[ducretet]

Hi everyone,
I have a friend's radio to repair. It is a zenette with 5 valves: 57, 58, 57, 47, 80. I have not found any scheme. It looks like a RFS with no reaction. The problem is that the RF transformer in the third step is cut off. The primary reads about 750 ohms. The secondary cut. Trying to see how the transformer was, the primary has been cut. A disaster !!!!!.
I do not know what to do. I've rewound Philcos coils, etc. But this case is impossible. It is small and I have no data. It was covered in wax.
Question: Could the coupling be made between the 58 and the 57 resistors?
Can you give me a solution? At the moment nothing else has occurred to me.
Thanks in advance.

[Radioroslyn]

If you could post a pic of two of the top and bottom of the chassis that would be helpful. Some of these early '30s set use a pentode as a mixer and osc so it can be a little confusing to sort out if it is a trf set or a superhet w/a low tube count.

My 2nd thought is that if the 2ndy is untuned then the coil is just used for coupling. I would wind 50t or so on the form and see how that works. If it's on the mw band to be some what resonant your looking at about 100-120t.

[Eliot Ness]

See if a Zenith 200 is similar to your set:

http://www.nostalgiaair.org/pagesbymodel...024785.pdf

And as Terry said, pictures would be very helpful.

[ducretet]

Hola Terry,

adjuntaré les imatges. Un d'ells correspon a l'olla on va el TRF danyat. El fil estava molt fi, però no sé el nombre de voltes. També el secundari estava unit a un trimer. [fitxer adjunt = 25317] [fitxer adjunt = 25318] [fitxer adjunt = 25319] [fitxer adjunt = 25320]

[ducretet]

Hi Terry,
I'll attach the pictures. One of them corresponds to the pot where the damaged TRF goes. The thread was very fine, but I don't know the number of turns. Also the secondary was attached to a trimer.

[ducretet]

Thanks John,
But it's different.

[ducretet]

Terry, one solution would be to rewind it. But,
number of primary turns?
number of secondary turns ?.
I've been looking for a similar scheme for days. Any !!!!

[Radioroslyn]

I'm not all together certain that it's a trf set. On a typical late '20s-early '30s trf set you would have a row of 3 rf coils that are pretty much identical. Your set they're all different looking. I'm thinking that it could be an early superhet.

One clue that I did find is that it seems that most of the Z sets with 47 output tube used an IF of 175kc which is good as it's a standard frequency (for early sets) and is not impossible to find. But I would take a listen at the 1st stage to see if there is something oscillating below the incoming signal (dial setting). You could connect a low frequency receiver to the ant wire of the zenette and power it up. If there isn't any other issues like shorts or like things that will kill the p/s or output stage. Check to see if the voltages look reasonable around the 1st tube.

[ducretet]

Hi Terry,
I think you're right. It is a superheteredine. Coincidentally I had a TRF FI of a GE of the year 33 approximately. I have connected it and I hear a very weak station. It is 175 Kc.
The speaker is bad. The field coil reads 30 ohms. Impossible !!!!!. They must have rewound it wrong !!!!. Generally the field coils are between 1500 to 2000 ohms.
Thanks Terry.
And it is true, the TRFs are practically the same.

Regards,
Ferran

[Radioroslyn]

You do find some low resistance fc in '30s 6v car radios.

[ducretet]

John, you are absolutely right. The scheme was correct. When Terry told me that he was a superheterodyne, I checked with the schematic. You were right!!!!.
The problem was finding the second FI that would work with the device.
He had a spare from GE.
The radio works !!!!. That yes, I almost went crazy !!!!

[Eliot Ness]