I would say spectrum analyzer with tracking generator - starts from $1500 new, stereo encoder - $300 used, good audio inerface for computer - $200 new, FFT distortion analysis software - $100, service manual - $20 if you can find one, experience in RF circuits tuning - at least two years, EE degree - $100K but optional.
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nobody touched the tuner in receivers
- Thread starter BranMPioneer
- Start date
I would say spectrum analyzer with tracking generator - starts from $1500 new, stereo encoder - $300 used, good audio inerface for computer - $200 new, FFT distortion analysis software - $100, service manual - $20 if you can find one, experience in RF circuits tuning - at least two years, EE degree - $100K but optional.
KentTeffeteller
Gimpus Stereophilus!
I do my alignments the markthefixer method. Halfway, won't get it for me. Kent's rule, the higher performance it was when new, the more attention to maintenance it needs to perform correctly. And inversely, the greater skill it takes to align and maintain it. And I also know, when it is more practical to get someone in who specializes in some difficult tuners. I can align many tuners, but not all.
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No manufacturer that I know of ever used electrolytic caps in an oscillator circuit in a tuner. Not consistent enough and too much tendency to drift in value. I've changed the caps in many tuners, and it changed nothing so far as reception is concerned (unless a smoothing cap was going bad and causing noise).
Without a SG, one can peak the front end, line up the dial (align the LO), peak the IF, and align the discriminator. IF you know what you're doing.
A SG and DM are required to set the separation, and set distortion to minimum. A frequency counter is needed to align the MPX oscillator if someone has twiddled it. This applies to tuners with modern ceramic filters.
Tuners with tuned circuit filters are a whole different ball of wax.
Without a SG, one can peak the front end, line up the dial (align the LO), peak the IF, and align the discriminator. IF you know what you're doing.
A SG and DM are required to set the separation, and set distortion to minimum. A frequency counter is needed to align the MPX oscillator if someone has twiddled it. This applies to tuners with modern ceramic filters.
Tuners with tuned circuit filters are a whole different ball of wax.
Have to agree, changing ecaps in a tuner, hard to see how that would affect the tuners alignment. Most, if not all, are used for supply filtering/signal-coupling and never used as an RF filter.
Most older SS analog tuners use either a quad detector(HA1137/CA3089,etc) or ratio detector as a discriminator. Usually need a DA to set these correctly, have a look at the HA1137/CA3089/Sanyo specs as a reference. Better SS tuners used the double tuned quad coil, cheaper units used the single coil.
Tuning ckts in the IF filter stages, I agree a real pain and more work, but most tuners use CF's, so they remove that problem.
Anyone aligned one of those "www.magnumdynalab.com" units? They seem to be one of the most sophisticated ones out there, from what I can tell.
Most older SS analog tuners use either a quad detector(HA1137/CA3089,etc) or ratio detector as a discriminator. Usually need a DA to set these correctly, have a look at the HA1137/CA3089/Sanyo specs as a reference. Better SS tuners used the double tuned quad coil, cheaper units used the single coil.
Tuning ckts in the IF filter stages, I agree a real pain and more work, but most tuners use CF's, so they remove that problem.
Anyone aligned one of those "www.magnumdynalab.com" units? They seem to be one of the most sophisticated ones out there, from what I can tell.
69sixpackbee
Well-Known Member
".... alot of you old ppl"
Hey, Conrad, I think he meant you!
LOL :thmbsp:
Moreover, that "term" is read rather loosely. That "term" can usually be construed as "experienced" to which I will reiterate...Hey, Conrad, I think he meant you!
And I unequivocally know M.T.F. is it this category as well
Bud
Hey, Conrad, I think he meant you!
LOL :thmbsp:
Moreover, that "term" is read rather loosely. That "term" can usually be construed as "experienced" to which I will reiterate...Hey, Conrad, I think he meant you!
And I unequivocally know M.T.F. is it this category as well
Bud
The problem is the audience we are writing to.... there is a large proportion that will not be able or willing to discriminate between the different stages of technology used in the tuners, from the older models that did everything in discrete components through integrated circuits.
BUT either way, you affect the discriminator tuning, thus taking a high end tuner and reducing it to MOTL or BOTL performance.
I would get too damn many complaints of "the tuner sounds WORSE after I recapped it - you steered me WRONG!!!" that I am UNWILLING to stick my fingers in that particular meat grinder.
And even IF the only sections affected are AFTER the discriminator - they STILL will sound WORSE (and generate complaints) until re-aligned.
Re: bran ... A little forgiveness and forbearance goes a long way.
BUT either way, you affect the discriminator tuning, thus taking a high end tuner and reducing it to MOTL or BOTL performance.
I would get too damn many complaints of "the tuner sounds WORSE after I recapped it - you steered me WRONG!!!" that I am UNWILLING to stick my fingers in that particular meat grinder.
And even IF the only sections affected are AFTER the discriminator - they STILL will sound WORSE (and generate complaints) until re-aligned.
Re: bran ... A little forgiveness and forbearance goes a long way.
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".... alot of you old ppl"
Hey, Conrad, I think he meant you!
LOL :thmbsp:
Moreover, that "term" is read rather loosely. That "term" can usually be construed as "experienced" to which I will reiterate...Hey, Conrad, I think he meant you!
And I unequivocally know M.T.F. is it this category as well
Bud
HEY, I didn't WANT to get old. I was havin so MUCH FUN it SNUCK UP on me.
Doesn't help that the big 55 is comin up in May... Man, the definition of "old fart" is really slippin further and further up the scale for me....
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phildoc
Well-Known Member
It does appear that way.
"Although at the moment, I need a good distortion analyzer to do them right. "
Lots of discussion on diyaudio forum about making a DA. Many are using an external notch filter to reduce the fundamental by say -60dB, then passing the residual to the sound card. Seems to be free FFT SW out there to run on the PC. So the tradition DA equipment is not necessarilly needed anymore.
If you want more info I can provide some links.
Lots of discussion on diyaudio forum about making a DA. Many are using an external notch filter to reduce the fundamental by say -60dB, then passing the residual to the sound card. Seems to be free FFT SW out there to run on the PC. So the tradition DA equipment is not necessarilly needed anymore.
If you want more info I can provide some links.
Very true, and a point that I sometimes overlook myself. And really, if one doesn't really know what he is doing, one should touch ANY adjustment in a receiver or amplifier. I've lost count of the the number of threads where the owner of a vintage amp or receiver has blown the output transistors trying to set the bias and DC offset himself.
I only have a crummy Sencore SG-165, Leader 231, and Meguro DA for tuner work.
69sixpackbee
Well-Known Member
Hey, it's not that crummy. I have one too
I admit its not the greatest but it has been good for me as a learning tool. I have a Fluke counter and a Thurlby FG and a good 4-channel Tektronix scope.
I've been dabbling a bit with these on "Junkers" to get a feel for them. Still, I am sending my STA-2100D to Mike (PunkerX) for a "proper" alignment.
Sent from my iPhone using Tapatalk
That misses the fundamental point: the RF signal going INTO the tuner HAS to have an ULTRA LOW DISTORTION modulating signal applied. How else can you judge the clean output - trying to NULL distortion on a 1 percent or 0.5 percent distorted source signal?
You COULD get away with ULD Mono FM, and a dirty FM stereo signal to set the pilot rejection and channel separation. But then you really have to know what you are doing.
And WHAT is the latency of these PC calculated numbers, it will drive you NUTS trying to adjust and null the discriminator with any sort of delay, and will be worse for the less experienced.
Not refuting, just pointing out where the theoretical departs from the practical.
I would LOVE to have a real time audio FFT readout I can use, just flip a switch or boot up and use it like a scope.
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That misses the fundamental point: the RF signal going INTO the tuner HAS to have an ULTRA LOW DISTORTION modulating signal applied. How else can you judge the clean output - trying to NULL distortion on a 1 percent or 0.5 percent distorted source signal?
You COULD get away with ULD Mono FM, and a dirty FM stereo signal to set the pilot rejection and channel separation. But then you really have to know what you are doing.
And WHAT is the latency of these PC calculated numbers, it will drive you NUTS trying to adjust and null the discriminator with any sort of delay, and will be worse for the less experienced.
Not refuting, just pointing out where the theoretical departs from the practical.
I would LOVE to have a real time audio FFT readout I can use, just flip a switch or boot up and use it like a scope.
Even dedicated spectrum analyzers can take up to a minute to boot up. Software like TruRTA has less than 1 second delay in FFT processing if you turn off averaging (and thus accept lower resolution). It is enough for near real time tuning of things like turntable VTA setting.
leesonic
Captured on security camera...
(ahem)...
The few receivers I've worked on, I have always changed the caps in both the amp and tuner sections. Ironically, of the two units I took pictures of and posted here, only the Pioneer SX-535 had all the caps replaced. The SX-626, I only replaced the caps (and transistors) on the power amp board, and for an added dose of irony, was sold to a fellow AK'er who planned on using it as a pre-amp only.
I've done quite a few tuners as well, I seem to run into a lot of Kenwood KT-7500s, so they're the ones I have most pictures of. But none of them I've ever performed an alignment on, mainly because I don't have the equipment to do it.
As for the whole "re-cap or not debate", my view is this. If you're got the thing open to investigate and repair a fault, why not replace these old caps while you're at it? The small signal capacitor costs are usually a drop in the ocean compared to the cost of replacing the main power supply smoothing caps, this being especially true with amps that have two per channel, like the Kenwood KA-7100 or Pioneer SA-7800. There are pieces of equipment that I have successfully repaired just by re-capping, just two examples I can think of (and that I have pictures of) are a Technics turntable and an RCA power amp.
Lee.
The few receivers I've worked on, I have always changed the caps in both the amp and tuner sections. Ironically, of the two units I took pictures of and posted here, only the Pioneer SX-535 had all the caps replaced. The SX-626, I only replaced the caps (and transistors) on the power amp board, and for an added dose of irony, was sold to a fellow AK'er who planned on using it as a pre-amp only.
I've done quite a few tuners as well, I seem to run into a lot of Kenwood KT-7500s, so they're the ones I have most pictures of. But none of them I've ever performed an alignment on, mainly because I don't have the equipment to do it.
As for the whole "re-cap or not debate", my view is this. If you're got the thing open to investigate and repair a fault, why not replace these old caps while you're at it? The small signal capacitor costs are usually a drop in the ocean compared to the cost of replacing the main power supply smoothing caps, this being especially true with amps that have two per channel, like the Kenwood KA-7100 or Pioneer SA-7800. There are pieces of equipment that I have successfully repaired just by re-capping, just two examples I can think of (and that I have pictures of) are a Technics turntable and an RCA power amp.
Lee.
Tuner discussion
hey Lee, good input.
Mark;
Actually off topic, how many tuners do you actually do a year? Never said that the equipment is what is required for a production line, needing a fast responding DA/FFT analyzer, this is just a general discussion and I am offering some soultions for the folks that can not afford something expensive. I have worked in a radio factory, for 7 years, you may have heard of them, "Motorola", I think they maybe close to where you live, they tuned radios by the thousands, so I have an idea of what it takes.
Don't criticize these PC solutions unless you have actually done some evaluations of what is out there. So, what PC DA/FFT solution's have you evaluated so far, results? I have only read so am certainly not an expert.
All depends on what your testing, very few tuners are able to get lower than 0.1% THD. Cheap tuners are usually spec'd at 0.5% mono. Of course you can not use a 1% source to measure 0.1%, this is rather obvious I would think. There is one thing to null a demodulator for lowest distortion, then another thing to measure it with absolute accuracy. The audience is service people in this discussion not EE's designing/testing the latest tuner.
What are you folks using for a low distortion SG's? general test setups, I'd like to know.
I have a HP 8656B, I have measured its distortion, using a 8901A Modulation Analyzer and a Amber 3501 DA. I measure it be around 0.1%@1Khz, not too bad, there are few of them that are better, more worse, but I am only a hacker that chooses to afford cheap test equipment from eBay.
I'd love to have one of these: R&S SML01, wouldn't every one like one for xmas.
hey Lee, good input.
Mark;
This was not my point at all!!
Actually off topic, how many tuners do you actually do a year? Never said that the equipment is what is required for a production line, needing a fast responding DA/FFT analyzer, this is just a general discussion and I am offering some soultions for the folks that can not afford something expensive. I have worked in a radio factory, for 7 years, you may have heard of them, "Motorola", I think they maybe close to where you live, they tuned radios by the thousands, so I have an idea of what it takes.
Don't criticize these PC solutions unless you have actually done some evaluations of what is out there. So, what PC DA/FFT solution's have you evaluated so far, results? I have only read so am certainly not an expert.
All depends on what your testing, very few tuners are able to get lower than 0.1% THD. Cheap tuners are usually spec'd at 0.5% mono. Of course you can not use a 1% source to measure 0.1%, this is rather obvious I would think. There is one thing to null a demodulator for lowest distortion, then another thing to measure it with absolute accuracy. The audience is service people in this discussion not EE's designing/testing the latest tuner.
What are you folks using for a low distortion SG's? general test setups, I'd like to know.
I have a HP 8656B, I have measured its distortion, using a 8901A Modulation Analyzer and a Amber 3501 DA. I measure it be around 0.1%@1Khz, not too bad, there are few of them that are better, more worse, but I am only a hacker that chooses to afford cheap test equipment from eBay.
I'd love to have one of these: R&S SML01, wouldn't every one like one for xmas.
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BranMPioneer
Member
++1