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Old 11th Sep 2020, 9:59 pm   #1
FERNSEH
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Default Ultra 1781 TV with motorised tuner and FM radio.

After sorting out the Murphy V659X here's another TV set with a motorised channel selection system.
The tuner unit itself is the familiar Cyldon type C fitted with more modern valves, for 1960 that is, 30L15 and 30C15.
This particular Ultra set has FM radio. Three channels are allocated on the twelve position tuner, H,T and L. Home, Light and Third.
The owner of the set mentioned the tuner was never used on account of it's erratic behavior, press a channel button and the mechanism would jam up. Cleaning the contacts solved that problem and now the station selection, including the three FM positions is completely reliable.
The twelve channel buttons have a springy contact arm which makes contact to the back stop disc. When a TV or FM radio station is chosen the drum assembly rotates until it reaches the twelve-o-clock position. What intrigued me was what mechanism causes the rotation to stop at the correct position? Simple, all that is used to stop the motor is an insulator fitted between the contact arm and back-stop ring. The attachments show how it is done,
The FM radio performs very well in this receiver because a separate three valve 10.7Mc/s IF amplifier is employed. Valves are 2 Mazda 10F18 and a 10FD12 (UABC80) The series connected valve heaters are supplied from the HT supply via a 1460ohm 15 watt resistor. Timebase HT supply switched off on radio.
It's amazing the FM radio ever worked properly because on of the solder connections to the first 10.7Mc/s IF transformer had never been soldered to the tag, see attachment No.5

DFWB.
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Last edited by FERNSEH; 11th Sep 2020 at 10:07 pm.
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Old 12th Sep 2020, 10:46 am   #2
FERNSEH
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Default Re: Ultra 1781 TV with motorised tuner and FM radio.

The original Mazda CRT still displays a sharp and bright picture.
The tube is the short neck CME1705 which makes it possible to make a TV set which is only eleven inches deep.

DFWB.
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Old 12th Sep 2020, 10:55 am   #3
peter_scott
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Default Re: Ultra 1781 TV with motorised tuner and FM radio.

The motor must be quite torquey to overcome the usual turret detents. Nice screen performance.

Peter
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Old 12th Sep 2020, 11:39 am   #4
FERNSEH
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Default Re: Ultra 1781 TV with motorised tuner and FM radio.

Hi Peter,
The tuner is the same unit that was fitted in many mid-fifties TVs. Remember the effort it took to change channels? The knob would break and the user would use a pair of pliers to change channels, and that was in the days of reversible mains plugs so the control shaft would be at full mains potential.

DFWB.
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