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Old 21st Nov 2017, 1:38 pm   #1
FERNSEH
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Default PCF84 TV tuner valve.

I believe the PCF84 was employed in only one TV receiver, the Decca DM35. The characteristics of the PCF84 are similar to the PCF80 the only difference being the connections to the electrodes.
http://www.r-type.org/exhib/abd0010.htm

DFWB.
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Old 21st Nov 2017, 2:31 pm   #2
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Default Re: PCF84 TV tuner valve.

The question is what benefits does the PCF84 have over the PCF80 or was it a “ploy” to try and tie the replacement market just to Mullard?
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Old 21st Nov 2017, 4:11 pm   #3
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Default Re: PCF84 TV tuner valve.

Quote:
Originally Posted by Nuvistor View Post
The question is what benefits does the PCF84 have over the PCF80 or was it a “ploy” to try and tie the replacement market just to Mullard?
Hi Frank,
The PCF84 does have two cathode connections which I suppose will reduce inductance. Perhaps the valve was developed at the behest of a tuner manufacturer, possibly Brayhead. The pentode pin connections are similar to the EF80 in having the control grid pin 2 flanked by the cathode pins 1 and 3.

Was the valve was unique to the UK? The developer was Mullard.

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Old 21st Nov 2017, 6:38 pm   #4
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Default Re: PCF84 TV tuner valve.

All these minor mechanical changes with little if any improvement to performance, must have almost bankrupt manufacturers design and tooling departments. J.
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Old 21st Nov 2017, 7:40 pm   #5
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Default Re: PCF84 TV tuner valve.

Does the PCF84 correlate with the Mazda 30C13 or 30C15?

Both of those Mazda valves had their base connections arranged for maximum suitability for printed circuit applications, and for minimum pentode cathode lead inductance. The second pentode cathode pinout was shared with the triode cathode.


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Old 21st Nov 2017, 9:55 pm   #6
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Default Re: PCF84 TV tuner valve.

It's safe to say that the Mazda 30C13 was never employed by any tuner manufacturer, the same goes for the 30F27 RF tetrode.
No information to hand for the 30C13.

From the 1960/61 Radio and Television servicing book, page 31:
A new Ediswan series of frame grid valves for domestic receivers includes the 30C17 and 30F27.
The introduction of these valves has not greatly affected basic circuitry but has materially increased sensitivity, making possible the use of indoor aerials in many areas and the combined standard/fringe chassis.

Pin connections for the 30C15 and 30C17 are the same.

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Old 21st Nov 2017, 10:16 pm   #7
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Default Re: PCF84 TV tuner valve.

The pin connections given by the Valve Museum for the PCF84 are incorrect. According to the 1961 Mullard Maintenance Manual the pin connections for the PCF84 are: pin 1 g2. Pin 2 anode pentode. Pin 3 anode triode. Pins 4 & 5 heater. Pin 6 grid triode. Pin 7 Cathodes g3 screen.
Pin 8 control grid pentode. Pin 9 as pin 7, kg3s.
The characteristics of the pentode section of the PCF84 are slightly better than the PCF80.

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Old 22nd Nov 2017, 8:53 am   #8
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Default Re: PCF84 TV tuner valve.

30C13 data can be found here:
http://www.mif.pg.gda.pl/homepages/f...47/3/30C13.pdf

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Old 22nd Nov 2017, 12:51 pm   #9
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Default Re: PCF84 TV tuner valve.

Hello Jac,
Thanks for finding the information for the Mazda 30C13, it is evident that it is not a direct equivalent to the PCF84. The data goes on to inform us that the 30C13 was developed for TV tuners with printed circuit boards just as the PCF84 most likely was.

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Old 22nd Nov 2017, 2:32 pm   #10
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Default Re: PCF84 TV tuner valve.

I don’t remember any VHF tuners with PCB’s, apart from the Philips printed coil biscuits but I don’t think this applies to that range of tuners.

Were there any valve VHF tuners made on a PCB?
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Old 22nd Nov 2017, 2:41 pm   #11
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Default Re: PCF84 TV tuner valve.

Hi Frank,
I seem to remember the horrible Cyldon PC80 push-button tuner employed a printed circuit board. Valves used in that tuner were 30L15 and 30C15.
Can't remember if the Brayhead turret tuner fitted in the Decca DM35 employed a PCB, I don't think it did. Perhaps the PCF84 was chosen because it had those two cathode connections (pins 7 and 9) to reduce connection inductances.

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Old 22nd Nov 2017, 5:04 pm   #12
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Default Re: PCF84 TV tuner valve.

I heard about the Cyldon PC80, luckily never saw one.
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Old 25th Nov 2017, 9:38 pm   #13
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Default Re: PCF84 TV tuner valve.

Re. PCF84, it resembles w.r.t. timing and function the PCF86, with as main difference the pinning. All these valves had a pin lay-out that allowed to run a shielding screen more or less through the centre of the valve socket, half of the pins being on the one side and the other half on the other. For many RF valves of the period (end 1950s- early 1960s) Philips released two valves, with the pinning such that one could choose between the heater connections 4 and 5 on top or at the bottom but from an application perspective no change. As example the PCF84 and PCF86 (note the reverse numbering on the 86!)

PCF84
pin 1 2 3 4 5 6 7 8 9
G2 AP AT F F GT KG3 G1 KG3
PCF86
pin 9 8 7 6 5 4 3 2 1
G2 AP AT GT F F KG3 G1 KG3

The same happened with the PCC84-->PCC89 and PCC88-->PCC189.
For the PCC89 and PCC189 we see parallel use, with the majority using the 189.
For the PCF function the 84 was hardly used as far as I see, with the majority of tuners using the PCF86 and after that the pin-compatible PCF806.

Hope this helps, cheers, Pieter
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Old 22nd Dec 2017, 4:16 am   #14
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Default Re: PCF84 TV tuner valve.

The PCF84 was mentioned in connection with a Cyldon printed circuit VHF TV tuner, as described in Wireless World 1958 June:
Cheers,
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Old 22nd Dec 2017, 10:55 am   #15
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Default Re: PCF84 TV tuner valve.

I think the PYE incremental tuner used a printed circuit board. Early versions, PCC84/PCF80. Later versions the PCC88/89 / PCF80.

The later Philips tuners from 1960 used printed circuit coils strips in a conventionally wired unit. John.
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