Components for your Lamington III are readily available. All of the parts with the exception of the output valves are readily available from Australian suppliers Jaycar, Altronics and WES Components.
Be open to the possibility of scrounging resistors, capacitors from old TV sets, VCR’s etc. If you can get your hands on such an old piece of gear, you will probably find most of the smaller electronics parts for your amp. Where possible, check any salvaged resistor for correct value before using it in your amp.
Transformers are available from Altronics, WES Components and Jaycar. The power supply transformers, M6672L (30V 1A) and the M2154 (18V 1A) are readily available from the above suppliers. The M1130 output transformer is available from Altronics and WES Components.
My recommendation is to purchase your valves from Ebay. You can regularly see 6CM5/EL36 valves for sale from Australian sellers and you can also find Soviet equivalents 6P31S from overseas sellers quite cheaply. Beware of the Soviet 6P13S valve advertised as a 6CM5 equivalent – it is similar but not the same pinout. 12AX7s can be purchased from Altronics and Jaycar and you can also find them on ebay from Australian and overseas sellers.
I highly recommend that you download data for your chosen valves from the Web – just do a Google search for data for your valve type. Read the data in detail – it will give you not only pinout data for your valve, but also a heap of further info that will help you understand valves better.
For further info on valves you can download an electronic version of any issue of the ARRL Amateur Radio Handbook, or the Radiotron Designer’s Handbook. These are invaluable resources for the valve enthusiast.
Power Supply Capacitors
The main power supply capacitors C1-4) can be sourced from Ebay or Altronics – Altronics have 470uf 400V capacitors available.
However a much cheaper (free) option is available however.
Do the rounds of your local computer repair shops, and ask for any faulty/dead computer power supplies that they may have lying around. The older AT and ATX supplies each contain a couple of these 200V capacitors. Some later supplies only contain one 400V capacitor, but that could still be useable if you can find a similar supply with a similar value capacitor. You need two pairs of the capacitors for your amp, so any value from 220uf to 560uf is fine as long as you have a pair of the same value for C1 and C2 and another pair for C3 and C4. These computer capacitors are ideal as they have very low internal resistance, and are designed for high current – they are ideal for your amp. These salvaged capacitors are what I used for the prototype and work really well.
See the parts list below which will assist you in gathering the components for your amp. Fortunately, there are several sources available for each component, so you should have no problems locating the parts that you need.
Amplifier Parts list
R24 100 1W
R25 100 1W
Power Supply Parts list
RV1 100K trimpot
T1 M6672 transformer
T2 M6672 transformer
T3 M2154 transformer