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Old 17th Sep 2017, 9:09 pm   #1
Pieter H
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Default Philips-Mullard TV tuners 1953-54

Hi all,

I'm trying to pieve together the history of the Philips TV tuners. For the Continent the mid 50ies picture is fairly complete, but the UK is less clear.
In this period Philips/Mullard brought out the following sets:
1952: 1114U and 1115U
1953: 1426U and TG1437U
(The first 2 digits refer to the screen size, the 3rd to the year of design (1=1951, etcetera) and the 4th indicates the ranking).
All these sets had a 5-channel VHF-I tuner using two EF80's. I suspect, but have no proof, that this was the same capacitively tuned device as used in the early Dutch TV models (TX400A, TX500A) where it covered four channels.

In 1954 a new Philips TV family appeared, the 1446U and 1746U. These were offered with either the old 5-channel or a new 12-channel tuner (for 6 pound 6 shilling more). I suspect that 5-channel tuner, although four years old by then, was still the EF80-based model, whereas the 12-channel model was the first turret tuner, similar to the Dutch/German AT7530.

Does anybody have more details of these two tuner models as used in these televisions? Type number, factory code and possibly circuit diagrams?

Cheers, Pieter
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Old 17th Sep 2017, 11:00 pm   #2
FERNSEH
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Default Re: Philips-Mullard TV tuners 1953-54

Hi Pieter, UK made Band 1 only Philips TVs did not have a five channel switchable tuner.
Channel changing was achieved by plugging in the appropriate coil set to receive any one of the five BBC channels.
The information given here is from 1953/54 Radio and Television servicing book and applies to the model 1748U. Models 1114 and 1115U employ a similar 5 channel front end.

DFWB.
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Old 17th Sep 2017, 11:56 pm   #3
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Default Re: Philips-Mullard TV tuners 1953-54

The 1955/56 Radio and television servicing book informs us that Philips models 1446U/45 are single channel models to which an AT7520 tuner unit can easily added when required. whilst the other models (those without the /45 suffix) incorporate a multi channel tuner.
Pages 504 to 506 of the 1955/56 R & T book are dedicated to the Type AT7520 Band III tuner. From the text: "This unit is a twelve position turret type and will operate on any transmissions in Bands I and III if the appropriate coils are fitted".
Type AT7521. When supplied for the conversion of Band I receivers the tuner unit is known as the AT7521/??, the suffix depending on the model the kit is designed for converting.

DFWB.
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Old 18th Sep 2017, 3:51 pm   #4
Pieter H
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Default Re: Philips-Mullard TV tuners 1953-54

Hi Fernseh,
thanks a lot, very helpful.
In the meantime I found a circuit diagram of the 1114/1115/1726/1437, which confirms that they all use a single-channel front end, not tunable and integrated on the main chassis. From your input it is now clear that the "5 channel" refers to the five different settings of this front end, not to a 5-channel tuner. This concept seems to have been carried over to the 1446, 1746 and 1748 for the cheap versions with suffix /45. But these sets were all prepared for an upgrade to the AT7520 or 21 12-channel turret tuner. Which is indeed, as I expected, from the AT7510-AT7550 family.

Thanks a lot!

Cheers, Pieter
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Old 19th Sep 2017, 7:10 pm   #5
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Default Re: Philips-Mullard TV tuners 1953-54

These two pictures show the 12 position Philips Band 3 converter. It is fitted with B9A adapter plugs replacing the two EF80's. This is the external free standing version. They were a very good unit.

Versions were produced with B8A rimlock adapters to replace the two UF42's in earlier models. The 'M' before the serial number shows it was built at the Philips 'Mitcham Works'.
If you wish to see the internals I will open it up.

Most of the Philips Band 1 models had interchangeable plug in coils for the 5 channels John.
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Old 22nd Sep 2017, 9:13 pm   #6
Pieter H
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Default Re: Philips-Mullard TV tuners 1953-54

Hi John,
thanks a lot for the info (another type number added to my list) and the picture.
Initially I thought this was simply a tuner in a box with the power supply and AGC going in and the IF coming out. In that case I would know (or at least expect) what's inside the black box and no need to open it.
But if I understand it correctly, and indeed confirmed by the picture, the unit worked by plugging the two connectors in the sockets of the two EF80's that were removed, correct?
In that case the unit has quite a non-standard interface, and modifications would be required compared to a standard AT7520 tuner. For example the antenna matching would remain on the chassis and should be omitted from the tuner box. So yes, it would be interesting to have pictures from the interior of the box, and/or a circuit diagram!

Cheers, Pieter
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Old 24th Sep 2017, 6:48 pm   #7
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Default Re: Philips-Mullard TV tuners 1953-54

No problem Pieter. I will open it up on Monday. Yes you are correct, the two B9A plugs replace the two EF80s. Th original aerial socket mounted on the chassis is replaced by Co-ax sockets on the tuner. John.
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Old 26th Oct 2017, 6:57 pm   #8
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Default Re: Philips-Mullard TV tuners 1953-54

Thanks for your PM Pieter. I must admit I had completely forgotten to take the pictures.

It would have been easier to raise the Titanic rather than open that tuner box.
Philips at it's fiendish!

The two presets adjust the gain of the Band 1 and Band 3 signals via a wafer switch on the back of the tuner.

It is fitted with 'biscuits' to cover channels 1 9 and 8. Additional coil biscuits could of course be obtained from Philips as Band 3 spread across the country but by 1960 most of these now 10 year old receivers were being retired.
Regards, John.
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Old 28th Oct 2017, 3:15 pm   #9
Pieter H
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Default Re: Philips-Mullard TV tuners 1953-54

Dear John,

thanks a lot (and again apologies for being persistent).
Even more so now that we know about the engineering work you had to perform for opening the box. Much appreciated!

Based on these pictures I think the concept is clear now. When using this box in combination with an older single-channel front end TV set, the antenna was connected to this box RF input, and the first plug was inserted into the input EF80 socket, picking up the 180V anode voltage and the two heater connections. (On your first picture I indeed see three wires, red, blue and yellow, so that seems to fit). The second plug with the shielded cable was inserted in the socket of the second EF80 (the original mixer-oscillator) on the chassis, where the IF output was connected to the original anode pin, thus inserting the IF signal into the regular chassis signal chain. This would imply that in the tuner box the internal IF output filter was omitted, because the one on the chassis was still used. Thus justifying a separate tuner type number.

Again, many thanks for helping to get insight into this interesting tuner version.

Cheers, Pieter
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