Dave Richards AA7EE

August 14, 2015

A Sproutie is Born in France, to Henri F6GMQ!

Filed under: Amateur Radio,Ham Radio — AA7EE @ 12:10 pm
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Around the same time I heard from Andy M6YAO that he had finished his Sproutie, I heard from Henri F6GMQ, who was also building a Sproutie and close to completion. A Sproutie in Orsay, in the North of France – how inspiring! To my knowledge, there are now 3 Sprouties in existence – Henri and Andy came in joint second.

Henri built his regen in an old measuring instrument case. He kept the original 12V power supply, for powering the circuit. The variable capacitor came from an old tube radio. He’s already thinking of constructing a second one, in a nice wood or aluminum enclosure. Love those instrument handles!

A view from the back, showing the side braces that help to make the structure more solid. We must be thinking alike Henri, as my most recent version of The Sproutie also has instrument handles and side braces –

Henri’s first coil gives coverage from 5.5 – 7.2MHz. He says he has been able to listen to SSB, CW and broadcast stations and that selectivity and sensitivity are great, considering the relative simplicity of the circuit –

It’s interesting to see how other people build things. It looks as if Henri made his own Manhattan pads. Nice job! He also mentioned that he likes the AF stages of this receiver. Our thanks go to Charles Kitchin N1TEV for that, as they are the AF stages from the regen he described in the Feb 2010 issue of CQ magazine. Henri said that the receiver behaves exactly as I described. I do try to accurately reflect my experiences, so thank you for mentioning that Henri. I don’t think there’s any point in covering things up. If I think there’s a potential issue, I’ll mention it so you, the reader, will know what to expect.

Henri is looking for ideas for a simple 40M VFO, as 40M is his favorite band. He is thinking of building a high performance receiver for 40. If anyone has any ideas, you can leave comments underneath so that Henri will see them. He’ll be very grateful, and interested in all ideas, I’m sure.

Thank you very much for sending your photos Henri. It’s really great seeing how others build things, and it’s really great to know that there are now Sprouties in the US, the UK, and also France. Also, a big thank you to all who were involved in designing the circuit elements that make up this cool little receiver. They include (but are not limited to) GI3XZM, GM4HTU, G3RJT, G3VMU, G4RGN, VK2BHT, G3RJV, and N1TEV.

August 8, 2015

Andy M6YAO Builds A Sproutie!

Andy and I have been communicating via e-mail since April. He is M6YAO now but back in April, he was plain old unlicensed Andy, who was about to apply for his Foundation License in the UK. He had built a Mark regen from Walford Electronics, which seems to have given him a taste for regens. He mentioned that it was a good receiver and worked well but that the tuning, accomplished by a polyvaricon with no reduction drive, was a bit critical, so he was looking for a regen to build that represented “the next step”, so to speak. It turned out that The Sproutie was that next regen for him.

I haven’t built any of the currently available regen kits but The Mark from Walford Electronics, and The Scout from QRPKits both strike me as good ones for anyone who has never built a regen, and wants to get their feet wet. However, when you’re ready for more, there’s nothing like a quality air-spaced variable capacitor and a nice solid reduction drive with calibrated dial to make you feel like you’re navigating the airwaves in style. In my secret (and perfect) world, there is a kit version of a regen with a pre-drilled and engraved, large and stout aluminum chassis, top quality air-spaced variable capacitors and reduction drives, and a variety of accessories (wooden enclosure, extra formers for adding bands, etc). Also, in my perfect world, this kit wouldn’t cost the many hundreds of dollars it would need to in the real world we all live in. If anyone were admirably eccentric enough to produce such a kit, I think that very few would actually buy it, due to the high cost.

Andy and I continued to e-mail each other, as his Sproutie gradually took shape. It was really interesting viewing the progression of his project as he encountered challenges, experienced setbacks, asked questions and one by one, solved his problems. It was a process that all home-brewers will recognize from their own pursuits, and a pleasure to observe. We have all had the kind of projects that present issues we are unable (or unwilling) to solve, so it is a fantastic feeling of achievement when projects succeed despite the obstacles that occur along the way. I get as much of a kick out of others’ successes as from my own – especially when it’s with a receiver like The Sproutie that is rather dear to me.

Incidentally, in the UK, when upgrading from a Foundation to an Intermediate license, there is a practical element to the requirements. Andy wanted to use his build of The Sproutie to qualify. The RSGB website says, “First, a practical skills assessment is taken which demonstrates your competence in basic electronics. This involves soldering a rudimentary circuit together using some of the components you learned about on the course.” A successful Sproutie build would seem to more than fulfill these requirements.

Bit by bit, Andy sourced the parts from various sources, including some from the US. He ended up with more reduction drives than he needed, and had to decide which one to use. He also incorporated a DC ripple filter from VE7BPO’s blog (I’m not sure if that became part of his final build). As the receiver slowly began to take shape, he was still deciding what to use for an enclosure. Whenever we build something, we make multiple decisions along the way, and it was interesting to follow along as Andy went through this process. I’m not sure if he experienced this, but I sometimes find that the plethora of decisions to be made really slows me down. Planning a project is a bit like playing a game of chess, as a decision you make now will affect many other moves in the future.

Although the AF amp board worked, on connecting all the boards together for the first power-up of the complete receiver, Andy was greeted by – a big nothing. We’ve all been through that and it can be somewhat dispiriting, but this is where our valiant builder’s homebrew mojo really kicked in, and he earned his stripes. He checked a lot of things, which all seemed to be in order, but didn’t give up. Finally, one afternoon, I received an e-mail that was titled “Eureka moment”. It turned out that his RF board was connected to the +ve supply line, but not to the ground. This is one of those “How on earth did I miss that?” moments that anyone who has ever built anything will know all about. Andy did experience a few more issues as he cased the set up but as they arose, he dealt with them. He said, ” I have learnt lots and I think it will help me in other projects I undertake in the future. ”

He used a metal file case for an enclosure, and the main tuning dial and drive is a NOS (New Old Stock) Muirhead Type C, with a 50:1 reduction ratio. 50:1 is huge – you must have fantastic slow tuning Andy –

Andy reports that it works well, fills the room with sound, and the bass boost works too. Because the file cabinet has a lid with a latch, he stores the unused coils inside the lid, held by spring tool clips. The plate on the top will have a legend, indicating the frequency ranges that the various coils cover –

Andy also owned a Tecsun PL-880 but he says that compared to The Sproutie, it seemed sterile. He writes, “The Sproutie seems to live and breathe in comparison and requires user interaction instead of just punching in a number through a keypad. ” He recently sold the Tecsun because, in his opinion, although it was probably technically better, it didn’t provide the same user experience as his new regen. A convert! This is exactly how I feel about direct conversion receivers and (particularly) regens. The simple circuit architecture leads to a relatively unprocessed sound and makes me feel as if I’m in more direct contact with the airwaves (or perhaps it’s just the lack of AGC!) It’s very affirming to hear the same sentiment voiced by someone who is a relative newcomer to these intriguing receivers.

Andy will be taking the exam in October to upgrade from his Foundation license to an Intermediate license. He already submitted his Sproutie build as the “simple” radio project part of his exam and of course, it passed.

Congratulations Andy, and thank you for sharing your Sproutie build with us!

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