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Capacitance Evaluation - Example

Line Matching Transformer 50 to 500 ohms.

Frequency range 50 to 150 kc.

Power output 100 watts.

Primary voltage = √(ZW) = √(50 · 100) = 70.7 volts.

Secondary voltage = √(500 · 100) = 224 volts.

Core 2-mil oriented silicon steel.

Ac = 0.45 sq in., lc = 6 in., lg = 0.002 in. (incidental), core weight 3/4 lb.

Window 5/8 in. · 1 1/2 in.

Primary 31 turns No. 22 wire. Mean turn 3.8 in.

Secondary 100 turns No. 30 wire. Mean turn 4.6 in.

Windings arranged as in Fig. 166.

Insulation between primary and core, and between secondary and primary 1/8 in. of organic material.

Secondary effective capacitance 40 μμf.

Bm = 350 gauss.

Secondary OCL = 20 mh.

Secondary leakage inductance = 260 μh.

Core loss = 8 watts per lb · 0.75 = 6 watts. This is practically the only loss.

XN/R1 at 50 kc = (6.28 · 50,000 · 0.020)/500 = 12.56.

fr = 1,560 kc.

B = 5.00.

According to Figs. 108 and 109, this transformer has nearly flat response over the entire range.




Last Update: 2011-01-24