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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 22nd Mar 2021, 4:35 pm   #301
Helder Crespo
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Default Re: My first telly TV22

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Originally Posted by Travellingwave View Post
I found a couple of 500pf 500v silva mica caps, so I’ve connected them in series , and put the series pair in parallel with the tuning caps so now I must have getting on for 1000 pf including the origional 470 pf, plenty of width now , with slider about 60%

Will try with screening can back on next
Any change with respect to the image size dependence on brightness for this new tuning cap setting?
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Old 22nd Mar 2021, 5:54 pm   #302
Travellingwave
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Default Re: My first telly TV22

Not noticed any

I will get a video - and with the old PL81 too tonight
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Old 22nd Mar 2021, 6:23 pm   #303
Helder Crespo
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Default Re: My first telly TV22

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Not noticed any

I will get a video - and with the old PL81 too tonight
Thanks! Your set is looking great, and I hope you'll be able to enjoy it soon, say a full film at full width!
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Old 22nd Mar 2021, 7:44 pm   #304
Travellingwave
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Default Re: My first telly TV22

Hi Helder just sent you a PM

Do you think there is any difference in performance between the later PY81 and the PL38 in your set. I had no problem sourcing a new in box PY81 (mullard) from a well known auction site for not much money.
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Old 22nd Mar 2021, 7:57 pm   #305
Helder Crespo
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Default Re: My first telly TV22

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Hi Helder just sent you a PM

Do you think there is any difference in performance between the later PY81 and the PL38 in your set. I had no problem sourcing a new in box PY81 (mullard) from a well known auction site for not much money.
Thanks Travellingwave. Putting in a PL81 would require some changes, both in the socket and in the circuit. My problem should not be related to having a PL38, as many people (most people I guess) have sets with this valve and don't have the same problem, so it could be a problem in my particular valves (both the original and the NOS presently installed in the set). Yesterday I got yet another NOS PL38, also from a well-known auction site. Not a Mullard, but it looks good/new and the seller has quite a few for sale right now. Not exactly cheap, but less than half of what some companies are proposing on their websites. Compared to the time I've already spent trying to solve the issue, it's actually peanuts. So I will give it a try next time I'm in London, where my sets are, and where the valve should be arriving soon (the seller posted it today).
Helder
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Old 22nd Mar 2021, 8:12 pm   #306
Helder Crespo
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Default Re: My first telly TV22

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Originally Posted by Travellingwave View Post
Hi Helder just sent you a PM

Do you think there is any difference in performance between the later PY81 and the PL38 in your set. I had no problem sourcing a new in box PY81 (mullard) from a well known auction site for not much money.
Performancewise, the PL81 enables getting higher EHT (some 500V more, so in principle a brighter image) which also requires reducing the line scan amplitude proportionally. According to the trader sheet, this requires an additional choke compared to the standard/earlier Mk2.
The PL81 also has a lower heater voltage and dissipates less power than the PL38. I don't know about reliability though. Many members here have stated that the PL38 is very reliable, and some even say they never had to change one. If your original PL81 behaves as well as the NOS one, I guess this reinforces the hypothesis that it is also a reliable valve.
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Old 22nd Mar 2021, 8:14 pm   #307
Travellingwave
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Default Re: My first telly TV22

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Originally Posted by Helder Crespo View Post
Quote:
Originally Posted by Travellingwave View Post
Not noticed any

I will get a video - and with the old PL81 too tonight
Thanks! Your set is looking great, and I hope you'll be able to enjoy it soon, say a full film at full width!
Thanks Helder - I have only got this far with all the help and advice form members of this forum - In particular with the what to do when XYZ happens advice , you cant beat theory but also you cant beat good practical knowledge and experience.
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