ozarka: 78 Battery

The Schematic shown here is for a Battery set , YET shows AC tubes in use,

This is NOT correct.

 

Any others have a comment ?

 

Bob T

Wilmington, NC USA

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1928?

it's listed as 6: 26 26 26 26 27 71A

26 (x 4) is: Vf 1.5 V @ If: 1.05 A (Direct type) 

27 (x1) is : Vf 2.5 V @  If: 1.75 A (Indirect, DC or AC)

71A (x1) is: Vf 5.0 V @ If : 0.25 A (Direct type).

 

I'm not an expert on 1928 Radio, but mamy people had no electric then and unlike late 1930s to end 1950s (100mA, then 50mA by 1939 and then 25mA post WWII) the "Battery" tubes where very heavy on LT and you can use an AC Indirect tube on Battery, but while "direct" filaments have been used on AC, it's more of a problem.

The 26s seem to be in parallel.

The 27 & 71 are shown in parallel I think, which makes no sense.. So indeed something is wrong

Conclusion

The tube line up given makes no sense with the filament wiring, thus it's wrong. The schematic does corrspond with Riders, but that only seems to list the Tubes for 89.

So I think you are right as the PDF I have shows mains version (89) and battery version (78) but only tubes listed  for the Mains version. There may be a "78 AC" which I presume is a 89 chassis and 78 cabinet. I don't know. Here is the 89 It has an extra 71A and a rectifier tube.

The 78 may have used all 201A (according to some forums) but maybe not the UX201A (5V filament), maybe the Western Electric "1.5V" filament via rheostat from 2V Lead Acid battery? A contrary view here. There "could be" a battery version with the tube line up given, but the schematic certainly isn't corresponding to those tubes listed. The AC version of 78 does use the listed tubes according to various people.

Maybe there is a 78AC adapted for batteries?

 

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Dear Bob,

I do not know this model, anyway no wonder about battery operated sets with AC vacuum tubes inside. As far as I know many sets used a mix of batteries and even indirectly heated tubes. A classic example is the SCR-211-* family of frequency meters. But even 14-tube Hammarlund Super Pro receivers, SP-110L or LX, according to the manual could be battery operated. They just required five 45V 'B' and one 45V 'C' dry batteries, one 6V 'A' storage battery and a cable supplied on special order.

Regards, Emilio

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I have the Original Instructions for an Ozarka 78 chassis.

 

I will attempt to copy them here.

 

There is a Full Battery set with 6 O1A tubes and then an AC/Battery Version

using 301A tubes and a 71A tube

 

It is a lengthy booklet.

Bob T.

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Here it is external link. (some of my personal space)

It's 1Mbyte and the upload limit is 200K.

There is little about the tubes

Click to see full size

So the 78 Battery (from Factory) rather than Mains/Battery or later conversions is 5 x CX301 and 1 X CX112

here is smaller article that suggests the incorrect Tube line up in the 78 Battery page is from the 89

(attachment).

 

Attachments:

• M0043594 (39 KB)

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