I was going through my massive piles of boxes in the basement and found a gem in one. In high school electronics class we all built a kit AM radio. The Graymark Model-510 5-tube AM. Apparently it's based on a fairly standard design my Dad referred to as "the all American 5 tube" design.
I have no memory of how much the kit cost or if the school provided it then, but the new-old stock kits seem to be going for $300 on eBay.
I took a risk with the capacitors and just plugged it in. It still works after 40 yeas of sitting in a box!!!!
It takes about 30seconds to warm up. And "warm-up" is the right term. The top of the radio feels uncomfortable warm on one side. ;D
It seems just a little deaf, so I'm trying to find the manual for it so I don't have to do an alignment without guessing.
(http://i120.photobucket.com/albums/o170/cockpitbob/SAM_2337_zpsojzqdzqp.jpg) (http://i120.photobucket.com/albums/o170/cockpitbob/SAM_2337_zpsojzqdzqp.jpg)
Beautifully clean inside.
(http://i120.photobucket.com/albums/o170/cockpitbob/SAM_2342_zpsgkqpubve.jpg) (http://i120.photobucket.com/albums/o170/cockpitbob/SAM_2342_zpsgkqpubve.jpg)
It's all point-to-point wiring. No circuit board! I did pretty good soldering back then, though my dressing the wires wasn't very artistic.
(http://i120.photobucket.com/albums/o170/cockpitbob/SAM_2339_zpszy5zlruh.jpg) (http://i120.photobucket.com/albums/o170/cockpitbob/SAM_2339_zpszy5zlruh.jpg)
So, if an EMP takes out all my transistor based stuff, I've got an all tube receiver. Of course with the grid down I have no idea how I'll power it since it needs high voltage to run the tubes :o
Very nice Bob! Does it plug in the 110V grid power directly? Power supply is the main reason I haven't built a tube radio yet..
Gil.
Yeah, it's AC powered. I found a schematic for it. I haven't found a manual, but the 5-tube AM is such a common design I've found old and modern articles on how to do the alignment.
There's no chance of powering it from batteries. It's a hot chassis rig! :o Note the 5 tubes' filaments are in series directly across the AC power line (lower right corner) and V1 is rectifying the AC, so it's got 170Vdc inside!
But it works! I was listening to part of the $h!t show, I mean Presidential debate on it last night while I was looking for more info on it.
(http://i120.photobucket.com/albums/o170/cockpitbob/usa_Graymark_kit_510_AA5_poster_zpspxxlcllb.jpg)