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All American Five radio receivers

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Re: All American Five radio receivers

#51

Post by neilv »

13of40 wrote: post #50
neilv wrote: post #34

Even when the local department store was selling home computers based on microprocessors, they still devoted a chunk of retail floor space to a self-service vacuum tube tester. https://www.ebay.com/itm/195497221166 https://www.ebay.com/itm/324762243586 https://www.ebay.com/itm/403979880899 I wonder when these finally disppeared from stores, and what the market is like for vacuum tubes for antique TVs and radios?

I remember them, and it would have been the late 80s or early 90s. I had to ask my dad what it was, but I remember thinking maybe I would need to use that service someday. If you want to go down a rabbit hole, here's a classic video where a guy makes a brand new tube by hand: https://youtu.be/EzyXMEpq4qw

I love that video. Very relaxing. (I've sent it to people many times.)

Re: All American Five radio receivers

#52

Post by Dalrymple »

This high voltage hot chassis was clearly a dangerous design but at least there has been little use of it in the last fifty years. I find dangerous designs in current products fairly frequently.

As an example I was debugging my electric clothes dryer that stopped drying and found the wire to the nichrome heating unit was disattached. It had been attached to the heater with a push-on, pull-off spade connector at the factory. I maintain it should have been attached with a bolt-on connector with a lock washer. Having what is probably a 230 volt wire slip-off its connection due to normal dryer vibration and bounce around the steel chassis is concerning. If the dryer ground had been faulty (it was good) that could have placed a 230 volt potential on the entire metal cabinet of the dryer in a laundry room that may have a little water on the floor and usually has other ground paths like turn-off faucets for the washer as well - a super dangerous situation. This danger is increased because dryers are heavily used by kids, women, and non-technical men, most of whom have no idea of the risks involved.

Re: All American Five radio receivers

#53

Post by Aloha »

gumboza wrote: post #42
Aloha wrote: post #40

Earlier quoted context omitted.

And at 110v, thats a risk I'm willing to take. I wanna note, I worked as an FSE for a telecom, I've been 'bit' more than once by 130v, and by 160v B+ in shit, the sparks from crossed neutral are fine. Anyone who is deeply concerned can buy an isolation transformer.

110v can fuck you up. Don’t take your own advice please. At least no one else should. Isolation transformer will only stop you getting killed one of three ways. Worth backing my experience up as well. Ex EE covering RF and power in defence sector. There is no room for arrogance or assumptions in dealing with safety.

How would you work on these things?

Re: All American Five radio receivers

#54

Post by dbcurtis »

neilv wrote: post #34

Even when the local department store was selling home computers based on microprocessors, they still devoted a chunk of retail floor space to a self-service vacuum tube tester. https://www.ebay.com/itm/195497221166 https://www.ebay.com/itm/324762243586 https://www.ebay.com/itm/403979880899 I wonder when these finally disppeared from stores, and what the market is like for vacuum tubes for antique TVs and radios?

Well, Halted had a tube tester in the corner until the day they closed a couple years ago. There are NOS audio tubes still available. But if the random stuff showing up in my Youtube feed is any indication, the cool kids these days are learning glass blowing and making vacuum tubes from scratch.

Re: All American Five radio receivers

#55

Post by dbcurtis »

FpUser wrote: post #39

When I was a little kid one of my favorites was staring at the back of the huge tube based radio. It had boatloads of glowing tubes and the whole thing looked to me like a small city.

That sentiment resonates with me. I first got my ham license back in the days of vacuum tubes. There is nothing like the smell of a warm, dusty vacuum tube. I can’t describe the emotions that evokes.

Re: All American Five radio receivers

#56

Post by Jeema101 »

gumboza wrote: post #37
jhallenworld wrote: post #22

Earlier quoted context omitted.

Yeah, they are dangerous, but their safety can be improved: add polarized cord (probably have to move the power switch to the hot side for this) and replace the chassis ground capacitor. Table top FM radios and TVs also tend to be hot chassis.. (that mains transformer is just too expensive). Even today you can find capacitor dropper powered devices which are hot. AA5s are nice in that you can almost always get them t…

Polarised cord only works if your house sockets are wired correctly which is not necessarily the case and your earth bond might not be as good as you think it is. Always assume that the lowest competence is applied when it comes to safety evaluation. At this point I wouldn’t run one of these things at all. If you drop dead you have no idea if some relative is going to plug it in and kill themselves with it. They were…

Okay but assuming there's no exposed metal parts, is one of these radios with a polarized cord really more dangerous than a regular old two pronged lamp with a polarized cord?

If you plug that lamp into an outlet with positive and neutral wired wrong you will have mains voltage on the light bulb threads and socket threads instead of ground, and that's gonna be pretty unsafe for anyone changing the bulb.

But lamps are so common, we don't even think about them as safety hazards.

Re: All American Five radio receivers

#57

Post by ctechbob »

userbinator wrote: post #7

https://www.youtube.com/user/glasslinger is a good YouTube channel that shows the servicing of these and other vintage radios.

Paul Carlson also has a pretty big body of work when it comes to lots of things vacuum tube, lots of A5 restores.

https://www.youtube.com/@MrCarlsonsLab

Re: All American Five radio receivers

#58

Post by analog31 »

aidenn0 wrote: post #33
buescher wrote: post #23

The hot chassis design is mind-blowingly dangerous by contemporary standards. These things weren't designed to modern creepage distances either. I would worry about creepage to controls on these things. THe article mentions screws potentially being hot as well as other shock hazards finger-accessible through vent hols so no joke be careful to unplug a radio before moving it or otherwise handling it in a way beyond tu…

Even wiring the chassis to the neutral line with a polarized plug would be a bit archaic today, though it greatly improves things (assuming the power-switch isn't on the same line as the chassis, which on many of these radios it is !!)

Early guitar amplifiers were expected to be used that way. There was a polarity switch, and you flipped it to the position where the neutral was "connected" to the chassis via a capacitor. This arrangement is now known as the "suicide cap."

There's a general agreement among players, that having a tech install a proper grounded cord doesn't spoil the "vintage value" of an old amp.

Example here:

http://www.thevintagesound.com/ffg/schem/deluxe_5e3_schem.gi...

Re: All American Five radio receivers

#59

Post by Manuel_D »

Aloha wrote: post #26
buescher wrote: post #23

The hot chassis design is mind-blowingly dangerous by contemporary standards. These things weren't designed to modern creepage distances either. I would worry about creepage to controls on these things. THe article mentions screws potentially being hot as well as other shock hazards finger-accessible through vent hols so no joke be careful to unplug a radio before moving it or otherwise handling it in a way beyond tu…

The safety interlock cover was mandated at one point by law (or by the UL), because of this - because there are user replaceable components inside (tubes), they mandated a pressboard cover that contained the power lead, so you couldn't hook it to power while also having the case open.

I've modified and disassembled several of these radios. There's a second connection behind the cover. This will be disconnected as you remove the cover, but you can easily reconnect it afterwards. I've done so myself to probe the various components (I only manipulated it while the power was off, though).

Re: All American Five radio receivers

#60

Post by JKCalhoun »

FpUser wrote: post #39

When I was a little kid one of my favorites was staring at the back of the huge tube based radio. It had boatloads of glowing tubes and the whole thing looked to me like a small city.

I was recalling the same thing. For me it was our little black and white TV we had when I was young. I loved going around to the back and side and looking in at the little city inside.

I've made my share of tube amps from scratch off and on for a few decades now. Must be due to nostalgia of some sort.

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