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Heatercathodeshort · 9th Feb 2012, 10:59 am

Yes you are quite right Matt. The circuit in the Newnes books is a microdot! C49 is the 12uf. C51 .1uf cathode decoupler PL81 and C53 .001uf across the width coil. Not a lot to go wrong. The scan coils should be OK as they are not constructed on the same lines as the V4 series but 60 bad storage years have passed, so they cannot be ruled out completely. On the good side they are very reliable. They can be disconnected for a test and if the line output stage perks up considerably they may be worth closer inspection. The LOPT may be very damp and a simple test is to run it for say 15 mins and see if the overwind is getting warm. If it is, the saturation problem may be the cause of weak EHT and a long drying out may improve matters. Sometimes just switching it on for a period each day, increasing the time by 10 mins or so does the trick.
The PY81/800 or more likely the PL81 may be a bit low forcing the LOPT to struggle.
[Glad to here you VT2 is till working Kevin! ] Regards, John.

9th Feb 2012, 10:59 am	#6
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Pye VT2 EHT problems Yes you are quite right Matt. The circuit in the Newnes books is a microdot! C49 is the 12uf. C51 .1uf cathode decoupler PL81 and C53 .001uf across the width coil. Not a lot to go wrong. The scan coils should be OK as they are not constructed on the same lines as the V4 series but 60 bad storage years have passed, so they cannot be ruled out completely. On the good side they are very reliable. They can be disconnected for a test and if the line output stage perks up considerably they may be worth closer inspection. The LOPT may be very damp and a simple test is to run it for say 15 mins and see if the overwind is getting warm. If it is, the saturation problem may be the cause of weak EHT and a long drying out may improve matters. Sometimes just switching it on for a period each day, increasing the time by 10 mins or so does the trick. The PY81/800 or more likely the PL81 may be a bit low forcing the LOPT to struggle. [Glad to here you VT2 is till working Kevin! ] Regards, John.