More old wireless parts (7)

The contents of yet another junk box

 As it says on the label, an HF choke made by Lissen in the late 1920s or early 1930s. This helps to keep radio frequency currents where they belong.

Here's an interstage transformer with quite a high step-up ratio of 5:1 made by Varley with the trade name "NICLET" and manufactured circa 1933. A ratio of 5/1 is a rather loose term as it's really 1/5.


 Below is an upmarket coupling unit for setting two coils apart. This was done usually for controlling reaction or positive feedback. This was a feature used in the UK to increase the gain of a receiver. In the USA this technique wasn't as common because US manufacturers didn't have to pay Mr.Marconi's tax on each receiver valve so just added extra valves to step up receiver gain.

An early "Post Office" style switch which would have been used for switching wavebands.


 Here's a radio dial. Note that it's marked in wavelength with the old style nomenclature with LW meaning what it does today but medium waves were known as "Short Waves".

A little later and descriptions became standardized as Long, Medium and Short weavebands. About this time international organisations attempted to fix broadcasting standards and frequency allocations. After a couple of attempts at convincing broadcasters to toe the line dials were able to meaningfully show station names. Before this a list of stations versus dial readings had to be kept. In fact some radio sets included a chart fixed to the case on which could be pencilled station names. See the Halcyon. Before dials showed wavelengths they merely had a scale 0-180 degrees. Below is an echo of this where you can see a logging scale marked 0-100.

This scale says it was made by "MONIX" and has a provisional patent number 16523/31 presumably indicating it was made in 1931.

Below is a solid dielectric tuning condenser made by POLAR. It's value is marked 0.0003 which is 300pF. This type of condenser was used for reaction tuning and is much more lossy (and cheaper to make) than the air-spaced condensers used for tuning.


This view shows that it has two sets of stator plates coupled by a rotor set which can be grounded if necessary to reduce hand capacity. Setting reaction was critical and sometimes quite tricky as, once perfectly adjusted, moving one's hand away from the control upset the setting. It was known as a "Differential Reaction Condenser".



Two views below of a good quality tuning condenser, using aluminium and ebonite, made by Ormond with code numbers, Registered Design 719828 and Patent Number 19262215.


The knob was also made by Ormond and 180 indicates maximum capacity or lowest frequency. The vanes are have a logarithmic shape and therefore linear frequency response.


The rear view of a solid dielectric tuning condenser made by Ormond. The spring connects the rotor to the terminal thus avoiding crackles.


Another reaction condenser. This one was made by Telsen in bakelite and has their code W354 and cost 2/6d in 1930.


Below is a POLAR tuning condenser. You can see the ball bearings indicating a reasonably good quality component.


Another bakelite tuning condenser made by FORMO and carrying the brand name "FORMO-DENSER". Tuning was effected by twisting the centre knob and setting the knurled nut to fix the tuning. This is a Type J and can be varied from a min of 0.000025 to a max of 0.0003 (25pF to 300pF). Units are seldom given as sales were aimed at amateur set builders.


Below is a fixed resistor with screw terminals for mounting in a "breadboard" constructed set. Some came without terminals and were known as "cartridge" resistors for clipping into a holder carrying screw terminals. Marked "GRID LEAK" it has the patent number 252759.


Another TELSEN reaction condenser, it's three terminals showing it's a differential type marked ".0001" or 100pF. This one, coded W353 sold for 2/6d in 1930 although I suspect this example is slightly later as it has dispensed with the wire connection to the rotor.


A later addition to the junk box. A Dubillier Type 691 mica condenser marked with the RAF code number 10A/8496 and value 0.01uF.


Back a decade and an example of a Dubilier Type 9200 wet electrolytic condenser, marked 0.05uF at 300 volts DC.

Note the screw formed in the base for mounting on a socket on a baseboard.


Four examples of a switch designed for disconnecting one's aerial from the radio set. Three terminals are provided so that an earth wire carried away current from a near lightning strike (or very heavy static charge). When the switch was in the normal reception position the spark gap would limit any high voltage to maybe 5000 volts or so. The setting must have been adjustable as the second example has a much greater spark gap?


And below is the box carrying a suitable warning. The switches were made by Ashley Wireless Telephone Company of Finch Place, London Road, Liverpool. I think this area off London Road was destroyed in WW2 bombings.


Here's a product looking for a market!! Just in case you had rising damp stretching up to your picture rail you could safely use these pushpins to insulate your aerial.

ELECTRON insulator pins. Only one pin remains in the box so someone must have made use of them....



Below is an early semiconductor diode called a Westector. The W6 and similar devices were used as detectors in place of diode valves before poit contact germanium types were made. The Westector uses a row of copper oxide coated beads to provide rudimentary rectification of small AC currents.


Would a W6 function well in a crystal set I wonder? Must try it sometime....


Finally, wrapped in a little cotton bag is this roll of string. The TITAN Line was for restringing the cord in a wireless set. Lot's of guarantee for this Scottish product...


Return to Reception or

if you're really hooked on old things look here for more