I have a Rogers 10-12 with out the power unit and I have another Rogers radio for parts.
I plan on using this other radio to build a power unit using the 80 tube and transformer and new caps. I don't know what to use for choke coils?
Here is a photo of what the original power unit looks like.. The transformer that I plan to use for a new power unit is much smaller than the one in the photo..
Can I build a smaller power unit for this radio?? The one in the photo is quite large so I don't know if the one I build from this other radio would supply enough power.
Does size really make a difference,in this case????
I am looking for a parts list for the 10-12.. I have the schematics and they are hard to read
. I suppose some of you guys from Easten Canada would be able to help me a little.
Thanks Dan

That huge transformer looks like it was made for 25 cycle operation. You don't need one quite as large but Rogers 10-12 draws a lot of current and uses a 5Z3 rectifier. Doubt a transformer used with 80 will be large enough.

http://www.nostalgiaair.org/PagesByMode ... 029191.pdf

Hi Dan,
I'm not from eastern Canada, but I'm more east than you!

Anyway... I think if it were mine, I'd try to ballpark (from collective
light and filament currents and plate currents) the loads the
10-12 would place on the low and high voltage windings of the
power transformer, and compare that with the loads the donor
radio places on its transformer. That would give you a clue as to
whether the donor transformer could do the job without making
toast.

There is hope... just looking at the lamination stack in that photo
suggests that it may be one of those 25-60 Hz power supplies. For
60 Hz only, a physically smaller transformer might well be fine.

If it doesn't look good, check out http://www.oldradioparts.com/

GL, Nelson

P.S. I see Norm said in 2 lines what it took me 12 to say...

The output stage is Class AB2 Triode, for 13 watts at 2% distortion. This should sound wonderful. The output current for two tubes increases from 48 to 92 mA at max, so you need a large transformer and 5Z3 rectifier to provide a steady voltage. The 6F6 driver tube needs 34 mA and there are plenty of other tubes. You have a choke-input supply, for better regulation, but it needs a higher secondary voltage. Depending on how the original voltages were measured, you need 1000 volts center-tapped (or more?) on the secondary. The 6 volt winding needs 6 amps to supply dial lamps and tubes. 5 volts needs 3 amps.
This exactly matches the Hammond 282X, made in Canada http://www.hammondmfg.com/263.htm
Maybe you can find a Canadian supplier, AES has it in the USA.
The link has the dimensions, scroll down to X14, and compare this to the larger transformer you have now.
I hope someone else can double-check my power calculations for this transformer, it is one of the biggest ones Hammond makes.
Don

Thanks for the information guys.. I always learn something every time I ask a question. I may have to look up a lot of things to understand the answer but hopefully I learn..
I talked with the Hammond distributor in Calgary and they can get the transformer for $140.00..
I still have to change all the caps and get a tube since I dropped the only tube that I don't have a replacement for[6C5]

What could I use for a choke coil with the larger transformer.. The schematics dont show any values or ohms
or anything that I can understand. ...Also ,the schematics don't give a value for the electrolytic caps in the power unit. How correct would I be using 50 uf @ 1000 volts???

Here is a clearer diagram of the model 10-10, seems to be the same power supply with two 16 MFD capacitors. There are two chokes, so 16 MFD is all you need for filters, 50 is way too much. The rest of the diagram is a lot clearer, will be a good reference. Haven't found the choke values yet.
http://www.nostalgiaair.org/PagesByMode ... 029190.pdf
Don

Totally agree, modern value 22 mfd 450 VDC would be OK, but don't go higher, especially on the first one in the voltage divider. If you are planning to use a PM speaker, you may be able to replace choke with a resistor, it'll be a high wattage type, but we need to know more about the other requirements of the set. Then again if the old speaker field is still patent and you have room for it and it's pole in the cabinet, it still can remain as a choke.

This is a choke-input supply, so the first choke limits the current pulses at the rectifier, and a larger first filter capacitor won't damage the tube. However, the transformer voltage is much higher, and the voltage at power-on may go over 700 volts DC. You might need two 32 MFD or 47MFD 450 or 500 volt capacitors in series to replace each 16 MFD capacitor.

EDIT: I am not sure about the power-on voltage, how high it will go with a choke input supply, while the other tubes are warming up.

Don

Don ,,,Thanks for the link to the 10-10 schematics,,the ones for the 10-12 are not as clear.
I will be using the factory speaker with the radio and it is not a PM. If you looke at the schematics at L7 and L6 it shows voltages of 378 and 345.. When I get a transformer,, How will I know what coils to use for L6and L7??
I do have some coils from my parts Rogers.. I only wish I knew more about these things.
Most of you guys can do this stuff in your sleep but for me I am at a grade three level
BUT I really appreciate The information and the pace you are feeding it to me..
One more question,,,,In the photo I posted showing the original transformer,,what would be in the large black box in front of the transformer??Would that be the choke coils inside it???
Thanks again for the help..Dan

When I enlarged the picture I could read "L6 & L7" on top of the box, so the chokes were under the cover.
The RCA tube manual shows choke values for a 5U4 rectifier, a modern octal socket version of the 5V3, and suggests 10 Henries. We don't want the winding to break down, so an 800 volt rating and 200 Ma will cover everything. That leads us to Hammond 193J, and you need two of them. http://www.hammondmfg.com/193.htm
AES has it as P-T193J http://www.tubesandmore.com/ They also have the power transformer P-T282X.
Your Canadian supplier could get the chokes along with the transformer.
This is looking expensive, no wonder pentodes and smaller power supplies without chokes were used later.

EDIT: I edited my earlier answer, as I realized a choke-input supply has a steadier output voltage and I don't know how high it goes at power-on when the 5V3 or 5U4 warms up but the other tubes have not. This is important for the capacitor and choke voltage rating.
Although the RCA tube manual suggested 10 Henries, I don't know what Rogers used in this set originally. Can anyone help on this?
Don

OK, I looked more carefully at the RCA tube manual and other books, and see that you need a minimum load of 25 mA at all times so the DC voltage won't climb to 700 volts. There is a voltage divider of R26 through R30 that seems to be providing this load, but just barely. You will have to measure from Pin 4 red wire to pin 5 brown wire on the DC power plug, to check continuity all the way through the radio including the speaker field. This resistance will show if there is enough load to keep the DC voltage reasonable during warm-up.

This schematic looks familiar, other people have had great difficulty getting this set to work. In any case, check the resistance of the audio transformers T8, T9, T10 and the speaker field. If any of these are open, that's more expense. The parts set won't have these transformers.

Now I see that there are 4 6F6M tubes, one is driving the tuning indicator lamps. So we definitely need those 200 mA chokes and transformer, this is a monster.
The original chokes probably had exposed paper and windings and needed a cover. The larger chokes I listed have end bells so they can just be mounted on a chassis without a cover, for better air circulation.

Maybe I should not recommend spending money on this set, as there are too many unknowns especially without the original power section, and I have not repaired anything this big either. The radio frequency section and tuning indicator section have challenged the experts here, and I have been in awe as they finally prevailed. Here is the post I remember, about the similar 10-10 model viewtopic.php?f=6&t=178818&hilit=Rogers+10

Don

Don ,thank you . I may be in over my head on this ,but I have recapped the set and
I will read and go over all that you guys have written, to see if I can build a power unit..
As far as $$$$$ are concerned,,I bought the radio for $25.00 so possible I can talk myself into
investing a little more.
The cabinet is very very nice so I would like to get it going.
Once again,,thanks for all the information although most of it is above my level of expertise
but it helps me Learn.... Dan

Deleted my idea to create a Frankenradio
Don