Missy Lisa. . . .




Not being certain of your degree of expertise in techno comprehension, I will just start off with some preliminary info.


Your problem with the Airline set is very probably related to an incremental drying out of the “moist” electrolyte within a canned electrolytic capacitor used in the power supply section of that set over a 50+ year time span.


Instead of the pure DC voltage that it is supposed to be supplying to the tubes in the set, it is instead, replicating, to somewhat of a degree, the AC waveform which you are feeding into the set from the AC line. Thus, the undesired . . . .subtle. . .moderate . . .or overpowering HUMMMMM . . . . which is now emanating from the sets speaker.


I might now ask for you to confirm that the noise is STILL present, even when you have the sets volume control set to its MINIMUM volume position.


Placed below is a marked up thumbnail schema of the sets power supply.


Looking at the far left center one sees the AC line plug with its two flat pin connectors, of which the bottom positioned ones goes to the right and on down to the switching mechanics of converting between battery and AC line operation. THAT line is not the one of interest, instead, it is the FUSCIA marked up one that routes to the right and ends up getting connected to the selenium rectifier of the set, a photo of a selenium is also shown at the bottom, with your sets unit probably having fewer plates and being larger in squared area, their color schemes vary also. Mainly, my referring to the selenium was merely a land mark on the route to the two section power resistor that has its positive output terminal then being initially connected to resistor R13-B . The tap of that resistor finally connects to the first section of your mystery. . . .canned electrolytic capacitor . . .. Its four sections have been YELLOW highlighted as well as my having re-designated their values to 21st century, common, easy to locate values, for replacements, in place of the 4 sections older values that were being given.

That can be done by the using of four SEPARATE individual units in place of the 4 sections contained within the old can.

The cans 4 individual terminal wiring clusters are individually lifted and each connected to its own insulated terminal mount. The individual 4 new capacitors are then wired to those 4 terminals with the capacitors negative leads sharing a common buss.

The picture choice of the of the “altered” can capacitor shown was mainly for the presence of the side lettering logo, that shows that the 4 lugs coming out of the center of the can are marked with symbols of a half moon-square -triangle and the fourth being a blank or no designation at all. They are either being embossed into the bottom phenol disc that the terminals are coming out from, OR sometimes being CUT into the phenol, right NEXT to the terminals. That manner then identifies the capacitor section / value to its associative terminal.


C14- A and D. . . . . . 47 ufd @250 VDC rating

C14-B. . . . . . . . . . .220 ufd @ 16VDC rating

C14-C. . . . . . . . . . . .22 ufd @ 16VDC rating

Since the back opens on your set, I would expect the can being covered with a protective black cardboard insulative cover, in which case, expect that terminal info to be embossed into that cardboard cover.

MMe Basson . . . .


With your alll important NEW info of working on connections associative with the loop antenna, the info on the power supply
might just need to be set aside for the present.


That being, in consideration, that the radio might have initially been picking up a few strong stations WITHOUT the presence of the now overpowering background sound.

I have looked upward from the power supply circuitry and am now seeing that your set is incorporating the rarer seen utilization of a RF stage, in its front end use of the first 1T4 . That should reallly afford performance a step above, in its picking up of the weaker or more distant stations.

The attached markup schama is concentrating on the problem area, with the [ RED ] highlighting representing your loop antenna proper.

The designators of L(oop) A(ntenna) 1 and 2 are the points where the loop antenna wires connect into the radio. With that loop antenna consisting of a series of turns of wire the dimensions of the outer periphery of the front cover. Those two connections would then have to get connected in to the radio circuitry to the top [ BLUE ] buss mark-up and also the lower [ FUSCIA ] mark-up.

Now you are working with a blind person at this end, so I don't know WHAT those two connections look like or how the interconnections were made.

You gonna have to fill me in, with some questions having to being asked. . . . note the yellow box markups of the (once?) BROWN wire and the BLACK wire which are the sets provisions for the connecting of an external long wire antenna/aerial and an earth ground. Both of those would be conducive of better reception of distant, weak stations, PARTICULARLY, if the unit is being used solely on batteries.

Question. . .are those still present inside the set and stored as hanks of wire, or there only short lengths of wire and wire stubs now left ?

I would suspect after MYRIADS of front cover openings and closings that the metal wire/thin flat copper/brass /phospor-bronze foil has been subject to extensive repetetive metal flexure fatigue and failed.

Lets just initially ask to see if you might be able to ascertain which "wire" was involved, by your consulting the mark up schema.


The one associated with connecting the loop into the top [BLUE] buss or the one that connects the bottom loop conection into the FUSCIA buss down at the bottom.

If not, lets initially do a test that I think for sure that that you will be able to handle, in its respect of only needing two test leads with attached clip leads and a length of hook-up wire . . . .10-15 feet or even an unused extension cord ?


Brace your self. . .hang on tight. . .cranking up the Harley. . . .here we go.


Note that the unit has a 3 section tuning condenser with its three sets of semicircular plates/vanes and their companion fixed sets mounted down within the framework. The outer movable parts are called the Rotors and the fixed positon units are called the Stators. The rotors are all commonly connected, and also connected to the metal outer frame of the tuning condenser. The inner stators are separate and each is an individual entity. I have marked up the three sections of the condenser in BLUE-GREEN, and micro designated the RF, Mixer and Osc sections.


We are interested MAINLY in the RF section and a bit of the MIXER unit, note that the RF section has its rotor and stator connections marked with the YELLOW BOXED R and S designations.

What I am really worried about is possibly your connection was not good on the repair or else that a wire got connected where it shouldn't be. Heavy on my mind is the bottom side of the loop antenna wire not getting connected into the common GREEN connection which is actually an interconnection between some components and the frame of the tuning condebnser which you can see is common and between all of the sections of the tuning condenser. . . .since they are THE common frame of that condenser.
The point of interest is that the GREEN buss does NOT go to ground, but instead to the isolated AVC buss which is shown as the marked up BLACK-GREEN buss. Now, should that GREEN buss have ended up connected into either of the the small dual RED arrow mark-ups . . that being. . . at one end of C6 or your BLACK hank of ground wire, that could be your problem.


To find out now, locate the RF portions stator section. . . .in a narrowing it down for you. . . .its NOT the one with the smaller vanes. Plus, the wiring coming from its stator is initially connecting to C21--- a 220 pf capacitor and then the other end of that capacitor routes to a pair of 4.7 megohm (jellow-sweet violet-green) resistors and then the end connection is pin 6 of the RF anp 1T4.


(Pin 6. . .???? WHAT PIN 6. . . .in viewing the socket from the bottom , note that there are seven pins, but having the space for having an additional pin. So mentally transposition that "gap" as being at 12: 00 clock on a clocks dial face and then, clockwise, its. . . .wun-tew-fwee-fo-fibe-SIX . . . and THAT pin is where the RF input trail ends.


Should be easy to find, as your only other sections posssibility, is its routing having a direct connection to pin 6 of the 1R5 !

Now with the set having powered down thru all of the testing to now , and now knowing the RF section , take jumper clip and one end gets connected to the metal frame of the tuning condenser and the other clip goes to either the wire lead of the C21 cap that comes to the stator of the RF section or to the stator terminal if it will clip on OK.