Clark,
Spreading or compressing the turns on the L1 and L2 toroids is the way
to do it. So, do whatever you need to to accomplish that. Actually, you
do not have to adjust all the turns, just move the end turns closer
together or further apart.
Yes, you should be able to achieve a bit more power on 20 meters, but
remember that the KX1 LPF is a compromise - play with the toroids a bit
to see what you can accomplish.
Actually, you may be better off rewinding L2 on a new core (assuming you
have one). I have found that some of those yellow cores vary in
permeability, and if the one you have installed has a greater
permeability than normal, the cutoff frequency of the LPF may be too low
and shunt some of the 20 meter RF energy to ground.
73,
Don W3FPR
On 3/29/2015 1:55 PM, engineercm wrote:
Hi, all.
I recently uncovered a bad solder on C41 that had been there from my initial
build some years ago. Now I get 4.1w on 40m and 2.7w on 20m--both much
higher than I've ever seen. I'd like to get more power out on 20m even if
it takes away from 40m. L2 is wound pretty tight so there isn't much
movement in spreading the windings. In searching the mail list for ideas,
it does seem as if 20m should be closer to 40m. Should I rewind L2 loosely
so it is easier to move around? Or leave it alone? And, yes, I've checked
the number of turns on L1 and L2 as well as the capacitor values multiple
times. These measurements are with the ATU out of the circuit.
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