[Amps] a common topic here tspa

[Joe Subich, K4IK]

Rich writes: 
 
> Joe -- Are you suggesting that Eimac's 8877 development team grounded 
> the grid through long thin wires?

As I recall, and it has more than 20 years since I was able to set down 
with some of the best tube guys at Eimac over beers (while we were taming 
"experimental" UHF TV transmitters).  Since all of us were hams, the 
conversation always turned to amateur amplifiers ... 

They told me that the grid resonance in the 8877 was above the plate 
resonance and if the grid were properly grounded (a low inductance, 
low impedance connection), the phase relationship between the grid 
and anode was such that the tube would not oscillate.  The "problem" 
with the tube was those designs that used "long" thin leads from the 
grid pins on a socket ... and worse yet were those that inserted 
other devices and attempted to bypass them with capacitors.  

Their advice was to use a collet of finger stock, or at least the 
Eimac socket with four wide grid contacts bolted directly to the 
chassis and do any grid current metering, including a grid current 
trip, in the cathode (float the B-).  
 
73, 

   ... Joe, K4IK