HP 204C Oscillator 5Hz - 1.2MHz 1974 test teardown

Рет қаралды 1,474

Күн бұрын

super nice all transistor and fets oscillator it is from july 1974
found date stamp inside, look back side of variable capacitor,
main design released by HP 1968, there is also a HP 204D
with attenuator switch.
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#teardown
#hewlettpackard
#vintage
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Пікірлер: 18

@garyramsey4275 6 ай бұрын

Love your videos, Thomas. It always amazes me that you have a different instrument to show us almost every single day! This is the solid state version of HP’s classic 200 series oscillators. I worked on many of these when I was at HP in the 1980s. I currently own two of them, one of which had the rechargeable NiCd battery option. In that version, the batteries were actually used to provide voltage regulation. The batteries are now dead, of course, so I replaced the batteries with a simple zener diode type circuit, so now it works perfectly, but on AC only.

@TeardownOZ2CPU 6 ай бұрын

good point yes a battery can be a nice noise free zener :-) but of course the voltage will change with state of charge, i prefer a mains supply only solution, with exactly the same regulated voltage, but in 1980 portable was a buzz word, people wanted that, we dont see or understand this today

@originalfallinggirl 4 ай бұрын

I love this! I want to hear it 🙏❤️

@Edisson. 6 ай бұрын

Hi Thomas, you ruined my day with that logo, I bought an old gauge on e-bay to replace the missing logo on my 209A and I got the same gauge, but the logo was milled into the panel. So it stands next to the 427A like a poor brother, because the 427 has a logo. I even tried the service organization of measuring devices to see if there was a logo, but unfortunately everything they had was without a logo (that's what they sell at the bazaar). they sell at the bazaar). The capacitors in your generator have been changed, some of the types you have are not original, Tantalums in this design are almost immortal - I have never seen a defective one. The 209A was made for audio applications, it has a range of 2 - 20, the output is sine and square. Nice day 🙂 Tom

@TeardownOZ2CPU 6 ай бұрын

it was easy to get the logo, many of my friends save front plates or other special parts from broken instruments, just for the fun of it

@Edisson. 6 ай бұрын

@@TeardownOZ2CPU I envy such possibilities and friends 😉😁

@RensePosthumus 6 ай бұрын

Very nice! I have the 204D version (with logo ;-)). Apart from an atten. knob it also has a sine/square wave switch a sync output and a terminals for 600 ohm output.

@TeardownOZ2CPU 6 ай бұрын

wow you got the upgraded version :-)

@VintageElectronicsGeek 6 ай бұрын

Very nice oscillator....I have a HP nixie tube freq counter that uses almost that same case. What was the black test gear you used at the ending? ~Jack, VEG

@TeardownOZ2CPU 6 ай бұрын

it is my Minilyzer ML1 from NTI, it is still a current available product

@originalfallinggirl 4 ай бұрын

@@TeardownOZ2CPUwhoa! The Minilizer is on my wishlist but they never come up used on eBay and they list new for about $1k.

@TeardownOZ2CPU 4 ай бұрын

@@originalfallinggirl yes it is super nice, so much in a tiny package, i scored it broken, and replaced the screen many years ago it was still avail as a sparepart,

@bmboldt 4 ай бұрын

The large frequency knob on my 204D is hard to turn. What do you recommend using to lubricate it? Should I only lubricate the bearings up front or can I also take care of the shaft contacts back by the tuning fins?

@TeardownOZ2CPU 4 ай бұрын

you got any pure alcohol ? Ethanol Metanol, what ever, the most clean type i prefer is called IPA, use a pipette or such to apply small drops to all stuck parts, the shaft and entry, and then move parts, add more when it starts to move better and better, this way you wash out all old gum like oil, then add sewmachine oil, again small drops, and continue to move parts, now it is fine and nice for the next 20 years

@bmboldt 4 ай бұрын

@@TeardownOZ2CPU I have 91% IPA and sewing machine oil. Thanks

@timburns9754 4 ай бұрын

Nice video. I am curious what the maximum peak to peak voltage this produces at the lowest possible frequency. Hoping you can provide an answer. Thanks!

@TeardownOZ2CPU 4 ай бұрын

2.5vrms into 600ohms, or 5vrms no load, 5Hz is the lowest freq.

@timburns9754 4 ай бұрын

@@TeardownOZ2CPU Thank you for the quick reply. I am just learning to use oscillators (aka signal generators) but have access to one of these. Are there any good references (or videos) on how to achieve either of these two outputs? Thanks again.