Hello from Jimb. Can anyone tell me if the plug in voltage regulator,is the ballast resistor shown in the circuit diagram in series with the mains lead.If so what value should it be , I guess it's power rateing would.need to be about 100 watts this is missing from the chassis .
Would anyone have one, or any other parts ? What would its resistance be the set is 110volt do not know if it ran on 25 cycles or 60 cycles originally. It is a 1929/1930 manufacture.
Regards Jimb

Some discussion of the value of the line ballast here:

http://antiqueradios.com/forums/viewtopic.php?t=74913

and here:

http://antiqueradios.com/forums/viewtopic.php?t=88132

Hi Jimb,

I looked up Volume 1 of my Riders and found the Stewart Warner 950 AC radio in it. Sadly the circuit is so small you can't read the ballast values. One thing I can make out is that different values are used depending on operating frequency.

If you want I can email you volume 1, maybe you will have better luck reading the circuit.

Regards, Frank.

What appears to be the case here is that there are two different transformers one for 25Hz and an other for 60Hz

P/N 66491 for 25Hz and
P/N 62152 for 60Hz which is the one you need.

The transformer appears to be of a shielded type, which I ground & there is a 0.001cap on the mains which would be on my hit list (not safe).

I downloaded the "Rider" pdf from Nostalgia Air. They changed their mains voltage upward from 110 to around 115 -120V. One of the temporary ways around this to be considered, would be to get it into a state where it is safe to operate & power it from a Variac (slide transformer) wound back to say 40V & measure the heater / voltages with the rectifier out. That would give the voltage needed. there are clamp meters that can safely measure current. One might be able to find the Part cross referenced?

I am skeptical of a dim bulb being safe for the valves: Valves in.

NB: Heaters 2.5V; 45 has filaments.

The Americans seemed to be reluctant to add cost & use tapped transformers like us. A lot less Zeniths would not have cooked theirs, had they done that.

Sadly the circuit is so small you can't read the ballast values

It doesn't show values, just part numbers for the two ballast resistors.

The Forum articles I linked to in #2 above discuss how to calculate the required resistance.

My issue is the dissipation of the 43Watts and if its on the mains side protecting it.

It would be great to know the actual primary voltage, which seems to be around 85V. I would be more comfortable with a Transformer.

Jimb, for the benefit of future searchers, you might like to fix the spelling of Stewart in your thread title, (Use edit post).

Thank you GTC, Frank and Marcc, for your valuable inputs .
Firstly GTC I have corrected the spelling of Stewart thanks, and have looked at the suggested Link thank you that is helpful.
Frank thank you for the circuit offer I managed to buy a manual , happy to help anyone else if they need it.
Marcc you have made some good suggestions I am contemplating replacing the transformer down the track and eliminating the 110 problem. My Brother bought this radio to save it from an unknown fate and although he is more capable than me to fix it , I have more time, it is still at his place at the moment . It is in a console cabinit with sliding doors on the front a nice piece to have .
I want to take each step with caution to try and keep it looking original.

I have NEMA plugs on all 110-115V Volt stuff so it has to be plugged into one of the transformers. I have a Variac(Slide regulator) they would get you out of trouble whilst you repair the set. I often think a UPS 240V in &115V 60Hz out would be useful around here.

Variacs are Auto transformers, but as your set is transformer, the chassis is not live to mains & as long as you set it correctly it would get you out of strife while you repair the set. The catch 22 is that they are not cheap new.

Marc