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Decca CTV25 LOPT: Tripler Conversion

Vrat Founder Admin
Posts: 11067

Recently there's been a little discussion on converting a CTV all valve derived line output to solid state. This procedure being detailed in the past by Hugh Cocks in 'Television" of March 1976

My Decca CTV25 in the past had suffered from a failed over-wind and was converted to use a solid state tripler. Thankfully a NOS LOPT replacement was found, the TV was then reverted back to its original specification, full valved derived EHT.

I've kept the converted LOPT as a backup should the worst happen and the replacement fails. The chances of finding another NOS Decca CTV25  LOPT is virtually non-existent, by hanging onto this converted one it will at least ensure this fairly rare and humongous early CTV can be kept going for many years to come.

Thought folk might find it interesting to have a look at the converted LOPT as you don't often see an example, if ever!

Topic starter Posted : 03/01/2019 12:01 am
Focus Diode
Honorable V-Ratter Registered
Posts: 729

I did this to a G6 using a universal tripler. The small size allowed it to fit inside the PD500/GY501 insulator.

Wishing to keep some originality I retained the valved focus supply.

Surprisingly the warm up time was the same as before with this arrangement, the only difference was a fully sized out of focus picture appeared which focused after a few seconds.

Before the modification the raster would shrink on perfectly focused just like a B&W set with a valved EHT rectifier.


Posted : 03/01/2019 5:28 am