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Old 1st Aug 2016, 9:24 am   #140
dazzlevision
Dekatron
 
Join Date: Sep 2003
Location: Near Swindon, North Wiltshire, UK.
Posts: 3,622
Default Re: Earliest BBC2 Sets?

Hello,

In the early 1970s, I converted a Murphy V739 to UHF/625 only operation. The V739 is a 19" Astra Mk 2 set, rental model, without pushbutton tuning - just a large round knob to change channels, coupled directly to the VHF tuner's turret.

I stripped out the VHF tuner, 405 IF stages and 405 video amp. I then fitted the two small PCBs from a gutted Murphy UHF converter plinth in their place, plus a varicap diode UHF tuner (ELC1043) and 30V/12V power supply (derived from the HT line). I also fitted a 4 pole wafer switch that was operated by the existing channel selector knob and shaft, to control the Varicap tuner.

Finally, I stripped out all the system switching (factory fitted) on the main chassis and the Octal converter socket, wiring the set for 625 only operation.

The result was a very good 625 picture and sound (the tired original Mazda CRT had previously been replaced by a Mullard AW47-91).

Unfortunately, I didn't keep the set.

Regards,

Dazzlevision
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