The Other Not Ultralinear PCL86 Monos

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Mike H
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Re: The Other Not Ultralinear PCL86 Monos

Post by Mike H » Tue Oct 09, 2018 12:37 pm

Yeah I'm getting that, but the 'scope doesn't lie, most of the noise is coming down the supply wires, which in turn come from SMPS modules.

Also I mustn't forget the sig gen is quite noisy too, hence I mostly want to run it at 1 Volt output or higher.

Also I think the 'scope is picking up RF from the general environment, e.g. there's a lamp on the table with a low-energy bulb in it. Might have to enable the low-pass flter function.

Onwards!
 
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Re: The Other Not Ultralinear PCL86 Monos

Post by Mike H » Tue Oct 09, 2018 3:37 pm

Playing with the new power supply, on the heater circuit:
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APS300-D PCL86_2188.jpg
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APS300-D PCL86_2189.jpg
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Re: The Other Not Ultralinear PCL86 Monos

Post by Mike H » Tue Oct 09, 2018 11:00 pm

Right so - made the filter 'board'. TBH this is better than my original idea (still haven't found those chokes :shock: )
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PCL86_2190.jpg
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EDIT: ^ One filter (15 mH) for HT, t'other (4.5 mH) for the heater supply. Caps are 100 nF.
 
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Re: The Other Not Ultralinear PCL86 Monos

Post by Mike H » Tue Oct 09, 2018 11:07 pm

Oh and I was right, one of the valves is duff. So at the mo it's using the good Tungsram, and the spare, which is a Siemens. Both 2nd hand used. So both channels work well now, albeit a slight difference in gain. Not a matched pair.
 
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Re: The Other Not Ultralinear PCL86 Monos

Post by Mike H » Tue Oct 09, 2018 11:26 pm

OK so the above supply input filters seem to have got a handle on the noise:
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PCL86_2193.jpg
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Also I was sure there's some of bandwidth filter on the 'scope - and there is - second menu item, "BW Limit", drops 100 MHz to 20 MHz...
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PCL86_2201.jpg
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Cleans things up quite a bit.
 
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Re: The Other Not Ultralinear PCL86 Monos

Post by Mike H » Tue Oct 09, 2018 11:33 pm

According to the oscilloscope, the rise time (square wave @ 1kHz) is 3.6 µs. :shock: As low as that.

Don't know what the sig gen's is, forgot to check :oops:
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PCL86_2202.jpg
 
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Re: The Other Not Ultralinear PCL86 Monos

Post by Mike H » Tue Oct 09, 2018 11:39 pm

Aaa-and, according to the 'scope, the OPT ringing freq. is 73.53 kHz.
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PCL86_2203.jpg
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I like this 'scope!
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Shot of the working PSU's...
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PCL86_2192.jpg
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The heater supply is a netbook PSU...
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PCL86_2204.jpg
 
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Re: The Other Not Ultralinear PCL86 Monos

Post by Mike H » Wed Oct 10, 2018 8:40 pm

Making ack-chewl noises!! Image
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PCL86_2208-b.jpg
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Cressy Snr
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Re: The Other Not Ultralinear PCL86 Monos

Post by Cressy Snr » Wed Oct 10, 2018 8:42 pm

Well done that man! :D
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Re: The Other Not Ultralinear PCL86 Monos

Post by Mike H » Wed Oct 10, 2018 8:46 pm

This is after a power cut from 4:45 pm until about 7:40.

And I'd just screwed on the bottom plate and was going to plug it all together for some moosik. Image

More pix:
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PCL86_2206.jpg
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PCL86_2207.jpg
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Re: The Other Not Ultralinear PCL86 Monos

Post by Mike H » Wed Oct 10, 2018 8:50 pm

Have you noticed the front panel push button switch is replaced with a green neon. The switch packed up - stayed permanently on regardless whether in or out. Took it part, put it back together, now works again. Image
 
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Re: The Other Not Ultralinear PCL86 Monos

Post by Mike H » Wed Oct 10, 2018 8:51 pm

Cressy Snr wrote:
Wed Oct 10, 2018 8:42 pm
Well done that man! :D
Ta muchly ever so very much.
 
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Re: The Other Not Ultralinear PCL86 Monos

Post by Mike H » Wed Oct 10, 2018 10:22 pm

New schematic:
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My Mullard 3W amplifier.jpg
 
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Re: The Other Not Ultralinear PCL86 Monos

Post by Mike H » Thu Oct 11, 2018 6:55 pm

PCL86_2210.jpg
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Re: The Other Not Ultralinear PCL86 Monos

Post by Mike H » Wed Oct 17, 2018 12:23 am

The second case has arrived so I did a Herculean bit of building today (meaning, did the whole job in one afternoon and evening) and so now have a matching PSU unit.
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PCL86_2221.jpg
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Innards of the SMPS:
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PCL86_2222.jpg
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PCL86_2224.jpg
 
I never make the same mistake twice. Instead I prefer to fill my day with a variety of different mistakes

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