RE: [Repeater-Builder] Re: Receiver Tuning
Neil, Your very correct, I have three Sinadders and never hook them to receiver audios. What I use them for is the audio level meter and the 1000 Hz tome generator to trace signals through audio circuits. Paul -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] Behalf Of [EMAIL PROTECTED] Sent: Thursday, March 09, 2006 11:43 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: Receiver Tuning I used the Sinadder when it first came out ... once my ear had learned what to listen for, I quit using the it. Neil Original Message From: [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: Receiver Tuning Date: Fri, 10 Mar 2006 02:12:08 - So I snuck in a minute to play with the new toy. If my meter is reading right, I'm at 0.24uV for 12dB sinad. I tuned by ear, and got 0.26, so not THAT bad, but with the meter I don't have to listen to the tone and noise that drives me nuts. This is a Hae Dong meter, there are more on Ebay for $30 or thereabouts. It's used, and no manual, but hey, it's got a 110Vac plug and a BNC input. What manual do you need? :) Yahoo! Groups Links Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[Repeater-Builder] Re: Receiver Tuning
Well, I should be able to answer those questions soon, as my Sinadder just arrived. No time to play tonight, but ASAP. I did a quick check, plugging it into the tone out on my HP generator where it shows 20dB with the 1kHz tone on, and 0 with the 400Hz tone on, pretty much as expected. But, it will have to wait as I'm on a crash project for work. Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[Repeater-Builder] Re: Receiver Tuning
So I snuck in a minute to play with the new toy. If my meter is reading right, I'm at 0.24uV for 12dB sinad. I tuned by ear, and got 0.26, so not THAT bad, but with the meter I don't have to listen to the tone and noise that drives me nuts. This is a Hae Dong meter, there are more on Ebay for $30 or thereabouts. It's used, and no manual, but hey, it's got a 110Vac plug and a BNC input. What manual do you need? :) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] Re: Receiver Tuning
Got an item number.. Hae Dong turned up nothing.. mike -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] Behalf Of Dave VanHorn Sent: Thursday, March 09, 2006 9:12 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Receiver Tuning So I snuck in a minute to play with the new toy. If my meter is reading right, I'm at 0.24uV for 12dB sinad. I tuned by ear, and got 0.26, so not THAT bad, but with the meter I don't have to listen to the tone and noise that drives me nuts. This is a Hae Dong meter, there are more on Ebay for $30 or thereabouts. It's used, and no manual, but hey, it's got a 110Vac plug and a BNC input. What manual do you need? :) Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: Receiver Tuning
Try item# 7598024261 Dan On 3/9/06, Mike Perryman [EMAIL PROTECTED] wrote: Got an item number.. Hae Dong turned up nothing.. mike -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] Behalf Of Dave VanHorn Sent: Thursday, March 09, 2006 9:12 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Receiver Tuning So I snuck in a minute to play with the new toy. If my meter is reading right, I'm at 0.24uV for 12dB sinad. I tuned by ear, and got 0.26, so not THAT bad, but with the meter I don't have to listen to the tone and noise that drives me nuts. This is a Hae Dong meter, there are more on Ebay for $30 or thereabouts. It's used, and no manual, but hey, it's got a 110Vac plug and a BNC input. What manual do you need? :) Yahoo! Groups Links Yahoo! Groups Links -- Dan Simmons KC2BEZ President North Country Amateur Radio Club W2LCA Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[Repeater-Builder] Re: Receiver Tuning
Just search on sinadder Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] Re: Receiver Tuning
I used the Sinadder when it first came out ... once my ear had learned what to listen for, I quit using the it. Neil Original Message From: [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: Receiver Tuning Date: Fri, 10 Mar 2006 02:12:08 - So I snuck in a minute to play with the new toy. If my meter is reading right, I'm at 0.24uV for 12dB sinad. I tuned by ear, and got 0.26, so not THAT bad, but with the meter I don't have to listen to the tone and noise that drives me nuts. This is a Hae Dong meter, there are more on Ebay for $30 or thereabouts. It's used, and no manual, but hey, it's got a 110Vac plug and a BNC input. What manual do you need? :) Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[Repeater-Builder] Re: Receiver Tuning
Ok, I wasn't thinking in this direction before, but I do have an audio band spectrum analyzer handy. Question is, how can I translate this to a Sinad measurement? Looking at the receiver in question now, the second harmonic of the 1kHz tone is -40dB, and the noise is at about 5dB below that. It's an interesting study in using the wrong instrument for the job. I get a very detailed look at the spectrum of the audio output, but what I need is a very non-detailed measurement of out-of-band energy. Tried doing it on my scope too, which can subtract Chan 1 from chan 2, but there's almost 180 degrees phase shift, and the amplitudes are very different, and it would take some significant messing about to fix that up. I need a sinadder. Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: Receiver Tuning
I recall reading somewhere that the SINAD measurement is the residual signal after the 1kHz tone has been filtered out. Assuming you have a full-quieting input signal with 3kHz deviation and you've notched that out, there snould be nothing left to measure. As the signal gets noisier, the harmonics (if any) and the noise will be measurable. When that level gets to 12dB below the no-signal noise level, you've reached the point of 12dB SINAD. This is a very simplified explanation, and the 1kHz tone is used as the reference level. A distortion analyzer is basically the same thing. A narrow filter notches out the fundamental, and the voltmeter reads what's left. HP331, 332, 333, and 334 units are fairly cheap and they can do triple duty as an AC voltmeter, distortion analyzer, and SINAD meter. The necessity of notching the 1kHz tone is what makes the 12dB SINAD measurement more difficult than the 20dB quieting method, but the SINAD method takes into consideration any distortion of the demodulated signal, which is certainly going to be audible. The 20dBQ method just goes for a reduction of wideband noise. With that audio spectrum analyzer, adjust it for full scale on the fundamental, and look at the noise and any harmonics. Increase the RF signal level until this drops to 25% (1/4) of the level of the 1kHz tone. This will be the 12dB SINAD point, assuming that the wideband noise etc doesn't add up to more than the -12dB signal amplitude. Once you calibrate your equipment with a real SINAD setup, you should be able to continue using the audio SA. A poor-man's SINAD would have an adjustable amplifier, a relatively sharp filter at 1 kHz, and a voltmeter following it. This might be easier to come up with than a real SINAD meter. I'm still an old-timer, and I prefer the 20dBQ method because it's easier to reproduce and only requires a simple AC Voltmeter. Plus, I've learned that on MaxTracs, this level of quieting occurs when all the crackles on a dead carrier disappear. I don't even need a meter. If nothing else, it gives me a way of comparing one radio to another just by feeding in a weak signal. Bob M. == --- Dave VanHorn [EMAIL PROTECTED] wrote: Ok, I wasn't thinking in this direction before, but I do have an audio band spectrum analyzer handy. Question is, how can I translate this to a Sinad measurement? Looking at the receiver in question now, the second harmonic of the 1kHz tone is -40dB, and the noise is at about 5dB below that. It's an interesting study in using the wrong instrument for the job. I get a very detailed look at the spectrum of the audio output, but what I need is a very non-detailed measurement of out-of-band energy. Tried doing it on my scope too, which can subtract Chan 1 from chan 2, but there's almost 180 degrees phase shift, and the amplitudes are very different, and it would take some significant messing about to fix that up. I need a sinadder. __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[Repeater-Builder] Re: Receiver Tuning
--- In Repeater-Builder@yahoogroups.com, Bob M. [EMAIL PROTECTED] wrote: I recall reading somewhere that the SINAD measurement is the residual signal after the 1kHz tone has been filtered out. Right When that level gets to 12dB below the no-signal noise level, you've reached the point of 12dB SINAD. Well, if everything were simple, that would be it. What I measure, is a noise floor that slopes 20dB between the lowest frequency I can measure (near 0) and 2kHz, with the 1kHz tone in the middle. So do I average that noise floor, or take the peak reading, or something else? A distortion analyzer is basically the same thing. A narrow filter notches out the fundamental, and the voltmeter reads what's left. HP331, 332, 333, and 334 units are fairly cheap and they can do triple duty as an AC voltmeter, distortion analyzer, and SINAD meter. That's why I was thinking of the SA in this application, because it gives a good measure of noise and distortion, but it gives me too much detail, and takes about 10 sec to do a sweep. With that audio spectrum analyzer, adjust it for full scale on the fundamental, and look at the noise and any harmonics. Increase the RF signal level until this drops to 25% (1/4) of the level of the 1kHz tone. :) I have to mod my receiver then, I can't adjust the squelch to hold in that low. These daniels receivers don't come with the ability to run open squelch, unless you hold down a front panel button, which I may change over to a toggle switch. A poor-man's SINAD would have an adjustable amplifier, a relatively sharp filter at 1 kHz, and a voltmeter following it. This might be easier to come up with than a real SINAD meter. I don't have any problem doing the filtering, but not a lot of data out there on how sharp the filter needs to be, or what frequency response the system should have outside the filter. One approach would be to do it with a boxcar integrator, which can act as almost an arbitrarily narrow filter. You average up a copy of the tone, and then subtract that from the output. Another way would be to do it in DSP, and not mess with the analog at all. I'm still an old-timer, and I prefer the 20dBQ method because it's easier to reproduce and only requires a simple AC Voltmeter. True, but it can end up with the bandwidth too narrow. I made that mistake here, and the local 2M club machine, not tuned by me, has the same problem. When the weak guys deviate a bit more than normal, they fall out of the squelch. They aren't over-deviating, it's just that the receiver does better on unmodulated carrier. Plus, I've learned that on MaxTracs, this level of quieting occurs when all the crackles on a dead carrier disappear. I don't even need a meter. If nothing else, it gives me a way of comparing one radio to another just by feeding in a weak signal. Yup, makes a good quick quality check., Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: Receiver Tuning
At 3/6/2006 09:38 AM, you wrote: Ok, I wasn't thinking in this direction before, but I do have an audio band spectrum analyzer handy. Question is, how can I translate this to a Sinad measurement? I've been trying to figure this out too, as I've been working on an audio spectrum analyzer program wanted to throw in a SINAD meter. Subsequent post from Bob M.: With that audio spectrum analyzer, adjust it for full scale on the fundamental, and look at the noise and any harmonics. Increase the RF signal level until this drops to 25% (1/4) of the level of the 1kHz tone. This will be the 12dB SINAD point, assuming that the wideband noise etc doesn't add up to more than the -12dB signal amplitude. Once you calibrate your equipment with a real SINAD setup, you should be able to continue using the audio SA. So I guess I could remove the 1 kHz data from the FFT'd spectrum, do an inverse FFT ratio that result with the original 1 kHz signal to get SINAD. Or maybe just add the values of all the remaining frequency bins, but somehow I think that may not yield the same result. ? Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: Receiver Tuning
Wouldn't the SINAD be the distance between the 1kHz tone Spike and the noise Grass? On 3/6/06, Bob Dengler [EMAIL PROTECTED] wrote: At 3/6/2006 09:38 AM, you wrote: Ok, I wasn't thinking in this direction before, but I do have an audio band spectrum analyzer handy. Question is, how can I translate this to a Sinad measurement? I've been trying to figure this out too, as I've been working on an audio spectrum analyzer program wanted to throw in a SINAD meter. Subsequent post from Bob M.: With that audio spectrum analyzer, adjust it for full scale on the fundamental, and look at the noise and any harmonics. Increase the RF signal level until this drops to 25% (1/4) of the level of the 1kHz tone. This will be the 12dB SINAD point, assuming that the wideband noise etc doesn't add up to more than the -12dB signal amplitude. Once you calibrate your equipment with a real SINAD setup, you should be able to continue using the audio SA. So I guess I could remove the 1 kHz data from the FFT'd spectrum, do an inverse FFT ratio that result with the original 1 kHz signal to get SINAD. Or maybe just add the values of all the remaining frequency bins, but somehow I think that may not yield the same result. ? Bob NO6B Yahoo! Groups Links Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: Receiver Tuning
I'd think it might, but the AC voltmeter is measuring the average (or RMS-calibrated) signal that remains after the 1kHz tone has been removed. I suppose it only has to be attenuated by at least 12dB (probably more) so it doesn't contribute to the rest of the signal. But if the 1kHz tone level is measured at the peak, then the noise can probably be measured the same way. Someone with both setups should do an experiment and see what the correlation is. Another test would be to go for 20dB quieting, which is easily measured, and see what the audio SA shows for the noise amplitude compared to the unsquelched noise. Bob M. == --- DCFluX [EMAIL PROTECTED] wrote: Wouldn't the SINAD be the distance between the 1kHz tone Spike and the noise Grass? On 3/6/06, Bob Dengler [EMAIL PROTECTED] wrote: At 3/6/2006 09:38 AM, you wrote: Ok, I wasn't thinking in this direction before, but I do have an audio band spectrum analyzer handy. Question is, how can I translate this to a Sinad measurement? I've been trying to figure this out too, as I've been working on an audio spectrum analyzer program wanted to throw in a SINAD meter. Subsequent post from Bob M.: With that audio spectrum analyzer, adjust it for full scale on the fundamental, and look at the noise and any harmonics. Increase the RF signal level until this drops to 25% (1/4) of the level of the 1kHz tone. This will be the 12dB SINAD point, assuming that the wideband noise etc doesn't add up to more than the -12dB signal amplitude. Once you calibrate your equipment with a real SINAD setup, you should be able to continue using the audio SA. So I guess I could remove the 1 kHz data from the FFT'd spectrum, do an inverse FFT ratio that result with the original 1 kHz signal to get SINAD. Or maybe just add the values of all the remaining frequency bins, but somehow I think that may not yield the same result. ? Bob NO6B __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: Receiver Tuning
At 3/6/2006 01:52 PM, you wrote: Wouldn't the SINAD be the distance between the 1kHz tone Spike and the noise Grass? I assume you mean distance in amplitude. Not quite. I think the noise would have to be summed over all frequencies, including any harmonics of the 1 kHz that get generated as a result of distortion in the RX. Since each frequency bin in the FFT represents a voltage, each value may have to be squared first, then square root the result. That is the part I always have trouble with when doing statistical math on signals. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: Receiver Tuning
I checked the manual for my HP 334A Distortion analyzer. The notch filter in that unit seems to be capable of 80dB, and the bandwidth is quite narrow, under 0.01%. This unit just removes the fundamental and measures whatever is left. I found several good articles and explanations of SINAD measurements and equipment on the web. The simplest description shows an RMS meter at the input, a 1kHz notch filter, and another RMS meter at the filter's output. You adjust the input RF signal until the two meters show 12dB difference, and you've got the 12dB SINAD sensitivity. Some use an AGC amplifier in the input and do away with the first meter. I would think that the distortion analyzer does essentially the same thing. In the SET mode, you measure the 1kHz tone amplitude and adjust the input level for a specific value. In the DISTORTION mode, that tone is notched out and the residual signal is measured. This could probably be done with an audio spectrum analyzer if you could measure and sum (RMS) all the signals except the fundamental 1kHz tone. If the SA has that function, you should be good to go. I don't know if this would give the same reading, but one time I tried feeding in a 1kHz tone at 3kHz deviation with a full-quieting signal, and noted the amplitude of that signal on an RMS voltmeter. I then removed the modulating tone and reduced the RF level until the meter read 12dB below the level with the tone. I didn't notch the 1kHz tone, I just turned it off. This would leave just the noise, so I suppose any distortion produced by the IF and detector stages was eliminated from the measurement. It would be an interesting experiment to compare this measurement to what a real SINAD meter shows. Bob M. == --- Bob M. [EMAIL PROTECTED] wrote: I'd think it might, but the AC voltmeter is measuring the average (or RMS-calibrated) signal that remains after the 1kHz tone has been removed. I suppose it only has to be attenuated by at least 12dB (probably more) so it doesn't contribute to the rest of the signal. But if the 1kHz tone level is measured at the peak, then the noise can probably be measured the same way. Someone with both setups should do an experiment and see what the correlation is. Another test would be to go for 20dB quieting, which is easily measured, and see what the audio SA shows for the noise amplitude compared to the unsquelched noise. Bob M. == --- DCFluX [EMAIL PROTECTED] wrote: Wouldn't the SINAD be the distance between the 1kHz tone Spike and the noise Grass? On 3/6/06, Bob Dengler [EMAIL PROTECTED] wrote: At 3/6/2006 09:38 AM, you wrote: Ok, I wasn't thinking in this direction before, but I do have an audio band spectrum analyzer handy. Question is, how can I translate this to a Sinad measurement? I've been trying to figure this out too, as I've been working on an audio spectrum analyzer program wanted to throw in a SINAD meter. Subsequent post from Bob M.: With that audio spectrum analyzer, adjust it for full scale on the fundamental, and look at the noise and any harmonics. Increase the RF signal level until this drops to 25% (1/4) of the level of the 1kHz tone. This will be the 12dB SINAD point, assuming that the wideband noise etc doesn't add up to more than the -12dB signal amplitude. Once you calibrate your equipment with a real SINAD setup, you should be able to continue using the audio SA. So I guess I could remove the 1 kHz data from the FFT'd spectrum, do an inverse FFT ratio that result with the original 1 kHz signal to get SINAD. Or maybe just add the values of all the remaining frequency bins, but somehow I think that may not yield the same result. ? Bob NO6B __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[Repeater-Builder] Re: Receiver Tuning
Another item to throw into the topic is the crystal osc alignment also changes your sensitivity. Freq-center may not give the best sensitivity depending a number of other parameters. One might hope it does, but it's not always the case. skipp Dave VanHorn [EMAIL PROTECTED] wrote: I've noticed that I can get a lot better sensitivity on my receivers if the source I'm measuring against is either unmodulated, or I set the deviation to 1 or 2 kHz. When I get up to 3-5 kHz deviation, the apparent sensitivity of the receiver is significantly less. I notice this on many systems, where a weak station will be in until they talk a little louder, then they drop out. Is there a tuning method I can use to minimize this effect? Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[Repeater-Builder] Re: Receiver Tuning
Depending upon the symmetry of the IF and detector component responses, there will be a difference in the apparent sensitivity with different deviation levels. The operative word is apparent. If you intend to use the receiver for FM voice which averages about 3 kHz deviation, then you should use the EIA standard method of tuning to 12 dB SINAD with 3.0 kHz deviation of a 1 kHz tone. If you optimize the tuning on an unmodulated test signal, then the receiver's sensitivity to voice modulation will likely be poorer than it would be if tuned with a modulated signal. I hear ya, but no sinadder here. So, I can tune to min noise with 3k Dev tone, or anything else I can measure or hear. I wouldn't mind building a sinadder, but I don't know how I'd calibrate it. Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[Repeater-Builder] Re: Receiver Tuning
--- In Repeater-Builder@yahoogroups.com, Bob M. [EMAIL PROTECTED] wrote: I thought that's the whole idea behind the SINAD measurement method, and why it's so much better than the 20dB quieting method. It may well be, but for those of us without sinadders, then what? Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: Receiver Tuning
I'm willing to guess that if you built one, someone here on this list could help you calibrate it against their service monitor. Chuck WB2EDV I wouldn't mind building a sinadder, but I don't know how I'd calibrate it. Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: Receiver Tuning
Hello to the list. A very good and super inexpensive Sinad meter can be an old Heathkit audio distortion meter. Any distortion meter will work, but the old Heathkit units are around and are super cheap. Simply connect across the loudspeaker and with a strong signal into the radio to be tested, modulated with 3 KHz of a 1 KHz tone, set the distortion meter up for full scale on set level and then notch out the 1 KHz tone (set for the distortion measurement). this should be certainly way less than the 12 dB shown on the meter face. Then reduce the RF signal into the receiver until the noise starts to bring the meter up to the -10 indication on the meter. Tuning the receiver from this point on will give a true indication of SINAD (Signal in noise and distortion). Recheck the +2 full scale usint the set level position and again confirm the 12 dB reduction in the noise and distortion. A little practice gets this to be a very quick, cheap, easy, and accurate 12 dB Sinad meter. The model number for the Heathkit is of Model IM-58 vintage and is called a 'Harmonic Distortion meter'. Works quite well, look for them at flea markets or ebay... 73's all Curt W1FSM Dave VanHorn wrote: --- In Repeater-Builder@yahoogroups.com, Bob M. [EMAIL PROTECTED] wrote: I thought that's the whole idea behind the SINAD measurement method, and why it's so much better than the 20dB quieting method. It may well be, but for those of us without sinadders, then what? -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.375 / Virus Database: 268.1.2/274 - Release Date: 3/3/2006 Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
