rca: BP-10 article

ID: 260774
? rca: BP-10 article 
03.Aug.11 22:09

Tom Warnagiris (USA)
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Tom Warnagiris

I've written an article regarding the history of the RCA BP-10 radio.  I have it available in both .PDF and Microsodt Word form.  It's about 1.5 Meg in size.  What's the most convenient method of forwarding in to the model administrator for review and eventual posting?  


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06.Aug.11 05:53
71 from 17532

Joe Sousa (USA)
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Joe Sousa

Hello Tom:

I look forward to your article. 

These instructions about mulipage pdf uploading may be of help.



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16.Oct.11 17:01
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Michael Watterson (IRL)
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Did this article ever get uploaded?  I don't see it here: List of PDFs

RCA BP10: Earliest Compact Portable?

I think the BP10 was one of first B7G based Miniature valve radio sets. So compact for 1941 compared to the "boxes" in UK of 1950s. Though was the Marconi or Marconiphone P17b (1947) a design  via HMV / RCA connection? It's a very similar outer shape though different chassis layout and single B114 combo 67V/1.5V battery pack (later called a 70V/1.5V). One version has used MOV X17 W17 ZD17 N17 and other DK91, DF91, DAF91 and DL91 (both essentially the RCA 1940 1R5 1T4 1S5 1S4 series used in the BP10). Marconi appears to have made the Ever Ready Personal B, or perhaps supplied the chassis with DK91, DF91, DAF91 and DL91 and box fitted by Ever Ready as the internal front panel is different. The 3S4 is a centre tapped 1S4, thus the later European equivalent is the DL92.

There may be no connection at all apart from similar "form factor" and  tube line up between the 1941 RCA BP10 and 1947  Marconi/Ever Ready P17B/Personal B. As LW was important in UK and not in US, the Ever Ready B2 in 1948 used higher inductance oscillator coil and frame aerial for LW and the "wave band" switch for MW simply adds two parallel inductors on the aerial coil and oscillator coil to give approximately the B model MW tuning range.

Similar form factor 1941 radios with the RCA 1R5 1T4 1S5 1S4 design were the Crosley Commuter and Emerson mini portable.

"Communications for April 1941"

The Personal Radio Receiver

This is a six page article discussing with drawings or photos with schematics of:

GE LS-412

GE (a 2nd similar set pictured)


Zenith 4K600


Emerson FF series (FF411 includes "economiser" switch). The Emerson mini-portable is illustrated (are these the same or different models? The text does discuss Emerson "models" differences )

Farnsworth CT59

Farnsworth KD57

Fada mentioned?

Admiral (Continental) 29-G5

Crosley Commuter

Garod BP20

Motorola A1

Dewald 564

Dewald 410

Air Castle (45V)

Case Materials used listed: Wood, Plastic, Bakelite, Polystyrene, Aluminium, Tenite, Acetate, "metal", "cloth"

Most of the mains / battery sets use filaments parallel on battery and series on mains (7.5V). The Motorola series on Battery. The 7.5V versions (mains or battery) need to use the 3S4 (later in 1947 the DL92) centre tapped version of IS4

Some models in the text or schematics are not those illustrated.

10 photos/illustrations of radios, 10 schematics. All 1941!


Did the WWII kill these off or was performance and battery life too poor in such small packages?

Then during WWII we had the Miniature Receiver Type 31/1 (from 1943) aka "Sweetheart three tube IT4 regenerative radio designed by a Norwegian in UK, dropped behind German lines. It used 2 x 15V hearing aid batteries like the B121 in AVO meter and a 4.5V "flat" torch battery (still only just available for cycle lamps. Short and long "brass" strips on top) and the miniature 1943 Polish designed (in UK) Miniature Receiver OP-3 Type 30/1 a dual band superhet presumably using the RCA 1R5 1T4 1S5 1S4 design (battery arrangement unknown to me).

After WWII RCA an attractive Aluminium style model RCA 8BX6 globetrotter and the  1954 RCA Victor 6BX6A.  The 1951 Braun Piccolo is slightly  similar style to the 8BX6. Many attractive German and Philips portable tube sets, often with LW, MW, SW and later many with VHF too. Yet most UK models for entire 1950s are large Rexine (leatherette cloth) covered wooden boxes. Even after the 1/2 LT current DK96, DF96, DAF96 and DL96 introduced. Ever Ready, Vidor, Pye/PAM/Invicta, Marconi, Ferranti, Bush etc.

Personal Radio Receiver 1

Click each part of page separately for full size (jpg for "photos" to fit < 200k)



(click on above for full size)



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Earliest Compact Portable(s) 
18.Oct.11 14:09
311 from 17532

Konrad Birkner † 12.08.2014 (D)
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Konrad Birkner † 12.08.2014

Just a humble addition to the amazing article above:

According to M.B.Schiffer "The Portable Radio in American Life" The first radios which made use of the new "miniature" tubes are the RCA BP-10 and the Sonora Candid (so called "camera style", slightly bigger than the "coat pocket radios")

In Germany only one "coat pocket" model of the flip top style was produced: the 1950 Metz "Baby".


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Comparison with later models 
18.Oct.11 15:07
328 from 17532

Michael Watterson (IRL)
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Thanks for the confirmation on the RCA BP10. There is also model above there (labelled "E" a Philco) deliberately designed to look just like camera (with the two knobs on top).

However while they are small, few of the radios in the article would win a beauty contest. Germany and (Philips Colette 1956, Annette etc)  made many beautiful styled portables in the 1950s where "koffer" (suitcase) is unfair. The UK mostly made small "suitcase" (briefcase, hat box, valise, "jewel box" and attaché case) wooden boxes with Rexine in the period.  Example Braun Piccolo 1951 Also models from Akkord, Grundig and others. I'm no expert on German 1950s portables though.

As mentioned earlier there are only a very few  well styled very portable UK models (the Marconi/Ever Ready mentioned earlier is the only "pocket" model.  The "Romac Portable" of 1946 is an exception (I see you remark it is even the first UK model apart from Wartime Covert Radio with B7G valves in UK). The Romac is very like the Philco "camera" styled model "E" above. What happened to case design in UK? The perspex Pye "sunrise" portable was recalled (because the case broke easily or because of "rising sun" motif?). One theory is that the British Public wanted "Wooden boxes" and was not concerned with a more miniature design. Wood for cases in late 1950s and early 1950s was in short supply which is why many Bakelite table models produced, even Bakelite TV sets as in the late 1940s the Makers did not even reach production quota allowed by Government in UK due to shortage of wood for cabinets!


Not featured in the Communications April 1941 Article:

1R5 1T4 1S5 1S4
P17B (1947)
X17 W17 ZD17 N17

P17B (1948)
DK91 DF91 DAF91 DL92

Ever Ready
Personal B
(Marconi P17B)
DK91 DF91 DAF91 DL92
Ever Ready B2
(adds LW)
DK91 DF91 DAF91 DL92
Metz Baby4
DK91 DF91 DAF91 DL92


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18.Nov.11 00:08
575 from 17532

Tom Warnagiris (USA)
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Tom Warnagiris

I apologize for the delay in getting back to you.  I’ve recently learned that the article that I was intending to send to you will be available on the Internet next year.  Antique Radio Classified (ACR) published it in their February 2011 issue.  I had planned to revise the article for you so as not to conflict with what was published by ACR.  But, since it will be online as part of ACRs 2011 archived articles, I will not ask that the Radio Museum host it.

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Some other non-USA personal Sets 
29.Oct.12 21:03
2352 from 17532

Michael Watterson (IRL)
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The Roberts R77 is 1957, maybe a little larger, strange as there were transistor "personal sets" by 1957.

4: DK96 DF96 DAF96 DL96 So total 125mA LT rather than 250mA

MW and LW


The Vidor CN353 is 1947 so contemporary with the Marconiphone/Ever Ready Personal (both probably made by Plessey).

4: DK91 DF91 DAF91 DL92 (1R5, 1T4, 1S5, 3S4) 250mA LT

Very similar to BP10 concept, but MW & LW


The Championette from 1949

4: 1R5 1T4 1S5 3S4

Again similar to the RCA BP10 Personal concept. 67V HT

250mA 1.5V LT, MW only


Marconiphone P20BX and also K12 P20B 1948

Again HT is 67.5 or 69V to reduce HT size

4: X17 W17 ZD17 N17 (1R5, 1T4, 1S5, 3S4)

A bit fatter than the earlier P17B / Ever Ready B but LW & MW


Stromberg-Carlson 4P17 from 1947 in Australia

4: 1R5 1T4 1S5 3S4

Same reciepe, MW only of course


It's puzzling that the "Personal" set didn't have a reappearance with 25mA Dx96 series and ferritte rod from 1953 to 1956/1958  (First Transistor sets 1955, common by 1958) without the awkward flip lid aerial. The cheap supermarket DAB sets have only 4hours to 5 hours battery life compared to 25 to 60 hours possible with a "Personal" tube radio!


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Some USA Personal Models 1940 to 1949 
04.Nov.12 01:20
2906 from 17532

Michael Watterson (IRL)
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This isn't a comprehensive list. Some are listed as >8 " portables and some as smaller portables.
All are 1T4, 1R5, 1S5, but may vary in output tube. Some manage to fit in a mains supply too. 67V and 1.5V D cell (or two in parallel!) is common rather than 90V HT to reduce battery size.

Candid 1940


RCA 1940

BP-10 Personal


Westinghouse 1940


(yes, identical to BP10)

Allied-radio Corp 1940?  

Knight B-10506

45V HT


Lafayette 1940  


Lafayette 1940 ?

 Admiral 1941 ?


67V HT and 110V AC mains


Dewald 1941




Montgomery 1941



Zenith Radio 1941

"Poketradio" 4K600P

"Poketradio" 4K600R

"Poketradio" 4K600W


Zenith Radio 1941

"Poketradio" 4K600 Ch=4B01


Detrola 1941



Emerson 1941

432 Power-Mite


General Motors Radio  1941  

Pocket Portable 985775


Admiral Radio 1941  

Bantam 29-G5 


Admiral 1941  

29 Ch = G5


Admiral 1941  




Emerson 1941

379 Personal Radio Ch= DU


Emerson  1941

380 Personal Radio Ch= DU


Farnsworth 1941


Firestone 1941

S7397-1 Air Chief Ch= E442



Fada 1941?  

Series 33 L33


Fada 1941



USA motorola
Radio 1941 S $ 



Sentinel 1941

General Electric 1942


(also a 1941 model LB-642, but no clear photo)

Crosley 1942?

45 Commuter Ch= 45


Lafayette 1942  



RCA 1946  (many versions)





Emerson 1946



RCA  1947

54B5 "The Solitaire"


Airking 1948  



Airking 1948



Automatic Radio Co.  1948/49

B44 Tom-Thumb Bike Radio

67V HT


Automatic Radio Co. 1948

TomThumb Camera


Automatic Radio Co.  1949

TomThumb Buddy

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Is it the Last (in Europe)? 
08.Jan.13 18:09
3342 from 17532

Michael Watterson (IRL)
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Braun Exporter 2 1956 to 1959

Only 175 x 120 x 50 mm @ 0.9kg
Using only 50V HT to save space.

There is also the Braun Exporter (listed as 1.1kg, but same size)

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