Hi Allison,
On 6/16/19 9:33 PM, ajparent1/kb1gmx wrote:
I feel that's even more divergent from Johns work here as he is
working on Baluns and transformers that don't melt at 100 to
QRO power levels. A pair of FT240-43 are not light when put
in a Polycarbonate box. At QRP levels the problem is
manageable and the losses can be kept down. Its a big
part of the considerations that go into matching the radio
to whatever antenna..
Very correct. The design I've suggested is using two FT114-43 cores, not
2.4" cores. The Selection was a compromise between size and loss,
attempting to keep core loss below 0.3 dB for a QRP 80M to 10M device. A
single FT114A-43 could be used with just slightly greater loss. I had
114's in my inventory.
Selecting a -43 core and turn count based on core loss can be performed
using:
Examples:
FT82-43 4T primary 7.5uH @ mi -> ~0.7dB core loss
FT82-43 3T primary 4.2uH @ mi -> ~1.1dB core loss
FT82-43 2T primary 1.9uH @ mi -> ~2dB core loss
John KN5L
