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Old 4th April 2012, 06:49 PM   #151
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The patch cords are dangerous anyway. The hot end should be a protected female.

You may be getting some hash from the diode switching, you may get it from some oscillation as the voltage on the MOSFET is pulled down.
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Old 4th April 2012, 08:07 PM   #152
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Quote:
Originally Posted by jackinnj View Post
The patch cords are dangerous anyway. The hot end should be a protected female.

You may be getting some hash from the diode switching, you may get it from some oscillation as the voltage on the MOSFET is pulled down.
The only exposed points are the test points and my plan is to put some type of hood over the pins. What is a protected female jack? I can't find anyting that mount under the chassis with some type of hook to attache to probes to.

My Plate drive is very simple, same as the Tek 570.

Variac>Transformer>Full Wave Rectifier>Series Resistor>Plate. I can try with some caps accross the diodes.

Thanks

Alfredo
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Old 4th April 2012, 09:28 PM   #153
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I rigged the connection from the tube sockets with mini-banana plugs -- these plug into the anode/grid female jacks. It's just something I've been doing since my ham radio days.

Here's the Pomona "sheathed" female: http://www.pomonaelectronics.com/pdf...2_01_24_06.pdf
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Old 4th April 2012, 10:38 PM   #154
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Quote:
Originally Posted by jackinnj View Post
I rigged the connection from the tube sockets with mini-banana plugs -- these plug into the anode/grid female jacks. It's just something I've been doing since my ham radio days.

Here's the Pomona "sheathed" female: http://www.pomonaelectronics.com/pdf...2_01_24_06.pdf
Not sure I follow, these are very similar to the ones I am using.

The patch cord is made from cut up voltmeter leads. Male Plug and female Jack mate very solidly. I thought you were talking about the X and Y test pins.

Alfredo

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Old 5th April 2012, 01:16 AM   #155
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Not quite the same, the protected plug and jack look like these:

Click the image to open in full size.

Click the image to open in full size.

Jaz
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Old 5th April 2012, 03:24 AM   #156
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Ahh!, yes. Makes sense. However, I still have the exposed pins where I connect the probes to. These have to be taken care of first. I will do a search to see if I find something I can purchase.

I put some .01 1KV caps across the 1n4007's but they where clicking. Once I removed the caps the weirdest thing happened, the hash went away. Wonder if it was just a cold solder.

I mentioned that I was using an analog storage scope to capture he curves. It is a HP 1223a in pretty good shape. Paid 40 dollars, I thing it was worth it as it is very easy to take pictures of the curves without having any refresh issues.

Now I need to put in the finishing touches. Need to install the voltmeters, one for the heater voltage and another for the external screen voltage. I have some but they are meant for a smaller square opening. I would need to fabricate an adapter plate or purchase some new ones.

For the lettering I will give inkjet decals a shot, my handwriting wont cut it. Also need to fabricate new sides. I had to add some spacers between the top and the bottom to make everything fit. The original sides are too short now. I will fabricate new sides and front from MDF and paint the same hammer green as the socket adapters.

Cant wait to finish to do something else.... Next is a 6528 PP amp

Alfredo
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Old 5th April 2012, 03:35 AM   #157
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"It is a HP 1223a in pretty good shape. Paid 40 dollars..."

Now you are just trying to make me jealous.

Jaz
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Old 5th April 2012, 10:06 PM   #158
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With the hp 1223a i can cheat a little. Grid to ground. One screen voltage at the time, saved into the storage memory.

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Old 8th April 2012, 07:51 PM   #159
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Default 6080 dual power triode

More testing today....

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Video showing the matching feature of the curve tracer on the RCA 6080. The 6080 was the first one that I pulled from my batch of NOS tubes, all are RCA. I was very surprised that both sections are spot on.

I checked this feature with a bunch of used 12AT7 and only two out of 7 were close enough, most were way off.
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Old 8th April 2012, 09:51 PM   #160
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one more...

A trioded PL-36. On this one I tried 2 captures on the storage oscilloscope to extend the grid steps past -60. BTW, the plate voltage is way past what the datasheet specifies. Datasheet specifies 250V max.

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