CZ and Simon ----
That was the source !! A-P gen on/off does do anything of the sort. The on/off only selects the freq you have put in. Other wise the internal gen is on the last freq you turned' On'. It is actually a 'select' or 'enter' button. And the real On-Off is the button to the left called output "A" and the one to the right called output "B". They truely turn on and off the generator.
Thank you for the sharp eyes and feedback.
Here is the 2H and 3H of a 1.5KHz signal from david's osc/generator source. No 10KHz
THx-RNMarsh
That was the source !! A-P gen on/off does do anything of the sort. The on/off only selects the freq you have put in. Other wise the internal gen is on the last freq you turned' On'. It is actually a 'select' or 'enter' button. And the real On-Off is the button to the left called output "A" and the one to the right called output "B". They truely turn on and off the generator.
Thank you for the sharp eyes and feedback.
Here is the 2H and 3H of a 1.5KHz signal from david's osc/generator source. No 10KHz
THx-RNMarsh
Just an interesting side issue for me to look into........ the Panasonic VP-7722A reads .00033% THD+N and the A-P reads .00022% Both with david's gen set at 500Hz signal at 2.5 v and both filtered for noise at 400Hz and 30KHz. maybe filter slopes are different or Pana has more noise within BP.
THx-RNMarsh
THx-RNMarsh
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This is a bit better than what I measure. The noise floor of the TT and 0204 is higher and makes it appear as if the distortion in into the noise floor. This quite is reveling. I measure around -135dB at 20kHz. I'm interested to see what the AP measures.
Thanks for all you diligent work in getting these measurements.
Now for round two, the post amplifier.
CZ and Simon ----
That was the source !! A-P gen on/off does do anything of the sort. The on/off only selects the freq you have put in. Other wise the internal gen is on the last freq you turned' On'. It is actually a 'select' or 'enter' button. And the real On-Off is the button to the left called output "A" and the one to the right called output "B". They truely turn on and off the generator.
Thank you for the sharp eyes and feedback.
Here is the 2H and 3H of a 1.5KHz signal from david's osc/generator source. No 10KHz
View attachment 428560
Should read..... A-P gen on/off does NOT do anything of the sort.
THx-RNMarsh
It been my pleasure.
Fast reverse to a year ago .... I found it was very useful to be able to vary/tune the notch filter to get the true or accurate harmonic level reading... esp 2H... but 3H as well. I tried the B&K and HP332 variable notch but it was not low distortion and too much work to get that piece useful for every low distortion measurements. I suggested we really needed a variable freq osc AND a variable freq notch filter to go along with it. Preferably auto-tune.
Any volunteers? We need a volunteer.
The final part of the distortion test setup is the ADC and SW. That is done on several fronts. It can always get better.
You will get lots of help in all ways and means.
THx-RNMarsh
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Richard the 10kHz distortion is elevated by leakage from the sync signal off the zero crossing detector. It is this signal that's routed to the micro controller for frequency counting. This showed up at the last minute when I was packaging the SVO to send to you. I didn't have time to clean it up. I thought the shielded cable connecting the boards would be enough, but it isn't. The isolator IC has schmitt triggers at it's inputs. I think the sharp edge is causing the problem. I might try a different form of isolation like a miniature transformer.
A digital audio trafo might work fed by a sine rather than square wave form. Control signals have to be shaped to a soft form in oscillators or we get this sort of thing.
The input to the micro has a schmitt trigger. I don't think it needs to be done twice. It improves if the shielded cable is disconnected from the control board.
It's not causing the 10kHz problem at other frequencies though. This signal is in phase with the oscillator. It is derived from it.
I just got home from work. I'm tired. And the town is full of smoke from the forest fires.
The smoke overcasting the sun drives the heat up. We are cooking here. I have no air conditioning. Remember last week?
Beginning to ask myself the same question. I dont want to go the last cm to find out as the time goes up exponentially.
This osc/generator is cleaner than the A-P generator. Noise about the same. The A-P analyzer is very very good though.
I might have to get the ShibaSoku 725D analyzer and look at its monitor output on the lowest range to get an answer. I think Demian has lowered the noise some amount in it and that will help go deeper with the distortion analysis.
Otherwise, as a stand-alone audio signal generator, one could assume anything they measure in an audio amp, at least, will have to be better than -130 or -135dB before running into test generator issues. Or better than .000032 to .000018%
THx-RNMarsh
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It may be easier to send the oscillator here. I have two 725's set up and other possibly useful devices including the AK53954A ADC which has a distortion floor close to -130db when everything is just right. Used with a notch (the ones from Jens are getting built) the floor will be pretty low. I can also turn up the resolution of the ADC to a pretty ridiculous 16M points (at 44.1 it takes a long time to make a measurement) and get much further into the noise floor. Probably should be looking at correlation to get deeper into the distortion.
Sorry to hear about the forest fire smoke. I "vacationed" near Yosemite during the big fire there and its was really bad when the wind came our way. Its not healthy in any sense.
Sorry to hear about the forest fire smoke. I "vacationed" near Yosemite during the big fire there and its was really bad when the wind came our way. Its not healthy in any sense.
Hi Demian,
I think you might be able to go very low below the noise floor with 16M points. And see some harmonics the A-P doesnt. But a distortion floor of -130dB will not be good enough as you can see from the A-P graphs. Just to know what it can do so it can be told to others who might build/buy one.
When I do my own testing I learn more than just getting the distortion data. Like all the extrainious noise sources that come into the picture and solutions for my test environment. Even that -140dB 10KHz signal was something I can apply to other gear/DUT. All learning experiences.
Before I let go of the generator, I want to see what more I can do and learn.
THx- RNMarsh
I think you might be able to go very low below the noise floor with 16M points. And see some harmonics the A-P doesnt. But a distortion floor of -130dB will not be good enough as you can see from the A-P graphs. Just to know what it can do so it can be told to others who might build/buy one.
When I do my own testing I learn more than just getting the distortion data. Like all the extrainious noise sources that come into the picture and solutions for my test environment. Even that -140dB 10KHz signal was something I can apply to other gear/DUT. All learning experiences.
Before I let go of the generator, I want to see what more I can do and learn.
THx- RNMarsh
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The smoke is pretty high up. But it makes driving seem kind of weird. There's a darkness that isn't there on an overcast day. Mostly it's unbearably hot. We think much about having a/c up here. Most of the year it's -25 deg C. That's -13 F. I'm sure by now there won't be a single a/c unit left in town.
You welcome to check the SVO out whenever Richard has had his fill. I'll leave that between the two of you.
HP339A Level Pot Other General Questions
Hi Dave,
If you can think back to your HP339A when you changed that OSC level
pot, do you recall if there was room for a standard shaft diameter?
The bourns cermet pot y'all used I assume you had one in your box?
That you didn't have to order one? I recall a quick discussion about wirewound would have less distortion than the boruns cermet pot.
That OSC level pot was PN: a 51SADU25A15L. It has a 3mm
dia shaft. Do you think a 1/4 inch shaft O.D. will work?
Richard, did you have a part number for that spectrol 3/8" 3/8"
you used?
Then before I dig into my 339 wondering what you found
that you liked for the Low Noise Quad JEFT opamp.
Did you use that also for the filters and other the null?
TLO74? is there a better one to use?
I guess I need four of these?
or
How goes that mod with the SOIC to 8 pin DIP for the
filters with that other chip, the OPA1654?
Then for the JFET A1Q2 The control FET (Variable Resistor)
Was that replaced with the 2N4092?
Also, after that, to dial it in I guess I need to buy a QA400?
As I don't have any spec analyzers.
There seem to be a lot of the .1uf 100V ceramic caps. Are these worth
replacing while I'm in there?
I'm kind of late to the party and I think what you've laid the foundation
for DIY guys like me is great. I hope to get a lot of good use out
of the 339A. While I'm in there and have it open of course I'm going
to replace the electrolytics in the power supply for reliability sake.
I guess it wouldh't hurt to choose 1500uf 100V 105C caps vice the 1000uf caps that it came with.
I'll be keeping an eye out for the Tants that seem to be all over the 339A.
especially the back to back caps.
Dave, Demian, Richard (RNM), DickMoore aka (Rich EEEEEm) Dimiri,
Scott, und Der Schweizer (Samuel), Jack in Joysey, and anyone else I missed,
THANK YOU.
2000 post brain dead some 1700 to go.
If there is any interest I can start a WIKI for this which would summarize.
The problem with the WIKI I think your only limited to 10 pictures.
Hi Dave,
If you can think back to your HP339A when you changed that OSC level
pot, do you recall if there was room for a standard shaft diameter?
The bourns cermet pot y'all used I assume you had one in your box?
That you didn't have to order one? I recall a quick discussion about wirewound would have less distortion than the boruns cermet pot.
That OSC level pot was PN: a 51SADU25A15L. It has a 3mm
dia shaft. Do you think a 1/4 inch shaft O.D. will work?
Richard, did you have a part number for that spectrol 3/8" 3/8"
you used?
Then before I dig into my 339 wondering what you found
that you liked for the Low Noise Quad JEFT opamp.
Did you use that also for the filters and other the null?
TLO74? is there a better one to use?
I guess I need four of these?
or
How goes that mod with the SOIC to 8 pin DIP for the
filters with that other chip, the OPA1654?
Then for the JFET A1Q2 The control FET (Variable Resistor)
Was that replaced with the 2N4092?
Also, after that, to dial it in I guess I need to buy a QA400?
As I don't have any spec analyzers.
There seem to be a lot of the .1uf 100V ceramic caps. Are these worth
replacing while I'm in there?
I'm kind of late to the party and I think what you've laid the foundation
for DIY guys like me is great. I hope to get a lot of good use out
of the 339A. While I'm in there and have it open of course I'm going
to replace the electrolytics in the power supply for reliability sake.
I guess it wouldh't hurt to choose 1500uf 100V 105C caps vice the 1000uf caps that it came with.
I'll be keeping an eye out for the Tants that seem to be all over the 339A.
especially the back to back caps.
Dave, Demian, Richard (RNM), DickMoore aka (Rich EEEEEm) Dimiri,
Scott, und Der Schweizer (Samuel), Jack in Joysey, and anyone else I missed,
THANK YOU.
2000 post brain dead some 1700 to go.
If there is any interest I can start a WIKI for this which would summarize.
The problem with the WIKI I think your only limited to 10 pictures.
It makes for some spectacular sunsets.
Makes for some intense red suns,
orange moons.
It makes it sound like a commercial for breakfast cerial
Lucky Charms, it's magically delicious.
Dave you told us what the low temps are,
wondering what the hot temps are?
What's your humidity up there, AAAAA?
Create fake masterpiece art and earn 80 Million USD.
Create a fake Jackson Pollack using yellow paint
that wasn't made until 17 years after Pollack's death
and make a kewl 17 Million USD.
I have an old art history book shoved somewhere
amoung my electronics books.
Thanks for the bandwidth,
I know it's slanted topic,
I'll try to stay on topic.
Cheers,
@SyncTronX -- I bought a number of better quad amps but have yet to make any mods to my 339 other than the oscillator control FET's gate feedback trimpot-- just haven't had time, and summer is more about yard and house.
I hope to go back to the 339 in the fall and try to run down the sources of the relatively high 2nd harmonic in the notch amp that limits the 339's THD+N result; certainly a deeper null would be good too, but it seems to run about -115dB on my unit, so that's pretty good. A 10dB overall improvement result (0.0003%) would be about the most I expect and would satisfy me for this unit.
I hope to go back to the 339 in the fall and try to run down the sources of the relatively high 2nd harmonic in the notch amp that limits the 339's THD+N result; certainly a deeper null would be good too, but it seems to run about -115dB on my unit, so that's pretty good. A 10dB overall improvement result (0.0003%) would be about the most I expect and would satisfy me for this unit.
Hi SyncTronX,
To use a 1/4" OD you'd have to find a shaft coupler to reduce it to the 3mm/0.125".
Then there is alignment. You might have to use a flexible shaft coupler. The mounting is designed for 1/8" shaft part. I did order this from Digikey. A wire wound part might get you a bit less noise but the wiper after some time can cause just as much or more distortion.
A micro layer of corrosion between dissimilar metals will form a mild diode.
You might try a opa1644. It only comes in SMT so you would have to use a breakout adapter. The 2n part is no longer available but you can use the PN4092 or PN4392.
They don't seem to work quite as well as the HP selected part but better than an off the shelf same part number.
I think the production of the QA400 is halted at the moment but do confirm this with QuantAsylum.
I don't think replacing the ceramic cap will give you any measurable performance boost with the 339A. The noise is too high to even notice.
Yes rebuild the power supply.
You probably don't need to touch the tantalum caps. The ones HP used seem to last forever.
I think I went to 4700uF caps because they came in same lead space.
The back to back caps can be replaced with high quality bipolar elecro.
Cheers,
Parts and Congrats for Dave
Dave,
I just backed up and read the latest on your OSC.
That looks great from the FFT, CONGRATS!
I've read enough to know that you worked your *** off
on that. I know that at points you were frustrated, pissed,
discouraged, tired, fatigued, brain dead, anything else that
I missed...you walked away, then came back and worked your
way through the challenges. Well done.
It is way over my head, but I can appreciate what you accomplished.
It makes me kinda feel funny asking for info about a pot, LOL.
It is what it is.
I'll just go with the Bournes cermet and be done with it.
I'll pick up a few LT1468s for the OSC and some w/o compensation.
If whatever for the Q2 by the OSC, I'll just leave it alone then, no sense
buying something worse to put in there.
Will do for the P/S. Yeah, I have some 4700 electro's and various others too. I'll put in there what ever fits.
It will also save me a lot of work not replacing all the Tants.
Will have to give all the pots and switches a good careful cleaning.
Dick,
What do you think for that quad JFET opamp?
As an aside, we forget here in Texas what you northerners have to go through.
How short your summers are and how you want to take advantage of it.
Get out doors and do things. Unlike what Dave is going through.
Dave, this time of year here in Texas it is hotter than a ships bell.
We want to stay inside to survive the heat and crank up the A/C.
And if you don't have it you are miserable. Richard knows too, he burned up over in Thailand. While he was overseas it hit 115 in California, he dodged the bullet.
It won't do you any good Dave to know it takes 6 to 10 weeks for your body
to acclimate to high temps. W/o A/Cs you might be able to make a swamp
cooler too good effect. Maybe a fan or two blowing over wet towels over
a milk or egg crate might work. Or Blowing over a large pan of water.
Swamp coolers work best with low humidity.
It might give you some needed relief. And just think, you can build
something that will make you physically more comfortable.
Cheers,
Dave,
I just backed up and read the latest on your OSC.
That looks great from the FFT, CONGRATS!
I've read enough to know that you worked your *** off
on that. I know that at points you were frustrated, pissed,
discouraged, tired, fatigued, brain dead, anything else that
I missed...you walked away, then came back and worked your
way through the challenges. Well done.
It is way over my head, but I can appreciate what you accomplished.
It makes me kinda feel funny asking for info about a pot, LOL.
It is what it is.
I'll just go with the Bournes cermet and be done with it.
I'll pick up a few LT1468s for the OSC and some w/o compensation.
If whatever for the Q2 by the OSC, I'll just leave it alone then, no sense
buying something worse to put in there.
Will do for the P/S. Yeah, I have some 4700 electro's and various others too. I'll put in there what ever fits.
It will also save me a lot of work not replacing all the Tants.
Will have to give all the pots and switches a good careful cleaning.
Dick,
What do you think for that quad JFET opamp?
As an aside, we forget here in Texas what you northerners have to go through.
How short your summers are and how you want to take advantage of it.
Get out doors and do things. Unlike what Dave is going through.
Dave, this time of year here in Texas it is hotter than a ships bell.
We want to stay inside to survive the heat and crank up the A/C.
And if you don't have it you are miserable. Richard knows too, he burned up over in Thailand. While he was overseas it hit 115 in California, he dodged the bullet.
It won't do you any good Dave to know it takes 6 to 10 weeks for your body
to acclimate to high temps. W/o A/Cs you might be able to make a swamp
cooler too good effect. Maybe a fan or two blowing over wet towels over
a milk or egg crate might work. Or Blowing over a large pan of water.
Swamp coolers work best with low humidity.
It might give you some needed relief. And just think, you can build
something that will make you physically more comfortable.
Cheers,