Re: Introduction PCC189 in Mullard tuners?
The PC97 was employed as a RF amplifier [neutralized triode] particularly in Thorn's excellent tuners.
The RF stage tended to be very unstable on channel 1 probably as it was very close to the IF frequency and produced motor boating particularly with indoor room aerials. Thorn supplied 'loaded coils' [resistors across the tuning coils] to completely eliminate the problem.
In practice I used to fit the channel 2 coils and retune the oscillator slug to channel 1. Thorn frowned but all service engineers did it!
The cascode RF amplifier was very popular in UK tuners helped by the excellent valve designs from Ediswan Mazda at Brimsdown.
Philips tuners always performed with a slight cut above the rest with zero drift on Band 3. Other than the occasional contact cleaning I cannot remember ever repairing one as such.
Ekco tuners employed the Mazda valves and it is interesting to note that Pye, experts in tuner manufacture, continued to fit what appeared to be this rather large but electrically up to date tuner to their 1964 range after the take over of Ekco.
The last Philips valve tuner, PC900 and PCF801 was outstanding. Incredible gain and stability. This was bought it by many leading manufacturers. John.
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