I have 1296, 900, 432, 222, 144, and HF stacked. Used info from Directive Systems web site and ended up with the following. 144 on top 222 48" below 432 48" below 1296 and 900 on Half H frame 33" below Mosley TA-63N HF/6 15" below. All seems to work ok 73 George W1LVL EL99