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Old 18th Dec 2017, 10:11 pm   #1
Pieter H
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Default Philips tuners in UK sets

Hi,

this weekend I've uploaded the second part of my Philips tuner history, covering the last valve tuners and UHF introduction. The first part covered VHF tuners till the end of the 1950s. Thanks to all of you that have supported me in the several threads I've posted on this topic!

As you can see in the overviews, UK sets and tuners after badly under-represented after 1956, which is a pity given that the UK was an important and big market for Philips and its sub-brands. There must have been as many generations and models in the UK as I've found in the Netherlands, Germany and France. So I'm still hoping to find any info about the tuners used in Philips (or Cossor or Stella) 1960-70 UK sets. As you can read on the site, I'm potentially interested in all relevant information: service documentation of sets specifying the tuners used, circuit diagrams, factory codes and later service codes, drawings and pictures of the tuners in their sets.

Next I will move to transistor-based tuners, where the same requests apply . I look forward to any feedback or inputs!

Cheers, Pieter
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Old 19th Dec 2017, 12:18 pm   #2
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Default Re: Philips tuners in UK sets

A fascinating and highly-researched read, Pieter- thanks for posting. I'd always been impressed by the way that TV tuners were a combination of the leading-edge tech of the time combined with volume manufacturing- but, a little like car radios, that genuinely sophisticated package was hidden in a dull metal case that was itself hidden in something else and taken for granted by most. I have a gold-pin PC88 and a PC86 in the valve stash- not that I have any need for them but I couldn't bear to discard such examples of the art of valve development.

Keep up the good work, I look forward to the transistor tuner edition!,

Colin
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Old 20th Dec 2017, 6:10 am   #3
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Default Re: Philips tuners in UK sets

Hi Pieter:

Thanks for another most interesting article.

The background to the PC88 was particularly welcome, as I haven’t seen very much on this previously.

It would appear that all of the Philips European valved UHF tuners were of the three-gang type, with an aperiodic input to the RF amplifier. As a corollary, only the UK versions had the fourth gang for a tuned RF input, as necessitated by the significant increase in image rejection following the decision to move the IF from 38.9 to 39.5 MHz, whilst still retaining co-siting of n and (n+10) channel transmitters. I suspect that the noise factor suffered a little because of the tuned input. Here is the data for the Mullard AT6360-02:

Mullard AT6360-02.pdf

The AGC curves for the PCC189 and EF183 case are interesting. It looks as if the AGC bias for the PCC189 had around a 15-volt delay, with the slope then close to that of the EF183 bias curve. For the PCC84 and EF85 case, for system A, Mullard used a 3.5-volt delay for the PCC84 relative to the EF85, both AGC bias curves having the same slope. It also provided for AGC application to an EF80 2nd IF stage (which would have handled vision only), not delayed, but scaled down to be at -5 volts when the EF183 was at -13.5 volts, so having a lower slope. Optionally, for a PCC84 RF amplifier with EF80 1st and 2nd RF stages, there was a 2-volt delay for the PCC84, with the EF80 bias scaled to be at -5 volts when the PCC84 was at -10 volts. I think the latter would have applied in cases where the sound take-off was immediately after the tuner, and not after the 1st IF stage.

For the negative modulation case, with a PCC88 RF amplifier and EF80 IF amplifiers, Mullard showed the RF amplifier AGC with a 3-volt delay relative to the IF amplifier AGC, but a much steeper slope, so that both reached -5 volts at the same time.

I haven’t seen any information on how Mullard used the PCC89 and PCC189 in System A applications, but I’d guess that it was with sliding bias for the upper triode with a resultant reasonably wide grid base, similar to that of the PCC84 with sliding bias. Another unknown (to me) is the nature of the AGC bias (delay and slope) applied to the PCF86 and PCF801 pentode parts when used as UHF IF amplifiers.

In respect of IF choices for the Belgian and French multi-system receivers, it appears that French System L was accommodated with a 39.9 MHz picture IF, which allowed the sound to be at 33.4 MHz, the same as for Systems B, C and F. In some cases, System E picture IF stayed at 38.9 MHz, with sound at 27.75 MHz, but in others, it moved up to 39.9 MHz, the same as for System L, with sound thus moving up to 28.75 MHz. A post-facto rationalization of this change would be that the Nyquist slope over 39.9 MHz was gentler (±1.25 MHz for System L) than that at 38.9 MHz (±0.75 MHz) and so closer to the ±2.0 MHz that was ideal for System E. Also, assuming that lower edge bandstop events at and below 33.4 MHz were the same as previously, there was an extra 1 MHz of video bandwidth gained.


Cheers,
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Old 21st Dec 2017, 11:07 am   #4
1100 man
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Default Re: Philips tuners in UK sets

Good morning,
An interesting insight into UHF tuners, not part of a TV I had ever given much thought to.
It got me thinking about the UHF tuner fitted to my GEC 2000 from 1964 ish. The design & construction looks pretty much the same as the ones pictured- diecast metal box with 5 chambers. 4 gangs on the variable capacitor and PC86, PC88 valves.
The drive is via a knob & string like a radio- it even has a dial pointer.
The set was made by Radio & Allied Industries so is it likely that they would have come up with their own design or was it a bought in unit from Philips?
Did Philips licence their design to other manufactures?
It's interesting piecing all these little bits of history together!
Many thanks
Nick
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Old 21st Dec 2017, 8:43 pm   #5
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Default Re: Philips tuners in UK sets

The Decca DR123 was manufactured in 1965. The set I have in my possession is fitted with a Philips AT7639/22 VHF tuner. Valves are PCC189 and PCF86. The third attachment shows the slide switch fitted on the tuner, this cable operated switch is attached to the 405/625 change over control.

The push button controlled UHF tuner was not manufactured by Philips.

DFWB.
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Old 21st Dec 2017, 10:58 pm   #6
Pieter H
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Default Re: Philips tuners in UK sets

@ Synchrodyne, post #3
I think the reason for the IF changes in multi-norm sets was the following:
when there was only 4-norm VHF the picture IF was kept constant at 38,9, with the two sound IF's at 33,4 (CCIR-B and the two Belgian variants) and 27.75MHz (French 819lines VHF).
With the introduction of French UHF (6,5MHz picture-sound distance) it was easier to keep the sound IF's unchanged but change the picture IF (38,9 for CCIR-B and Belgium and French VHF) and 39,9 (for French UHF). This was integrally probably the easiest way, given that the sound IF's were narrow band and the video much more wide band. A bit of asymmetry on the Nyquist flank - which was probably the result of the rough IF bandwidth adaptation - was probably less of an issue than playing around with too many sound IF's.

And thanks for the AT6360 spec sheet, a nice addition. Interestingly, the UK tuners apparently introduced 4-section tuning already in valve tuners, where on the continent all valve UHF tuners remained 3-section, while 4-gang was only introduced with the transistor tuners (that will be described in pt3!).

@ Nick, post #4
So far I've only seen manufacturing of the tuners in Philips factories or affiliated ones, like CBRT in Belgium that was producing for Philips. Knowing Philips, which really started to make selling tuners a separate business starting around 1960, they would not license manufacturing but would try to sell tuners. Which was probably the case with Radio & Allied you describe. All other features you mention - wired control of the tuning axis, display - were all standard in the Philips sets (see the section in pt2 on UHF retrofit), and these concepts were probably sold with the tuner, like they were offered as internal retrofit sets.

@Fernseh, post #5
Thanks for the pictures!
The switch in picture 3 you refer to was officially the VHF-UHF switch, an integral part of the VHF tuner as described extensively. In UK sets this was of course equivalent to 405 (VHF) to 625 (UHF) switching.

Cheers, Pieter
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Old 22nd Dec 2017, 5:05 am   #7
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Default Re: Philips tuners in UK sets

Quote:
Originally Posted by Pieter H View Post
And thanks for the AT6360 spec sheet, a nice addition!
Here is the full the document from which the AT6360 data was excerpted. It refers to several other contemporary Mullard TV tuners, VHF and UHF.

Mullard TV Tuners.pdf

Cheers,
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Old 22nd Dec 2017, 11:28 am   #8
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Default Re: Philips tuners in UK sets

Philips multiband tuner type AT7672/90. This tuner was fitted in many Decca dual standard colour TV sets. Does the group of numbers 3112 108 65522 relate to the complete tuner assembly?

DFWB.
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Old 22nd Dec 2017, 11:36 am   #9
Pieter H
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Default Re: Philips tuners in UK sets

Hi Synchrodyne,

fantastic, thanks a lot!!!!!!
Some really valuable new data.

One of the remarkable facts is that again an AFC-enabled tuner is offered, in this case the AT6361/02 UHF tuner. The same happened consistently in VHF. This must have been a feature driven/requested by external customers, because, apart form one high end set using VHF AFC, I've not found any Philips TV's using AFC. It was simply too costly, requiring a substantial amount of additional circuitry including 2 (half) valves.
Is someone aware of any consistent use of AFC in other TV brands, preferably using Philips tuners?

Cheers, Pieter
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Old 22nd Dec 2017, 11:39 am   #10
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Default Re: Philips tuners in UK sets

In the mid 1960s the miniature Philips turret tuner type AT7650 was adopted by almost every UK TV manufacturer. It first appeared in Philips group TV receivers in late 1964? for example the Philips 19TG164, and by 1965 it was to be found in many other UK made TV sets. The AT7650 employed PC900 and PCF801 valves.
Was this excellent tuner fitted in Continental TV sets?

DFWB.
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Old 23rd Dec 2017, 12:02 am   #11
Pieter H
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Default Re: Philips tuners in UK sets

Hi Fernseh,

post #8:
yes, most likely the 12nc refers to the complete assembly of tuner plus 4-button pre-set mechanics. Every "product" that left the factory required its own 12nc, and because this module was almost certainly pre-assembled while at Philips the code refers to the total unit. Which is supported by the code structure: 3122 108 60xxx was normally the 12nc for transistor tuner-only modules. The 3122 108 65xxx code suggest a higher level assembly. However, still a bit speculative, I need for data to confirm the latter assumption.

post #10
Yes, the AT7650 (alias NT5703, V5B) was widely used in many countries and for all standards. I'm currently updating the table, but essentially all Philips platforms in 1965-1967 used this tuner: 23TX500, 510, 520, 530, 540 and 560 and their German (TD) and French equivalents (they still used the old coding structure, so TF2366, TF2373 and TF2381). All other factories undoubtedly also used it. From 1967 they were used alongside the first transistor tuners, being replaced in new sets around 1968. Still working on the details, this will be part 3.

Cheers, Pieter
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Old 23rd Dec 2017, 3:19 am   #12
Synchrodyne
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Default Re: Philips tuners in UK sets

Quote:
Originally Posted by Pieter H View Post
One of the remarkable facts is that again an AFC-enabled tuner is offered, in this case the AT6361/02 UHF tuner. The same happened consistently in VHF. This must have been a feature driven/requested by external customers, because, apart form one high end set using VHF AFC, I've not found any Philips TV's using AFC. It was simply too costly, requiring a substantial amount of additional circuitry including 2 (half) valves.
Is someone aware of any consistent use of AFC in other TV brands, preferably using Philips tuners?
I don’t have anything that directly connects AFC with Philips tuners, but here are some more general observations that might help to create a broad background picture.

AFC was used in some early American TV sets of the split-sound type. In those cases, the AFC bias was taken from the sound channel discriminator and used to control a reactance valve. The same bias could be and sometimes was used to control a centre-zero type tuning indicator such as the 6AL7GT magic eye.

With the advent and subsequent widespread use of intercarrier sound, AFC (and tuning indicators) disappeared from American practice in the early 1950s.

But it returned for the 1958 season, reintroduced by Westinghouse, by which time it was known as AFT (automatic fine tuning). This (rather complex) Westinghouse system was the subject of an article entitled “Automatic Fine Tuning is Here” in Radio-Electronics (RE) for 1958 February, page 56ff, and it was also described in an IRE paper (1). A key point was that the reactance element was a crystal diode, making it a relatively easy addition to the standard forms of two-valve VHF tuners.

Evidently by 1957-58 it had been realized that finding the correct tuning point for intercarrier receivers was not an easy operation for typical consumers, and that something better was needed. About a year or so before that Canadian Radio Manufacturing Corporation had devised a tuning indicator circuit, used in some Canadian Philips TV receivers, that used a conventional peak-reading magic eye. This was described in RE 1957 June, page 57ff. An interesting point was the care needed to derive a reasonably symmetrical peak around the vision carrier from an IF channel where the same carrier had been subjected to the Nyquist slope. I think that the same considerations would have applied to AFC when derived from the vision carrier. In fact. It had come up previously, in 1952, in GE’s effort to eliminate some of the intrinsic ills of intercarrier sound. It used an IF sidechain with a peaked and narrow bandwidth vision carrier, thus minimizing Nyquist phase modulation of it. The circuit was briefly described in RE 1952 January, pages 31 and 32. With the benefit of hindsight, one may see that the peaked vision carrier could also have been used to feed an AFC system and a peak-reading tuning indicator.

I don’t know to what extent AFT was adopted by American industry in the decade following 1958, but judging by several magazine articles, both AFT and tuning indicators were foci of attention again in the 1967-70 period, suggesting that AFT had not become “routine” before then. But its significance by the second half of the 1960s was indicated that a TV AFT IC, the CA3034, was c.1966 just the second release item in RCA’s planned range of TV ICs, the first having been the CA3014 intercarrier sound unit.

Turning to Europe, other than the UK, Wireless World (WW) for 1959 September, pages 403 & 404, had a brief item on German TV receivers in which it noted that AFC was universal in sets that covered Band III (surely that was all of them, and AFC was also used for Band I) but that only one setmaker, Graetz, had was using AFC for Band IV, as well. I have attached the pertinent WW page, which includes an outline of the Graetz circuit:

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If indeed AFC (at VHF) was “universal” in German practice, then one would suppose that some German setmakers were using Philips tuner variants equipped for AFC. And it would also be reasonable to suppose that if universal for VHF, AFC also became universal for UHF once the details were worked out. So, the German market requirements may well have been the driver for Philips’ introduction of AFC-capable VHF and UHF tuners.

Practical Television for 1962 December, page 123ff, carried an article on intercarrier sound, based upon then-current European practice, which included the comment that “…the great majority of good CCIR receivers have gone over to automatic frequency control of the main tuner.” The block schematic shown early in the article included an AFC loop with a PCF80 AFC IF stage, 2 x OA79 discriminator, PCF80 DC amplifier and AFC diodes in the tuners, CA159 for VHF and BA102 for UHF. I have attached the pertinent page from the article:

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In respect of the UK, WW 1959 April, page 159 reported that GEC had developed an AFC circuit using a silicon diode as the reactance element and controlled by bias derived from a discriminator in the sound channel. Whether it was ever used in a production receiver I don’t know.

WW 1959 October, page 441, provided details of the system used by Murphy to provide AFC, for FM only, on its combined TV-FM receivers. This used a point-contact germanium diode, controlled by bias from the FM discriminator by a triode DC amplifier. Given that FM and (AM) TV sound shared the same 6.31 MHz 2nd IF (Murphy had adopted conversion for the TV-FM sound channel about a year earlier), it is perhaps a little surprising that AFC was not also used for TV sound. I don’t know what make of VHF tuner Murphy used, but perhaps not Philips, as I am not sure that Philips/Mullard ever offered a Band I/II/III VHF tuner for the combined TV-FM case.

Then WW 1960 October, page 490, provided an outline of the AFC system used on the Dynatron TV50 TV-FM receiver chassis. This applied to both FM and TV sound. In the FM case, AFC bias from the 10.7 MHz discriminator was used. In the TV sound case, the 38.15 IF channel MHz included a double-diode that served as both a discriminator and AM demodulator. A junction diode was used as the reactance element. As the VHF tuner for the TV50 was shown as having Mazda valves, I suspect that it was not a Philips unit.

Thereafter I have seen nothing on British TV receiver AFC until the advent of colour, when it was used by some setmakers for UHF.

On the AFC vs. AFT terminology, I suspect that AFT was preferred for the “second wave” of TV applications for two reasons. One was that “AFC” in a TV context had become indelibly associated with flywheel line timebase systems, so that a different name was needed for what might be called the “tuning assistance” system. Deutsch, in his 1951 book (2), had a separate chapter on “Automatic Frequency Control”. The first part referred to the line timebase application, the second part to local oscillator control, so one might say that the line timebase case took priority.

And the other reason was that “automatic fine tuning”, dispensing with manual fine tuning, was the intended purpose of those second wave systems. Earlier AFC systems may have had as their primary purpose the holding on tune of a receiver that was initially set to the correct tuning point manually. On the other hand, American practice continued with AFC for systems frequently applied to FM receivers. In Europe, the association of “AFC” with line timebases had not been established, so that there was supposedly little or no confusion when AFC was used in connection with receiver tuning.

I was fooled once though, when looking at the schematic for the Sonly TUM-100, a System M outboard tuner (receiver)-modulator combination for use with the late 1960s CV-series of video tape recorders. On the one hand there was a circuit board identified as “AFC”, but on the other hand neither the VHF not UHF tuners (shown simply as blocks in the schematic) had any apparent inputs for AFC bias. Upon closer inspection it turned out that the AFC board contained a miniature flywheel line timebase system whose function was to generate properly timed gating pulses for the gated AGC system!


Cheers,


All of the above-referenced magazine articles are available at the excellent AmericanRadioHistory.com
site, at: http://www.americanradiohistory.com/, as follows:

Radio-Electronics: http://www.americanradiohistory.com/...aster_Page.htm

Wireless World: http://www.americanradiohistory.com/...d_Magazine.htm

Practical Television: http://www.americanradiohistory.com/...n_Magazine.htm



(1) The subject IRE paper was: Automatic Fine Tuning in Television Receivers; K. E Farr & L. J. Sienkiewicz, Westinghouse Electric; IRE Transactions on Broadcast and Television Receivers; 1958, BTR-4 Issue 2, pp.63-73.

(2) Sid Deutsch; Theory and Design of Television Receivers; McGraw-Hill, 1951.
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Old 23rd Dec 2017, 3:49 pm   #13
Maarten
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Default Re: Philips tuners in UK sets

Quote:
Originally Posted by FERNSEH View Post
Philips multiband tuner type AT7672/90. This tuner was fitted in many Decca dual standard colour TV sets. Does the group of numbers 3112 108 65522 relate to the complete tuner assembly?
The numbers on the same label relate to the same assembly. So if AT7672/90 refers to the complete assembly, not only the mechanics, so does 3112 108 65522. Yours was made in Monza, most likely week 16 of 1970. Alternatively, as the date code system changed in between those dates, week 1 of 1966 but that should be clear from the set it was found in.
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