I did NOT say "Go to Nymeria.com"; it doesn't go anywhere!
The correct link, that I gave, is ArtekManuals | Your one stop shop for out of print test equipment manuals
I trust that there are no vested interests behind this "Nymeria modification"!
The correct link, that I gave, is ArtekManuals | Your one stop shop for out of print test equipment manuals
I trust that there are no vested interests behind this "Nymeria modification"!
C35?
I know this is a old dead thread, but I need help. My HP339A was working well when you folks wrote all this. I have read most of it and searched also. But I am unable to locate C35 for replacement. I believe if I am seeing correctly it is at the output of the oscillator. Inside the cover I found a choke, but no cap. I have stared at the board a long time and am still not seeing it listed. The photo shows what I think maybe it. The blue thing is a relay. It's the little red cap with no listing next to the relay? I want to thank you all in advance for a great thread and all the help!
I know this is a old dead thread, but I need help. My HP339A was working well when you folks wrote all this. I have read most of it and searched also. But I am unable to locate C35 for replacement. I believe if I am seeing correctly it is at the output of the oscillator. Inside the cover I found a choke, but no cap. I have stared at the board a long time and am still not seeing it listed. The photo shows what I think maybe it. The blue thing is a relay. It's the little red cap with no listing next to the relay? I want to thank you all in advance for a great thread and all the help!
Thats it I think - between the relay and R76. its a small blue ceramic (rather than red) on my 339A.
Kerry
Kerry
Coming to the party late
As usual, I am arriving a few years late, but none the less, here I am, after having just found one of my 2, HP339As. Wondering if any of the original 6 or so guys in the first 60 pages of this thread are still following it? 😀
I bought these 15 years ago and have used one as is back then, the other was damaged in shipping and I can't find it (have 2 shops and a basement that it could still be packed in). I just pulled the cover off the good one and wow! I can't believe how well built these are, quite lovely inside. I am really reluctant to do anything other than clean the switches and such, but I may decide to at least do the minor recommended mods, update the OSC chip and a few R's and C's. Mine was built in late 1987 by the date codes on the parts, I think close to the end of production?? I have finished reading the first 60 pages...still plodding thru the rest. I found the WIKI with a summary of mods so will read that next. I have ordered the LT1468s and will decide how much further I want to go. I may continue searching for the damaged unit and mod it first, it was only cosmetic, broken knobs and such, I can't even recall if it worked.
Anyway, my adventure begins now, back to reading and looking.
Cheers
As usual, I am arriving a few years late, but none the less, here I am, after having just found one of my 2, HP339As. Wondering if any of the original 6 or so guys in the first 60 pages of this thread are still following it? 😀
I bought these 15 years ago and have used one as is back then, the other was damaged in shipping and I can't find it (have 2 shops and a basement that it could still be packed in). I just pulled the cover off the good one and wow! I can't believe how well built these are, quite lovely inside. I am really reluctant to do anything other than clean the switches and such, but I may decide to at least do the minor recommended mods, update the OSC chip and a few R's and C's. Mine was built in late 1987 by the date codes on the parts, I think close to the end of production?? I have finished reading the first 60 pages...still plodding thru the rest. I found the WIKI with a summary of mods so will read that next. I have ordered the LT1468s and will decide how much further I want to go. I may continue searching for the damaged unit and mod it first, it was only cosmetic, broken knobs and such, I can't even recall if it worked.
Anyway, my adventure begins now, back to reading and looking.
Cheers
I'm still interested in the 339A - although I haven't used mine much lately. I used the WIKI and the detailed info provided by others on this forum to fix mine - thanks everyone. Most of the work was on fixing broken knobs/damaged scale markings - but I also did the LT1468 oscillator upgrade and replaced the attenuator pot.
There is also lots of information on the HP-Agilent-Keysight-equipment@groups.io site.
Kerry
There is also lots of information on the HP-Agilent-Keysight-equipment@groups.io site.
Kerry
With respect Kerry, that's an e-mail address, not a website!
I went down the "Replace the Osc. IC with LT1468 and replace the pot route"; couldn't detect any difference, but this may mean one can't use an H-P 339A below .001%.
Trouble is anything suitable costs an arm and a leg...
I went down the "Replace the Osc. IC with LT1468 and replace the pot route"; couldn't detect any difference, but this may mean one can't use an H-P 339A below .001%.
Trouble is anything suitable costs an arm and a leg...
It's unfortunate that davada, RichieM, and 31697B aren't around anymore to thank for the great debugging and problem-solving they did on the 339A. Really superb work they did on an instrument that is still very useful.
I just finished repairing and upgrading one and it performs just like the others did; analyzer H2 about -105dB, H3 about -115dB, oscillator harmonics are below anything I have to measure them with. And it's fast and convenient to use. A nice addition to the bench.
I just finished repairing and upgrading one and it performs just like the others did; analyzer H2 about -105dB, H3 about -115dB, oscillator harmonics are below anything I have to measure them with. And it's fast and convenient to use. A nice addition to the bench.
Richard Marsh has asked me to post his email address for anyone who wants/needs to contact him about the 339A mods. It is rmarsh@calweb.com . Include the word "Audio" in the subject line so he knows is isn't spam.
Well, I finally got back to updating my 339A and only changed U1 to the LT1468 and put in a 5K pot in place of R51. I am able to achieve the following, just wondering if this is a decent result, I still will change the output pot but for now I am done.
Using just twisted clip leads going from out to in...
1KHz - .0012% at 3V out, 10V rises to about .05%
20Khz - .05% at 3V and 10V
100 Hz - .06% at 3 and 10V out
65KHz - .05% at 3 forgot to check 10.
I don't have any way to look at the Monitor output short of a scope, but my 475 doesn't display any wave forms, just noise so I don't know if my monitor out is faulty or this is normal. As I can't see H2 output I have no way to fine tune R51, and waht is the best setting for R30, the AGC, I measured -1.7VDC at TP8 before I started the mods, no change after but I recall someone stating .4VDC is a good value, just not sure why.
Your thoughts?
Cheers
Using just twisted clip leads going from out to in...
1KHz - .0012% at 3V out, 10V rises to about .05%
20Khz - .05% at 3V and 10V
100 Hz - .06% at 3 and 10V out
65KHz - .05% at 3 forgot to check 10.
I don't have any way to look at the Monitor output short of a scope, but my 475 doesn't display any wave forms, just noise so I don't know if my monitor out is faulty or this is normal. As I can't see H2 output I have no way to fine tune R51, and waht is the best setting for R30, the AGC, I measured -1.7VDC at TP8 before I started the mods, no change after but I recall someone stating .4VDC is a good value, just not sure why.
Your thoughts?
Cheers
I'd say you're in pretty good. shape.
I think if you keep your scope on the Monitor output and mess with Frequency knobs, you'll be able watch initial imbalance in null drop into the noise.
Marsh and others liked to view Monitor on a spectrum analyzer and trim R30 for perfect null of 2nd harmonic. I think HP's label of R30 as "Amplitude Adjust" is a bit of a misnomer. It trims the set point at TP8. My inclination would be to trim for lowest total HD, but again you have to use spectrum analysis to see the distortion beneath the noise floor.
Cheers!
I think if you keep your scope on the Monitor output and mess with Frequency knobs, you'll be able watch initial imbalance in null drop into the noise.
Marsh and others liked to view Monitor on a spectrum analyzer and trim R30 for perfect null of 2nd harmonic. I think HP's label of R30 as "Amplitude Adjust" is a bit of a misnomer. It trims the set point at TP8. My inclination would be to trim for lowest total HD, but again you have to use spectrum analysis to see the distortion beneath the noise floor.
Cheers!
