AWA Radiolette

This is an odd radio in that the chassis is stamped 619TX but that number relates to a battery set.

This radio is massive and is part of a series of top of the line radios from AWA. They were available in tabletop with 8 inch speaker, or console with 12 inch speaker. The tabletop version is 70 cm long and weighs 20 kg.

It's seven bands with a six valve line-up plus magic eye. Other than MW, the Short Wave bands are band spread for easier tuning.

Restoration

The radio was given to me free in Bendigo some years ago. The caveat was it was in bits. The cabinet had been sanded and the veneer had been sanded through in places.

It was generally in good condition, but very dusty, read dirty. The person who gave it to me admitted he had got bored with it.

It took many hours to get the cabinet back to reasonable condition. I then painted the trim and shellacked the cabinet. I'm not that happy with the result as you can see where the veneer was worn away despite me trying to replicate the grain.

Surprisingly the chassis wasn't so hard. I recapped it a selective way. Leaving out the next to useless Short Wave bands. Similarly, the alignment was only completed on the MW band.

Reassembly was straight forward if puzzling at times.

Magic eye

The magic eye was dead. The HRSA supplied a brand new one.

The difficulty was the original 6U5 is a 6 pin tube, the new 6U5G is an Octal. They are electrically identical. However, the pins are different. How hard can it be to rewire...

I wrote all the old connections on a sheet of paper with the colour of the wires.

I then looked up the changes on the internet. Differnt websites gave different wiring that varied with the Philips data books I have.

Out of pure curiousity I asked AI. It didn't even give the correct wiring for the filament that is 6.3 volts. AI was putting 250 volts across the filament!

In the end with the multimeter and some guess work from a similar AWA set I managed to get it right.

The Magic Eye works beautifuly.

Conclusion

First off, these radios don't sell for more than $100 restored.

They are a bit of nightmare to work on, and alignment is a 50 step process.

Having said that they are a labour of love and MW performs extremely well. If you have the space, the time, and patience of a saint they will reward with excellent performance for a radio of the time,

AI gets it wrong again!

Octal pin wiring should be as follows:

Pin 1 - Not connected
Pin 2 - Heater
Pin 3 - Anode
Pin 4 - Target
Pin 5 - Grid
Pin 6 - -
Pin 7 - Heater
Pin 8 - Cathode

design a circuit for the 6u5g octal pins from the 6u5 tube

The 6U5G is an octal-based "magic eye" tuning indicator tube. The following circuit design will allow the tube to operate as a basic visual indicator.
6U5G Octal Pinout
The base connections are as follows, viewed from the bottom of the socket:
Pin 1: NC (No Connection) or internally connected to Pin 6 on some variants
Pin 2: Ray Control Electrode (Grid of the internal triode)
Pin 3: NC (No Connection) / NP (No Pin)
Pin 4: Target (Anode of the indicator section)
Pin 5: Cathode (Common cathode for both triode and indicator)
Pin 6: Heater / Filament
Pin 7: NC (No Connection) / Key (Locating pin)
Pin 8: Heater / Filament
Basic Operating Circuit Design
This is a simple circuit to power the 6U5G and demonstrate its function. It requires two power supplies: a low-voltage AC/DC supply for the heater and a high-voltage DC supply for the plate and target.
Components Required:
V1: 6U5G tube
R1 (Anode Load Resistor): 1.0 MΩ (1 megohm) resistor
R2 (Grid Resistor): A potentiometer (e.g., 1 MΩ) for variable control voltage, or a fixed resistor to connect to an AVC line
C1 (Filter Capacitor): (Optional, for smoothing the control voltage)
Power Supply 1 (Heater): 6.3V AC or DC, 0.3A
Power Supply 2 (HT/B+): 100-250V DC (around 250V is typical for radio use)
Circuit Connections:
Heater Supply: Connect the 6.3V supply to Pin 6 and Pin 8. The heater should be powered whenever the tube is in use.
High Tension (HT) Supply:
Connect the negative terminal (ground/chassis) of the HT supply to Pin 5 (Cathode).
Connect the positive terminal (B+) to one end of the 1 MΩ anode load resistor (R1).
Connect the other end of R1 to Pin 4 (Target). The target will glow green.
Also, connect the positive terminal (B+) directly to the triode anode internally connected to the deflector rod. (This internal connection usually means only one B+ connection via R1 to pin 4 is needed).
Control Grid Input:
The control grid is Pin 2. This pin is used to apply a negative DC voltage (AVC voltage in a radio) to change the shadow angle of the "eye".
Connect a variable resistor (potentiometer R2) between the cathode (Pin 5) and a negative voltage source or the AVC line of a radio receiver to adjust the shadow width.
A voltage of 0V on the grid results in a 90° shadow angle, while a negative bias of around -22V (at 250V target voltage) will fully close the eye.

design a circuit for the substitution of 6u5g octal pins from the 6u5 6 pin tube

The 6U5 (with a 6-pin base) and the 6U5G (with an octal 8-pin base) are electrically equivalent tubes; the only difference is their physical base and pinout. To substitute the 6U5G into a circuit designed for the 6U5, or vice-versa, you need to use a tube socket adapter that maps the electrical connections correctly.
Pinout Mapping
The substitution requires connecting the corresponding elements (heater, cathode, grid, target) from the 6-pin base to the correct pins on the 8-pin base. The following table details the internal connections:
Element 6U5 (6-pin UX Base) Pin 6U5G (8-pin Octal Base) Pin
Heater Pin 1, Pin 6 Pin 6, Pin 8
Cathode Pin 4 Pin 5
Control Grid Pin 3 Pin 2
Target (Anode) Pin 2 Pin 4
Internal Connection Pin 5 (connected to Pin 4, Cathode) Pin 5 (connected to Pin 5, Cathode)
No Connection (NC) - Pin 1, Pin 3, Pin 7
Note: Pin numbers are typically viewed from the bottom of the tube base or socket.
Circuit Adapter Design
You can build a simple adapter using a 6-pin tube socket and an 8-pin tube base (e.g., harvested from a junk octal tube, or a chassis-mount socket wired to a tube base plug).
To wire the adapter, connect the corresponding pins point-to-point:
Connect the Heater pins: 6-pin Pin 1 to 8-pin Pin 6, and 6-pin Pin 6 to 8-pin Pin 8.
Connect the Cathode pins: 6-pin Pin 4 to 8-pin Pin 5.
Connect the Control Grid pins: 6-pin Pin 3 to 8-pin Pin 2.
Connect the Target (Anode) pins: 6-pin Pin 2 to 8-pin Pin 4.
Ensure Pin 5 on the 6-pin base (which is internally connected to the cathode) is connected to Pin 5 on the 8-pin base (cathode).
The unused pins on the octal base (Pins 1, 3, 7) should be left floating (not connected to anything).
This adapter ensures the 6U5G tube receives all necessary voltages and signals from a circuit designed for the 6U5 without requiring any modification to the original equipment's wiring.

Page last updated - July 2025