This old radio set is typical of a working man's receiver from the early 1930s. Remember that there was a depression around that time. Most families had very little money and the price of a ready made receiver was several times the average weekly wage.
There were dozens of magazines aimed at informing the public how the man of the house could make his own receiver and, no doubt, this particular set had its origins in a publicatiuon such as "Practical Wireless".
I should say that this set uses a ready-made cabinet as the top bearer for the nicely figured ebonite front panel is dovetailed into the sides, and you'd think anyone making a case from scratch would probably not bother with this detail.
The set originally had three valves and is contructed from a miscellaney of parts. Note the two transformers. The brown bakelite-cased one is from around 1930, but the other on the right from much earlier, around 1923, I should say. The tuning condenser is quite an early type and has a very pronounced shape to ensure fairly linear tuning overr the medium waveband. Resistors and fixed condensers were also pretty old when the set was constructed.
Unfortunately, several parts are missing, in particular the tuning coils and of course the valves.
Most sets of this vintage required what was called "reaction" which is another way of saying adding "positive feedback". Increasing the amount of reaction increased the set's overall gain, until at some point the whole thing would break into oscillation and howl. Because nearly everyone used a long wire aerial, up to the legal limit of 100 feet, which served equally well as a transmitting aerial, when a set broke into oscillation it would cause all other sets in the neighbourhood to howl in sympathy. Probably the first instance of anti-social behaviour.
This set uses a crude method of reaction control and probably caused its near neighbours much aggravation.
The set was given to me by my pal Bob Norman.
I bet not too many remember the
significance of "connect the instrument to the lighting circuit",
when this practice meant a string of two way adaptors dangling
from the light socket... iron, toaster, radio etc... and the extra
thick wire across the fuse.
Just
an empty box alas, but a perfect interior instruction label and
a decent Post Master General type approval badge.
The instruction card is quite interesting. First one must ask why the aerial emerges from the front of the house rather than the more discrete rear? Presumably possession of a wireless aerial in those distant days was considered a status symbol?
Although the aerial would be visible the receiver would not, and it's worth pointing out that this humble crystal set was considerably cheaper than those sets currently available at the time employing valves, which could cost as much as a years wages of an ordinary worker. Not that anyone would ever spend a years wages on a receiver but you get the drift.
Having shelled out more than two weeks grocery money on one of these crystal sets, and coughed up for a license (well you did put up this 100 foot advert for your receiver in your front garden didn't you!), the intial mastering of the operation of a crystal set was quite a technical achievement. Basically one fiddled simultaneously with a cats whisker and a tuning knob until a sort of ethereal hubub of voices was heard. Getting the crystal to work was a bit hit and miss... note the comment about giving up and trying the spare one! There were so many hurdles.. was the aerial connected properly? Did the crystal work? Was the cats whisker OK, and in contact with a suitable point on the uncertain crystal? Were the headphones working and connected correctly?
Of course, once initial success was behind one, in retrospect, it all seemed easy.
Tuning in this model was carried out with a "handle" that connected to tappings on a coil, which in conjunction with the aerial, resonated roughly at the frequency of the desired station, and once adjusted resulted in one station becoming slightly louder than lots of others. Daytime listening was a lot different than night time listening. During the day one would really only be able to hear one or two stations but, at night, when the sun went down, the airwaves came alive with dozens of strange foreign voices, often turning into English at pre-arranged times, as the continental stations were very aware of their avid British listeners and published programmes to suit.
Because of the very low average level of technical skills in wireless reception in the early 1920s, tuning a station was generally not an easy matter. First one had to have constructed a suitable aerial, a device covered by government legislation dictating that it was not to exceed 100 feet from distant tip to receiver terminal. Secondly, for decent reception a good earth connection had also to be made and, if one listened to the proper authorities and advertisers, it was pretty well essential to include a safety switch to minimise electrocution from lightning. There were also articles on making provision for getting the wire into one's house, using suitable porcelain insulators and the like. Next came the intricasies of connecting up the aerial and earth wires and headphones. In fact there were lots of pitfalls on the way to settling down and listening in. Once an enthusiast was successful and had demonstrated his prowess to his own family, no doubt he became a consultant to his neighbours.
The use of a loudspeaker in those early days was rare, and most listeners used headphones. It's worth pointing out that these headphones were very different to modern types. Crystal set headphones were high resistance instruments that would offer a relatively low loading on the simple crystal set circuitry (equals loud reception). Note that the instruction label above mentions the fact that two pairs of headphones can be used but implicit in the directions for their connection is the fact that these are wired in series not in parallel. Modern headphones are useless for crystal set use because they have a very low impedance. This would result in only a tiny fraction of the available radio signal getting to the listeners ear (equals very quiet reception), and anyone experimenting with an old crstal set would be very disappointed with the results unless high impedance headphones were used.
When
I bought this funny looking lamp from a junk dealer at Wimborne
Market I thought it was a Miners' Lamp but I've now discovered
it was used in sewers to detect gas. I don't know why this is
needed as I imagined that all sewers are filled with gas anyway
but presumably it's used as a means of letting the chaps that
visit such places that the level of gas is too high for safety?
The Spiralarm has the maker's name J.H.NAYLOR, WIGAN and has Type "S" marked on the label. I understand the Type "M" was used in mines and has a slightly different characteristic so that the gas type and percentage that it detects is different.
The patent number is given on the label as 352267.
http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=GB352267&F=0
reveals the patent details, from which can be seen that the design dates to 1931. I should think that my model is rather later than that, but I shall leave that to experts in the matter.
Operation is relatively simple. In the presence of an inflammable gas in the surrounding air the flame gets bigger and heats a bimetal strip which operates a set of contacts, turning on a lamp in the lower compartment.
The materials from which the lamp is chiefly constructed are aluminium (or one of its more robust alloys), and brass.
As you can see a spare wick is looped around the base.. in fact it's possible that the lamp has never been used and the original? wick never fitted.
Clipped onto the base is a mirror made from chrome plated steel.
A knurled brass adjuster is located underneath the base. This presumably to enable the flame height to be preset and to allow for wick to be raised when it's burned down.
An old REVO electric
fan from the early 1930s I think?It came fitted with an old two-pin 2-amp plug commonly used before WW2 and, on the underside, the makers' name "Revo" Model? "12" and Serial Number 62384.
It bears a marking for 200 to 220 volts 50 Cycles but etched next to this is "240 volts".
I haven't plugged it in because the wiring is a bit too brittle for my liking.
I think there are plenty of Electric Fan followers out there so maybe one would care to comment on the Revo's true age?
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