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28th Feb 2021, 9:25 pm
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#1 |
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Pentode
Join Date: Dec 2017
Location: Staines-Upon-Thames, Surrey, UK.
Posts: 122
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PYE P75 Mod
My P75 was pretty well dead when I bought it, but after making all the usual changes it's now working well.
Before I put it all back in the case, I would like to implement a mod that was described in this thread; https://www.vintage-radio.net/forum/...6&postcount=16 >> On a set I had I retained the electrolytic decoupling the AF stage (replaced with a new one) but added an extra 15k resistor and decoupling cap (0.1 mfd) to feed the EF41 and ECH42 screen grids. >> The addition of two cheap components made a considerable improvement! Can anybody give me a bit more detail as to where to connect the capacitor and resistor, and what difference this mod might make? Thanks HowardB |
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1st Mar 2021, 4:04 pm
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#2 |
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Pentode
Join Date: Dec 2017
Location: Staines-Upon-Thames, Surrey, UK.
Posts: 122
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Re: PYE P75 Mod
I'm assuming;
a) the resistor connects between C16 and the screen grids of V1 & V2. b) the capacitor goes between the screen grids and ground. as shown in the diagram. Can someone please confirm if this is correct? Thanks HowardB |
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1st Mar 2021, 9:08 pm
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#3 |
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Nonode
Join Date: Jun 2007
Location: Coulsdon, London, UK.
Posts: 2,169
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Re: PYE P75 Mod
I would make the same assumption.
I would solder the capacitor to the tag/contact on the IF valve holder (when the valve has been removed) and the nearest chassis connection. |
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1st Mar 2021, 9:26 pm
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#4 |
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Dekatron
Join Date: Jan 2005
Location: Oxford, UK.
Posts: 17,864
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Re: PYE P75 Mod
Just seen that Neil Breward has sadly passed away a year ago.
http://ruddington.info/parkrun-volun...utes-jan-2020/ Mods, could you update his details, please? Nick |
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1st Mar 2021, 9:34 pm
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#5 |
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Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,878
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Re: PYE P75 Mod
Thanks Nick details updated.
Cheers Mike T
__________________
Invisible airwaves crackle with life or at least they used to  Mike T BVWS member. www.cossor.co.uk |
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1st Mar 2021, 11:56 pm
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#6 |
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Pentode
Join Date: Dec 2017
Location: Staines-Upon-Thames, Surrey, UK.
Posts: 122
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Re: PYE P75 Mod
Hi Silicon,
Thanks very much for the confirmation. I'll make the change tomorrow. It will be interesting to see if it makes any significant difference. By the way, I was going to put this question directly to Neil, but I did a search and unfortunately found the same sad story as you, Nick. HowardB |
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