[AMPS] tuning up a tetrode amp

[measures]

>
>I am almost embarassed to ask this. However, since my ego is inversely
>proportional to my waistline.........I have recently acquired a superb HB
>amp covering 160 to 10. Uses Dahl components in the PS, vac. variables in RF
>deck. built professionally by a EE (now SK, RIP). The tube is a single
>4cx1500. 

An A or a B?  The difference is great.  

> My questions is how the heck do you tune this up? 

1. Switch the anode and screen supplies off.  With a watt of drive 
applied, the grid roller inductor (if the amplifier is neutralized) is 
adjusted for best swr.   
2.  Apply max. drive and adjust the bias V until grid current is nearly 
zero.  Do not readjust the grid bias V to set idling current.  Remove 
drive.  
3.  Apply anode and screen potentials. 
4.  Set the idling current (Zero Signal Anode Current / ZSAC) to the 
recommended value with the screen V adjust.  
5..  Apply max drive and tune/load the tank until the recommended screen 
current is reached when the output peaks with C-tune.  If the screen 
current is too high, increase loading and repeak.  note - If you are 
tuning up with high-speed dits, multiply screen current indication by 
roughly 2x.  



>I have used
>triodes all of my life sans my TS-820/830 which use beam power pentodes in
>the final (2X 6146) but I just tune for max power on these. I have always
>avoided tetrodes mosly due to my ignorance of the tune up procedure.
>
With a large tetrode,  a tuning chart is useful.  This will speed tuneup 
on often used frequencies.  . 

>The amp has metering for screen I and E and also grid I and E as well as
>plate I and E. What is the value I need to watch? 

No grid current. No more than max allowable screen current.  

>I assume that it is not
>safe to tune it like my 3-500zs which is usually just tuning for max power
>out with a string of dits at 60 wpm?
>
Tetrodes are different than triodes.  To adjust the tank of a tetrode 
amp. one does not need an RF output indicator.  It's all done with the 
screen current meter.  

cheers, Lane..

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