I bought a well used 200CDR back in 1971 from Eli Heffron's in Cambridge. i got it cheap because the output was pulsating - clean but the output was not steady. I pulled off the case and found it had a pair of 6V6 output tubes, those were supposed to be 6F6. The Rp of those two types is very different so I picked up a pair of 6F6's and all was well. The 6S6 bulb was dibe and the unit had very low distortion. That oscillator has been on my bench for 50+ years and has never given me a lick of trouble - not bad for the $30 i paid for it way back then.
Nice equipment! I like to tap on the glass (or metal) envelope of the tubes when doing short tests. I've found quite a few bad tubes with intermittent shorts that way. Also, I like to shake metal tubes, and if the sound like a salt and pepper shaker, no since to test. Take care.
Love these Wien Bridge Oscillators, I have made a 1Khz fixed version made with an op amp and a 12v bulb with a low distortion better than 0.01 % I bet Dr Hewlett would like to have seen it, great video !
9:44 It looks like your oscillator is relaxing too quickly, so I guess it's a carbon composite that has "shrunken" a little. Edit 13:00 Ok, I was wrong. What an interesting failure mode!
This was a low distortion design (VERY low for the time) the SG505 from Tek does beat it out with a slightly newer unit. the HP 200 was HP's first product and what started it all. This is the low frequency variant of the first revision being the 201 There is a wide band variant of the 201 the CD which is currently on my bench and in service as one of my test oscillators. The 201C had a lower top frequency but the output was WAY higher at 3 Watts.
@@ZenwizardStudios For those interested the technical article co-authored by Hewlett relevant to the HP 200 series is in IRE Oct 1939 Terman & Hewlett’s oscillator article, pgs 649-655. There'a an HP200J with original manual on the bench here beckoning for its refurb. Extended very low frequency range. Intended for mixing with various low frequency oscillators to generate sea-state waveforms in analog computation work. As you say, high quality design and construction.
I have 202 cr works great but it was nice to see how it comes apart, thanks for the video
I bought a well used 200CDR back in 1971 from Eli Heffron's in Cambridge. i got it cheap because the output was pulsating - clean but the output was not steady. I pulled off the case and found it had a pair of 6V6 output tubes, those were supposed to be 6F6. The Rp of those two types is very different so I picked up a pair of 6F6's and all was well. The 6S6 bulb was dibe and the unit had very low distortion.
That oscillator has been on my bench for 50+ years and has never given me a lick of trouble - not bad for the $30 i paid for it way back then.
Excellent! I still have a 200CD on the bench today just not the R version. They really are fantastic units.
Nice equipment! I like to tap on the glass (or metal) envelope of the tubes when doing short tests. I've found quite a few bad tubes with intermittent shorts that way. Also, I like to shake metal tubes, and if the sound like a salt and pepper shaker, no since to test. Take care.
Love these Wien Bridge Oscillators, I have made a 1Khz fixed version made with an op amp and a 12v bulb with a low distortion better than 0.01 % I bet Dr Hewlett would like to have seen it, great video !
9:44 It looks like your oscillator is relaxing too quickly, so I guess it's a carbon composite that has "shrunken" a little.
Edit 13:00 Ok, I was wrong. What an interesting failure mode!
Hasn't this been the first product of Mssrs Hewlett and Packard ?
There was one model before The original original was the 200. This is the 201.
Can distortioin be plotted across the spec'd frequency ranges? Was this their very low distortion design? Was one of HP's claim to fame?
This was a low distortion design (VERY low for the time) the SG505 from Tek does beat it out with a slightly newer unit. the HP 200 was HP's first product and what started it all. This is the low frequency variant of the first revision being the 201 There is a wide band variant of the 201 the CD which is currently on my bench and in service as one of my test oscillators. The 201C had a lower top frequency but the output was WAY higher at 3 Watts.
@@ZenwizardStudios For those interested the technical article co-authored by Hewlett relevant to the HP 200 series is in IRE Oct 1939 Terman & Hewlett’s oscillator article, pgs 649-655. There'a an HP200J with original manual on the bench here beckoning for its refurb. Extended very low frequency range. Intended for mixing with various low frequency oscillators to generate sea-state waveforms in analog computation work. As you say, high quality design and construction.