Subject: [Amps] Filament Choke Inductance
Can anyone tell me what inductance do I need in the filament choke for a
3CX3000A7 for 80M. I built one back in the mid 90's and had to wind one
around 3
ferrite 1/2" rods in order to keep the AC out of the tube(or was it to keep
the RF out of the transformer?). I have some filament chokes wound made
with 10ga
wire and they measure ±45uh. I guess I could always put 2 of these chokes in
series but they would take up more real estate under the chassis.
I use 2- 7 inch rods wound full of #10 wire on my 160 meter 3X3, and it works
fine. You put the chokes in parallel, not series, to handle the 51.5 amps of
current. Another scheme is to insulate the filament transformer from the
chassis,
and put a smaller choke in the primary.
I was going to suggest the 3X3 to you earlier, Bob. Makes more suds easier
than a pair of 8877's, and is "instant -on" with no warm-up requirements. My
160m 3X3 is always ready when that "rare one" appears for 5-6 minutes at
sun-up!
GL!
Phil, K5PC
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