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Bought my first cathedral. - Printable Version

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RE: Bought my first cathedral. - Jake Blake - 06-01-2019

". . . dinky, . . . "   Icon_lol

RE: Bought my first cathedral. - morzh - 06-01-2019

Also the bigger transformer is more reliable.

RE: Bought my first cathedral. - GarySP - 06-01-2019

You got lucky if you're only missing a 80 rectifier. They are plentiful and very reasonably priced. Take care, Gary

RE: Bought my first cathedral. - Radioroslyn - 06-01-2019

I was told by an old timer back in the 70's that for each finger width of core on a transformer that has a hv winding the finger width = abt out 100ma of current capability from that hv winding. Almost 50yrs later I say sometimes.

RE: Bought my first cathedral. - jake wells - 06-01-2019

Gary i got two spare 80's laying around i have been wheeling and dealing with a local collector that has a large stash and tube collection.

RE: Bought my first cathedral. - jake wells - 06-01-2019

Just wondering how well it is going to perform.

RE: Bought my first cathedral. - morzh - 06-01-2019

The performance is meh....same as 20 or early 70.
I'll give you a hint: Plate detector.

RE: Bought my first cathedral. - jake wells - 06-01-2019

Well i live between two blowtorch stations wsm and whas they come in pretty strong day and night so it shouldn't have trouble.

RE: Bought my first cathedral. - morzh - 06-01-2019

It's not that. Plate detector is, well, further from HiFi then the rest of'em.

RE: Bought my first cathedral. - jake wells - 06-01-2019

So it will sound like a tin can.

RE: Bought my first cathedral. - Radioroslyn - 06-01-2019

Well that's a good question.

You might have noticed by the schematic that the 50 is a trf set. Trf stands for tuned radio frequency in layman's terms it means that it a couple of rf amps, a detector and audio ouput stage.

+'s
It's not particularly selective so the audio frequency response is typically better than the average superhet.

Easy to service/simple design.

-'s
Broad selectivity may have it hard to separate strong stations that are close in frequency.

No avc. This means that as you tune across the dial if you set the volume control so the strong station is at a comfortable level weak station won't be heard and vice versa adjust it for a weak station and the strong station will be very loud.


I little trickier to connect an external audio input to as the the "volume control" controls the rf gain and the level of signal that comes from the ant. This is why the volume control has two sections.

Not sure about distortion from the detector stage but if it seems excessive there are way to deal w/that.

Common issues are caps, out of tolerance resistor (20%) is spec, open primaries on the rf coils. I had one w/a replacement power transformer, since that set uses 2.5v tubes the pt is hard to come by and expensive.
Always good to check output transformer and field coil for resistance.



GL

RE: Bought my first cathedral. - jake wells - 06-01-2019

I don't use external inputs it isn't my thing. I will check all the usual items but i usually don't do full restores i get them working safely i replace the bad and keep the good and all the old parts go into a box for safe keeping just encase the next owner wants to restore it back to how it was.
If all checks well i will replace the caps and resistors inline with the power supply and see if it works ok.

RE: Bought my first cathedral. - David - 06-04-2019

This you tube might help in understanding HZ.   https://www.youtube.com/watch?v=vGFgDSkdZjM