rca: BP-10 article
? rca: BP-10 article
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?
Thanks,
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Instructions
Hello Tom:
I look forward to your article.
These instructions about mulipage pdf uploading may be of help.
Regards,
-Joe
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PDF?
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)
RCA BP10
Zenith 4K600
Philco
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.
Click each part of page separately for full size (jpg for "photos" to fit < 200k)
(click on above for full size)
Attachments:
- Comms April 1941: The Personal Radio Receiver (1) (165 KB)
- comms_1941_8sets (105 KB)
- comms_apr41_PRR_2_txt (76 KB)
- comms_apr41_PRR_3 (177 KB)
- comms_apr41_PRR_4 (179 KB)
- comms_apr41_prr_5 (191 KB)
- comms_apr41_PRR_6 (31 KB)
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Earliest Compact Portable(s)
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
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:
| Candid KG-80 (1940) 1R5 1T4 1S5 1S4 |
Marconiphone P17B (1947) X17 W17 ZD17 N17 |
Ever Ready Personal B (1947) (Marconi P17B) DK91 DF91 DAF91 DL92 |
Ever Ready B2 (adds LW) (1950?) DK91 DF91 DAF91 DL92 |
Metz Baby4 (1950) DK91 DF91 DAF91 DL92 |
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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
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
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
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
Candid 1940
KG-80
RCA 1940
45V HT
28-G5
67V HT and 110V AC mains
Dewald 1941
Detrola 1941
Admiral Radio 1941
Emerson 1941
Farnsworth 1941
Fada 1941
Radio 1941 S $
Sentinel 1941
Crosley 1942?
RCA 1947
Airking 1948
67V HT
Automatic Radio Co. 1948
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coat pocket radio
here is another one:
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Is it the Last (in Europe)?
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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