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Old 22nd Jul 2019, 9:43 am   #1
Walkers-Bay
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Default Marconiphone P20B radio.

Good morning and greetings from New Zealand.

First time on this forum and please excuse my lack of knowledge.

What brings me here is the above radio, a marconiphone p20b.
How this came into my possession was at work today. The company i weld for has a rubbish skip business and i found this in a house lot of rubbish!

So, I've found was this little radio, in its card board box, with instructions, warranty card and a letter of thank you from the factory. Also a receipt of purchase and all tucked in a little envelope with the factory name, post address and stamp etc.
As it turns out it was purchased new from Metvan Simpson LTD of Dundee and went to Monifieth, Angus, Scotland on the 9-9-1949. It has since found it way to Invercargill, New Zealand. It looks like it may have been to Christchruch (nz) camping in 1958 by a receipt for a campsite also in the box.

I have done a little searching and have found a little information about these mostly around how to build a battery for them. I little bit about the repair of the valves.

What i would like to know is are these common radios, were they the kind of radio every working class man had in his lunch bag?
Was it worth saving from the dump?

Is this the kind of forum that i can upload photos straight onto or do i need to use tiny pics?

Thank you

Owen
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Old 22nd Jul 2019, 9:48 am   #2
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Default Re: Marconiphone P20B radio.

Hello and welcome to the forums.

Service information for this radio is available here:-

https://www.service-data.com/section.php/4646/1/p20b

If you upload large image files to the forums they will automatically be resized.
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Old 22nd Jul 2019, 10:29 am   #3
Lloyd 1985
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Default Re: Marconiphone P20B radio.

Very much worth saving from the dump, especially in its box with its paperwork! I have one of these radios, bought for me by my parents as a 21’st birthday present. Replaced a few old wax capacitors, have it some power and it works well.

Regards
Lloyd
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Old 22nd Jul 2019, 10:37 am   #4
Mike. Watterson
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Default Re: Marconiphone P20B radio.

They were not common in the UK and 1947 may have been the peak there. This is a 1948 model. The earlier 1947 model (also HMV badged and same chassis used in Ever Ready Model B) had no LW. Vidor and Romac also made Personal radios, much later named Lunch box models. The design concept was from RCA and first models sold by many USA makers in USA before they entered WWII in Dec 1941.

Marconi / HMV were EMI labels. They never made any more Personal sets after this model range till transistors and ferrite rods were available.
As a rule of thumb, a 12" diameter is about the minimum loop to be equivalent to a decent ferrite rod. All the early Personal used too small loops.

Issues
1) Expense. People could only afford one radio, so wanted a good one.
2) The loop aerial in the lid gets about 1/3rd to 1/4 of the signal of ordinary valve. So poor reception.
3) Battery life very poor due to small battery pack.
4) Sound poor due to miniature speaker and only 67.5V HT, giving an end point of about 48V, the HT cells couldn't be as used up as a 90V pack.
5) Poor performance generally due to small aerial, smaller IFTs and lower HT.

They cost as much or more to make as regular battery valve set.
People claim the perspex cased Pye Personal (1948) was withdrawn because of an alleged similarity between the Sun logo and the Japanese flag.
However the battery fitting was too tight and performance was poor. My theory is that it was withdrawn because it wasn't very good compared to Pye's other very high quality sets:

https://www.radiomuseum.org/r/pye_m78f_m_78_f.html

Better Pye Battery sets:
1946: https://www.radiomuseum.org/r/pye_l75b_l_75_b.html
1949 https://www.radiomuseum.org/r/pye_new_baby_q_79b79.html
https://www.radiomuseum.org/r/pye_p27ubq_p_27_ub.html
1950 https://www.radiomuseum.org/r/pye_p29ubqp_29_ub.html
(very many after 1949)
Pye and Ever Ready never made other Personal radios after 1949 till transistors were available.


The RCA BP10 was the first designed, but second to market.
https://www.radiomuseum.org/forum/rc...article.html#3

I have a version of the P20B, the older one same as Ever Ready, the Ever Ready B and B2, a couple of Motorola models, a Romac and the RCA BP10. Performance and battery life is terrible.
The battery pack can be easily made with 1 off Alkaline D cell and EIGHT PP3 batteries. Don't fuss that the PP3's make 72V as they will run down to 48V (the end point). The reason for the 67.5V was to fit 45 layer cells for HT and one or two F cells for LT (not sure how many).
The Personal Radio was basically gone by 1950 in the UK, though some compact sets using 2 x D cells or B141 pack were made after 1953 using 25mA valves (twice LT life) for UK by Vidor, Philips and Roberts. It continued to be made and sold in USA and Japan till transistors replaced it between 1956 and 1958. They miniaturised further by using hearing aid and/or military sub-miniature valves often with a single B7G type for the speaker if not headphone only. The last Japanese models used polycon miniature tuners, miniature volume control and smaller IFTs. All these later USA and Japan sets used 45V or 67.5V HT packs like elongated PP3s with a single torch cell (C or D) for LT.

Mostly rich people had them as second sets. A UK working class man would have had one cheap Bakelite mains model, probably via HP or rental. The 20% to 15% (1948 to 1950) with no mains electricity would ether have bought / HP / rented a battery table model (still some with Lead Acid till 1950 for lower running costs) or larger portable battery model. The Attaché type sets in the 1950s were often for 2nd sets for better off teens / young adults, or for car / boat trips and picnics. Though some did buy them as 1st sets in early 1950s not realising the low Ever Ready & Vidor prices was because they had most of the market for the batteries! A valve battery set for your main model in 1935 to 1960 if you had mains was a false economy!
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Old 22nd Jul 2019, 11:39 am   #5
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Default Re: Marconiphone P20B radio.

Thank you for the replies.
I've taken some photos of the radio and paper work.
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Old 22nd Jul 2019, 12:21 pm   #6
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Default Re: Marconiphone P20B radio.

A nice set and well worth saving even if you only keep it as a non functional decorative item.

You do find all sorts of odd radios turning up in Aus and NZ, brought by migrants from many countries but obviously mostly from the UK and Ireland.

Mike is right, these very small battery valve sets didn't sell well in Britain in the 50s because they were a luxury that most people couldn't afford. They were more popular in the US where disposable incomes were higher.
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Old 22nd Jul 2019, 2:35 pm   #7
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Default Re: Marconiphone P20B radio.

Lovely little set

I have a couple including one in i's box and I have the X version P20BX which I had sort of assumed was for Export.

The P20B uses a combined HT/LT battery B114 where as the X version uses a seperate HT Battery B101 and a U2 for LT.

It works respectably well but it's a bit shrill just like the early "Soap Dish" Transistor radios.

Despite poor sales they turn up suprisingly often I suspect in part due their small size, they just get put away to be discovered many decades later.

Cheers

Mike T
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Old 22nd Jul 2019, 5:38 pm   #8
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Default Re: Marconiphone P20B radio.

"X version uses a seperate HT Battery B101 and a U2 for LT." Because that was the original USA battery arrangement in 1941 and the B101 US equivalent widely available. Many people were suspicious of the Ever Ready Combo battery packs, though some models from other UK makers (Pilot, Pye, Ultra) did use combo packs that were also used in the USA. The previous Marconi/HMV/EMI model, MW only basically was the same chassis as the Ever Ready B (maybe all Plessey made?), so used the Ever Ready specific B114.
X probably did mean export, at least to Europe anyway.
Germany only ever did one such model, the Metz Baby. The Personal sets with 50mA B7G valves in the UK were 1946 (Romac) to 1949. There would only have been remaindered stock in the 1950s.
The later slightly larger 25mA sets DK96, DF96, DAF96, DL96 in mid to late 1950s with either plastic or leather/leatherette from KB (MP151), Vidor (replaced following year with transistors in the same case), Roberts R77 and the Philips using 2 x D cells and B101 (4x LT life of the original Personals) were more successful due to ferrite rod aerials, x4 LT life, better speakers etc.

The 1946 to 1949 UK Personals (copies of USA 1941 designs) are nice collectables. Only the last models (1948 & 1949) had LW, though it needed an even better signal. Ever Ready added a switch and little more than a loading coil and a capacitor to make the B2 add LW to B. The P20B is better designed chassis and proper dual band design.

A couple of models did have SW rather than LW, though it can't have been sensitive!
HEA of Austria sold three versions of the Romac in 1950/1951 branded Gipsy. That seems to be the last.

The Romac used the carry strap as a loop aerial. Unfortunately its design is deficient on the IF. It too used a D Cell and a B101. The B101 about x4 life of the D cell. The last version had mains dock you simply set the radio on.
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Old 22nd Jul 2019, 8:00 pm   #9
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Default Re: Marconiphone P20B radio.

These are a design marvel to have got so much into such a little space. They did work and quite well in the day, but not so good compared to other considerably larger plain looking wooden box radios.
Well worth preserving.

Mike
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Old 24th Jul 2019, 10:25 am   #10
Walkers-Bay
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Default Re: Marconiphone P20B radio.

Thank you very much for the information.
I've had a good look over it and it appears the rear cover has been damaged about the hinge and comes away from the rivets. There is also a broken valve.
However for having being 60 years old found in a rubbish skip I think its faired well.
I'm not entirely sure what I will do with it now but it won't find it's way to the refuse again.
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Old 24th Jul 2019, 10:58 am   #11
Mike. Watterson
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Default Re: Marconiphone P20B radio.

The valve is easily replaced, the audio transformer not. Thus the paper caps need replaced before applying power.
I've made the power socket from cut up coffee tin and marge tub plastic. The box is easy to do from cereal packet card. The appearance is best laser printed and glued on the card before cutting, using the white stick paper glues though ink jet works if sprayed with 3 light coats of car acrylic varnish top coat (or similar hobby spray, not PU lacquer).

I've also used a loop and signal generator with MP3s to feed MW as we only have night time stations from UK and Continental Europe. We do have daytime LW, but the loop is so small the reception is the poorest of any long wave radio I have except the Ever Ready B2 or Romac.
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Old 24th Jul 2019, 5:42 pm   #12
Leon Crampin
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Default Re: Marconiphone P20B radio.

I have a P20B and can confirm that the LW performance is poor. I suspect this is because the fitted loop aerial's inductance enables it to tune only the MW band with a suitable resonating capacitor. There is a loading coil added for LW to increase the total inductance - with no other change to the loop. So, the signal pickup on LW is consequently very poor.

Other than obvious capacitors, I found that the Dubilier 1/4W carbon rod resistors on this set were in a bad state. An important one to check is the 1k Ohm bias resistor for the output stage in the HT negative line, which is easily accessible.

Cute little sets though.

Leon.
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