Send wireless power long range with lasers and balloons

newscientist.com ^ | 06 December 2013 by | Hal Hodson

[Gene Eric]

I propose catapulting batteries.

[Bobalu]

BTW: Here is an image of the exact model Philco Tombstone farm radio I won in the bet.

I like these old Philco farm radios as they have permanent magnet speakers that you can drive from the audio out on a PC or an mp3 player. Most AC powered radios from that era (early 30's) had electromagnetic coils as the speaker magnet that needed to be powered before the speaker could function.

[Bobalu]

Oh, anyone can be taught to repair these lovely old radios in just a few hours time. Many times the problem is something obvious that has overheated and can be easily spotted.

The next most likely cause is old non-functioning capacitors and they can easily be replaced with modern equivalents.

If it's an old set with high-voltage filaments then it may be a bad heater cord. They used to drop 120vac or 120vdc down to a useable level by having the radios power cord resistively reduce the voltage to the set! The cords would get mighty hot too!...all this to save the cost of a transformer. It was a fireman's nightmare and can be repaired and made safer by placing a power resistor internally to take the cords place.

Then there is the chance of a bad tube. You need a tube tester for that and I recommend the old military TV7 series.

Here is an old video I put up for an ebay listing years ago to sell an extra TV7 I had. The old transmitter in the video was my first ham transmitter that I built from junk...a real squealer with 3.5 watts output on 40/80.

My first ham transmitter..has pwr supply on the board