Input please on 25 cycles radios 1930ish

[zane]

My Atwater Kent is a 25 cycles unit. Right now I am
only using it to keep my house from blowing away.
But I would like to play with it one day.

When I put 60 hz to it is where my questions start.
Will it just be weak or can you enlighten me a bit??

It is a 55F in a breadbox, I call it that cus
the other one is the breadboard.
It's the metal box if it has a name.
THANKS!
ps. if you know off the top of your head,
any of the tubes cost big bucks if I need to replace?
or please say no

[radiotvnut]

I'm sure that radio uses a type 80 tube and two type 45's. The 80 will be a little pricey (depending on if you go for an original globe envelope type or one with the newer style envelope) but the 45's are about $80 a pop from AES. You can think the audiophool crowd for that! Be glad they're not made by Western Electric or they'd be $800 each! I usually won't replace a 45 unless it's dead. I've seen plenty that would check "bad" on a tube tester; but, would still perform in the radio. The other tubes should be reasonable.

I think 25 cycle power was used in Canada and I've seen some Sears Silvertone schematics for 25 cycle versions of their normal 60 cycle radios. You may have to replace the power transformer with a 60 cycle transformer; but, let's see what someone else says first. IIRC, that power transformer is encased in tar in that model. So, you'd have to melt out the tar and install a newer transformer in the old case if you expected the radio to look original.

[Tom Bavis]

25 cycle transformer will work fine on 60 Hz - probably won't even get warm... there's twice the iron needed for 60 Hz.

[Reece]

Ditto what Tom said about the hefty 25 cycle xfrmr. It will just loaf at 60 cycles. As to tubes, they may all be OK, often are. I would look around on the net for tubes if required. Lots of sources, varying prices. Set ought to be gone over carefully, components checked, transformer windings rung out, etc. before trying to run it.
Reece

[AUdubon5425]

There were still some power systems (rural mostly) running on 25 cycles or DC or other variations through the 1940's. From what I remember reading a 25 cycle set should operate on 60 cycles - glad the above posters confirmed this.

[toxcrusadr]

I wouldn't power that thing up w/o a complete recap first, if you want to make sure you keep the power tranny, 80 and 45s in working order.

Tubes are best had from radio guys rather than audiophiles or AES if you want cheap prices. Last 45s I bought used were $20, from a lifelong radio collector with a basement full of tubes and gear. I've recently seen 80s sold for 10 bucks. And there are a number of smaller dealers besides AES that are cheaper. But you probably won't have to replace tubes.

[wa2ise]

Originally Posted by Tom Bavis

25 cycle transformer will work fine on 60 Hz - probably won't even get warm... there's twice the iron needed for 60 Hz.

One could run a 25Hz 120V primary transformer on 240V 60Hz and still not get warm. However, all the secondaries will produce twice their rated voltages. Which might be an issue for the high voltage secondary, as the insulation might not be up to it. Obviously, we'd be talking about this transformer separated from its radio set, if it were parted out and being reused elsewhere.

Generally, the higher the mains frequency, the less iron you need for the same amount of power. Aviation used 400Hz, for much lighter transformers (you care much about weight in aircraft). And this is also a major selling point with switching power supplies.

[merrylander]

I once had an old receiver that was for 25 Hz (used to be normal in Windsor) it ran PP 47s in the output. As has been noted it ran very well on 60 Hz, never got warm.

[Tom Bavis]

Out of curiosity, I looked this up... Niagara Falls supplied 25 Hz power to a wide area - Buffalo used more 25 Hz power than 60 Hz until 1952. The last five 25 Hz industrial customers weren't disconnected (for good...) until 2006 when a 66KV power line came down in a snowstorm.

[electroking]

There were significant areas of Quebec (the Gaspé Peninsula) that had 25-Hz power
as late as 1963. As noted earlier, the 25-Hz radio power supply should work fine
on 60-Hz.

[zane]

Thx for all the input, I thought it would be ok, but ya never know.
And with all the know-how here I had to inquire.
I have had magnetisim trouble with 400hz, but I have no
speariance in the lower hz levels.

Can you by the caps strait out, or is a roll your own deal?

[wa2ise]

Originally Posted by zane

And with all the know-how here I had to inquire.
I have had magnetism trouble with 400hz, but I have no
experience in the lower hz levels.

To a first order approximation, a transformer rated for 120V @ 400 will do (60/400)*120v=18V at 60Hz. Probably not too many uses for a 18V primary transformer But at the same way, the 120V 25Hz transformer could do (60/25)*120V=288V at 60Hz, assuming the insulation on all high voltages are up to handling it. Had a class in this back in the mid 70's in my BSEE major at Syracuse Univ. Some industrial environments actually have power at 277V @ 60Hz (480V delta would be 277V Y (3 phase)). Maybe that's where 277V came from, power companies making use of 25Hz transformers at 60Hz...

[Conchord]

Originally Posted by wa2ise

To a first order approximation, a transformer rated for 120V @ 400 will do (60/400)*120v=18V at 60Hz. Probably not too many uses for a 18V primary transformer But at the same way, the 120V 25Hz transformer could do (60/25)*120V=288V at 60Hz, assuming the insulation on all high voltages are up to handling it. Had a class in this back in the mid 70's in my BSEE major at Syracuse Univ. Some industrial environments actually have power at 277V @ 60Hz (480V delta would be 277V Y (3 phase)). Maybe that's where 277V came from, power companies making use of 25Hz transformers at 60Hz...

Most industrial environments are 480/277. Interesting proposition.

[Conchord]

Now ya got me thinking....the freq won't change...the goesinta equals the goesouta. A transformer can't change the frequency. Nope, flawed theory.

[gadget73]

277v comes from running one leg of a 460v 3 phase supply to ground. Nothing special about it. Lighting in industrial complexes is commonly 277v single phase, since its really simple to make that from the 460v 3ph mains. Where I work, we have 460v 3ph supplies, 277v lights in the warehouse, and a few 240 and 120v systems as well. We get our 240 and 120 from a couple of big step-down transformers installed throughout the building.


zane: The electrolyic may be a multi-section cap. Probably have to replace that with 2 or 3 (or whatever) individual capacitors. The rest you can just buy new. For radio use, the cheap yellow polypropelyne caps are just fine. I get mine from justradios.com. Possibly there are cheaper options, but I buy stuff from there because its easy to find what I need, and the shipping is reasonable and quick. If you happen to have a stash of suitable caps already, go for it. Radios really are not picky about what sort of caps you stick in there, so don't feel compelled to buy anything expensive or special.