Pictures of my 1920s wireless
and scans of magazine articles or adverts about some of its components
with grateful thanks to the excellent

This page 01/12/2023. To be updated once I've carried out more restoration/alterations
06/01/2024. Updated the circuit diagram - HT to valves (V4 now fed from HT2), rheostats for heaters

Drawing of the physical layout of my wireless
4-valve-layout.jpg - 142Kb

Circuit diagram of the above. This will need to be revised (rheostats for heaters)
modified-cct.jpg - 141Kb

Circuit diagram revised - HT2 to speaker/V4, HT1 to AJS choke, rheostats for heaters)
4valve-cct-B.jpg - 129Kb

A circuit I found where my wireless matches the first stages (V1, V2) of this design
four-valve-with-ri-unit-wireless-world-feb-1925.jpg - 72Kb

The set is built into a cabinet which I think originally housed a gramophone
wireless-1.jpg - 59Kb

Front panel
wireless-1a.jpg - 67Kb

Top left, between the 300pF variable and DE6 is a space for the (under restoration) AJS choke
wireless-2.jpg - 59Kb

Adverts for the "variometer"
ri-tuning-inductor-1.jpg - 139Kb

vario-advert.jpg - 47Kb

The beautifully engineered RI variometer / tuning inductor
Note the square cross-section, wiring used throughout the set

variometer.jpg - 57Kb

Advert for the anode reactance unit
ri-anode-reactance.jpg - 44Kb

Benjamin valve holder
benjamin.jpg - 67Kb

DER valve (V1, V2, V3)
der.jpg - 27Kb

DE6 valve (V4)
de6a.jpg - 37Kb

Another photo of the DE6 where the markings D.E.6 and 1.8v are visible
de6b.jpg - 40Kb

Marconi-Osram DER and DE6 valve data
der-de6-curves-1.jpg - 175Kb

der-de6-curves-2.jpg - 182Kb

der-de6-curves-3.jpg - 72Kb

Advert for the AJS choke, grid leak resistor, condensers
AJSchoke.jpg - 17Kb

Another advert for the AJS choke with more detail
ajs-choke-1st-stage.jpg - 44Kb

The choke was open circuit. I removed all the 42swg wire to reveal the cardboard(?) former
but weighed it before and after so I could work out (approximately) the length of wire

ajs-coil-former.jpg - 30Kb

Replacement coil (approx 11,500 turns of 42 swg ECW) wound onto a Delrin former
Kapton tape was placed on the turns at intervals and on the completed coil
The iron laminations were cleaned up and, as shown, will be inserted into the coil

ajs-choke.jpg - 32Kb

Re-assembled choke (but may have to be dismantled if the inductance is too high)
AJS choke E.jpg - 32Kb

Showing the cleaned-up condenser. Grid leak resistor to be fitted into the clips
AJS choke F.jpg - 33Kb

Advert for the Ferranti AF3 transformer
ferranti-af3-ad.jpg - 19Kb

My transformer. Again note the square cross-section, uninsulated wire
From articles I have read this was very common in the 1920s

ferranti-af3.JPG - 57Kb

An article from the BVWS (British Vintage Wireless Society) Bulletin. Volume 9, Number 3
with detail about the design, construction and specifications of the Ferranti AF3

Issue_09_03_p52.jpg - 250Kb
Issue_09_03_p53.jpg - 271Kb
Issue_09_03_p54.jpg - 75Kb
Grid bias battery. I managed to removed the original cells from the cardboard sleeve
Left is the replacement battery I made

grid bias.jpg - 56Kb

Brackets to hold the grid bias battery
bias-battery-brackets.JPG - 51Kb

2Mohm grid leak resistor. Original measures approximately 5Mohm
2 x 1Mohm 0.5W carbon film fitted into the original tube.

grid leak.jpg - 30Kb

A lash-up of a voltage multiplier. To be fed with 15v AC, 5 x 1N4007, 5 x 100uF 100V
The 10k 2W resistors were fitted to simulate current drawn by the anodes once the wireless is powered up
2 x 10k in series (= 20k) gave 18.5v, 36.6v, 53.9v, 71.2v, 87.5v at 4.375 mA
1 x 10k gave 17.9v, 34.6v, 49.5v, 64.5v, 78.4v at 7.84 mA
I plan to use the 5th voltage for the DE6, 4th voltage for the DER valves

high volts.jpg - 44Kb

The original 2 volt battery for heaters. Not recoverable! I plan to replace it with a 2v 5Ah Cyclon cell
willard-2v-a.jpg - 62Kb

willard-2v-b.jpg - 41Kb

A label with the 2v battery showing it had been recharged(?) by Danson's, Radio House, Fishergate Hill, Preston
battery-recharge.jpg - 31Kb

Ormond 300pF variable "condenser"
ormond-300pf.JPG - 42Kb

Ormond 1000pF variable "condenser"
ormond-1000pf.JPG - 44Kb

CE Precision grid leak resistor (approx 2.2Mohm) and Dubilier Mica Condenser (approx 340pF)
ce-grid-leak-dubilier-c.jpg - 55Kb

A basic pull-for-on switch. I plan to bypass this - the contacts are poor and may not restore well.
Also I need to re-wire the LT+ wiring to incorporate rheostats for each valve to control heater voltages.

on-off-switch.JPG - 23Kb

My BTH horn loudspeaker. 14 inch diameter
bth-horn-speaker.jpg - 35Kb

The 2.2k ohm driver of the BTH speaker. This appears to have permanent magnets and the wires are colour coded
red and black. Red goes to HT+. Connecting the wrong way round risks de-magnetising the magnets

bth-speaker-2k.jpg - 47Kb

I also have a "Browns" head receivers for wireless, Type F, 4000 ohms
but I think these are more suited to a wireless receiver with a lower volume output

Browns_TypeF_Box.JPG - 77Kb

Browns_TypeF_Headphones.JPG - 54Kb