Yes, what makes it more confusing is the use of a N/C valve pin on the 5Y3 socket as a tie point for the transformer HT secondary centre tap.. I've seen this done before - not nice but it does work.

The EL3 was marketed as allowing set makers to omit the 1st audio stage, because it has higher gain. It also tended to be unstable, which is probably why the electro was bypassed with a paper cap and probably also explains the back bias bypass cap (yellow Dubilier).

The speaker in my Radio Star (the set was a battery model with a Rola permag speaker - yours is an electrodynamic, i.e. with a field coil and hum bucking coil at the back) was rusted solid - I still managed to strip it down, clean and rebuild it. Tyre black does a great job of making a paper cone look new and helps hold it together. I think you'll find your speaker is screwed together as well so it's probably also fixable if you can first remove the cone and voice coil. That will be the trick.

Everything I said about being able to help you still stands.

Back bias was a way of saving on cathode resistors whilst setting a reference bias. Philips often sent the second filter cap as well as the first to the CT, on a back biased set. Elimination of the ecap across the back bias, or wiring it negative to chassis all created hum, with that arrangement.

Often you will see strategically placed NP caps on B+ where there are Electrolytic caps as Electrolytic caps are poor decouplers of RF

Shorting it out also caused havoc as you lost bias. I have one here to go into the cabinet, when they fix it, where the Monkey paralleled two metal jacketed caps. Fine but the securing to chassis by a bare wire to bare jacket, shorted out the back bias??? And you wonder why it had problems.

Marc

Ok it looks like a visit to Jaycar and Bunnings is in the mix. The speaker is nowhere near repairable so I will be looking for a new speaker and some hardware to make a mounting bracket for it.
The original speaker and field filter is riveted together and the speaker cone just crumbles to the touch but it is a kit radio so slight mods should not be a issue.

I notice one of the knobs on the front panel look like an Astor Mickey 1930's.
The knob could be worth more than the whole radio .
JJ

Give me the exact diameter of the speaker - I probably have a replacement that I'd be happy to donate to the cause. It'll be permag though - you'll need to add a dropper resistor and more μF in the filters - not a problem.

There's a guy - Don Davis - in the US that I sold a Radio Star to (not the one I was discussing). He restores old field coil speakers - nutty about them. If you want to chase it up I could email you his contact details.

That could be worth a look Ian rebuilding coils be on the cards. I have managed to find a suitable speaker and have hooked it up and gotten some results. I used a 3.3K 5 watt resistor in place of the field coil. I only got really good results after I hooked the antenna wire directly to the gang. When connected to the terminal on the chassis it was very very weak why would this be ?.

If you got the resistance as close as possible to the actual DC resistance of the existing one (which may be on its label) fine. However, I would be inclined to measure the voltage across it to get an idea of the current through it (Ohms law). Then apply Current squared by resistance to establish the wattage it is trying to dissipate.

E.g. The screen resistor in the little nipper was changed from 2 x 22K to 1 x 10K, as a result they are often cooked & high. Analysis of the screen currents at the voltage applied, sees them draw more than 10mA. 10mA is 1 watt and that is why the resistor fails, exacerbated by mains voltage excursions upwards. I.e. I have 245V.

Marc

I have actually used a 5 watt wire wound resistor in this case. The only issue I am having with it is that the antenna wire needs to be attached to the tag on top of the gang to get any type of decent performance so there is something amiss between there and the terminal on the chassis which offers next to no performance.
On a positive note it really performs well on the shortwave band , I picked up at least ten stations tonight. This little radio is going to be slow going from now but I am pretty happy with it.

I would be surprised if the gang works at all, is it actually tuning? From the oxide & crap on it and the Aluminium blades I would not be surprised if its not shorted.

My suggestion before was to see what wattage the resistor was expected to dissipate, not what it was rated at. If the calculation, based on measurement,exceeds the wattage of the resistor, then it will quickly fail.

Marc

Back to why connecting to the gang directly works better...

If the antenna coil is mistuned (probable) then it's not surprising a direct connection to the 6A8 grid will work better. What Marcc said is correct - there is so much corrosion there it probably isn't working properly.

Stripping the gang down and rebuilding it is a lot of work but justified in this case.

Could also be dirty contacts on the wave change switch. I use Silvo, followed by a wash down and a couple of days soak in metho, to restore these.

Hi GTC,

Sorry this changes the line of this forum topic.

"Yes, a bath of molasses diluted about 1:10 with water is a good rust remover, but it pongs to high heaven so don't do it indoors."

Thanks GTC for the tip, I will try putting in a piece of rusty steel in the mixture to be familiar with the process before putting in part of the radio chassis. Did not think molasses had rust removal properties.

I have also noticed in the past that when I have some fresh sawdust from the local saw mill loaded on the back of my truck, if the load has been left on overnight, the rust on the tray disappears but the side effect of this is that the steel goes black. That fades over time. Might not be a good idea for radio chassis.

Bushman

I will try putting in a piece of rusty steel in the mixture to be familiar with the process

Mate of mine restores vintage motorcycles. He's brought frames rusted beyond belief back to life in a bath of diluted molasses. In his case he has a stainless steel sink in a old brick barbecue in his backyard with a slow gas ring under it. The heat accelerates the process -- but spreads the pong throughout the neighbourhood.

Don't be tempted to richen up the mixture by adding more molasses. There's a point past which the chemical reaction will stop.

I will add that I actually have given this a fair clean since the photos I sent in. Yes the tuning gang is working. Still more to do but that doesn't matter as the cabinet will take a little time to do.

Hi Ian Robertson I would very much like to take you up on the offer of a design for one of these radios. Because even though I am repairing this one , I do have a spare clean chassis that I would like to put to use. I also have most of the parts needed so it should be a nice little project just so I can really say I have built my own Little General. So your assistance would be very much appreciated.

Hello Marcc could you tell me what you think the value of the volume pot would be. It is a wire wound one.