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Old 20th Feb 2019, 11:20 am   #125
FERNSEH's Avatar
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 6,347
Default Re: Baird T5 restoration project.

Hi Lee,
The cabinet reconstruction is progressing very well. The control panel is the last cabinet part to be made. I'll attempt to do this later this week. In the meantime let's take a look at the vision receiver. Signals are supplied direct to the mixer, no RF amplifier. This was a common practise in early TV receivers. Because the intermediate frequency is low the four stage amplifier should provide excellent gain. The Mullard TSP4 pentodes have a gm of 4.2ma/V which is a good figure for early television RF pentodes. Because the set employs a large CRT a full wave demodulator is employed in order to avoid a fine dot pattern appearing on the screen. A Mullard 2D4A double-diode is used as the vision detector. A TSP4 is used as the video amplifier.
Positive going video is supplied to the CRT grid via a capacitor. No DC restorer.

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Last edited by FERNSEH; 20th Feb 2019 at 11:30 am.
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