1.16 mH is what I came up with.
This was done:
Plate Voltage
2550
Plate Current
.550
(.6XPlateV)/Plate I
(2550*.6)/.550 = 2800 Ohms
Multiply that by 10 and you have 28K
XL = 2piFL
= 2 x 3.141592653 x 3.870 MHz x 1.16 mH
= 2.82E+04 ohms (to 3 significant digits)
= 28,206 ohms
Hope that helps bud. Maybe remove enough turns to get you to that point.
--Shane
KD6VXI
(Edit: I used the resting voltage on the BC1G listed in the manual for the transmitter. Since that doubles along with current, the plate impedance should stay close to the same. Also, this was done for 1Kw output. Who runs 250 watts?
Although the 250 watts shouldn't be much difference since the plate voltage and current will both drop by half at carrier)