就是那个小机器的pdf上写的,作者提到用ft-243和hc-6的晶体可以获得很大的下拉范围,大约50khz,他自己实验到25khz还很稳定. 其它的hc-18和hc-45晶体需要更大的电感才能拉到相同的范围.
google了一下,ft-243好象是一款很古老的晶体了. 不过现在还有卖的.
http://www.af4k.com/567mhz_crystals.htm
ft-243 - dimensions: 13/16" x 3/8" x 1-1/8" tall
dimensions: 0.8125" wide x 0.375" deep x 1.125" tall plus pins.
dimensions: 20.6mm x 9.5mm x 28.6 mm
with 2 pins, spaced 0.486" (12.3mm) and pin diameter = 0.093" (2.4mm)
pin length =3/8" (9.5mm).
(used in bc611, bc1335 and most ham transmitters from the 1950s and 1960s.)

