That the BN43-302 core is getting warm is no surprised? ?Its not enough for more than 10w
based on other amps I've made.? Two end to end or the 6802 (over an inch long) have worked?
much better at the 20W and higher level.? The turns radio and what wire used can have a
big difference at the higher end of the range.? Thin wire will heat significantly from the RF
current.??
If the core is getting warm at low frequencies it may not be the core but the lack of enough
inductance.? that is hard to fight as more turns may be moving further away from optimum
at 30mhz.? The solution is a bigger core, two is series making it longer may be enough?
or the 6802 core.
Its also possible to use two fb43-4852 (amidon) .200id, .375OD, 1" tall.? Two of those
run to 100W as a side by side pair using tube and strap construction.??
The 3312, I've run that to 65W in the WA2EBY amp during testing and it didn't get warm.
Its a big core.? I did have heating issue with the wire.? The 3 turn winding was revised to
7 strands of #30 kynar wire (used for wire wrap) in parallel and that also brought the
10M power up.
I still think the 2n3904s are the bottle neck for bandwidth and the mods are just trying to
push them higher.
Watching the input current to output power is a good thing to do as then you see the efficiency of the?
amp and less than 40% bears inspection and higher 45-55% is definitely better.
Allison
