Temperature rise measurement is appended to:
The temperature rise measurement was performed at 20W CW for two
minutes. The 2xFT114-43 4T primary Unun should be good for 50 CW or SSB
operation.
For perspective, a three turn primary FT140-43 Unun has about 0.5 dB
loss, which computes to 2.2 core dissipation at 20 watts. The FT140-43
3T is good for about 25W CW or SSB.
Assuming a 20 degree F temperature rise as the operational limit. The
measurement was performed in the open. There may be additional derating
required for a Unun mounted within a sealed enclosure. Even more if the
enclosure is black on a hot sunny 100F+ Texas day.
John KN5L
