Vidor My Lady Catherine CN435Z: Questions before attempt to revive

[Katar83]

I'd consider using DC step up converters instead of using multiple batteries, I use small ones MT3608 in all sorts of house equipment and they are rock solid, never had to use HT ones but they are out there and I suspect they should be at least as good as the mini ones. You could then just build a custom battery for it from a single smaller rechargeable battery pack. I use 18650 cells everywhere but there are of course other options.

[granazis]

Originally Posted by Katar83

I'd consider using DC step up converters instead of using multiple batteries, I use small ones MT3608 in all sorts of house equipment and they are rock solid, never had to use HT ones but they are out there and I suspect they should be at least as good as the mini ones. You could then just build a custom battery for it from a single smaller rechargeable battery pack. I use 18650 cells everywhere but there are of course other options.

DC step up to 90V? I haven't seen something like that.

[Sideband]

Originally Posted by granazis

DC step up to 90V? I haven't seen something like that.

Look on eBay! Just a simple inverter, the basic idea has been around since radio was invented! Modern types use a transistor or FET inverter circuit...something like 9 or 12 volts DC input and 90V DC output. They might also be known as DC-DC converters.

[granazis]

On a side topic. I was wondering what the audio frequency response for these, Vidor CN - and similar - radios is. From listening to it I would say something like 250Hz - 4000Hz top.
Is there any thread discussing vintage radios audio frequency responses? I am not asking about the stations' bandwidth. There are threads for that. But I haven't seen any assessing the audio fidelity of vintage radios. They seem to vary widely!
The audio fidelity of this Vidor CN435 seems no better than the 250-4000Hz area, quite possibly 300-3000Hz! It is in par with the late 1950s / early 1960s transistor radios I have. But I would expect more from the Vidor as it has a larger speaker. In fact I find the Vidor audio quality inferior to my other valve (mains) radios (1948 Mullard MAS221, 1959 Ekco U353). In fact the audio quality of the Ekco U353 is better than that of some modern DAB radios and very close to the later Roberts of the 1960s (R600, R700, which I consider the among the best among the vintage in that respect). That means that the "vintage radio audio quality" was not uniform at all, and could be good.
Is there any thread discussing vintage radios audio frequency responses? I am not asking about the stations' bandwidth. There are threads for that. But I haven't seen dealing with specifications or any assessing the audio fidelity of vintage radios. They seem to vary widely!

[granazis]

Now, I have established that the MW frequency range of my CN345 Z is from 522KHz - to 1368 at best. How can I make it go higher? It should go to at least to 1500 (200m on the dial) and perhaps a bit more.
Any ideas?

[marceljack]

Originally Posted by granazis

Now, I have established that the MW frequency range of my CN345 Z is from 522KHz - to 1368 at best. How can I make it go higher? It should go to at least to 1500 (200m on the dial) and perhaps a bit more.
Any ideas?

Check if there is an adjustale capacitor (trimmer) in parallel to the variable capacitor of the local oscillator and if yes reduce its value, it will go higher in frequency. Same thing for the RF circuit tuning.
But you will have to realign the RF part (OL and RF tuning) in order to have the indications OK at both ends of the dial.

[granazis]

Originally Posted by marceljack

Check if there is an adjustale capacitor (trimmer) in parallel to the variable capacitor of the local oscillator and if yes reduce its value, it will go higher in frequency. Same thing for the RF circuit tuning.
But you will have to realign the RF part (OL and RF tuning) in order to have the indications OK at both ends of the dial.

These is something marked TC1 in parallel with C5 on the schematic but it doesn't say what that is. But if touching that means realignment... I will leave it as it is.