Steve Pelissier's Two Tube Convertible Radio
How have you been? It's been a while but I just completed a new radio that I am proud to show. This one was a lot of work but it certainly paid off.
I sent a bundle of photos of the before, during, and after stages along with a schematic. The file is a little big but trust me it is worth the wait of downloading it. The radio that created is a combination of many ideas with a few of my own along with a lot of TLC. the chassis was originally a parts donor junker ocean hopper. To be honest It wasn't very useful to me so decided to use it for a better cause. I own another Ocean Hopper that has all the genuine parts and is in wonderful condition. That of course is being preserved. Also I am very fortunate to have several complete Ocean Hopper coil sets as well! The great thing is that everything is now being put to good use.
Over all if I had to credit the design inspiration to any source in particular I would say "Hikers Two". More of this design was influenced by the KB7NRN Hikers Two than anything else and I have to give the due credit. He used 3Q5's which are electrically the same as my 3S4's. My chassis was already punched out for miniature tubes so I made the obvious choice. I also chose the 3S4's over 1S4's for availability reasons only. The secondary factor in design is the Ocean Hopper "all band" plug in coil arrangement, and of course the physical layout. Finally some of my own tweaks and additions were added for listening comfort and minor performance enhancement. By the way I need to credit you for bringing the 6418 tubes usefulness to my attention with your 6418 radio and other uses. The possible applications of this great little tube may have otherwise gone forgotten.
The thing I like the most about this radio is it runs on just a few batteries while delivering unbelievable performance with relatively low draw. Draw on the filaments is only 200ma total which will provide more than several days of straight listening, and at comfortable speaker volume for most stations. Needless to say the draw is next to nothing on the 9V batteries so they would last for nearly a month of straight use (according to some calculations). If you are a headphone user the 6418 tube option draws only 20ma filament draw providing exponentially longer use from the same batteries! And the volume still can drive a low powered speaker comfortably on stronger stations. With the headphones everything is delivered at a very nice level. The 6418's seem to deliver a smoother regeneration control. When listening to distant signals I have a lot more leeway on regeneration to pull em in. For a headphone user like me they are perfect. The 3S4s are still great and they push out loads of VOLUME.
The idea of tube based battery sets is nothing new but I think this set raises the bar a bit. It is packed with features:
All band operation with six different plug in coils.
Battery powered and capable of days of straight operation (low drain and low voltage).
Loud speaker capable operation with separate volume control.
Simple two tube design that does more than many much more complex radios. Sensitive reception.
Extremely smooth regeneration control especially with the 6418 tubes.
No lethal voltages!
I hope you like the radio and perhaps my ideas on this project can inspire someone and provide useful information. Let me know what you think about it and drop me a line. There are some more projects coming soon, I promise! I gotta go as it is getting late. Talk to you soon,