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PYE 11 u chassis

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This is a question that's bugged me for years , on the PYE 11U series VHF tuner there are 2 symbols a square & a triangle
Can anyone explane the purpose of these ?


Topic starter Posted : 05/09/2015 2:43 am
Famed V-Ratter Registered

Hi Chris,
I think they are just to represent spare channels....on mine, there are no biscuits fitted in the tuner at those positions.

Posted : 05/09/2015 9:44 am
Famed V-Ratter Registered

Can you post that part of the circuit? The ones in the library does not show those symbols, or to be more correct I don't see them.

Apart from the occasional valve replacement and contact clean the VHF tuners gave me little trouble. The Philips rotary tuner fitted to some Ferranti sets had a mechanical problem in that the plastic fine tuning rod occasionally broke off. Fiddly but possibly to change in the house.
Looking at the two VHF tuner circuits in the circuit from the library I had never noticed that the UHF IF signal on one tuner uses both valves and on the other just the Pentode sectional if I had noticed it was long forgotten until just now :)

Posted : 05/09/2015 9:49 am
Famed V-Ratter Moderator

Can you post that part of the circuit? The ones in the library does not show those symbols, or to be more correct I don't see them.

The symbols are shown on the VHF channel selector knob. I'm nowhere near mine at the moment otherwise I'd post a picture to show. I assume they were for 'special' channels...cable perhaps? Maybe in flats that had cable distribution systems, special biscuits were available for the VHF tuner.

"edit". You can see the symbols in this old post of mine. You'll need to click on the picture to enlarge it.

?? four years ago?? The set looks and works much better than that now!

Posted : 05/09/2015 10:12 am
Famed V-Ratter Registered

I don't remember, seems a lot I don't.
The cable suggestion is a good possibility, the only other possibilities I can think of is the there are only 11 positions for VHF and there were 13 possibilities. They may have done that to fit biscuits for the channels not marked on the knob i.e 12 and 13, I can't make out what other channels are missing, there must be two others.
The other is for none standard channel pairing, i.e, normally 2 and 9 or 1and 9, 4 and 8, etc, the biscuits for the non standard channels could be put together. 2 and 10 for Yorkshire don't seem to be paired.
Both ideas are guesses however.

Posted : 05/09/2015 11:25 am
Famed V-Ratter Rest in Peace

That Pye tuner is a bit odd, having only 12 positions, including UHF!

Possibly Frank is right and these are dual purpose markings which could be used for missing channels on either standard.

I can't remember how the system switching is achieved on the 11U but I do remember the method adopted by Baird - which did, I believe, have the full 14 positions - and is probably similar to the Pye arrangement.

Baird had a pin on the end of the system switch operating lever which engaged in a slot on a metal wheel mounted on the rear of the turret spindle. The standard wheel moved to the 625-line position only for UHF but an optional wheel was available which increased the number of 625-line positions to four IIRC with the new positions occupying a similar position to the symbols on the Pye.

We used these for customers in council tower blocks which had VHF only distribution systems and translated BBC2 to a VHF channel - in our case, this was Channel C (61.75MHz Vision, 67.75MHz Sound) with 405-line signals on their off-air allocations of Channels 1 and 9.

Posted : 05/09/2015 2:34 pm