[AMPS] 4 by 10 inp Z ?

[measures@vc.net (Rich Measures)]

>
>Cathode inp Z should be in the 100 - 150 ohm region but
>if anyone has a more exact figure I would like to know.

My guess is a bit under 100 ohms.  1500w should drive it to the rated 
anode current.  However, if you use a 450 ohm terminating resistor at the 
grid, and drive the 4 by 10 at the grid instead of the cathode, c. 150w 
will drive it to the rated anode current. .  .   A diagram of such a grid 
circuit is available at my Web site:
www.vcnet.com/measures
see Figure 5  .  .   An ideal grid roller L for the 4 by 10 is currently 
being sold by Fair Radio Sales 419-227-6573.  Ask for the 5uH unit out of 
the Collins 180T.  The price is $10 for this little beauty.    Below 
6.2MHz the grid roller L can either be switched out, or a suitable fixed 
inductance added with a switch.    .  .  Typical power gain is 20db.      
                                                                          
                                                                          
                                                                          
                                                                          
                                                                          
                                                                          
                                                                          
                                                                          
                
cheers,  Jim
Rich...

R. L. Measures, 805-386-3734, AG6K   


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