[jepstr67]

Hi,

I see a good many wonderful and innovative ideas used in keeping these old critters working. I'm wondering if there is a place here with some kind of step by step instructions on learning how to fix and upgrade a radio so it is safe to use and works well.

I can disassemble my Jeep down to a pile of nuts and bolts and put it all back together, but find electronic stuff confusing and mystical. I know the AM radio is not that complex and once I learn to identify the parts is will be as easy for me to overhaul a radio as it is to do a Jeep. (there are way fewer parts!!) Where do I start?

I can look in the Radio and identify tubes, speaker, dial/tuning mechanism, and a transformer, but beyond that, what all the metal cans and other components do is still a mystery to me. I know there are sections of the radio that perform the different functions like choosing a signal, receiving a signal and amplifying the signal to the speaker but I don't know how to identify what parts do what functions. To compound the confusion, I can identify a resistor or capacitor on a radio made in the last 50 years, but I have know idea what their "grandfathers" looked like.

So again I ask, where do I start to learn how to fix old radios?

Maybe Ron could host a seminar.......

Thanks,

Todd

[codefox1]

Well, if you have a particular radio, you can get a schematic and/or sams photofact and you will soon know where everything is, and what it does. I would assume you would want to start with a pretty simple 5 or 6 tube set from the late 30's to late 40's . If it's a Philco, there is tons of information here.

Schematics also available for free at Nostalgia air http://www.nostalgiaair.org/ or for beitmans schematics, http://www.schmarder.com/radios/beitmans/index.htm .


If you want to do some textbook learning you can get gigs of free downloads at Pete Millet's site at http://www.tubebooks.org/technical_books_online.htm .

That's just a start. All these places have information from fellow hobbiests, and since it's all in the public domain, it can be shared.

You will need to have an isolation transformer to safely work on transformerless sets, a decent digital or VTVM, A variac to bring sets up slowly would be nice, and a signal generator completes the basic lineup. Nice to have is a scope, digital frequency meter, tube tester, capacitor tester/bridge. If you are patient, you can pick these up in a couple of months of searching Ebay, swap meets, etc...

You will also hear not to ever plug anything so old without changing out the electrolytic and all other wax capacitors first. It's true. Even then, it is wise to proceed slowly and carefully when powering up.

Your turn, Ron

[Carl Travis]

The Elements of Radio Servicing can be downloaded frrom this site:
http://antiqueradios.com/archive.shtml

[nash]

A nice site that explains the workings of a typical AA5 set in detail is http://www.angelfire.com/electronic/funw...AA5-1.html

Many problems with radios are due to failed capacitors. A good reference site on replacing capacitors, identifying, reading values, etc. is http://www.antiqueradio.org/recap.htm

Tube sockets are read looking at the bottom of the socket (under the chassis), counting clockwise from the right of the key, with the key at the top. The key is the gap between pins in 7 and 9 pin miniature tubes, the tab on octals and loctals, or the two large pins on older 6 pin tubes.

There are several good tube databases online for looking up tube specifications and pinouts. http://scottbecker.net/tube/index.html and http://70.167.193.117/Common/Tube/Excel/Tube.php

For schematics Nostalgia air http://www.nostalgiaair.org/ has been mentioned, I also find techpreservation useful. Note that techpreservation uses DjVu format. I use the DjVu-6.1.4-en-r2013 plugin with Firefox under Windows XP and 7.

Edit: fixed tube key reference. Learned something new

[Radioroslyn]

Tube sockets are read looking at the bottom of the socket (under the chassis), counting clockwise from the right of the key, with the key at the top. The key is the gap between pins in 7 and 9 pin miniature tubes, the tab on octals and loctals, or the two large pins on older 4 and 5 pin tubes.

Not to be picky or anything but 5 pin bases don't have larger pins. Pic is from an old post.

[exray]

True about the 5-pinners. Hold the tube to where "pin 3" is the odd man out and at the top. Easier to do than explain

[Radioroslyn]

Don't know for sure but the 5pin guys some may have an arrow pointing between pins 1 and 5. I know that 6pin tubes have an arrow between pins 1 and 6.
Terry

[jepstr67]

"It's like this. Except when it's not"

Thanks to the posts. some good stuff there.

Todd

[codefox1]

Well the fat pins always like up. The one on the left is always #1 and you count counterclockwise from there . Same applies to more modern 7,8,9,12 pins, some of which are probably extinct.

Of course this is looking at the pins as inserted in a tube socket freom below the chassis, just so you get your bearings. The fat pins are always (so far as I know) the filaments on real old receiving tubes, so you can check that out pretty quickly.