Hi Marco,
I don't detect any heat in the LPF but at this low power level it
could be difficult to detect it.
I already have plans to build the big T type LPF. I have the
T-225A-2 cores and metal to make a compartmented box. Capacitors are
on the way, could arrive around 29 December. I still need to order
the wire and some kind of material for mounting the big inductors.
I'm making that LPF because eventually I will also build the big
amplifier. I'm not sure when that will happen, probably a bit late
for this LF season.
The most curious thing is what seems to be some measurement error or
impedance transformation but the cause remains elusive. I hope to
find the reason so I can be more confident about measurements when I
go go high power.
73,
Paul N1BUG
On 12/25/2017 04:35 AM, [email protected] wrote:
Hello everybody,
it's ever interesting to read that somebody else has some troubles as
experienced from myself ;-)
Me too am grateful to Andy for the support I received
while struggling with odd experiences..
Let me join the discussion and share a possible solution: I see that
LPF is a PI version, similar to what I used in the past. It was nice in
RL, armonic suppression and losses when tested with low power
instruments, than I was increasing the wire diameter of coils because
it was a... warming thing! The current was indeed very high in the FETs
(2+2 FETs in push pull) and the RIP area was growing...
After I tried the T LPF (see attachment) no more problems, no more
warming boxes..
You could re-arrange your LPF components for a quick trial and save
some caps ;-)
In my version I had to make some change because the cores were not
available and used T200-A2 cores calculating the turns to get 59 and
109 uH coils.
Maybe it's worth to try ;-)
CU on 137kHz
Marco, IK1HSS
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