Dave Richards AA7EE

February 26, 2015

A Popcorn QRP Regen Receiver and Lots More Air-Spaced Variable Capacitors

Many of us in the home-brewer community were really disappointed when Todd VE7BPO recently discontinued his popular and very through-provoking site “The QRP/SWL Homebuilder”. An archive of the site is available for download in pdf form and is a great resource. Though not quite the same as having the site, it’s great to have a copy of it for reference. Todd was having some issues with the site. He didn’t take it down due to lack of enthusiasm on his part and by way of proof, he’s back in style, with the new “Popcorn QRP – Scratch Homebrew Component-Level Radio Electronics” blog. It’s great – just like having his old site back. Todd combines circuit analysis and a theoretical approach with a strong leaning towards practical circuits that can be built by the home experimenter. Economy of design and performance are both considered, and from reading the accounts of Todd’s exploits, one suspects he is having a complete blast. If you haven’t visited Todd’s current blog or his previous site before, please note that the intent isn’t to provide the home-builder with complete step-by-step instructions on how to build a series of projects. This is circuit-level stuff, but if you’ve had a little experience at building circuits from schematics, all the circuits presented are tried and tested by our faithful protagonist, VE7BPO aka retired Professor Vasily Ivanenko.

All this is leading up to something, and that something is that our intrepid experimenter recently announced he had been revisiting the subject of regenerative receivers. He had built 4, and was sharing one of them with us on his blog. Happy, happy, joy, joy! Even better, this circuit was the same basic topology that I used in The Sproutie – a  circuit that separated the Q-multiplier and detector into separate stages. It’s an arrangement that is well-behaved and performs well. The regen control, a resisitive component, exhibits no hysteresis, and the addition of an RF preamp means that the circuit doesn’t suffer from common mode hum. If you build it well, it will be frequency-stable too, but that part is up to you 🙂

The blog-post is here. It is based on the regen circuit published by Makota 7N3WVM, whose website is a treasure trove of circuits for the home builder. You’ll notice great similarity to the circuit of Nicky’s TRF that first appeared in SPRAT Issue 70 in 1992, and N1BYT’s WBR from QST Aug 2001. What’s really interesting though, is that Mr Ivanenko has added a bipolar transistor (a 2N4401) to the J310 FET infinite impedance detector, to turn it into a hycas (hybrid cascode) pair in order to increase the level of audio from the detector, as well as the reverse isolation, which can never hurt, right? Great idea! His circuit includes a bipolar RF preamp in common base mode to add isolation of the oscillator from the antenna, as well as a little bit of gain, and a 2-transistor preamp after the detector that he has used in other “popcorn” designs. He also makes his argument for continued use of the LM386 as a final audio amp in this post. The description in the 2nd paragraph, of the folklore surrounding regens is mirth-inducing – and spot-on.

I know that at least a few builders are considering making their own Sproutie and if you are still at the planning stage, you might want to think about Todd’s version of the front end. I haven’t tried it (yet) but Todd ain’t no slouch 🙂  If I were to incorporate it into my next regen build, my current thinking is to use his front end, and feed it into a one-stage active audio filter using a 5532 op-amp or similar, and then into a nice, low-noise LM380 with it’s fixed amount of 34dB gain. If I ever do this, I can promise you two things –

a) it will be many months, maybe even a year before I do it, because I am very slow at these things and

b) I’ll show you the circuit of my AF stages so you can join it up with Todd’s (ahem, I mean Vasily Ivanenko’s) front end circuit


Todd just revealed 2 encouraging pieces of news –

a) He just ordered some black and red chicken-head knobs for his next project and

b) He has decided to spend another 2 weeks working on regens

If you don’t already follow Popcorn QRP, it’s well worth adding to your RSS reader, bookmarks bar or similar.


The rest of this post may be a little annoying to those who have limited bandwidth connections, though I imagine anyone who is still surfing the internet on a dial-up connection or a very slow mobile connection learned long ago not to come here 🙂 I recently acquired some more air-spaced variable capacitors and I’d like to share some photos of them with you for no other reason than short-term visual gratification! As always, my preferred brand is Hammarlund. Not only are they of high quality, but I happen to like the way they look as well. They are drop-dead gorgeous.

I’ll start with a piece that was acquired a few months earlier, before the current flurry of buying activity. This is an MCD-50-M and may well end up as the main tuning capacitor of my next regen, unless I happen to find another MCD-35-MX like the one that was used for tuning The Sproutie. MCD means that is is a double-ganged unit (unlike the single-ganged MC units), 50 is the maximum capacity of each section, and the M at the end refers to the fact that the offset rotor plates give it a “midline” capacity characteristic, keeping the rotation vs frequency characteristic reasonably linear. Nickel-plated brass vanes for a good temperature coefficient, and all mounted on a high-Q ceramic base. Perfection! Look at those bright and shining never-been-soldered-to-before terminals –

Leaping forward in time to a couple of weeks ago, this MC-200-M “midget condenser” came into my life sporting an older original box, in almost as good condition as the capacitor itself. I love the graphic design on these older boxes –

Then came my haul of just a few days ago. I bought them all from the same seller. The boxes are a bit beaten up, but the capacitors are in great condition. First off, here’s the group shot-

Among them were two of these HFA-100-A’s. If you’re as picky as I am, these are not ideal for maximum stability in a VFO or receiver tuning control, as the vanes are only supported at one end. It would be fine as an antenna trimmer where it’s placed in series with the antenna lead, or as a reaction control, in a regen where a variable capacitor is used for this function. I’m not sure what material the vanes are made of in these parts –

In the same vein (vane?), I also scored an HF140. What a great part. It offers two methods of mounting. If I possibly could, I’d use both of them for maximum stability. This variable cap could be mounted underneath a chassis so that the nut on the threaded shaft helps to hold the front panel to the chassis, while the mounting bracket was screwed to the underside of the main chassis for extra rigidity. Rigidity is a very good thing with regens 🙂 –

An MCD-100-M (2 x 100pF).  Nickel-plated brass vanes, a ceramic base (steatite actually), regular plate-spacing, and a “midline” capacity characteristic . Such a beautiful part. What else can I say? The US was once a manufacturing powerhouse –

Also in the haul were 3 x MC-20-S. I used one of these (from another buy) as the fine tuning control in The Sproutie –

Lastly, here’s an MC-50-MX. Single gang with capacitance swing of 10.5 – 53pF, midline capacity characteristic (for reasonably linear rotation-frequency relationship) and extra-wide plate spacing. This would be great for a VFO –


I also very recently acquired this National gear drive with 3 x 250pF variable capacitor attached. My relative lack of knowledge on National products caused me to misjudge. I discovered when it arrived, that the gearbox is a later model that is smaller than the older “classic” National gearbox drives. Also, it doesn’t have an eccentric bushing for driving the micrometer-style dial. I read somewhere that National stopped using the classic dial in their receivers in response to upgraded mil-specs that negated it’s use. It’s in good condition and turns freely, though the grease is old and it would probably benefit from a cleaning and re-greasing. I may well put this one up for sale –

There’s a little bit of surface dust on the plates and shaft but otherwise, it’s clean, and those terminals have never been soldered to. Amazing! –

No cracks in the insulators –

There’s only one detail that would require some attention from a builder, and that is that it looks as if the underside received a thwack at some point – either that, or it’s a manufacturing defect. One of the mounting holes is distorted and would need re-drilling and re-tapping if it is to be used. I think this is a solvable issue –

Another view showing this issue –

Old grease on the gears. If I were to use this, I’d want to clean out and re-lubricate, but that’s par for the course with these old yet still very serviceable gearboxes –


That’s it for now. Hope you didn’t mind me sharing all these pictures with you. As a parting thought, if you’re still planning to construct a regen and haven’t completely decided what to build, remember to take a look at VE7BPO’s Regen #4.



February 17, 2015

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

Filed under: Amateur Radio,Broadcast Radio,Ham Radio,QRP — AA7EE @ 3:43 am
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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 🙂


February 9, 2015

Servicing A National PW-D Micrometer Dial and PW Gear Drive

A couple of weeks ago, I posted about some reduction drives I had acquired, including a classic National micrometer dial and PW gear drive, in nice condition. The PW drive has an output shaft that runs parallel to the front panel. Conversely, the drive in which the output shaft effectively runs straight through is called the NPW. I believe that PW stands for “Precision Worm” (EDIT – probably not – see Dave W9BRD’s comments underneath). The PW drive is the original design, and simpler than its counterpart, having only 2 gears – a worm gear and a main split gear, split for the purpose of counteracting backlash. This particular unit came with a quality variable capacitor attached to it which my capacitance meter measured as 245pF, but which I think was a nominal 225pF unit, based on a look at the 1947 National Radio Products Catalog. The dial and drive turned smoothly and worked well. On closer inspection, one of the ceramic insulators in the variable capacitor was cracked and while I was hoping this wouldn’t adversely affect it’s operation, the crack went all the way through and did indeed affect the physical stability of the unit. Nevertheless, the dial and drive were in great condition and were worth it for the price I paid. I will keep an eye open for a stator from a similar unit to replace this one with the cracked insulator. In the meantime, even though the dial and drive were operating smoothly, I couldn’t help wondering if they could be coaxed into operating even more smoothly. I had never owned one of these before, so didn’t know exactly what to expect from it. It was smooth, except for a slight jerkiness when attempting to make very small adjustments to the tuning with the dial starting from a stationary position. It’s picky, I know, but I was looking for an excuse to teach myself how to take it apart, lubricate, and reassemble it. Here’s the condition I received it in – On removing the 4 screws that secured the top of the drive to the main body, the top came off very easily, to reveal a main split gear coated in old yellow/orange grease. Unfortunately, I didn’t take a picture before removing the grease, but although there must have been a thin film on the pieces of metal that came into contact with each other (it did, after all, still operate smoothly), much of the grease had been pushed to the side of the gear and was sitting there doing nothing, having hardened somewhat over the years. The gentleman who sold it to me gave me the advice, “If it ain’t broke, don’t fix it!” but I wanted to clean and re-lubricate it, so I could be sure it was good to go for a few more decades. The other reason was that I wanted to understand how it worked – and not in a “book” way, by looking at diagrams, but by actually taking it apart and seeing how all the parts fit, and work, together. Here’s a rather rough sketch of the PW drive. Hopefully, even my poor drawing will give you an idea of how it works –   There is a great deal of information on servicing these gear boxes, and the National micrometer dial, on this page on the Western Historic Radio Museum website. Look a little over halfway down the page, under the heading “Lubrication and Assembly Of The PW Gear Drive” and underneath that, the section titled “PW-D Micrometer Dial”. This whole page is packed with very useful information on National HRO Receivers, and their restoration. Henry WA7YBS runs the Western Historic Radio Museum website. He ran the “bricks and mortar” Western Historic Radio Museum in Virginia City, NV from 1994 to 2012 and although the museum is no longer, the website is a very valuable source of information about vintage radios. It is a treasure trove. Henry kindly gave me permission to use National’s cut-away photo of this gear drive that I found on his website. It’s a lot more helpful than my drawing –

The National PW Gearbox, before about 1945, when the housing was made of cast metal. Photo courtesy of Charles Hentsch and Henry WA7YBS at http://www.radioblvd.com

I won’t go into a lot of written detail on how to disassemble, lubricate, and reassemble the drive and micrometer dial, as I learned it all from the National HRO page on Henry’s site. I would simply be repeating what is written there. With a gearbox and dial that is already operating fairly smoothly, it is possible to simply work a little extra grease into the parts to add to what is already there. I could have easily done that but once I get started with these things, I like to take them to completion.  I began by spraying WD-40 on the main gear and using a toothbrush to remove the old grease, but I ended up completely removing the worm gear, washers, spring and ball race from the housing, and removing every last trace of the old grease with a combination of an old toothbrush, WD-40 and lots of soapy water. Might as well start afresh. Here’s the partially disassembled gear drive, cleaned of all the old grease. The worm gear is no longer engaged with the main split gear. If it were, the 2 sets of gears in this photo would be much more closely aligned. I have also removed the variable capacitor from the insulated output shaft – I can be quite thick about some things. I knew what backlash was, and also knew that (obviously) an anti-backlash gear was some kind of arrangement that virtually eliminated it. However, I didn’t understand how it worked until I opened this gear box up and saw how it all fitted together for myself. This is why I recommend that you take things apart, play with them, and look at them. That way, you’ll understand how they work and will be able to fix them when they go wrong – Here’s the gear housing, elliptic bearing hub, and worm gear with the washers, spring and ball race assembled on it. Oh, and the end plate. I don’t know what it’s called, so I’m going to call it an end plate – A close-up of the worm gear assembly – The elliptic bearing hub is not actually elliptic. It is just that the hole through which the shaft of the worm gear passes, is off-center to the hub, so that the inner number dial on the micrometer dial is driven in an eccentric fashion. You can see that here – In this shot you can see the conical thrust bearing that is part of the casting of the gearbox in pre-1945 models – A couple more gratuitous shots. I am very taken with the types of mechanics and engineering you find in old radios – and this is in such good condition. It’s hard to believe that it’s around 70 years old. In these next 2 shots, you can see one of the springs that tensions the 2 sides of the split gear, and gives it the anti-backlash action – Henry indicates on his site that he uses Lubriplate 130-A as his main light grease. I was having trouble finding anyone who would sell me a single 14oz container (the smallest available). They all wanted to sell me a 6-pack, whether it was a bricks and mortar supplier, or an online one. Various outlets promised to be back in stock of the individual containers in a few weeks, but I wanted my grease sooner than that. A bit of online research indicated that Mobil 1 synthetic grease was a good (and newer) replacement and was in stock at a local auto parts store. Score! I have since found several restorers of vintage radios who use this grease, a fact which gave me extra confidence. A small pipette/syringe of the type used to administer medicines to cats and dogs, as well as a toothpick, and the judicious use of fingers, proved useful in applying it – Grease was applied (sparingly) to every point where there was metal on metal moving contact.  It was applied to the conical thrust bearing, the worm gear, the inside of the elliptic bearing hub, and the outside of the elliptic hub, where the micrometer dial would make contact. With a toothpick and a great deal of care, I also managed to get grease inside the ball race which of course, is very important. After applying it to the main gear, I put the washers, spring and ball race back on the worm gear, and reassembled the unit, setting the anti-backlash gears to about 1 1/2 teeth of offset, rotated the main gear through several revolutions, and cleaned the excess grease from the sides of the main gear. Once that grease has been pushed off to the side – it’s never coming back. Here’s what the main gear looked like after the excess was cleaned off – Next, the micrometer dial was disassembled and fully cleaned, with the usual generous amounts of WD-40 for degreasing, and lots of soapy water – I really enjoy taking photos of these beautiful pieces of engineering.  I hope it shows how taken I am with them. You’ll notice that the 2 springs that hold the (inner) number dial to the (outer) index dial have a slightly longer “loop” at one end than the other.  The springs fit best when the sides with the longer loop end are connected to the (inner) number dial. You’ll find that out by doing it. The 3 machine screws are for fixing the knob to the index dial. Close-up showing the springs that hold the index dial to the number dial – Sparingly grease the inside of the number dial only, where the toothed edge is. There is no need to grease the index dial. When reassembling, you want to line up the 2 dials so that the machine screws are aligned with the corresponding holes in the number dial, so that you can then screw the knob back on. When in this position, the number 250 should be displaying in the top number slot. You should be able to position the number dial so that 250 is showing. You can rock it back and forth and feel it gently click into place. The number 250 needs to be perfectly centered in the top window before proceeding. If it’s not centered or doesn’t look right in any way, try again. I actually had to remove and reattach the springs before I could get the  number dial to gently but firmly click into place and show the number 250 centrally in the top window. This is what the dial will look like from the back. Notice how the 3 machine screws are aligned with the holes. This only happens when the dial is indicating half-scale (250) – Now, rotate the tuning shaft on the gear box so that the main split gear is set halfway. There are end stops on the main gearbox that make contact with 2 lugs cast into the lid to prevent the main gear from turning more than 180 degrees. In the following photo (which also appeared earlier in this post), you can see the 2 end stops on the left-hand side of the main gear wheel. This is the correct position for when the dial indicates half-scale (250) – For comparison, this picture of an un-greased gearbox shows the gear set to one extreme of travel. Notice one of the end stops at the top of the gear wheel (on the right of the gear) – and notice the 2 “lugs” on the underside of the lid that make contact with the end stops – Slip the micrometer dial onto the shaft and the elliptic hub. It should slip on fairly easily. If it doesn’t, something is wrong. Do not proceed until the micrometer dial easily slips onto the elliptic hub. I fastened the dial onto the shaft with the set screw(s) in the knob, turned it back and forth a number of times and then, because I am particular about these things, disassembled it again and removed all excess grease with my finger. This is what it looked like before reassembly – The fully serviced dial and gearbox operate very smoothly, and should continue doing so for many years. Even better, I now know how to do this. I can pick up more dials and gear drives like this in the future, confident in the knowledge that if they are not operating properly, I can get them to work again. They are very elegantly engineered, with a small number of parts working together to make a very smooth tuning mechanism. They really don’t make ’em like they used to. Oh – and another quick plug for Radio Blvd.  It really is a great site for fans of vintage radios and their restoration. If you enjoy, and get use out of the site, I encourage you to make a small donation to help keep it online. There are links on the site.

The cleaned and lubricated National micrometer dial and PW gear drive, waiting for a replacement variable capacitor unit (spot the errant cat hair on the front of the tuning knob!)

February 7, 2015

N0WVA’s One-FET Regen Optimized For SSB/CW Sounds Great!

Since I began posting about regens, it has been gratifying to hear from fellow regen builders, and quite interesting and inspiring to communicate with other hams who are also taken by their charms. The Sproutie has proved to be a great little receiver and it’s a pretty straightforward circuit, but it’s not exactly a minimalist design. Some hams are so intrigued by the regen’s ability to deliver an impressive amount of gain and selectivity in just one stage, that they focus on building a station with an absolute minimum number of parts. Doug N0WVA has the goal of building a complete (and usable) station with just 2 active devices, and he’s halfway there, having come up with a regen receiver that works well on SSB and CW, contains just one active device, and has a total of just 9 parts including the coil. Better still – it works well. Doug writes, “I’ve been building regens since the 90’s and always wondered why the tube versions always ran circles around the solid state rigs that I had been building. Seems like it always took two transistors to equal what one triode could do as far as recovered audio. Well, I think I might have figured it out. You really can get all that and more from just one FET. Actually, I’d say now that a two tube Doerle will not be able to touch this one transistor rig for serviceability. My intentions are to have only two active devices for an entire CW station. It’s not difficult to get a half watt or so from one device, and even be able to slide around the band a bit via VXO. So the main problem was a decent receiver. Well, I now have that problem solved. All the SS (solid state) regens I had been building had a source resistor and cap. This is to supply self negative bias to the gate. It works, but audio suffers because of the use of a small bypass capacitance at audio frequencies. Larger electrolytics here cause howl when oscillating. By taking the source to ground you can then inject the negative bias through the 1 meg gate leak and set your optimum operating point with a 10k pot. However, this adds to the total parts count. I found that by using a green LED in the source worked almost as well, and bypassed all the audio to ground as well.  Also, since the receiver was to be optimized for CW, I wanted minimal pulling, even on strong stations. To do this we must keep the tank coupling very light. That way the capacitive changes in the junction of the FET has minimal effect on the tank. Finally, another plus for SS regens is the need for much less feedback to achieve regeneration. A properly built SS regen should need no more than 1 turn for a tickler. Much more than this and you get wild instability and a heavier loaded tank. One experiment I did was to try different coil forms and see which ones took less tickler feedback. I found that pill bottles were about the best form for low loss, as I could use just one turn spaced well away from the tank. Even better was a pill bottle with slots cut out of it for less loss, but the wire would try to crush the form. I am using a 1k to 8ohm transformer from Radio Shack to couple into Radio Shack phones, which are a bit more sensitive than other cheap headphones I have used. This results in audio that is loud enough to be highly usable, probably where you would normally run the volume on a regular receiver. The dial drive is a ball bearing vernier integrated into a gear reduction capacitor. The NPO trimmer is a band set. All capacitance is kept to a minimum. I find the less plates on a variable capacitor the better for keeping drift down. The regen control is actually a homemade tickler variometer inside the tank form.  This eliminates the need for a choke and throttle capacitor. I will attach some photos and schematic. Hopefully you will find them interesting. I still need to get the transmitter together and get this on the air. Having just two transistors for a complete CW station will be a blast I think.” Doug made the shaft of his variometer from the plastic barrel of a syringe. I have a number of syringe/pipettes here that I use for giving medicines to my cats and am thinking one of them would be useful for this purpose. Of course, anything cylindrical could be used for a shaft. Doug’s schematic was a fairly low-res scan, so I redrew it. Here’s my re-draw of the schematic of Doug’s one-FET regen –

Schematic of N0WVA’s single-FET regen. It is a monobander on 75/80M. Note: Barry W6YE looked closely at the bandset trimcap in the photos below (the one marked in the schematic above as being 10pF) and discovered, using the part number visible in the picture, that it is a 7-45pF part. Thank you for this information Barry!

I don’t think Doug mentioned the type of FET he was using, so I assume the usual suspects (J310, MPF102) would be fine here. He also doesn’t include coil winding details on the schematic but you should be able to get a rough idea from the photos and besides – if you’re hardy enough to give this receiver a go, you’ll want to figure out the exact values of inductance and capacitance for yourself. It’s good for the soul  🙂 These two online calculators should help – Resonant Frequency Calculator Coil Inductance Calculator (NOTE – Doug provides more details in the comments section at the end of this post) It occurred to me that a good pair of balanced armature headphones (the type referred to as sound-powered headphones and liked by crystal set enthusiasts) could work well. He replied that he had tried a pair of 2000 ohm headphones and they were rather loud, so he would probably need to incorporate a volume control if he used them. Just imagine that – a pair of headphones being too loud when the only thing separating them from the antenna is a single transistor – and with ham signals too, as opposed to big broadcast signals! Here are some pictures of what Doug’s single-FET regen looks like –

N0WVA’s single-FET regen. View from above. Photo courtesy of N0WVA.

In this side-view, you can see Doug’s home-made variometer tickler, with the syringe body that he used for the control shaft –

Side-view of N0WVA’s one-FET regen, showing the home-made variometer tickler, and control shaft. Photo courtesy of N0WVA.

N0WVA’s one-FET regen. Photo courtesy of N0WVA.

N0WVA’s one-FET regen. Photo courtesy of N0WVA.

View from the other side of N0WVA’s one-FET regen. Photo courtesy of N0WVA.

The front of N0WVA’s one-FET regen, along with the RS headphones that give good sensitivity. Photo courtesy of N0WVA.

Doug made a video of his receiver in action. He says it was a little difficult, as he had to use one hand to hold the headphone to the microphone for recording, while tuning with the other hand. If you can, while watching this, have another window open so you can see the schematic and remind yourself that the stable and well-resolved SSB signals you are hearing are coming from that simple circuit. Great stuff –

Original Video – More videos at TinyPic

I can’t wait to see the 1-transistor transmitter he pairs this great little receiver up with. Thank you Doug, for allowing me to share this info on your regen receiver. This is what ham radio is all about.

February 3, 2015

N2HTT Builds His First Receiver – A WBR Regen!

A few weeks ago, I received an e-mail from Mike N2HTT. He was building a WBR Regen, and had encountered a problem – the pesky thing didn’t work. That is indeed, quite a problem.  Luckily for me, he quickly discovered that the reason was an incorrectly wired JFET, before I had a chance to confuse him with my impaired troubleshooting skills 🙂

He got his WBR up and running in short order and after casing it up and actually labeling the controls (only very serious home-brewers label their front panels!), reports that it is working well. He’s tickled pink, because it’s the first receiver he’s built – and I’m tickled pink because he’s tickled pink, if that makes any kind of sense. There is a real magic that springs from hearing sounds come out of a speaker or headphones connected to a receiver you built yourself – even more so if you scratch-built it, as Mike did with his WBR. You can read the story of his WBR build here, and this post contains a link to a YouTube video of his WBR. I like how he describes the setbacks he encountered along the way, and how he dealt with them. In fact, looking further at his blog, I realized this was a common theme. Mike doesn’t just tell you what he did, and post a few photos; he effectively describes the odyssey of his life as a ham who is embarking on the task of assembling a station he built himself.  This style of narrative shines through in the 3 posts describing his building of a 2 tube W1TS transmitter for 40M. You can find them here – Part 1, Part 2, and Part 3.

Look at this lovely transmitter. It’s a classic home-brew project – it’s got an aluminum chassis, a tube, and a crystal in an FT-243 holder!

N2HTT’s version of the W1TS transmitter. Photo courtesy of N2HTT.

Mike was also featured in Soldersmoke for his Michigan Mighty Mite Build, as part of Bill Meara’s Mighty-Mite Madness, not once, but twice – here and here.

So Mike has got it going on. He’s building things, he’s making them work, and he’s telling us the stories of how he got them to work.

Here’s his WBR, in all it’s cased up glory. Read about it here, and here. There will be a 3rd post too, in which perhaps we’ll see pictures of his other WBR which he put on 80M. Yes, that’s right – Mike didn’t just build one WBR – he built two, thanks to the incorrectly wired JFET (you can read how this story unfolds in his blog).

N2HTt’s WBR Regen Receiver. Photo courtesy of N2HTT

Check out Mike N2HTT’s blog here. Way to go Mike, and thank you for sharing details of your personal journey towards a 100% home-brew station!




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