I acquired this set over 20 years ago now and its been sitting in the corner awaiting some attention.

It looks like it was built by a home constructor. I have uploaded some photos to go with this.
The cabinet looks early 30's (Beale style?) but was clearly got at in the 40's to put in a 'modern' tuning dial.

The chassis is 6 valve -- 39, 36, 39, 75, 42 & 80 (RF stage, autodyne converter, if amplifier, detector/af amplifier & output valve)
With Lekmek coil set - oscillator coil has Lekmek warranty seal.

From the valve lineup, I've assumed the design dates from ~ 1933.

So far with the exception of a Lekmek 4 valve superhet kit from Feb. 1933, I haven't found any other Australian sets using the 6.3V 36 & 39 valves. Or maybe, I haven't been looking in the right places!

Wondered if anyone recognises the kit and whether its a published design.

Thanks Nigel

One may have to make an attempt to reverse engineer it. 75; 42; 80 was a fairly common audio end for a lot of radios.

36 turned up in 6/31; 39 2/32 and became 44 in 1935; 75 11/33; 42 9/32. 80 9/27.

So the interesting ones are 39, 36, 39. 36 is the odd one out & actually listed in Philips as a Tetrode but a Pentode by RCA 39 is a remote cut off Pentode

Unless one of the 39's is a separate exciter (oscillator)

I would expect 1st RF #39; Mixer /oscillator #36; 1st IF #39; #75 detector 1st AF; #42 Audio output #80 rectifier. That would have a gang with 3 groups.

39/44 http://frank.yueksel.org/sheets/021/3/39.pdf

36 http://frank.yueksel.org/sheets/021/3/36.pdf

Photos uploaded.

Thanks Marc
I've traced out the circuit, its fairly straight forward and apart from the use of 39,36, 39 valves in the front end very "conventional".

I've been working on the cabinet in parallel. After removing the dark/oppressive shellac finish, I was surprised to find underneath a very intricate faux grain pattern that looks to have been printed on the pine somehow. Which suggests a lot more work went into the original cabinet than I had assumed from what appeared to be a fairly basic (crude even!) construction.

It will look a lot better with just a natural shellac finish over it and even better with a more period appropriate tuning dial/escutcheon.

Surprised its not nitro-cellulose finish at that age. I normally draw the layout, transformers, valves etc initially with an AutoCad & then print it then play join the dots using different colours, or its if it has one?

Hi Nigel, what was sitting between the 2 valves at the left to create the round brighter patch?
Fred.

It was the 2nd IF transformer.
When I first got the radio back in the early 90's, I attempted to repair it but found that one of the coils in the IF transformer was open circuit. On inspection the wire had broken/corroded right against the soldered joint. I tried to resolder without joy and gave up on the set and it sat in the corner of the room - without its 2nd IF can for the last ~25 years.

Now that I'm "retired", I found time to work on it again.
The below chassis wiring was a real cobweb of wires & passive components with out support/mounting strips.
I went through and tidied up the wiring adding mounting strips where needed, replaced all the electrolytics & wax capacitors (I checked them all most had leakage between 2 & 14 Mohms). Most of the "dog bone" resistors measured more than double their nominated value!. I replaced all with the exception of the ones in the AGC circuit until I had got the radio running.

I had another 30's home built kitset radio in the attic (AC/DC with P base valve holders ) which I "sacrificed" for its IF transformer.. hoping that it would be ~460 kHz.

I made the assumption that as the majority of Lekmek sets had an IF of 456Kz by the mid 30's then it was likely that my set had a smilar value (fingers crossed).

Anyways, I transplanted the IF and powered up the radio..and was immediately greeted with music. I did a rough tweaking of the trimmers on IFT 2 & bingo it was up and running.
I was surprised how sensitive this old set is - given its still running with the original early 30s balloon shaped valves (36, 39, 36).

Now, I've just got to finish off replacing the last of the dogbones and wondering whether I should replace IFT1 so that there is a matched pair.

Well done Nigel, if the IF works and the set is sensitive, leave it.
So long as it looks the part i'd be happy.
Like to see some pix of the underside as well.
Also keep us in formed on how the cabinet goes, i'm learning all the time.
Fred.

Well done Nigel

Seconded.

I would like to be that lucky at the moment. I have a Grigsby- Grunow that has two destroyed IFT's (175kHz) and I have now noted that the Monarch (one of 3 sets in work) had a 100k resistor to V1 plate as the primary of the coil between it & V2 is open & its not by the looks of it an external break on a coil, or node.

Good that that set fired up. Corrosive breaks near the pins are common, it is actually recommended that joints of dissimilar metals like at that point, with copper wire, be coated.

Thanks guys.
I've uploaded some more photos of the Cabinet work and the underside of the chassis as requested.

Please note the underside photo was the starting point!

My first priority was obviously addressing the many issues with the mains cable/wiring (ie new cable, cable gland & tagstrip added), re positioning the electrolytics (I didn't like seeing the reservoir capacitor physically wired across the transformers earth lug & heater winding of the rectifier ).

As mentioned before, I replaced all the waxies, electrolytics and dog bone resistors (with exception of those in AVC circuit (initially)). All wire wounds were within tolerance - with exception of an opencircuit one in the cathode of the converter (36).

Most components were just dangling from the wiring.

Photos of cabinet shows original condition, when all the shellac had been wiped off and finally almost completed after receiving several coats of shellac over 2 days.
Final step is in 1 weeks time to cut back with steelwool & beeswax.

I was surprised to find under the old shellac a faux wood grain which had been printed/stencilled/rolled onto the pine sides and plywood front panel. Was this a common technique?

Photos uploaded to Post 11.

I would monitor the start up surge, whilst that has a divider which may pull down the surge, in many sets with #80 / 5Y3 and those that behave in a similar fashion, that surge can get to, or exceed 500V.

I have seen several 450V types fail (and a couple of 500V ones, so I don't buy from that supplier). 500V is the lowest I go with those valves & diodes feeding heater valves..

Remember, if the set has 250V (most common) on the main supply rail, then the first cap before any form of choke (choke input filter) will be running at 300V, or more, which is why it is normally the first filter cap that fails.

Thanks for shot of underside, I love looking at old stuff. I guess by now all the carbon resistors, paper caps have been changed, plus those sub miniature blue electros! Those little caps have their place but not in a chassis where the HT heads for blue sky on power up. As Ian says the HT can go 600v plus for seconds before the output valve draws current. I have used the little blue caps in some repairs but put two in series and in critical places put 1m sharing resistors across them. Most of my repairs have reformed used can caps or reformed old stock large diameter units and only put in after bench testing for leakage and heat rise.

Good work on the cabinet laughed at the faux wood grain, that is an art to me.
Nice project.
Fred.

It looks to me that the dial is much later than the rest of the set. It was common for early sets to be "modernised" by having later type dials fitted. The "Serviceman Who Tells" in R&H writes of this.

The 36 and 39 were quite common in early AC/DC and DC mains sets, also car radios, but were quickly superseded by the 77 and 78 and by the 6C6 and 6D6. I have a DC mains Rexonola radio with a line up of 39, 36, 39, 36, 89 made about 1932. Others using the 36 and 39/44 include AWA 55C, Emmco DC5 TRF, Healing model 50, Lekmek 53-BM, 54-BC, etc.

Cheers.