Hey dudes, so I got this 1991 Honda Accord I bought for $300. 2 door manual trans. Shes old, has 355,000 miles with original everything. Everything been cool for about a year now but this morning it started doing something ive never seen before. So when I'm driving down the road my stereo blacks out. No power, seat belt light comes on starts beeping and my automatic antenna starts going down. Like 20 seconds later stereo comes back on, but all the presets and eq settings are the same. Does it once or twice on the way to work. On the way home it does it like 15 times before I turned the stereo off cause I was scared it might pop a relay or dude or some ****. But messing with it, it's like anytime the electrical power is pulled to anything but the stereo(brake lights, blinker, window,etc) it dies. What the heck is going on?

 

I have often found this to be the alternator and/or battery. I had this exact situation and it turned out in my case to be both a "right on the edge" battery not quite putting out the right voltage, but also a weak alternator not providing good and sufficient voltage to battery. As you said, when it pulls voltage it's just a bit too much and the car flips out. I would also have the ABS light come on and off. When I replace the battery, it worked for a bit, but then it started again. Once I replace the alternator as well, all issues disappeared.

 

You are getting an intermittent power failure that is not affecting the memory circuit.
If you are a kick panel kicker, you may want to check you haven't damaged the fuse or fuse box. Locate the fuse for the radio, not memory, and verify the fuse itself is seated correctly and not fractured.
When the radio cuts out, does anything else turn off as well? HVAC fan? Dash lights? Gauges?
It might be the ignition switch itself is beginning to crap out, but usually that kills the gauges/engine and would be quite noticeable.
I think one of the power leads for the radio and the cig lighter are on the same circuit, if you can plug in something(phone charger) to the lighter socket to verify it is also losing power, then you can eliminate the radio itself is faulty.
Power antenna is going to respond if the radio is turned on/off. It is not a causation problem, just a tandem affect from the radio being switched.

 

have your alternator tested

 

Also go and double check all your grounds. between Alternator, battery, grounds you cover most situations. However, the fuse panel is also a really good idea to inspect. While the car is just sitting there idling, I would be tapping the fuse panel to see if there is an issue and causes anything to happen.

Great to see a 300,000+ miles car still running.