[AMPS] 4-1000A amp design

[W6RU@aol.com]

One very important fact in the stability of the 4-1000A amp in "grounded grid"
is to use the plastic Eimac socket and run the 3 grid connections through the
side slits in the socket to chassis ground. This requires only about a 3/4
inch long lead.  I use copper strap about 3/16 inch wide. If you USE the tab
connections  hanging down from this socket and run connections to the chassis
you have an increased lead length of about 2 inches more. This additional lead
length AND the use of the aluminum socket yielding about the same lead length
will cause a large amount of hair pulling in trying to stabalize the
amplifier.
good Luck,
Terry - W6RU (ex W6TG N6UR)


In a message dated 8/10/98 7:22:56 AM Pacific Daylight Time, jono@enteract.com
writes:

<< >Greetings to the Group,
 >                    I've just come into possession of an Eimac 4-1000A, 
 >glass chimney, 
 >and matching socket and am looking for a proven HF amp design to press 
 >them into service. If anyone knows of any good designs in past ARRL 
 >handbooks etc. PLS let me know. I'd be happy to pay duplication costs if 
 >the designs are viable.
 >                                                                           
 
 Hi Steve,
 
 As someone who is fighting this tube right now in an amp design, I would 
 say that if this is your first HF PA design, it's not going to be easy.  
 I didn't believe others about this at first, but the 4-1000A has some 
 very pesky resonances that tend to make it unstable especially on the 
 higher bands like 10 meters.  It also needs very high voltage to get 
 adequate gain and lots of drive.  Lots of guys use 5 to 6 KV.  At that 
 voltage you get around 12 dB of gain.  Lower voltages give somewhere 
 around 10 dB of gain.  Lots of guys that have them (including myself) use 
 the bigger rigs like the FT-1000 that can put out 200 watts.
 
 On the bright side it's an extremely rugged tube and can take a lot of 
 abuse.  It's also kinda cool to see those plates glow bright orange!  But 
 it likes lotsa cooling.      --SNIP--
  >>

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