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4640 Model 20 big box

4640 Model 20 big box; Atwater Kent Mfg. Co (ID = 276436) Radio
4640 Model 20 big box; Atwater Kent Mfg. Co (ID = 135504) Radio
4640 Model 20 big box; Atwater Kent Mfg. Co (ID = 699906) Radio
4640 Model 20 big box; Atwater Kent Mfg. Co (ID = 699907) Radio
4640 Model 20 big box; Atwater Kent Mfg. Co (ID = 1625952) Radio
4640 Model 20 big box; Atwater Kent Mfg. Co (ID = 2115838) Radio 4640 Model 20 big box; Atwater Kent Mfg. Co (ID = 2115837) Radio
4640 Model 20 big box; Atwater Kent Mfg. Co (ID = 2115839) Radio 4640 Model 20 big box; Atwater Kent Mfg. Co (ID = 135310) Radio
4640 Model 20 big box; Atwater Kent Mfg. Co (ID = 423907) Radio 4640 Model 20 big box; Atwater Kent Mfg. Co (ID = 135311) Radio
4640 Model 20 big box; Atwater Kent Mfg. Co (ID = 135312) Radio 4640 Model 20 big box; Atwater Kent Mfg. Co (ID = 135314) Radio
4640 Model 20 big box; Atwater Kent Mfg. Co (ID = 135316) Radio 4640 Model 20 big box; Atwater Kent Mfg. Co (ID = 135318) Radio
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4640 Model 20 big box; Atwater Kent Mfg. Co (ID = 2115838) Radio
Atwater Kent Mfg. Co: 4640 Model 20 big box [Radio] ID = 2115838 933x870
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For model 4640 Model 20 big box, Atwater Kent Mfg. Co.; Philadelphia, USA
Country:  United States of America (USA)
Manufacturer / Brand:  Atwater Kent Mfg. Co.; Philadelphia, USA
Year: 1924 Category: Broadcast Receiver - or past WW2 Tuner
Valves / Tubes 5: UV201A UV201A UV201A or UV200 UV201A UV201A
Main principle TRF without regeneration
Tuned circuits 3 AM circuit(s)
Wave bands Broadcast only (MW).
Power type and voltage Storage and/or dry batteries
Loudspeaker - For headphones or amp.
Power out
from Model: 4640 Model 20 big box - Atwater Kent Mfg. Co.;
Material Wooden case
Shape Tablemodel, Box - most often with Lid (NOT slant panel).
Dimensions (WHD) 26 x 8 x 8 inch / 660 x 203 x 203 mm
Notes There is also the smaller 20C Compact in two versions ! They use the same label "20" (without the "C")!
Price in first year of sale 100.00 $
External source of data Ernst Erb
Source of data The Radio Collector's Directory and Price Guide 1921 - 1965
Circuit diagram reference Rider's Perpetual, Volume 1 = 1931/1934 (for 1919-1931)
Mentioned in Radio Manufacturers of the 1920s, Vol 1
Literature/Schematics (1) A.Atwater Kent, The Man, 2002

All listed radios etc. from Atwater Kent Mfg. Co.; Philadelphia, USA
Here you find 504 models, 324 with images and 327 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.


Forum contributions about this model
Atwater Kent Mfg. Co: 4640 Model 20 big box
Threads: 3 | Posts: 5
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atwater: Model 20 big box; 4640: Operating And Trouble Shouting
Georg Richter

Extracted from "Radio Digest" Vo.XV No.6 of November 14th, 1925. The author is yet unknown.

Operating And Trouble Shooting

For the Owner of an Atwater Kent Model 20

Extensive tests with this set showed that it could be used, with excellent results, on almost any type of antenna. Naturally, the best results are secured with a high outside wire since more energy reaches this type. The length over-all, including the lead-in and ground should, preferably, not exceed 100 to 150 feet. If one long straightaway wire is impossible and an aerial of two or more wires is used, the space between wires should be not less than 3 feet and greater separation would be to advantage.

Antenna and Ground

Between a loop antenna and an indoor wire, tryouts proved the indoor to be slightly better. A wire was strung straight down a hallway about 40 feet in length and 6 inches below the ceiling, attached at each end to the top of a door frame with insulators. This worked very nearly as well as the outside wire. Since an antenna strung behind the picture moulding of two rooms was available this was also tried and, while the volume was not quite as great, the selectivity was increased to knife-like sharpness and the range differed not at all. Although it was not tried, there seems good reason to believe that an attic antenna would give even better results than the wire strung in the hall.

The ground, as usual, was made by scraping the water pipe and tightening a substantial ground clamp around the clean portion. In this case the connection was made in the basement near a window, the wire run out through a small hole in the basement window frame and up to the window through which the antenna lead from the outside wire was passed. Both wires are brought, in porcelain tubes, through a board under the sash.

Tubes  and Batteries

Following the manufacturers' instructions, five "hard" tubes of the A type were used, instead of four A tubes and a soft detector. Although the set performed well on the first insertion of tubes, they were switched around while the set was left tuned to a station to ascertain whether any of them performed better as Radio frequency amplifiers. Some improvement in both volume and clearness was perceptible when the first Radio frequency tube and the detector tube were exchanged. The battery is a 6-volt, 120 ampere hour unit and, while it may be used for several days and then recharged for several hours at a high rate, it has been found better practice to charge it a little each evening while at dinner to make up what was used the evening before. A charging rate of 2 1/2 amperes for an hour seems to keep this one about right.

Model 20 was used on both storage and dry cell B batteries. Performance over a period of six weeks is apt to be more consistent with the former, but no difference could be noted during the two nights' test of this set, though the dry cell blocks were 10 per cent gone and the storage cells freshly charged. When making connections to this receiver/ or any other for that matter, make one cornplete connection from set to battery at a time, rather than making five connections to the batteries and then connecting all the loose wires to the set. Care should be observed when connecting the loud speaker that the cord with the red htread interwoven in it is connected to the post marked "Red Tracer Lead."

Check all battery, antenna, ground and speaker connections once before putting in any tubes; then insert one in any socket and pull the filament switch out. Turn the rheostat over slowly and, if tube lights dimly it will be alright to insert the other four tubes. Turn both rheostats to right nearly to the maximum position, and one is ready to tune in sations.


It will be found that the second and third dials will always be at very nearly the same setting for any given stations, while the first dial will be at some point slightly above or below them, depending on the position of the tap switch. This switch is provided to adjust the set to any antenna with which it may be used. A few trials will show on which tap it should be set for maximum results, after which it can be left there. In the case of our tests it was found that tap number 2 worked slightly better than the others.

First of all set dials 2 and 3 on, let us say, 56. Then swing dial 1 slowly from 40 to 70. If no program is heard, even faintly, shift dials 2 and 3 to 54 and again swing dial 1 through the short arc. After
two or three shifts, a station will be heard and all dials can quickly be set to maximum response. Then adjust the two rheostats to the point where both volume and clearness are at maximum, but do not turn them any further to the right as this would merely be burning up energy uselessly and will shorten the life of the tubes.

With a distant station tuned in, try shifting the switch located between dials 1 and 2 and reset the dials slightly. If any increased response is noted write down the dial settings and then tune in another station with the switch back on the point at which it Was before. Then shift switch and reset dials as before. This procedure on different stations located in several directions will determine once and for all the switch setting and it should then be left alone. It will be found an excellent idea to keep a little red tag or something else bright in color attached to the filament switch for a few days, as otherwise if one leaves the set at a time when signals are not tuned in, it is very easy to go off and leave the tubes burning, possibly for many hours. The tag Serves to attract one's attention and remind that the switch should be pushed in. After the fact that the switch is there and is to be used, has been sufficiently impressed on one's mind; the tag can be removed.

Dial Settings

The dial settings we found with the antenna compensating switch on point 2 are shown here and it seems reasonable to believe that other Model 20 sets will follow these settings very closely.

Wave Length Dial 1 Dial 2 Dial 3
278 18 22 22
309 24 28 28
337 30 34 34
380 41 45 45
429 52 56 56
469 64 68 68
492 70 74 74
517 78 82 82
536 84 88 88


Hits: 1783     Replies: 2
atwater: (Model 20 big box); 4640
Jürgen Bauch

Ich habe aus den USA eine AK Big-Box erhalten,die im NF-Bereich so gar nicht

mit der normalen BIG-Box übereinstimmt.

Sie hat 6 Röhren (2 X UX201A und 4 X Daven MU20 ).Da die Big Box nicht verbastelt

aussieht stellt sich hier die Frage ob es sich eventuell um einen Prototyp handeln kann ?

Für Hinweise zur Aufklärung würde ich mich freuen.



Konrad Birkner † 12.08.2014

Hallo Herr Bauch,

das war mal eine AK20 big box, aber das gesamte NF-Teil hat mit Sicherheit niemals die Firma Atwater Kent gesehen:

1) ein solches Trägermaterial findet sich nicht bei AK
2) AK hätte niemals fremde Trafos verbaut, noch dazu unterschiedliche Fabrikate. So etwas findet höchstens der  Bastler in seiner Kiste.
3) UX-Fassungen, während im originalen Teil noch die richtigen UV-Fassungen sind.
4) die Bauteilfassungen und die Verdrahtung ist auch weit unter AK-Standard der 20er Jahre. Bei den "Blechwannen", beginnend mit  Modell 37 kommen ähnliche Elemente vor. Das war aber eine völlig neue Generation.

Atwater Kent hatte immer einen sehr hohen Qualitätsanspruch. Was hier zu sehen ist wäre dort kaum akzeptiert worden (wenn nicht gar in den Müll gewandert und der Verfertiger möglicherweise gefeuert worden....)

Darum halte ich die Idee mit dem Prototyp für ausgeschlossen. Das Gerät ist ein Bastlerprodukt, nicht einmal sonderlich gut gemacht.

Tut mir leid, Herr Bauch, aber es ist ja nicht Ihre Schuld.
Aber die MU20 sind ein interessanter Fang, der sicher einiges ausgleicht!

Mit freundlichen Grüßen,

Jürgen Bauch

Hallo Herr Birkner

Danke für Ihre ausführliche Stellungnahme zu meiner Frage betreffs meiner BigBox.

Ich habe mir schon fast denken können,dass es sich bei der NF-Stufe um ein Bastelteil


Nochmals vielen Dank !

Mit freundlichen Grüßen


Jürgen Bauch

Hits: 2035     Replies: 0
F. Quintana-Calduch


Ultimamente he estado reacondicionando algunos modelos de AK, concretamente los modelos 20 normal y el compacto.

Es una experiencia nueva e interesante ya que hay que conseguir las valvulas tipo "01" con los 4,0 voltios en filamento - sin catodo - y es necesario confeccionar un suministro de continua, mejor con baterias recargables, ya que de lo contrario, o sea, con supresores de bateria, hay siempre una componente de rizado de alterna que molesta la recepción

Lo más complicado de todo es la sustitución en casi todos los casos de los transformadores de BF, de relación 1/3 ó 1/4 con el primario abierto. La sustitucion se hace con nuevos conseguidos en USA y encapsulados en los antiguos recipientes, para respetar el aspecto.

El resultado es siempre enriquecedor, sobre todo porque da la impresión de trasladarte al principio de la radio y la emoción de la sintonización de las distintas emisoras.

Dispongo de las direcciones donde se puede conseguir ese material antiguo. La fuente principal es en e-Bay para las radios antiguas y Antique Electronic Supply en USA para componentes.

Un saludo


Atwater Kent Mfg. Co: 4640 Model 20 big box
End of forum contributions about this model