introduction
这款天调主要用于低功率的qrp场合,当然如果材料特别是电容耐压(>5000v)允许,也可以用于100w的发射机。这种天调的特点是选材容易,制作、使用方便,可根据需要方便的切换,通过不同的组合,可以覆盖3-30mhz宽广的频率范围,省略了通常电路需要的两个可变电容的组合方式。
国内如果可找到动片>2mm的可变电容(我做的电容约2mm的间隙,100w偶尔也打火),还有这种滑动式连续可调的电感制做就方便了。喜欢diy的ham不妨尝试以下。
使用方法
use
connect the transmitter output to the swr meter, the swr meter output to the input of the transmatch, and the antenna to the output of the transmatch. set the capacitance switch to 0 (center), adjust the variable capacitor to the mid point. adjust the inductor to near the minimum inductance. briefly transmit and observe the swr reading.
increase the inductance until the minimum reflected power and maximum forward power is observed. adjust the capacitance for the best swr reading. it is necessary to go back and forth on the adjustments to find the best match. if the best match is found with the capacitor at the max value, switch in either the 270pf or 510 pf parallel capacitors and re-adjust the variable capacitor and inductor.
be careful not to leave the transmitter on for too long in the unmatched condition, doing so can damage the output transistors. if your transmitter has a variable output power, tune up at low power then re-adjust the circuit at full power. if you are using a vacuum tube transmitter, don't worry about it. caution: higher power transmitters can generate high voltages in this circuit, don't touch any of the wires when the transmitter is operating. the set screw on the roller inductor knob may be electrically hot during use, you may want to cover it with a drop of plastic glue after tightening.