View Single Post
Old 20th Oct 2019, 7:57 pm   #10
Synchrodyne
Nonode
 
Join Date: Jan 2009
Location: Mt. Maunganui, New Zealand
Posts: 2,567
Default Re: Pye black box G63

As well as the Pye G63, there was the G63/T with the HFT113 FM-AM tuner, which was covered by a supplementary service sheet.

The HFT113 was from the Pye hi-fi series, and appears to have been the replacement for the HFT111. The HFT113 fitted into a Mozart-sized case, and had the valve line-up ECC85, ECH81, EF89 and EF184. The valves were mounted horizontally.

There was an FM-only counterpart to the HFT113, namely the HFT109, which I think was released a little after the HFT113, and replaced the Mozart HTF108. I haven’t seen the schematic, but the valve line-up was said to be ECC85, EF80, EF89 and EF184. Whether the HFT109 was ever used in the G63 I do not know.

As to the unit at interest, it could be that Pye South Africa installed a locally-made FM tuner in order to meet local content requirements. Pye products in the “colonies” were often different to their UK counterparts for this and other reasons.

The 3 x EF89 IF strip is probably somewhat unusual. Philips was on record (Philips Technical Review 1955 June) as preferring the ECH81, EF89, EF85 line-up, with the EF85 said to be the optimum choice as the amplifier/limiter for driving a ratio detector. (Although the EF80 was generally the industry choice for driving a Foster-Seeley discriminator.) So one might have expected 2 x EF89, 1 x EF85 for the FM-only case in a Philips circuit.


Cheers,
Synchrodyne is offline