Design | Construction | Components
And now, some comments on parts availability. All of the parts with the exception of the output valves are readily available from Jaycar, Altronics and Futurlec.
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. As of August 2014, supplies of the M2860 seem to be drying up and are becoming difficult to source. The good news, however is that the M6672L, a 30V 1A transformer is readily available from the above suppliers and is a suitable replacement.
My recommendation is to purchase your valves from Ebay. You can regularly see 6BQ5/EL84 valves for approx $40 a pair and 12AX7’s for $20 from Australian 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
These capacitors can be sourced from Ebay or Futurlec however a much cheaper (free) and better engineering solution 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. These 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. These 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. Another source of suitable electrolytic capacitors for free are used disposable cameras from your local film processor. The capacitors in the various brand flash modules range from 80uF to 120uF at 330 volts working.
All of the other components are available from the usual electronic component suppliers in Australia. Fortunately, there are several sources available for each component, so you should have no problems locating the parts that you need.
Parts are available from Jaycar, Altronics stores directly if you are near them, or alternatively available from internet sellers.