INTRODUCTION
The Wireless Set No.62 is a low power HF transceiver, covering the frequency range of 1.6 to 10 mHz, in two bands. The radio produces AM and CW up to 1 watt. It was designed to replace the WS No.22 radio, and fielded in late WW2. It was used as a portable set, for vehicles, aircraft, and for animal or backpack use. It has a built in power supply and aerial tuner, so is a lot smaller and lighter than a WS No.22 radio. The radio operates from 12 volts DC, and consumes 3 amps on receive, and 5 amps on transmit. The radio is 20 1/4 inches long, 10 1/4 inches high, 12 3/4 inches deep, and weighs 30 pounds. This example was made by PYE in 1945, and was reconditioned in 1955.

WS No.62 Front View

MECHANICAL DESIGN
The radio is in a metal case, similar to a WS No.19 case. It has dimples in each side to give the panels strength. At the left hand end is a rubber aerial mount which can hold a whip aerial. The mount is such that the radio can be used horizontally, or with the radio standing on one end, or mounted on an operators back. There is a small frame on the rear, to allow a shoulder harness to be attached. At the right hand end of the back is a large strap that goes around the waist of the radio carrier. The Mark I version had a metal waist strap, but this was changed in the Mark II version to a flexible strap, so that the radio could fit into a paratroop kitbag for dropping from aircraft. There was also mechanical strengthening incorporated in the Mark II. The case has a gasket along the front edge, and is waterproof for 5 minutes. Each knob has a waterproof gland on each shaft. The inside is tropicalised.

There are two drop cords that provide microphone, headphones, and morse key connection, at the left hand end. Also here is the 2 point DC connection for 12 volts input, and a clamp to hold the cable on. At the right hand end is a double 3 point socket for connection of a frequency calibrator and a remote control. There is a crystal socket at the same end, to allow crystal frequency control.

At the left hand end are 2 large knobs for aerial matching; an aerial tuning control (a roller inductor), and an aerial coupling control (a variable capacitor). These have a lock. There is a window to show the roller inductor position. The aerial is connected to a terminal here, and can match a long wire aerial. Alternatively, with a short wire to the mount, it can match the case mounted whip aerial.

Below these knobs, is the on and off switch, which can select receive only, or transmit as well (ALL ON). Note that the BFO is not on during REC ON (receive only). The BFO heterodyne switch is next to this knob. Then the next knob is the mode switch, which selects RT or NET or CW. To the right of this is the gain control, which is audio control for RT, and RF gain control for NET and CW. The nameplate is below it.

To the left is the large frequency dial, the tuning control, and the band switch. There is a lock for the tuning, which can also select the spot (or flick) frequencies. There is a switch to select the MO (master oscillator) or a crystal. The main dial has 2 spot frequency locks. There is a window to show which lock is selected.

In the center at the top, is a meter. The switch below it can show the 12 volt DC input voltage at LT, the high tension on receive at HTR, and the AGC voltage. It can also show the high tension on transmit at HTS, the drive to the final amplifier, and the aerial current at the AE position.

WS No.62 Top View

Inside the case, there is a conventional aluminium chassis, with 2 shields and the dynamotor box underneath. There is a protective cover over all of this. On top of the chassis, are the valves, the tuning capacitor on the right, and the roller inductor on the left. There are 2 struts in the mid chassis position, and 2 legs at the rear ends of the chassis. Most of the capacitors are in metal tubes, and clamped to the chassis. The front panel has a handle at each end, which protects the knobs.

ELECTRICAL DESIGN
The valves used are 2 and 6 volt English types, and connected in a parallel and series filament combination. It has a standard superheterodyne receiver, and a 1 watt transmitter. It has a dynamotor power supply, but later models were fitted with a transistorised inverter. It has two shortwave bands, from 2 - 4 mHz and 4 - 10 mHz.

The aerial enters the radio, and goes through the transmit current sensor, the roller inductor, and the variable coupling capacitor. It then goes to the grid of the RF amplifier (VP23 or CV1331). There is a tuned circuit in the plate, and it changes depending on the band switch. This is capacitivly coupled to the mixer valve (VP23 or CV1331). The mixer plate circuit uses a 460 kHz IF transformer and couples to the first, second, and third IF transformers and two IF amplifier valves (VP23 or CV1331). This is then coupled to the detector and AGC rectifier valve (HL23DD or CV1306). The audio then goes through the gain control to the audio amplifier valve (PEN25 or CV65). The HF oscillator is a pentode (VP23 or CV1331) and is injected into the mixer screen grid. It can also use a crystal, which has to be 460 kHz above the receive frequency. The receiver is tuned to the desired frequency using the band switch and main tuning. When it is switched to crystal, the main tuning can be peaked.

The transmitter uses three indirectly heated valves, switched on when the mode switch is in the ALL ON position. The triode/pentode mixer valve (ECH35 or CV1347) uses the receiver local oscillator and the BFO to generate the transmit frequency. There are tuned coils in the plate circuit. The BFO is fixed at the IF frequency. The buffer valve is a pentode (EF50 or CV1091) and also has tuned coils in the plate circuit, and an RC circuit to even the drive across the bands. This is capacitor coupled to the PA amplifier valve (QV04/7 or CV309). The plate of the PA is capacitor coupled to the aerial roller inductor and coupling capacitor, and the aerial current sensor. Note that the NET and BFO will only work, when switched to ALL ON.

The microphone connects to a transformer, and then to an amplifier valve (PEN25 or CV65). This then connects to the PA grid to produce AM modulation. In the Mk I radios, the AGC/Detector valve was also part of the microphone circuit. The receiver RF amplifier has no HT during transmit. It acts like a diode and rectifies a small amount of the transmit signal which is used as side tone.

WSNo.62 Underneath View

CARRYING
The manual shows arrangements for carrying the radio in a Jeep, carried on a pack animal, and carried by a soldier. The second soldier carried the 12 volt battery.

WS No.62 Carrying on the Back
Wireless For the Warrior, Vol 2, Louis Meulstee, page W.S.62-21

WS No.62 Case

RESTORATION
The radio was cleaned on the outside. It was then removed from the case, but everything was clean inside. The dynamotor box was unscrewed and opened, and the bearings greased. Power was applied, and it span up and produced the HT voltage correctly.

WS No.62 Dynamotor

WS No.62 Dynamotor

One drop cord was missing, and the other had rotten rubber. One was found in the junk box. Some new (old) cable of the correct diameter with the correct colours was unearthed from the wiring box. The connectors were cleaned. Two new drop cords were made and fitted to the wiring board inside.

WS No.62 Drop Cords

WS No.62 Drop Cord Connections

A power cable was found in the cables box. One of the 12 volt posts on the radio was repaired. Some of the knobs were seized or difficult to turn. They were disassembled and the old grease removed from under the gasket. They were re-greased and re-assembled.

WS No.62 Knob Gland

The dynamotor was installed, but not wired up. A bench power supply was used to provide the 12 volts DC. It was slowly wound up from zero volts. The current appeared to be normal. The valve filament and heater voltages were checked and they all seemed to be correct. A set of headphones were connected. A variable high tension supply was connected, and it was slowly wound up from zero. Noise could be heard and the controls, appeared to work. An aerial was attached and there were good signals on both bands. A signal generator was connected and the sensitivity results were 1.5 micro volts on the lower band and 1.7 micro volts on the upper band (for a 10 dB signal to noise). This indicated that the receiver was operating properly and did not need alignment.

WS No.62 Aerial Sensor

The dynamotor was wired in, and the receiver tested again, but the radio was still working well. A morse key was connected and the WS No.62 was turned to transmit. When the filaments had heated, the key was pressed, and there was an indication on the HTS meter position and the DRIVE meter position. A test set type FT1 was connected, and the aerial tuning and coupling controls adjusted, until there was 1 watt showing on the FT1. However, there was very little showing on the meter in the AE position. The meter drive box was removed and tested. This is located behind the roller inductor. The parts were replaced one by one, but there was still no change, the AE reading was still very low. The FT1 meter was removed and a DA-43/U watt meter was used. This allowed series capacitors to be inserted, and the input impedance to be changed. The best result was with a 6 ohm reading and no capacitance. The watt meter still read 1 watt, but the WS No.62 meter now gave a 75% AE meter reading, and adjusting the aerial tuning and coupling was now much easier. The manual recommends 10 ohms and 60 pF for a transmitter load. The meter drive box was reassembled with its original components.

WS No.62 Aerial Current for 40, 20, 10, 6 ohms dummy load

DA-43 Dummy Load (set for 6 ohms)

FT-1 Dummy Load (fixed at 50 ohms)

After about 10 minutes on transmit, the drive began to fade away and the output power reduced. A capacitor was found to be getting hot. It was replaced and this fixed the fault.

PERIPHERALS
The radio normally used a combined microphone and headset.

WS No.62 Microphone

There was also a morse key.

WS No.62 Morse Key

There was a remote control called a Type L. This was connected to the radio using the 3 point plug for power. It also used the drop cord for the microphone and headphone connection. It used a different microphone and headphones.

WS No.62 Type L

WSNo.62 Headphones

WSNo.62 Microphone

CONCLUSION
The radio is easy to use. The receiver is sensitive, and the whip aerial can be tuned quickly. The only problem I found was attempting to tune in CW and SSB, and then realizing that the transmitter had to be turned ON, to do so. Then I had to wait 20 seconds for the transmit BFO to warm up. SSB required juggling the BFO, RF gain and tuning controls to resolve the signal properly. The radio is heavy to carry, but not impossible. The radio was used as a backpack on 3590 Kcs AM for the WW2 NET at the May 2021 Field Day.

WSNo.62 In use as a Backpack

REFERENCES
PYE Wireless Set 62, General Description

Wireless Set No.62, Working Instructions, ZA27690, October 1945

Wireless For the Warrior, Vol 2, Louis Meulstee, page W.S.62-21

WSNo.62 Circuit Mk I

WSNo.62 Circuit Mk II

Copyright
Ray Robinson

INDEX