Guitar amplifiers are often quite high gain, and the cables sometimes get kind of dirty or bits of adhesive on the connections which can act as a diode. You can also get corrsion on the spring contacts of the input jack.
When the ground shield is not making good contact the cable itself can make a better receiving antenna, and you sometimes hear a station when all the elements align. Lots of guitar pickups are ferritic coils too. But there usually has to be a strong station nearby broadcasting at the lucky frequency.
Wasn't able to read the article but for me the two major portables were the automotive and the handheld.
Car radios were AM for decades before FM got popular. Originally there weren't that many stations across the country so there was less interference, but car radios were really top-shelf items so they could be sensitive enough, to pick up weaker nearby signals as well as sometimes hear powerful stations a hundred miles away or more.
By the 1960's they were even more modern, more sensitive, and expensively made, but the financing made it only a few dollars more on the car payment. If you didn't have a sensitive reciever, driving across the country was lots of radio silence.
Take a look at a 1966 Mustang with its factory AM radio. These were very sensitive recievers with a very extensible antenna, the taller the better for AM because you're working around buildings and geography to pick up from far away pretty much relative to line-of-sight.
This wasn't a directional antenna so it didn't matter what direction the car was going, what mattered was the station's power and the obstacles between you and it.
With hand-held or portable household radios having the internal ferritic AM antenna, these are highly directional so you have to carefully position the radio for best reception and often reposition the radio when changing to a different AM station.
For FM radios added to '60's cars you would retract the antenna down to a couple inches less than an American yard to match wavelengths better, these were not directional either. Eventually there were lots of aftermarket affordable AM/FM tape players after FM took off, not as many people listened to AM and these recievers had an AM section that was usually not so great electronically. With the antenna all the way up it still wouldn't pick up what the factory AM radio could do.
Once the dipoles embedded in the windshields came along, you then had more directional reception and it was tuned for FM by design, so AM gets even less love.
The modern vehicles which do have a conventional fender-mounted whip antenna are usually non-extensible and fixed at the short height that's best for FM.
fuzzfactor|3 years ago
When the ground shield is not making good contact the cable itself can make a better receiving antenna, and you sometimes hear a station when all the elements align. Lots of guitar pickups are ferritic coils too. But there usually has to be a strong station nearby broadcasting at the lucky frequency.
Wasn't able to read the article but for me the two major portables were the automotive and the handheld.
Car radios were AM for decades before FM got popular. Originally there weren't that many stations across the country so there was less interference, but car radios were really top-shelf items so they could be sensitive enough, to pick up weaker nearby signals as well as sometimes hear powerful stations a hundred miles away or more.
By the 1960's they were even more modern, more sensitive, and expensively made, but the financing made it only a few dollars more on the car payment. If you didn't have a sensitive reciever, driving across the country was lots of radio silence.
Take a look at a 1966 Mustang with its factory AM radio. These were very sensitive recievers with a very extensible antenna, the taller the better for AM because you're working around buildings and geography to pick up from far away pretty much relative to line-of-sight.
This wasn't a directional antenna so it didn't matter what direction the car was going, what mattered was the station's power and the obstacles between you and it.
With hand-held or portable household radios having the internal ferritic AM antenna, these are highly directional so you have to carefully position the radio for best reception and often reposition the radio when changing to a different AM station.
For FM radios added to '60's cars you would retract the antenna down to a couple inches less than an American yard to match wavelengths better, these were not directional either. Eventually there were lots of aftermarket affordable AM/FM tape players after FM took off, not as many people listened to AM and these recievers had an AM section that was usually not so great electronically. With the antenna all the way up it still wouldn't pick up what the factory AM radio could do.
Once the dipoles embedded in the windshields came along, you then had more directional reception and it was tuned for FM by design, so AM gets even less love.
The modern vehicles which do have a conventional fender-mounted whip antenna are usually non-extensible and fixed at the short height that's best for FM.