saba: UA-345 (UA345-X); - High plate voltages for 117V Operation?

Dear members,

I have not yet been able to resolve how the existing schematic resolves the high plate voltages developed for the radio without the netz trafo, and no full-wave rectifier, to act as voltage doubler.

The schematic depicts 196Vfor the mixer plate; and 170V for the UAF plate, and the 215V for the power pentode plate.

Is there a possibility that the UY41 rectifier is actually configured very much like some of the erarly CY1 tubes produced - which were in fact "dual diode rectifier" capable.

Our esteemed emeritus engineer Hans Knoll has stated that Robert Sarbell occasionally finds some peculiar receivers!

If there is additional technical data that was available when these variant models were introduced by Mario, and inferred from the Notes section, could some member please enlighten me?

Respectfully,

Robert Sarbell

Nnote: I am aware of the inner electrode connections between pins 4,6, and 7 for the UY41, and this tube can be adapted for different transformerless power sources.    

 

To thank the Author because you find the post helpful or well done.

Hello Robert.

 

Your Voltages was given for 220 AC not for 117V

RV (160Ohm) only for 220V on 117V she is shortet.

 

See here: 

Edit:  Mr. Georg Richter send me and Robert "cleaned" Curves to the UY41

I thank for this good job and attached as  Info here.

 

hans

Attachments:

• Datas for UY41 special for 117v Ac in USA (137 KB)

To thank the Author because you find the post helpful or well done.

 

Attachments:

• Philips Circuit RF- Part (76 KB)
• Philips Circuit Audio- Part (81 KB)

To thank the Author because you find the post helpful or well done.

Hello Hans,

Thank you so much for the technical data - several days ago I found 2 models from Philips (France) which use the UY41 rectifier; and the schematics depict the circuit values when the input is from 110V or 127V AC. The models are BF121U and BF251U

The voltages listed on the schematics are much closer to the voltages which I have measured on my small SABA UA345 - with the AC mains of 122V. 

I have been experiencing some of the intermitent "flashover" problems described in one of the Philips technical notes. Some technicians call the problem "sputtering". I understand the problem could possibly cause tube failure if left unresolved.

I have located and purchased an NOS UY42 rectifier, from a seller near me . . . . .and will consider installing that tube when it arrives.  

I am hoping that will solve my intermittent malfunction.

Respectfully,

Robert

To thank the Author because you find the post helpful or well done.

 Buona mattina carissimo amico Roberto and good evening to Hans,

Regarding the absent normal operation voltages on the schematics for the 117 AC power voltage, did you consider to use a doubling transformer from 117 to 220 VAC and to operate the UA 345 adjusted for 220 VAC. After the normal voltages operation are checked/corrected the set can be used at the normal operation 117VAC.

Respectfully, Bruno.

To thank the Author because you find the post helpful or well done.