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Old 15th July 2005, 06:27 AM   #1
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Question diy guitar tube amp help.

Ok, somewhere, someone is going to read this any wonder why.....

About 3 years ago, I found a Hewlett Packard Audio Oscillator, Model 200B, a little rough.... but in working condition. I played around with it for a while and then put it on a shelf and forgot about it until tonight.

Lately, I've been reading about DIY tube amps and started thinking if it is possible to use some of the parts in the Oscillator to make a guitar tube amp?

I looked at the tubes in it...... 5V4G Rectifier Tube and Two 6K6GT tubes. I still don't see anything info wise on the Transformers, but then again...this was built in 1939 so I'm sure that dust from over the years is covering that up quite nicely.

I've done some searching on the internet but found sites that when you do the pricing for parts....well, I want to spend little as possible.

Is it possible to use some parts on this to make a guitar tube amp? Or should I just say forget it and try to sell it to someone that will actually use it and enjoy 30's Technology?

Any help for this learning DIY'er would be great!!!!!

Here is a pic of the cover off and looking down inside of it......
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Old 15th July 2005, 06:31 AM   #2
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Here are close ups on the left and right sides, along with eh front view.
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Old 15th July 2005, 06:33 AM   #3
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Right side
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Old 15th July 2005, 06:39 AM   #4
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Front View.
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Old 15th July 2005, 08:40 AM   #5
SHiFTY is offline SHiFTY  New Zealand
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If it goes, then you can use it.

I wouldn't turn it on for too long thouugh, the old components might go pop. Don't re-use any old capacitors or resistors, they might be a fire risk.

I would guess that if the oscillator has speaker outputs, then the transformer on the right is an output transformer, probably single ended. Otherwise you will need to buy one.

What you could do is completly strip that cool looking chassis down and build something like this Fender Princeton on it. Sub one 6K6 for a 6V6 and a 5V4 for a 5Y3, and all you need is a 12AX7.

http://www.kbapps.com/audio/schemati...ceton5f2a.html

If you can show the connectors and the underside of the unit, I can tell you more.

Also please read the safety thread
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Old 15th July 2005, 09:58 AM   #6
EC8010 is offline EC8010  United Kingdom
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Of course, some people would say that the HP200B is an important part of audio test equipment history and that you shouldn't destroy it...

I doubt if any of it is suitable for conversion. Many old oscillators did have a loudspeaker amplifier in them, but it would only be a Watt, or so.
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Old 15th July 2005, 10:16 AM   #7
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a 6K6 is just a slightly smaller 6V6. it looks like you might even have a P-P 6K6 output stage! see how they are wired to the output transformer. Also see if the thing can drive a speaker. If the output transformer can't drive a speaker there is no point is using this chassis. It looks like there are at least two small pentodes in there. use these for preamp and Phase inverter if needed.

First check to see if the HP200 is worth anything. If it is, resotore it and either hold on to it, use it (I find my function generator very useful for amp debugging), or sell it to buy more old tube junk!
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Old 15th July 2005, 10:39 AM   #8
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IŽd clean this baby, change all small components and use it. Scrapping something like this is like killing someone.
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Old 15th July 2005, 10:43 AM   #9
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If I remember correctly, this oscillator has a 600 ohm output.
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Old 15th July 2005, 10:53 AM   #10
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if it's 600 ohm output, you should just clean it and replace the capacitors and use it. Especially if you don't already have a function generator. quite usefull things. I'd say the order you should get test equipment should be....

working brain, then a good multimeter, then a scope, and then a function generator. Once you get a scope and 'generator, you don't want to go back to the days where you only had a lowly multimeter....
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