singer tone generator which does arbitrary pairs of frequencies.

These days, the easiest way to create a tone combination is usually to
use PC software. Generate two sinewave tones at the two frequencies
you want, with 50% amplitude or less, then mix 'em with the
appropriate relative amplitudes. There's lotsa free software which
will do this - e.g. Audacity on Linux and no doubt many others.

You can then play the mixed file out through your PC sound card, or
burn it to a CD-R and use a portable CD player to reproduce the
sound... whichever is most convenient. In either case, feed the
line-level output signal to a fixed or variable attenuator to get the
voltage level you need.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Michael Black wrote:

"John Walton" ) writes:

A Square Wave is all the harmonics of the fundamental, so a 1.9kHz square
wave will have all the harmonics which will complicate the measurement --

If you take a square wave and filter it you can get a relatively low
distortion fundamental -- it's much easier than you might think -- use an
NE556 dual timer to generate 1.9kHz and 1.3kHz square waves, combine with
10k resistors into an opamp buffer, filter with an MF-10 (now upgraded to
LMF100) switched capacitor low pass filter -- voila.


And why not start with a sinewave oscillator in the first place? That's
the way it used to be done, two transistors each making up phase shift
oscillators.

A square wave oscillator followed by a filter is, in some ways, easier
to implement than a phase-shift oscillator -- particularly if you want
well controlled frequency and amplitude without having to use
sophisticated AGC circuits.

A sqarewave won't complicate measurements, it will downright give
different results. The whole point of two-tone testing is that the
first tone causes a "carrier" out of the SSB transmitter (the single
tone translates to an RF frequency), and the second tone adds modulation.
If the tones aren't pure sinewave, the output of the transmitter will
be radically different.

That's probably why the guy doesn't advocate using it: he's recommending
a square wave that's heavily low-pass filtered to get rid of the
harmonics. If done right this will result in a clean stable sine wave
at the desired frequency.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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.

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

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

But the IF input for the bandscope is for older Kenwood transceivers.

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

"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.

"Asimov" wrote in message
...
"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.

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