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Old 5th Dec 2019, 5:52 pm   #1
Dick Glennon
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Default Proper valve lineup in a Philips maybe 50s set

Hi, I have a Philips possibly 50s set (no number) . The valves are in place but I am not sure if they are in the right place. Looking in from the front from left to right is EL 84,EBC81! EF80, ECH81, and EZ81 I think. Anyone come across a small Philips set with piano keys with this valve lineup Thanks, Dick.
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Old 5th Dec 2019, 5:57 pm   #2
Nuvistor
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Default Re: Proper valve lineup in a Philips maybe 50s set

Those valves have specific functions, can you check the wiring to valve holders, it would be obvious which valve goes in which socket by checking the wiring.
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Old 5th Dec 2019, 6:07 pm   #3
turretslug
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Default Re: Proper valve lineup in a Philips maybe 50s set

Also if you can put up a picture with the back removed, some educated guesses can be put up as regards location- e.g. the ECH81 will often be nearest to the tuning capacitor, the EZ81 nearest the mains transformer (or even, especially Philips, on a bracket attached to the transformer), the EF8x between two IF cans. These aren't hard-and-fast rules, but they can form a guide to successive elimination if nothing else.

Incidentally, both EZ81 (a relatively high-current rectifier more appropriate to things like small stereo amps/medium power mono amps) and EF80 (a "straight" general-purpose pentode) would be unusual choices in a set like this but, being commonly found valves, may have been substituted on the basis of "well, it seemed to make it work",

Colin
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Old 5th Dec 2019, 6:35 pm   #4
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Default Re: Proper valve lineup in a Philips maybe 50s set

Perhaps a couple of photos of the set would enable someone to identify the model number so that service information could be located.

Alan
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Old 5th Dec 2019, 7:18 pm   #5
Dick Glennon
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Default Re: Proper valve lineup in a Philips maybe 50s set

Hi, I will get photos posted in a few days time. Dick.
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Old 5th Dec 2019, 7:34 pm   #6
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Default Re: Proper valve lineup in a Philips maybe 50s set

The EF80 is likely to have been an EF89 originally. The two valves are pin compatible but have different electrical characteristics, so subbing an EF80 will work after a fashion but won't perform well.
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Old 5th Dec 2019, 11:20 pm   #7
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Default Re: Proper valve lineup in a Philips maybe 50s set

The EF80 valve is almost certainly wrong, as it is a 'straight' (sharp cut off) valve, where normally a 'Variable mu' valve would be used. It will be the I.F. amplifier valve (in that valve line-up) and a controlled valve from the AVC (AGC) control voltage. Therefore I would suggest that it should be either an EF85 or an EF89. Both of which are (variable mu).

The EZ81 is a high power version of the EZ80, and although they both will work, the EZ81 has a higher Heater current consumption than the EZ80. However, with that valve line-up you mentioned, the EZ80 is more than adequate for the job it has to do.

To work out the correct valve line-up, you would need either the service sheet, or failing that, workout from the chassis layout and wiring. The ECH81 is the frequency changer, and would normally be somewhere near the tuning condenser. The (EF80, which should be EF85 or EF89) is the I.F. amplifier and would normally be near or between the two I.F. Transformers. The EBC81 is the second detector, AVC, and first Audio Amplifier. The volume control will normally be connected sometimes via a coupling capacitor (and possibly, a 'grid stopper' resistor in series), to the control grid (pin 2). The EL84 is the Audio output valve and pin 7 (the anode) will go to a terminal on the output transformer. The EZ80 (EZ81) is the rectifier and pins 1 & 7 go to the H.T. winding on the mains transformer, pins 4 & 5 may go to its own dedicated heater winding, or be part of the heater chain. Pin 3 will go to the reservoir Capacitor to supply the H.T.
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