I bought an old Hewlett Packard signal generator dirt cheap and inside there is a small transformer with a center tapped primary of 32k and 12 Ohm secondary winding. Could it be used for a small mono amplifier with a small signal dual triode in push-pull or is it just garbage?
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Wow beautiful equipment. I would keep it in untouched and original condition as its very rare today.I don't think there's a single semiconductor in itI think it was from 1966
The thought crossed my mind. It is a marvel of engineering and craftsmanship.
Thanks. I will check if there are any 5687 tubes in it. Maybe I can use the existing ones for experimentation
HP opt for flea power
A few years back I built a push pull 6sn7 amplifier with a pair of those.
They can handle 300v just fine, just make sure to bias each section separately.
Mine powered a pair of full range 12" 8 ohm rca speakers.
Using 12" full range speakers are essential if you want to hear deep bass with these. I tried many speakers, but found 12" sounded the best.
A few years back I built a push pull 6sn7 amplifier with a pair of those.
They can handle 300v just fine, just make sure to bias each section separately.
Mine powered a pair of full range 12" 8 ohm rca speakers.
Using 12" full range speakers are essential if you want to hear deep bass with these. I tried many speakers, but found 12" sounded the best.
I reckon you would do better with small mains transformers with the two identical primaries. Give the sig gen a good service and keep it for testing amplifiers as it covers the correct range.
I have a Marconi TF1101 that I use for testing amps. It has a push pull transformer in it just like yours for the lower audio ranges but in my case it goes a bit lower. It also has another smaller transformer for the higher ranges going up to 200Khz. I also use it for calibrating frequency counters by getting the output to make a beat signal against a local AM radio station at 198Khz. It has proved very stable when doing this task. It just needed a few basic components to restore it to full working order. These were mostly capacitors and none of them were all that bad but there was a risk of them going leaky and taking out the wound components.
I would restore yours and keep it as there is no modern instrument that can produce nice analogue sine waves with no digital artifacts like these classic instruments do.
Definitely keep it and if you do not want to use it swap it for a normal audio output transformer with another member whom will use it.
I have a Marconi TF1101 that I use for testing amps. It has a push pull transformer in it just like yours for the lower audio ranges but in my case it goes a bit lower. It also has another smaller transformer for the higher ranges going up to 200Khz. I also use it for calibrating frequency counters by getting the output to make a beat signal against a local AM radio station at 198Khz. It has proved very stable when doing this task. It just needed a few basic components to restore it to full working order. These were mostly capacitors and none of them were all that bad but there was a risk of them going leaky and taking out the wound components.
I would restore yours and keep it as there is no modern instrument that can produce nice analogue sine waves with no digital artifacts like these classic instruments do.
Definitely keep it and if you do not want to use it swap it for a normal audio output transformer with another member whom will use it.
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The signal generator is now gutted for parts. The output transformer and the 5687 tube are safely tucked away in the workshop.
I found the reference schematics for the push-pull amplifier but I need to figure out which of all the other tubes to use for a phase splitter and how to hook it up to the 5687. Any help would be most appreciated. I found a scan of the service manual for what I first thought was my model of Hewlett Packard generator but I can not find the 5687 tube in that version of the manual so I guess there are different generations of it.
I found the reference schematics for the push-pull amplifier but I need to figure out which of all the other tubes to use for a phase splitter and how to hook it up to the 5687. Any help would be most appreciated. I found a scan of the service manual for what I first thought was my model of Hewlett Packard generator but I can not find the 5687 tube in that version of the manual so I guess there are different generations of it.
Did you use 6sn7 instead of 5687 in the output stage? What kind of tube did you use for phase splitter? I am contemplating a phase splitting transformer but it may be a bit of a waste since the specs of the output transformer is 100-10kHz so a custom phase splitting transformer for ~150 USD just doesn't seem right.
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