I have a "Sterling" branded radio, apparently manufactured in Western Australia. Does anyone have any info at all in regards this make?

It uses an "80" rectifier and a "42" output valve.

What other valves does it have?

The likes of 6A7,6D6,85 I’ll bet.
So 1930’s, possibly pre-superhet, probably has a field coil speaker, and likely fun to get going
Do you know about, and/or have checked out the usual sites with schematics?

It looks like at least some models are in an AORSM:
http://www.hws.org.au/RadioHistory/manufacturers/Sterling.htm

All the Sterling schematics in the AORSM are for battery sets (volume 1, pages 270 to 273).

Mingays Radio Trade Annual & Service Manual for 1939, pages 346 & 347, has two Sterling schematics for four models from 1935. The S5A & S5M are a console and a mantel respectively. Valve line-up: EK1, AF2, 6B7, 42 & 80. Models 10C & 12C valve line-up: 6C6, 6D6, 6C6, 42 & 80. I.F. for both is 456 kHz.

According to Arthur Courtney's HRSA Radio Brands list, Sterling were a Sydney based firm.

Update: Sterling Radio Limited were a very short lived radio firm operating roughly between 1934 & 1937. They were situated at 539 Elizabeth St., Sydney & 29-37 Abercrombie St., Chippendale.

A very nice-looking radio! Hopefully you can get it going.

Here are some photos of the rear of the set.

The full valve compliment is....80, 42, 6D6, 6C6
It's a superhet, and a PM speaker
I've re-capped and replaced several dodgy resistors.
The radio works, but performance is not good, audio output is low and distorts at much above a whisper.
B+ rail is around 240 v which seems ok. 220 v on anode of output valve, similar on screen grid.

Thanks mono TV.....it sounds like a 10c or 12 c according to valves used.

I've got a bit of an issue with it, where would I be able to get a copy of the circuit diagram? (See post above).

Circuit diagram here:

Sterling S5A S5M 10C 12C Circuit Diagram

The Sterling in this thread only has four valves. The 10C & 12C has an extra 6C6.

The PM speaker is not original and maybe this has something to do with the low volume. That balloon shaped 80 might be a bit tired too.

Measure the volts across R7 if it has similar? (chassis will be positive). There should be a resistor to replace the choke / field, or a choke is it there? The first filter cap should not be grounded, if there is a resistor like R7 (back bias). The worst offender for distortion is an anode bend detector running out of spec.

If that has a centre tapped heater supply make sure only the centre tap is grounded.

Marc

Hi guys... Thanks for the comments. Anode bend detection, I guess that's done by the 6D6?
Does tham mean replace the valve?
I've actually owned this radio for about 20yrs and did the restoration then. It's always been one of those "gunna do jobs", and I recon I've been putting it off long enough.
The HT appears healthy enough, although I was thinking of soldering a couple of 1N4007 diodes across the anodes/cathode of the 80, and adding say a 2k dropping resistorin the HT line.
I'm guessing a HT at cathode of the rectifier of about 240v is about what you'd expect to find?

R7....I take it that it runs from the neg side of the main filter cap to chassis, across which a voltage is developed. How many volts should I expect to measure?

R7 provides the bias voltage for the type 42 output valve. At 240V on the plate, you'd be looking at about 16V across R7.

What we must be careful of is that we do not know the circuit that it has. If it is back biased the resistor I call R7 from the 5 Valve circuit has to be there & goes from the centre tap of the HV winding to chassis. When the set is running properly the voltage a cross a back bias train, measured CT to chassis will be that of the grid bias of the OP tube.

This should be about 16.5V 250VDC "B voltage" chassis positive (CT is the most negative point), Has it got a choke or a resistor of perhaps 2500 Ohms: That is important as we need to see what the B+ voltage is

The components & voltage around an anode bend detector are critical. Often the anode bend detector will have a very high value cathode resistor. Its failure will guarantee distortion and can cut the valve off electrically.

We do need to sort the circuit out, I have had to resort to reverse engineering some, to actually get a circuit to analyse.

Marc

Thanks for the tips.....I think I'll need to get a pen and paper and draw the circuit by working out what components are hanging of the 6d6 and 42. Go hunting for resistors that may have "gone high".