[Amps] Advice on how to work this thing...

[Bob Good]

Dear Chris.  Oh Boy!  Now this is just what an old timer like myself really 
enjoys.  I remember well my old push pull TZ-40's with a swinging link tank. 
You have asked a chapter full of questions, so lets get started.  The coils 
that fit with the swinging link are the final tank coils.  If they are 
numbered, they might indicate 80, 40 etc on them.  If not,  the one with the 
most turns will be the 80 meter coil and so on decreasing the coil turns. 
As they decrease in number, they will likely get larger in wire size.   160 
meters back then was limited to low power and other restrictions and would 
have required additional plate capacitance to be switched into the circuit, 
so I feel sure that we can rule out that band.  The number of turns on the 
swinging link allows you to match the output to the characteristic impedance 
of the feedline.  The feed system on popular antennas would likely have been 
balanced line.  These may have consisted of zip cord, twisted cotton 
insulated line, twin lead or home made balanced feeders of up to 6 inches 
spacing.  You can feed coax from a link coupling.  More on that another 
time.  The plates are fed through the center of the tank coil.  The variable 
capacitor in the tank circuit is your plate tuning control.  You control the 
plate loading by closing the link into the center of the coil axis.  You 
must use push pull in the input tuned circuit as well or otherwise you wind 
up on DSB !  Don't want that.  These coils will likely be smaller in size 
and will also have individual units for each band.  Most likely here we will 
find a fixed link coupling to the exciting stage.  You will resonate the 
circuit by tuning for maximum grid current in the finals using the input 
variable capacitor.  You have not told me enough to determine if you need to 
limit the drive.  This can be done in the grid of the driver tube via a 
linear taper pot.     I also do not know enough to give you information on 
the keying for cw.  It should be biased near cutoff to keep the quiescent 
current within safe limits.  I noticed in your schematic that appearantly 
the amp switches between class "C" and "B".  He is using the filament 
transformer to derive grid bias needed for class "B".  The capacitors 
between the plate and grid circuits are the neutralizing  "condensers". 
Neutralization needs to be done before firing up the unit.  More to follow 
there also.  The 250TH use 75 watt filaments.  You should expect to see 
color in the plates under load.  Tell us more so we can enjoy writing more 
epistles.   Best wishes.....Bob , K4BG, Sylvania, GA