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What frequently killed the PIN diodes on that amplifier was loss of 12-Volt power with the radio still attached.


This amplifier had to have power applied to function on standby.


Yep, the weak link in the chain was the PIN diodes.


A relay-based amplifier can be used as a barrel connector with the power removed. It won't care.


The original 5300 could only pass your barefoot power safely through it with 12-Volt power applied. Needed power to 'turn on' the PIN diodes that provide the standby path to transmit barefoot through it.


Remove power, and keying the radio would blow out the input-side diodes. Next time you key it with power applied, the output PIN diodes would fall like dominoes.


Nice idea, just a little ahead of its time. Every one of them we repaired in the 80s got converted to use relays.


Haven't seen one in decades.


73