The SP-400X covers 540 kc to 30 mc, the SP-400SX covers 1.25 mc to 40 mc. Those
were the only two versions produced, whereas the SP-200 was produced in more
than 17 versions counting the military and civilian versions.
Les Locklear
Monitoring since '57
Collins 51J4
Hammarlund HQ-120X
Hammarlund SP-600JX-14
Ten Tec RX-350D
Yaesu FRG-100
Alpha Delta Sloper
Quantum QX Loop
Various Longwires http://www.hammarlund.info/homepage.html