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I think that a lot of people use the 71As in place of the 483/183 tubes. I did find a pair of 483s for this radio.
The max plate voltage of a 71A is 180V with a plate current of 20ma with a grid voltage of -40.5V.
The (max?) normal plate voltage for a 183 is 200V with a plate current of 20ma and a grid voltage of -45V
As I recall, I measured the B+ 180 - 200V while working on this one.
For a while I used 45,s with the filaments wired in series, an easy mod. They worked, but this was before I had the interstage transformer working. I was using a substitute that was not a good match and vol was low. Also I am not sure how wiring the filaments in series affects the "self bias" since this adds a resistor to one leg (the other tube filament). The specs on a 45 give you a lot of room to make adjustments.
The max voltage is 275V with a plate current of 36ma and a grid voltage of -56V.
You know that an 182A has almost the same specs as a 183, but they may be even harder to find. The Sparton manual says to never mix 482B and 483s.
It looks to me like you could mix 182A (482A) and 183s at the risk of adding a little hum to the audio.
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