Dave Richards AA7EE

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!

4 Comments »

  1. Congratulations Andy, you had a great teacher to help you along the way. Looks great, like it’s alive!

    Comment by Joel KB6QVI — August 8, 2015 @ 5:26 pm | Reply

  2. Real nice build

    Comment by Robert L. Pendergast, N5JYW — August 8, 2015 @ 5:37 pm | Reply

  3. It’s a strange feeling when you power up a home brew for the first time. Your natural enthusiasm encourages a belief that the project will burst into life but life experience cynically suggests that it won’t. And it doesn’t! You trace wires and tracks to and fro but there is nothing obvious until, as you say, the Eureka moment and you find ‘it’.
    Yesterday I worked for hours trying to fatham the attachments on a rotary switch that I was convinced was a ‘three position with four contacts’ when, in fact, it was a ‘four position with three contacts’. How I mistook its credentials is beyond me – but I did.

    Comment by Tony Goldsworthy VK3APH — August 9, 2015 @ 4:14 am | Reply

  4. Reblogged this on Amateur Radio News from Jon Stow, G4MCU and commented:
    Hands across the pond. Good to hear.

    Comment by Jon Stow — August 9, 2015 @ 8:50 am | Reply


RSS feed for comments on this post. TrackBack URI

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Blog at WordPress.com.

%d bloggers like this: