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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 |
"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? |
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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? |
In article ,
Gary Schafer wrote: 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." Here's my guess: it's a standard, which would be available in almost any professional radio test lab. Hence, it may simply be a convenient signal to use when performing ALC and audio-pathway calibrations. As is sometimes said, "The best thing about a standard is, sometimes, that it's a standard. If it happens to be a _good_ standard, so much the better!" -- 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! |
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I can get down to 0.01% THD with 4th order active filtering of a square
wave -- as measured on an HP339 THD analyzer. For the fellow who had asked the original question I suggested the switched cap filter -- but there is always going to be some noise clocking through. Using the interactive filter software on Analog Devices or Texas Instruments website is pretty easy, but necessitates more parts. Sorry not to have included "odd harmonics" but I guess you know what I meant. "Tim Wescott" wrote in message ... 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 |
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