I recently acquired the above radiogram. I am interested in the chassis to 'play' with, but not the cabinet. The circuit looks very original and complete. Brad and Marcc will be pleased that this chassis is not an AC/DC set. Valve line-up is 6AN7, 6N8, 6M5 x 2, 12AX7, 6V4.
Q.1. Is anyone interested in the cabinet?? Dirty, but good condition. Melbourne SE suburbs or Geelong Region.
Q. 2. The valve labelling is 'powdering'. How can I preserve the labelling without affecting the valve performance?? Sticky tape wrapped over the labels or new paper labels????
Q. 3. The external aerial feeds into an inductor (compensating coil) wound (in parallel) around a resistor (5.6k). My reading suggests that this inductor is 'compensating' for a capacitative aerial to produce a series resonant aerial-earth circuit; is the resistor dampening out the resonance? Am I on the correct path here???
Q. 4. From the circuit diagram, I have located a 3 to 30pF Wire Trimmer (?) across the Oscillator variable capacitor. Cylindical in shape several mm in dia and about 15mm in length with wire wrapped around it. When the time comes, how do I adjust this trimmer??
As you can see, I am new to this stuff and will appreciate any help.
Thanks, Ian

1. It's not often you'll get someone interested in a cabinet without a chassis. The only time you'd be likely to get a sale is when a collector already has a chassis but no cabinet and this doesn't happen often and when it does happen it is usually a rare coloured bakelite set.

2. It doesn't look as authentic but the best way I've found is to write down the valve number on paper then go about washing the valve. Then I note which way the valve sits in the receiver an then I write the valve number on the glass near the base with an Artline texta, making sure the writing faces the front of the receiver so it cannot be seen when looking through the back.

Some people like to clean valves with a cotton bud, being sure to miss the part of the glass containing the valve number and the familiar octagon that surrounds it however I much prefer to have a perfectly clean valve as it looks more presentable and at the end of the day the chalk is going to come off at some stage - it can't be avoided without leaving part of the glass dusty/grimy.

3. Not sure about the inductor/resistor setup. I must admit that tuned circuits aren't one of my strong points.

4. Buy February's edition of Silicon Chip and read up on the featured Mullard Meteor in the magazine's vintage radio column. The columnist, Rodney Champness, speaks about this type of condenser, explaining the need for care when adjusting it.

Brad,

2. Re valve designations 'powdering' - I will follow your suggestion about Artline texta. Have accidentally rubbed more of the markings off today when tracing through the wiring.

4. I will get Silicon Chip tomorrow, hopefully.

A couple of more questions if I may:-

5. I will send photo of circuit for inclusion in this email.
The paper wax caps will be replaced.
What about the electrolytics at XXXX?? Can anyone suggest their age and if they need replacing?? There is no sign of leakage etc.
Similarly the smaller caps at YYYY??? What are these caps and is it advisable to replace them prior to powering up???

6. There are 2 types of Mica caps - MS and SS. What is the difference????

7. I found an earlier Version of this radiogram with exactly the same valve line-up and I was surprised to see that anode voltages and screen voltages were between 5 and 15 volts lower for the more recent radio. Also there are differences between the circuits.
I guess that I was expecting the circuits to be identical , that the operating efficiency of these valves would have been maximised etc, given the same valve line-up and only 4 years difference in age.
Is there anything significant in this observation?? Or am I just seeing part of an evolutionary process of improvement in the circuitry??

Click on image for larger resolution

Hi Tinkera,

Have you a photo of the cabinet if you still have it?

Hi LP,
Yes, I still have the cabinet; no, I don't have a photo of it. The cabinet is not at my home, it is stored near Geelong, Victoria.
I have removed the radio and speakers, some-one else had removed the Record player. From memory the cabinet itself is in good condition, all legs, opening top, sides, back plate etc are all there; one or two stains, polish is faded.
Email me via this site if you are still interested and I will get some photos for you at my next opportunity (maybe a couple of weeks). I can get this cabinet to Melbourne for transporting to you. Cabinet is free to a good home, transportation is your cost.