HP 200C Wein Bridge oscillator up for sale on eBay. $125. <http://www.ebay.com/itm/Vintage-Hewlett-Packard-HP-200C-Vacuum-Tube-Audio-Oscillator-/361862146302?hash=item5440aa28fe:g:ROkAAOSw2xRYXvsQ> "Thank You For Looking At Are Item"
The HP Original for sale
Started by ●July 2, 2017
Reply by ●July 2, 20172017-07-02
The 200C isn't the original 1939 model. It was the last tube instrument HP sold (CRTs and PMTs apart) and was in their 1985 catalogue. (Yes, I have one.) ;) Cheers Phil Hobbs
Reply by ●July 2, 20172017-07-02
On 07/02/2017 06:15 PM, pcdhobbs@gmail.com wrote:> The 200C isn't the original 1939 model. It was the last tube instrument HP sold (CRTs and PMTs apart) and was in their 1985 catalogue. (Yes, I have one.) ;) > > Cheers > > Phil Hobbs >Wow, that late? I'm trying to think of other 1930s era industrial designs that had such a long life cycle. GG1 locomotives? Iowa class battleships? GM straight six?
Reply by ●July 2, 20172017-07-02
On Sun, 2 Jul 2017 21:46:43 -0400, bitrex <bitrex@de.lete.earthlink.net> wrote:>On 07/02/2017 06:15 PM, pcdhobbs@gmail.com wrote: >> The 200C isn't the original 1939 model. It was the last tube instrument HP sold (CRTs and PMTs apart) and was in their 1985 catalogue. (Yes, I have one.) ;) >> >> Cheers >> >> Phil Hobbs >> > >Wow, that late? I'm trying to think of other 1930s era industrial >designs that had such a long life cycle. GG1 locomotives? Iowa class >battleships? GM straight six?Not '30s, rather '40s, but B52s are still flying and from what I gather, they'll be flying another 30 years and perhaps longer. There are three generations of pilots who have flown the same bird.
Reply by ●July 2, 20172017-07-02
pcdh...@gmail.com wrote: ---------------------------> The 200C isn't the original 1939 model.** That was the 200A - see full manual with schem: http://www.hparchive.com/Manuals/HP-200A-Manual-1951.pdf FYI: Since my mid teens, I have owned a fairly similar oscillator - all valve using a large, dual tuning gang from an old radio. A 30:1 reduction, worm drive is fitted to the gang which is fitted inside its own steel box. Means the unit works perfectly with the cover off. A pair of 6AM6s (aka EF91s) operating as triodes form the oscillator, amplitude is stabilised by an R53 glass bead thermistor. A single 6BQ5 is used as a cathode follower for low Z output. Has three ranges, covering from 18Hz to 22kHz. The original metalwork and basic circuit was built by staff at the Kodak factory at Coburg in Melbourne as a low frequency oscillator for motor drive, it originally used a large, dual gang WW pot. I fitted the tuning gang and other bits to make it a general purpose audio oscillator including square waves using a 12AT7 wired as a Schmitt trigger. I still have it and gave at a major overhaul a couple of years back. .... Phil
Reply by ●July 2, 20172017-07-02
bitrex wrote: -----------------> > > Wow, that late? I'm trying to think of other 1930s era industrial > designs that had such a long life cycle. GG1 locomotives? Iowa class > battleships? GM straight six? >** Well there is the DC3 with many flying examples. But the 6L6 beam tube takes the prize since it has *never* been out of mass production since 1936. ..... Phil
Reply by ●July 3, 20172017-07-03
On 03/07/17 02:46, bitrex wrote:> On 07/02/2017 06:15 PM, pcdhobbs@gmail.com wrote: >> The 200C isn't the original 1939 model. It was the last tube instrument HP >> sold (CRTs and PMTs apart) and was in their 1985 catalogue. (Yes, I have one.) ;) >> >> Cheers >> >> Phil Hobbs >> > > Wow, that late? I'm trying to think of other 1930s era industrial designs that > had such a long life cycle. GG1 locomotives? Iowa class battleships? GM straight > six?B52s have an expected ~90 year product lifetime, 1950s to 2040s.
Reply by ●July 3, 20172017-07-03
On 3.7.17 04:46, bitrex wrote:> On 07/02/2017 06:15 PM, pcdhobbs@gmail.com wrote: >> The 200C isn't the original 1939 model. It was the last tube >> instrument HP sold (CRTs and PMTs apart) and was in their 1985 >> catalogue. (Yes, I have one.) ;) >> >> Cheers >> >> Phil Hobbs >> > > Wow, that late? I'm trying to think of other 1930s era industrial > designs that had such a long life cycle. GG1 locomotives? Iowa class > battleships? GM straight six?DC3 / C47 from Douglas Aircraft. -- -TV
Reply by ●July 3, 20172017-07-03
On 07/02/2017 10:23 PM, Phil Allison wrote:> pcdh...@gmail.com wrote: > > --------------------------- > >> The 200C isn't the original 1939 model. > > ** That was the 200A - see full manual with schem: > > http://www.hparchive.com/Manuals/HP-200A-Manual-1951.pdf > > > FYI: > > Since my mid teens, I have owned a fairly similar oscillator - all valve using a large, dual tuning gang from an old radio. > > A 30:1 reduction, worm drive is fitted to the gang which is fitted inside its own steel box. Means the unit works perfectly with the cover off. > > A pair of 6AM6s (aka EF91s) operating as triodes form the oscillator, amplitude is stabilised by an R53 glass bead thermistor. A single 6BQ5 is used as a cathode follower for low Z output. > > Has three ranges, covering from 18Hz to 22kHz. > > The original metalwork and basic circuit was built by staff at the Kodak factory at Coburg in Melbourne as a low frequency oscillator for motor drive, it originally used a large, dual gang WW pot.The manual mentions a rackmount model - I'd never heard of that! Google only turns up an image of a rackmount "200CDR" which looks to be a later product with a significantly different design> I fitted the tuning gang and other bits to make it a general purpose audio oscillator including square waves using a 12AT7 wired as a Schmitt trigger. > > I still have it and gave at a major overhaul a couple of years back. > > > .... Phil >Tangentially related - the audio sine wave oscillator I've been using for several years is a solid state box labeled "LofTech"; manufactured by "Phoenix Audio Labs, Manchester, CT". It's mostly full of LM13600s and TL074s with date codes from the middle of 1986. I don't have a THD analyzer so I can't say what its specs are now in that regard; visually at least the sines it puts out look math textbook perfect on a scope. The brochure claims a maximum THD of 0.5% Unfortunately frequency stability isn't good - it's very drifty with time and temperature; sometimes 3-5 Hz up and down over time just sitting in a shop at room temperature, which is annoying. The brochure scan online doesn't say anything about drift specs so I don't know if that's normal for the product's design or if it should be serviced. I managed to find a schematic: <http://www.ka-electronics.com/images/jpg/Loftec_TS1.jpg>
Reply by ●July 3, 20172017-07-03
