ILER-20 MK2 SSB QRP Transceiver Kit Page 20
Toroidal transformer T5
T5 is an impedance matching transformer. A FT37-43 is used (black toroid with 9.5mm/0.375in OD). It
has a 10-turn primary and a 3-turn secondary.
- Take 17cm (7.5”) of 0.5mm diameter enameled wire and wind ten (10) turns on a black FT37-43
toroidal core. Spread the turns evenly around the toroid and wind t hem tightly so that so that they follow
the contour of the toroid and are as tight against the tor oid as possible. The turns should be evenly
distributed around the circumference of the toroid. Leave pigtails of 10-20mm (0.70”).
- Now take about 8cm (3.5”) of 0.5mm diameter enameled wire and wind three (3) turns on the other
side of the toroid, spacing the turns within the space between the turns of the previous winding. Leave
pigtails of 10-20mm (0.70”).
- Before inserting them on the circuit board, use a cutter or sandpaper to scrape off the enamel from the
pigtails of the windings. Solder them in place. Mount the toroid with approximately 0.5 - 1mm distance
from the board.
- The 3-turn winding is facing towards output transistor Q14 and the 10-turn winding towards C69 - C70.
Counting the turns: Count one turn for every time the wire passes through the center of the t oroid.
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