View Single Post
Old 14th Jul 2012, 12:54 pm   #4
FERNSEH
Dekatron
 
FERNSEH's Avatar
 
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,014
Default Re: PYE TT1 - First Transistor Portable UK TV

For starters, a picture of the Pye TT1.
The frame oscillator is free running in the sense that it does not need sync pulses to activate it. The set displays a blank raster when no signal is received.
Transistor V25 is the blocking oscillator and works in a conventional manner. The transistor conducts only during the flyback time and discharges the sawtooth forming capacitors C74 and C75. Frame repitition frequency is determined by C72, R74 and and the frame hold control R75.
The oscillator drives the V26 and V27 in a straight forward circuit.
It follows that to make a start on the restoration all those capacitors in the frame timebase should be checked or replaced as a matter of course.
The transistors OC72 and OC23 can still be found or the later types AC128 and AD149 could be considered as subsititutes.
The Pye TT1 is actually mentioned in the 1960/61 Newnes R & T serviving book.
I consider this to be an important historic receiver. It has a big 14" CRT, when around the same time it was made other manufacters were using quite small tubes for their transistor TV sets. Perdio and Ferguson used small CRTs.

DFWB.
Attached Thumbnails
Click image for larger version

Name:	PyeTT1pic.jpg
Views:	769
Size:	78.1 KB
ID:	68606   Click image for larger version

Name:	PyeTT1_1.jpg
Views:	584
Size:	47.7 KB
ID:	68607   Click image for larger version

Name:	PyeTT1_2.jpg
Views:	454
Size:	49.1 KB
ID:	68608   Click image for larger version

Name:	PyeTT1_3.jpg
Views:	433
Size:	62.5 KB
ID:	68609  
FERNSEH is offline