Extra Coils For The Sproutie Regen, With Coverage Up To 30MHz

Since completing The Sproutie Regen in it’s basic form in August of last year, I have been spending lots of time listening to it, and also some time winding coils for extra bands. On top of that, I wanted to add some extra thoughts and observations on building it and instead of creating a new blog-post every time I wound a new coil, or found something new (such as the fact that it seems to work quite well all the way up to 30MHz), I have chosen to add to the original blog-post. I have also been editing the post a little while adding new material, the point being to improve it and make it as informative as possible to anyone thinking of building it. Also, if I added a new blog-post for every new piece of information, then potential builders would find it harder to access all the info. This way, if you want to learn about, and maybe build The Sproutie, reading the one original post will always bring you up to date.

Since finishing The Sproutie, I have added coils for 2063 – 2670KHz, which covers the 120M BC band, 49M, 31M, 25M, 19M, 16M BC/17M ham, and an experimental coil that covers ~24-29MHz. The coil box is now full, and a picture of it has been added to the original post. I have also updated the coil tables to include full details. The experimental coil for 24-29MHz was wound out of interest, to see if this receiver would work passably at the higher HF frequencies and indeed, it does seem to. I copied SSB on 24M, as well as SSB  and CW on 10M, and local CB’ers on 27MHz. (EDIT on 2/18/2015 – this afternoon, I copied 10M beacons from K5AB in Texas on 28280KHz and WA2DVU in NJ on 28257KHz) I added no padders or series caps to taylor the coverage to a specific band. I didn’t even add a link winding – plenty of RF was being coupled into the circuit from pin 7 of the octal base without it, though a finalized coil would probably include a small loop to couple as much RF as possible, withut overloading the detector or stopping the oscillator.

Blog posts aren’t much fun without photos so, although I just added this photo to the original post, here’s what my coil box looks like now that it’s full up with coils.  If I wanted to add coils for specific ham bands, as well as the remaining BC bands above 16M (and the 22M band), I daresay I could fill another coil box!

The cigar box full of Sproutie coils. The unmarked one sitting above the 25M coil is experimental, and covers approx 24-29MHz.

If you’re getting a bit fed-up with me talking about this little receiver a full 6 months after I finished building it, take it as evidence that it’s a good ‘un. 6 months after building it, I still think that it was a very worthwhile project, and continue to derive much enjoyment from it.  The sounds of Radio Habana, Cuba fill my apartment on many evenings, and on the same frequency (6100KHz), music from KCBS Pyongyang in the mornings, as well as Radio Australia are my main morning staples. I’ve heard Spanish numbers stations, air-traffic control, coastal stations, military communications, and all sorts of weird and wonderful bleeps and bloops that you expect to hear in the shortwave bands. Before I end this post, allow me to say just one more thing that I have said many, many times before. If you are going to build a regen, make sure you pay careful attention to the physical construction. There, I said it. I promise I won’t mention it again 🙂



7 thoughts on “Extra Coils For The Sproutie Regen, With Coverage Up To 30MHz

  1. Dave can you send me the parts list for the sproutie receiver also can you send me a closer diagram of the RF board and the audio board ? I enjoy reading about every piece of information you have for the sproutie receiver keep it up .

    Juan. AD4IM

    1. Juan – I sent an e-mail to your QRZ address, but it was returned to me as undeliverable. Can you send me your current e-mail address please? My e-mail is good on QRZ.


  2. Dave – as a 20+ year ‘appliance operator’ I have loved the entire Sproutie series. The story (and your blog in general) are hugely inspirational and have caused me to break out the mothballed soldering iron. Keep it up!

    1. Scott – that’s great. I just share what I’m doing, so I’m really happy that it’s inspiring you. Thanks for letting me know. The Sproutie is my best regen so far, and a very rewarding receiver to build and operate. Glad you like it. Have fun with that soldering iron!


  3. Dave – I like the sproutie it appears very stable and “hands-off-ish”. Just what you desire in a regenerative receiver. Have you given any thoughts toward building a companion qrp transmitter?
    Paul – AA9MJ

    1. Yes Paul – whenever I hear people talking about regens that screech and are “touchy” to operate, I think “Not this one!” VE7BPO just published the results of his experiments with this particular regen topology in his Popcorn QRP blog, and it’s very interesting. I haven’t tried his version of the circuit yet, but I do believe he has improved on it.

      No thoughts about building a companion transmitter. My focus with the regens is on general SWL’ing and SW broadcast band listening. I stick with my K2 for QRP operating.

      So – are you going to build a Sproutie of your own?


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 )

Facebook photo

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

Connecting to %s