What the heck is this load?

[JoeAlders]

Is there a connection between the 12AL8 and Philips? Or is this just a manner of speech?

The 12AL8 was developed by Tung-Sol (source: Radio Bulletin, April 1957, page 280 / https://nvhrbiblio.nl/biblio/tijdschrift/Radio Bulletin/1957/Radio Bulletin 1957-04-OCR.pdf). The 12AL8 is not on the Philips Factory Valve Codes list but probably this list is not 100% complete.

That remark made me also curious. What on earth is the connection with Philips?

 

[Cagomat]

Do you have a source for this? Or an example of this tube being used like that?

Why would Tung-Sol develop a tube for 800 Ohm loudspeakers which were only made by Philips and (as far as I know) were hardly solded/used in the USA?

Besides that: The power output is only 40 mW (see post #9 and/or the datasheet)

The speaker was sold with a different brand and model number also in USA but dont remember the name

 

[56085]

The loudspeakers of Philips were sold in the USA under the Norelco brand. As far as I know only few of them would have been 800 Ohm types.

But this does not (dis)prove if the 12AL8 was (also) intended to drive 800 Ohm speakers. For me I am pretty sure that the 12AL8 was not designed with that in mind. I never saw an example of a 12AL8 driving an 800 Ohm speaker.

 

[mashaffer]

Yes, the test jig makes the most sense. I suppose if one wanted they could use it as a headphone am using an OPT that gives 800 plate load.

 

[Cagomat]

philips amp 800 ohm speakers

 

[JMFahey]

equipment in which the 12AL8 was used: 12AL8, Tube 12AL8; Rohre 12AL8 ID3809, Triode-TetrodeIn all three the 12AL8 is not being used for audio but as a relay driver.
......
Looking at some of the rest of the schematics I get the impression that the 12AL8 is being used as a relay driver there too

Didn´t go though all the registering process but the ´63 Corvette schematic bit is enough for me:
In a fully transistorized radio, the 12AL8 is used as "trigger" , guess it activates a Relay and something changes (Mute? - Turn hungry Class A power transistor ON?)

As mentioned above, it´s triggered straight from the AM (tuned signal) detector.

A ´63 Vacuum Tube Fet?

Engineers tend to do wild things .... if they solve a problem

 

[56085]

To Cagomat:

The discussion is not about whether or not 800 Ohm loudspeakers exist. They do exist ofcourse (I have 24 of them, including some 9710AM's, and I own a Philips AG9015 amplifier that is mentioned in the topic you linked to. My internetsite is called OTL800 for a reason).

In post #19 you stated that the circuit with the 12AL8 (post #1) was used for the 800 Ohm version of the Philips 9710. I asked you for a source or an example.

 

[56085]

Didn´t go though all the registering process but the ´63 Corvette schematic bit is enough for me:
In a fully transistorized radio, the 12AL8 is used as "trigger" , guess it activates a Relay and something changes (Mute? - Turn hungry Class A power transistor ON?)

As mentioned above, it´s triggered straight from the AM (tuned signal) detector.

A ´63 Vacuum Tube Fet?

Engineers tend to do wild things .... if they solve a problem

I think you are right. It seems to be a muting-function (silent tuning?).

 

[PRR]

Seek/scan.

It may also mute, but the geee-whizz was that it tuned to the next station magically.

 

[56085]

You are right. It indeed says so on the page where one of the schematics in post #13 came from. The link to the page: Delco 985396 Corvette Car Radio United Motors Service Delco,