TRC-77 Ops:  I hate mods (I know, I know) but this problem has drained my battery too many times.
When the radio is switched to XMIT there is no other indication that the HVPS and filaments are powered waiting for a Key closure in QSK/Break-in mode.  It draws 2 amps while waiting.  So I added a simple LED indicator that shines through an existing panel hole to alert me that I left it in XMIT mode by mistake or accident.  Dumb!
Other details here, about halfway down the article: https://www.n6cc.com/trc-77-hf-cw-transceiver/

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Flame Shields Up !!
FYI, Tim
N6CC