SG-402, radio from 1940

[Terry]

Where is  the speaker in the schematic, perhaps the coil at the anode of the EBL1?

The speaker isn't shown but you're on the right lines!

The anode load is the output transformer which matches the low impedance of the speaker to the high impedance of the valve.

The speaker itself is connected to the two terminals on the secondary.

Incidentally, the side contact base of the valves in this receiver are notorious for poor contact. You could try cleaning them to see what happens but a useful guide can be obtained by placing thumb and forefinger on either side of, but not touching, the top cap of each valve in turn and rocking the valve in a circular motion.

If all the contacts are clean, you won't hear any difference but, if they are dirty, you'll soon hear about it!

[Peter08012018]

The receiver does have "Lautsprecher Dynamischer LS, mit Erregerspule (elektrodynamisch)" a dynamic speaker, not with a magnet but with a coil the creates the magnetic field. This could be a source of humm, too?

I wll try whether the speaker is plugged, or screwed (geschraubt), as suggested by the scheme. Which would allow another speaker, or the historic ear piece. I will open the receiver and see, using a camera and a plastic box to document and not lose the screws.
       

[peter scott]

The inductor between the AZ1 rectifier and C24 is probably the magnetising coil of the loudspeaker.

Peter

[Peter08012018]

when I wiggle the valves, (or moved the receiver from storage to the work bench) the "endstufe" NF amplifier EBL1 scratches and goes off, after more easy turning of that valve (Röhre), a few degrees flat forth and back, it fastens and the humm is again constant.

The metal brick below the valves and large condensators (or shielded tubes) is closed, and no chance for me to access it, without spoiling it.

I will try to find a new owner as it is.

However I am curious and would still like to find: can I see the tuning circuit work, or the IF work. What I do have is a dip meter that I don't know well how to use. But to get understanding of the dip meter I can build an LC circuit, I do have blue inductances, and a coil marked "50" historical (and of course C in any quantity and capacity and know the formula). The blue inductances would be sized like large tantal C, not coily form factor.

           

[Refugee]

Those cylinders are the RF transformers and will not need any work done on them.
The set is in good condition and will only need a couple of small capacitors changed to get it going.

[Peter08012018]

The receiver is now selling at 60 swiss francs and I did the remark that it only needs a few condensators. If one is curious you find it by "ricardo an964066752".

I'm still interested, for my personal education, whether I can see the tuned circuit in it with the aid of the dip meter, or any LC circuit at all.

(And I remember GDO from a detective story where a young did an emergency radio call with the aid of a grid dip oscillator to get out of a locked situation).

[Peter08012018]

quite interesting and disturbing, the receiver did not sell at 60, not even at the initial price of 10 Swiss Francs. But it got now a good place in the hands of a radio amateur who will enjoy repair it.

And I don't get the Trio SG-402 manual in PDF form... because I can't reach the threshold. Но вместо того у меня инструкция напечатаная и ещё похожая от Leader Test Instruments LSG-16, у которого точно тот внешний вид, только внутренняя модулация 1000 Гц вместо 400 Гц.

I can't reach "it" even with extending the story about the dismantled DKE-38 which is now complete. The VY2 was most hard to find in the darks of the flat .

PS and ЗЫ home language would be german.

[Terry]

There is a link to the SG-402 manual here on this forum:

http://golbornevintageradio.co.uk/forum/...p?tid=4238

[Peter08012018]

I will never get the 15.

I can do the scan myself and I do have someone in the East who is very good at converting to PDF including text content.

[Peter08012018]

There is a link to the SG-402 manual here on this forum:

http://golbornevintageradio.co.uk/forum/...p?tid=4238

Unfortunately I can't get it because I do not meet the 15 points requirement.