airline15

[stusnyder]

Hello all,
Last year I picked up a airline 15 and decided to see if the thing works or not.
Can't find a correct schematic on this set. Riders says it's a 120 volt set, but this is a battery set. The closest I found is a u-15.
On radiomuseum the pictures for the model 15 are the same thing I got, but the schematic shows the set is 120 ac with a transformer Again this is a battery set.
It has 5 201 tubes. Hookups are aerial, ground, speaker, a+, a-,B+, B-, B+ det,
B+ amp.
The u-15 has voltages listed as 90, 45, and 6.
I believe the 6 is the "A" voltage. Anyone know what the "B" voltages should be?

[Reece]

Is yours the table model shown on Radio Museum with the built in speaker? With 201A tubes, 6 volts for filaments would be correct, cut down to 5 volts by the filament rheostat. B voltages on sets like this would be usually 22-1/2 for the detector, 45 for other tubes, and 90 for the output tube. That's what I'd start with. Check the horn driver with an ohmmeter first: could be open, in which case you'd sub an ordinary output transformer primary there connected to a modern PM speaker. Could use any transformer in the junk box from an AA5. Put your voltmeter across the filament terminals of a tube, start with the rheostat off and don't go over 5 volts. 201A's could have a max of 135 on the output tube but would work better with C voltage of about 4.5V to bias the output tube. Does your set indicate connections for a C battery?

[stusnyder]

Nothing on the set about c voltage. So what voltage should I try for B+ det and B+ amp????
This does not have the stand with it, appears to be just a table top model.
I did hook up the A voltages and the tubes do light up.
I want to pull the chassis and make sure everything is intact.

[Reece]

B+ det try 22-1/2, "regular" B+ try 45, and amp try 90. Does it have the built-in horn?

Edit: this may have the grid leak resistor next to the detector tube open. It might be one of the ones that fits in like a cartridge fuse. It should read a couple of megohms. If open, tack in a resistor around 2 megs.

[stusnyder]

Resistor ok. No horn built in, takes a external one.
Hooked it up like you said, don't get any sound. There is a transformer underneath, checked the windings and they seem intact.
There is also a square can under the chassis with 4 wires going to it. Looking at the photo, lower right is marked "P", lower left "+", top left "F", top right "G"
Is this some kind of capacitor??
A schematic would make things so much easier........

[Reece]

That box is an interstage audio transformer. P goes to plate of the first audio, + to B+ for that tube. G goes to grid of the second audio, F to its filament. With power off, check the two windings with your ohmmeter: P to +, and then F to G. Neither winding should be open. Often they are. There are small modern replacements to hide under chassis if the transformer is open. There is also a work around to get it going temporarily if needed.

[stusnyder]

They are both open, both sides. Whats the work around, the .047 cap, 1meg and 100k resistor trick???? Where would I hook these up?

[bob91343]

And I thought Cardwell just made variable capacitors.

http://antiqueradios.com/forums/viewtopic.php?t=30375

[Reece]

There's a picture of a similar Cardwell transformer in this thread:

http://antiqueradios.com/forums/view...?f=15&t=187051

The workaround is similar to what you stated: here's a good explanation of it:

http://www.antiqueradios.com/chrs/jo...nsformers.html

[stusnyder]

Originally Posted by Reece

There's a picture of a similar Cardwell transformer in this thread:

http://antiqueradios.com/forums/view...?f=15&t=187051

The workaround is similar to what you stated: here's a good explanation of it:

http://www.antiqueradios.com/chrs/jo...nsformers.html

I'll try it this weekend...see what I can blow up

[Reece]

It would be a good exercise to trace out the wiring and make a schematic. These mid-twenties TRF sets were mostly similar.

[stusnyder]

what is the symbol for plate and grid?

[stusnyder]

Originally Posted by Reece

It would be a good exercise to trace out the wiring and make a schematic. These mid-twenties TRF sets were mostly similar.

Well I tried that work around, still no sound. I found what appears to be a capacitor, small square can painted green. One end was grounded, the other end connected to one of the round wound coils. It looks like the cap leaked.
There are no markings or stamping on the can
Also the volume control does not change the current to the tubes, although the control seems like it's working via a ohm meter. Tube brightness stays the same regardless where the control is.

[bob91343]

Plate is either a heavy line, or a very narrow rectangle. Grid is either a zizag line like a resistor, or a dashed line.

[bob91343]

The volume control isn't necessarily a filament voltage control. That was an early system that was quickly abandoned because it added distortion and was sluggish.