<That seems very low drive for passive grid. The NCL-2000 could use up to
<100W in the high drive positon at 50 Ohms and 20-25W into the low drive 100
<Ohm configuration.
<Carl
## NCL-2000 didnt use a 4CX-1500. He used bird wattmeters on both sides
of the hb 4CX-1500B. 10 watts for 1.5 kw on low bands
and 20 watts on upper HF bands. Dunno how much B+ and screen voltage
used. I believe he terminated the grid with a 50 ohm globar he
removed from his heathkit dummy load.
## Local buddy has an Alpha 8410, with a pair of
4CX-1500Bs. Dunno how much drive it requires, I will ask him.
He sez it does an easy 2 kw output on 80m.
## Those OM-4000 amps, that use a pair of chinese FU tetrodes, sorta
their version of a
4CX-1500B, only require 20-25 watts of drive for 4+ kw output...per the
folks I know that own them.
A fellow in Colorado I know, just bought the manual tune version of the
OM-4000. Input attenuator removed,and an easy 5 kw out.
They removed the FCC approved input attenuator, or bypass the attenuator.
Then they end up with the
same version OM-4000 as the rest of the planet gets.
## Remember that tetrode that Rich built ? He used a surplus 500 ohm
globar and a 1:9 trifilar . 20 db gain. Ideally,
a 450 ohm globar is used. Then a small amount of uh in parallel with the
globar, to cancel out the tubes stray input C / XC.
## Im not a grid driven tetrode expert, with minimal experience, except
for the G2DAF congig..... which I would not recommend to anyone.
Jim VE7RF
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|