256aff29   
   From: phil_a@tpg.com.au   
      
   "Engineer"   
      
      
   > But the large output transformer is a conumdrum.  It's Hammond type   
   > 1682 from their PA line in catalog #65 (not "Hi-Fi", rather for PA   
   > with the extra line output.)  The P-P impedance is 1900 ohms (it tests   
   > to this.)  It's also rated at 120 watts (not 250) so perhaps that's   
   > all the original amplifier produced... if it ever worked, that is!   
   > Anyway, 1900 ohms P-P seems a bit low to me, even for 4 O/P  tubes.   
   > It means 3800 ohms P-P for two 807's in ordinary push-pull.  I've not   
   > drawn any load lines yet, but does this seem reasonable?   
      
   ** For maximum possible power output it is about right.   
      
   I take it the unloaded B+ is about 450 to 500 volts for plate and screens ?   
      
   A pair of 807s or 6L6GCs can do 60 watts like that.   
      
   For a PA amp, bias current would be set low near to Class B conditions and   
   the load presented by a 70V or 100 V line speaker array is all over the   
   place anyhow.   
      
   BTW:  An output tranny can always handle more than its nominal power rating   
   provided you tolerate higher percentage losses and/or restricted output at   
   the lowest frequencies.   
      
      
      
   ...   Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)