This maybe a dumb question but here it goes. I restored a AA-5 radio with all new caps and checked all resistors and did a complete alignment. The radio plays great but when I do a full volume the speaker distorts the sound. At medium volume the radio plays well. Must be something I'm just missing.

Robert: When you say full volume, do you volume control turned all the way up or do you mean playing radio loud but not turned all the way up? I don't think any of my radios can be played turned all the way up without distorting unless it is a weak station. Mark from Kalamazoo

:Robert: When you say full volume, do you volume control turned all the way up or do you mean playing radio loud but not turned all the way up? I don't think any of my radios can be played turned all the way up without distorting unless it is a weak station. Mark from Kalamazoo
:
Yep when the volume is all the way up. maybe I'm just getting picky.

Turn the radio back down to medium volume, and enjoy your restoration.

Not picky, silly. What do you intend to do with the radio, listen to it from across the street? Try using some common sense.

:Yep when the volume is all the way up. maybe I'm just getting picky.
:

:Not picky, silly. What do you intend to do with the radio, listen to it from across the street? Try using some common sense.
: there might one hell of a gome going on and I want the neighborhood to here,lol

:
::Yep when the volume is all the way up. maybe I'm just getting picky.
::
:
:

Most AA5 radios should produce about 2 watts of undistorted sound, which should be somewhat uncomfortable to listen to at close range, depending on your hearing.

If you are not obtaining this without significant distortion, you should check your resistors for proper value (disconnected), check the output transformer for proper resistance (in case that there are shorts), and possibly check for weak/gassy tubes.

Resistors in the audio section can drift fairly high before affecting performance adversely. Increase in plate and grid resistors will add bass to the music, but at a certain point the amplifier will become weak.

The output cathode bias method is critical. If the bias between the cathode and the grid becomes too great, often due to a drifted resistor, maximum undistorted power output can drop. The bias keeps the grid operating in the linear range of tube conduction.

Thomas, you're back! Missed seeing your responses. Mark from Kalamazoo

:Thomas, you're back! Missed seeing your responses. Mark from Kalamazoo

:)

In my ventures for new and different career paths, and kind of interested in starting my own business, I decided to throw all of the services (clean) that I am capable of on Craigslist, and one of them was antique radio repair. The only response I got was for the antique radio repair from a guy south of me who sells guitar amplifiers, guitars, records, jukeboxes, and antique radios, and the first project I am working on for him is a Philco 81.

Sadly I think that I am charging way too little for labor, and think that I will have to adjust this as I go along. Thankfully I didn't quit my day job, and I certainly don't intend to.

The radio is recapped. I did it the quick way with exposed modern caps and binding posts, as it would not be profitable for either of us to restuff the bakelite blocks.

I was told that the radio worked 25 years ago, but was kinda weak, except if he touched the antenna cap. Well, after the recap, the radio actually did play quietly, and played much louder when I touched one of the grid caps. I forgot which one. At any rate, I probed around and found that the secondary of the 2nd detector coil was open. There was a tap drawn down within the coil that wasn't connected to any terminal, and both halves of this tap were disconnected to eachother, and so I soldered them together. The coil measures proper resistance now, but now the receiver is completely dead reception-wise. It actually starts to have static when it is first turned on, but that goes away after a second or two. I noticed that the 2nd detector plate and screen voltages are low. They are about 25 volts, and should be like 75 and 40 respectively. Couldn't find anything wrong in the circuit. Resistors are just fine. Swapped tubes and same thing. Voltage at grid and cathode are fine, and B+ is fine, too.

All coil resistances are fine. No trimmer shorts or anything.

Eh. I'm going to bed now. I wish I could charge the amount of time this is actually taking me. Boo.

...but I was on here looking at schematics, and thought I'd take a look at the Forum. Hello!

The Tubes section isn't currently working, but I have my handy Tung Sol book to refer to. I'm just too lazy and would rather look data up here.

http://www.nostalgiaair.org/PagesByModel/852/M0013852.pdf

....of course what they don't tell you in the schematic (unless I just didn't read far enough) is that actually that top part of the winding (2nd detector secondary) is actually NOT supposed to connect to the rest of the coil. No resistance value is given. Considering that this is a detector, I was curious as to what detection method was being used. There was no indication of a very high cathode bias or exceptionally low plate voltage (well, 70 is kinda low, but not really), and no grid leak capacitor set-up. However, a clue that one does exist is that R19 is 4Meg.

...........and so I am going to disconnect the two wires that I soldered together and leave the very top portion of the winding disconnected from the rest. It will be connected by capacitance only.

Incidentally I also found one of the #77 tubes to be glowing purple inside, and so I have swapped it out for a good one. At this point there was no improvement, but hopefully with the coil set up as it should be, the set will perform well.

YAY!

...And it works!

:...And it works!
:
Thanks for the Info, I am out traveling and just checked the forum.
One question I do have also is what everyone uses for wind coils that won't cost a fortune. I was looking on Epay, which I am looking at across the street, some of the coil winders are way out of price. Any suggestions.

Sadly I just wind my coils by hand, but I don't wind that many coils. Lately the last coils I wound were for FM, and that doesn't take much doing. Would be nice to have a zig-zag winder.

T.

T,
I've done the FM types by hand as well many years ago. More recently I built an electro-mechanical winder to do the so called zig-zag types. Worked well using cotton thread (similiar to Litz wire) used in AM radio IF cans. Tried, but couldn't find small qtys of Litz wire for proof of concept. It was far too costly, and mostly in spools of 10k feet.

marv

:Sadly I just wind my coils by hand, but I don't wind that many coils. Lately the last coils I wound were for FM, and that doesn't take much doing. Would be nice to have a zig-zag winder.
:
:T.
:

I think I saw your zig-zag winder a long time ago, and it was pretty awesome.