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Posted (edited)

Maybe we should group-buy the Tek probe and share it around. I suspect that we will not often have a situation where more than one builder at a time is at the stage where construction is near completion and he needs to measure stuff.

I actually found one "AS-IS" for more than I wanted to pay, but less than most out there. Risks are fun!

The deal is, it's lacking the power supply and some of the probe accessories. Looks like it needs a simple 9v 500mA wall wart, but no idea what the plug size is.

I guess we'll see. If it works out, I'd be willing to rent it out.

I'm wondering if I could just plug this into my distortion analyzer directly? I need to do some more research. If so, that's very sweet.

Edited by luvdunhill
Posted

they're $51.10 at the 1-24 qty, and get as low as $35.26 at 100-249 qty.

The price was $34.86 for 10 in 2006

That's much better. Hard to swallow the $100 price tag for a single connector.

Posted

Isn't he mawied to Incontinentia Buttocks?

;)

No, no. If memory serves Cocus Knobus married Venerialla Vulva.

Incontinentia Buttocks married Pussicus Uerethra.

Posted

Got the Amp and PS done, just working on the umbilical cords. I'm going to make them 30" which allows for both side x side or stacked configurations.

Amp...

misc023.jpg

PS...

misc024.jpg

Posted (edited)
very dense Red Mallee Birl.

So i think i will make a few more knobs tomorrow

.

The colour will more in keeping with the thermal qualities of the T2...... :D:rolleyes:

Edited by wink
Posted

OK. I've got one umbilical cord ready and I'm going to go through a final check before powering this puppy up. Any last thoughts from the group?

Posted

OK. I've got one umbilical cord ready and I'm going to go through a final check before powering this puppy up. Any last thoughts from the group?

yeah, check again after that.

Posted
OK. I've got one umbilical cord ready and I'm going to go through a final check before powering this puppy up. Any last thoughts from the group?

.

Check the life insurance and hospital cover.

Get ready to purchase lottery tickets......

Posted (edited)

Double checked everything and fired up one channel at a time. I was able to adjust both batteries to 740V without any issues.

My outputs are all sitting around +18V (seems close), but I'm getting some noise. A bit of crackling and buffeting (shifting white noise). Not too loud, but very present. Interesting it is pretty much the same on both channels.

I'm going to start checking some more voltages.

Any thoughts?

EDIT: Both channels play music. When I connected a source to the right channel (SE) it seems to have stopped the noise (I need to double check this). Left channel still has noise, but plays music.

EDIT 2: I've got both channels up now at the same time (finished the other umbilical). The right channel is identical to the left channel with respect to noise. I mistakenly thought there was no noise on the right channel because I plugged the headphones into the jack without bias power (since I only had one side powered).

Both channels now play music, but the noise is still there. As I turn the volume up, it seems to diminish a bit but is still present. I can already tell that this going to sound remarkable.

Edited by Kerry
Posted

I've checked a bunch of differnt voltages and everything seems fine. I also put the amp up on the oscilloscope to check for any oscillations, but only see what looks like random noise.

I'm starting to suppect the input tubes and Kevin felt that that could be the issue. I'm going to try and get some cheap input tubes to confirm the diagnosis.

Posted

Totally ignorant and out of my league here, but since you've asked for thoughts I'll throw in my two cents.

The input tubes are a good place to start. Cheap spares that have worked in another circuit are excellent for test purposes.

Are the pins clean and shiny on your input tubes? I've had trouble with NOS tubes making noise because of dirty or oxidized pins. This can also happen with sockets.

I'm sure you've considered this, but since the noise is common to both channels, did you scope all the power supplies, including the bias, at their outputs ?

If the power supplies are clean, I'd work my way with the scope back from the output , looking at the input signal to each stage. If the noise was on one side only, I'd be thinking a bad connection or wiring error somewhere, but since it's in both channels, it's got to be something in common. Either power supply or defective components that are used in both sides.

Hopefully you'll hear from somebody who knows what they're doing here.

Posted

I did scope the outputs and I'm seeing random noise on the scope. Because of the feedback, I'm guessing it will carry its way throughout the circuit. If there is noise on the bias line, it would not affect the outputs on the scope.

You are right and I will check the all of the power supply outputs on the scope, though I'm not expecting that to be the issue since I'm scoping each output with reference to ground I'd likely see any oscillations in the outputs. Also, the noise is not in sync between the left and right channel. Same type of noise, but different and in stereo :D

The pins do have some oxidation so I was going to try cleaning. Not sure of the best method yet. Recommendations welcome.

I appreciate your two cents :)

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