I just began working on a 1935 Airline Model 62-211. The schematic is available on this site. This is a battery operated set. From 1st and 2nd detector is shown L1 and L2, each labeled "single filament reactor". I'm new at this and am unfamiliar with reactors. Can anyone explain what they are and if there is anything I need to check on them? THANKS.
Steve

Think they are intended to block undesirable coupling of RF signals between those two stages. As long as the reactors have continuity they should be good which you will know if the tube's filaments glow.

Richard

I think "reactor" is another name for a choke or coil.

Or a capacitor. Note the caution about the 2 volt filament. Don't take much more to blow these. But I don't understand if set is DC and a purpose of a reactor is to oppose the flow of AC. You got me.

Bill VA

:I think "reactor" is another name for a choke or coil.

Since all of the filaments take their voltages from the same battery, RF coupling is possible. With portables like the Zenith 5-G-500 (the one I know so well), the filaments are strung in series. Condensers are used at various points before and after the oscillator tube. These filter out RF currents that can otherwise pass between the oscillator and IF tubes, which would cause unwanted oscillations. If you remove any of these condensers, a rushing sound is heard (not necessarily every time a condenser is removed, but sometimes this happens). The choke coils serve the same purpose in a parallel wired filament circuit. A reactor is usually a coil.

Thomas

Thanks guys. I think I have a better idea of what I have now. There is continuity on the coils, so I guess I'm OK there.
New Problem - I have no continuity on the output(?) side of the audio xfmr. The primary side shows 1000 ohms, but I get nothing between either the end or center taps of the secondary side. Shouldn't there be continuity here?
The primary side is fed from the 1st AF 30 plate and B+135V. The secondary end taps are connected to the Power 19 grids with the center tap going to C-4 1/2V. Can anyone give me an idea of what the impedence of these should be, and where I might find a replacement? Not sure if it will help but the number stamped on the bottom of the xfmr is U-50X11M-5C.
Thanks again,
Steve

Usually the secondary resistances are in the thousands of ohms, but sometimes they can be higher. Check using your most sensitive meter setting (X10,000). Also check from each end to the center tap. One side might be blown. If one side is blown and the radio hasn't obviously been soaked in water, you may be able to find the break in the wire by removing the outermost paper from the transformer (if the transformer is of that type). Often the wire will break right at the lead. Be very careful when removing the paper wrapping, as the wire used in this transformer is extremely thin.

If you cannot repair any troubles, new transformers may be found at www.tubesandmore.com. They are not very expensive. You can go with a universal push-pull interstage transformer. Unless you know the AC impedances of the original transformer, this is the best way to go. You may not find a push-pull transformer that has a single primary (not center tapped). In this case use one with a center tapped primary and use only half of the primary. For both the primary and the secondary, use the tap that produces the nicest audio. Too large an impedance on the primary will cause the audio to be mushy and distorted (perhaps, but not necessarily). Too small an impedance on the primary will cause a lack of bass. The opposite holds true with the secondary. Neither too large nor too small will likely cause distortion when dealing with the secondary, though too large a setting may cause too much gain.

If you know the DC resistances of both your primaries and your secondaries (if one side of the secondary works, the other should be the same), you may simply try matching these on the new transformer. DC resistances aren't usually given on audio transformers, but can be found easily enough by using your meter. However, depending upon the wire used and the amount of wire necessary due to different iron size and count on the new transformer, using same DC resistance settings may not produce same results.

Transformer impedance settings are not that critical for a radio of this type, so just go about it in a trial-and-error way. Be sure, of course, that whatever you choose as your impedance for each secondary half, is the same for both secondary halves. They should match.

Thomas

Here's the schematic: http://www.nostalgiaair.org/PagesByModel/349/M0011349.pdf

T5 is an interstage audio xfmr. I'm a little surprised that both ends of the CT secondary are open, so double check your work.

You could give this replacement xfmr from AES a whirl: P-T124E @$23.95. A cheaper possibility is their P-T124D @ $18.95. RadioDaze has the same models for the same price. Like Thomas says, there is a relatively wide range of ratios that will produce satisfactory performance.

Regarding how both sides of the CT secondary could be blown: I wonder if somebody in the past hooked up the C battery backwards?

Thanks everyone. I rechecked the leads by going up and down the scale several times with no luck, so I decided to dig deeper as Thomas suggested - it certainly couldn't hurt at this point. I found both end leads separated from the coil. I was able to get a reading of 635 ohms from one end to the center tap but as yet can't get a reading on the other end. Hopefully I'll be able to find where that problem is. The primary reads 980 ohms. That seemed low from what I am hearing you say, so I checked it on another meter and got the same readings. Is this indeed low resistance for this type of xfmr?
Steve

No, that's a pretty resonable resistance.

Thomas