Category Archives: Kits

KM4CFT’s Iambic Paddle Kit for the Elecraft KH1

Many thanks to Jonathan (KM4CFT) who notified me that his new KH1 iambic paddle kit is now available to order.

I know Jonathan has been working on this little key for a while and I’m pleased to see it come to fruition.

Click here to check it out on eBay via Dan (W7RF).

Note that this is an eBay partner link that also supports QRPer.com at no cost to you!

QMX – From Kit to Field!

by Matt (W6CSN)

The Radio

The QMX by QRP Labs is a five band, multi-mode radio introduced by Hans Summers G0UPL at FDIM in 2023. The QMX is the next logical step in the radio development journey at QRP Labs, bringing together the innovative approach to FSK modes like FT8 from the QDX and the CW performance of the QCX series. This is all done in same enclosure as the QCX-Mini which is not much larger than a deck of playing cards.

Size of the QMX compared to standard deck of playing cards.
The QMX is about the size of a deck of cards.

The keen observer will notice that the QMX also sports a built-in microphone which, along with associated circuitry, supports future introduction of voice modes by way of firmware update. Other notable features include SWR metering with protection as well as solid-state “PIN” diode T/R switching, plus the option for “high band” coverage of 20 through 10 meters in addition to the original 80m-20m version.

Most hams have, at one point or other, forgotten to throw the antenna switch, adjust the tuner, or even connect an antenna before transmitting. The SWR meter and protection really sets the QMX apart from earlier QRP Labs radios. There are plenty of sad tales on the QRP-Labs forums from QCX or QDX users that “smoked” the BS170 mosfet finals in a moment of operating into a badly mismatched load. It’s remarkably easy to do, ask me how I know!

The Build

Based on experience with the QCX-Mini and having put together several QDX’s, I admit to being hesitant to starting assembly of this radio. The level of integration in the QMX as a multi-band, multi-mode unit is probably the highest yet to come out of QRP Labs. The components that were merely small in earlier radios are absolutely tiny in the QMX, specifically the LPF toroidal cores. The main board, internal switching power supplies, display, and controls board are all sandwiched together in a tight fit for the custom enclosure.

photo showing a partially completed circuit board
Most of the electronic components installed on the main board.

The build started with a slow and methodical approach of doing a little bit each day and working in the morning when my mind was fresh and there was good light on my workbench, a.k.a. the dining room table.

The first “disaster” happened when performing the factory recommended modification to Revision 2 boards shipped in 2023. The mod calls for a protection diode to be installed across a SMD mosfet. Several leaded 1N4148 diodes were available in my “junque” box so I attempted to carefully fit one of these in the right position on the board. While soldering the diode in place I managed to lift C508, a microscopic .1uF SMD capacitor, clean off the board!

photo of circuit board with modifications
The suggested modification adding a protection diode.

Given the tools at my disposal, there was no way I was going to be able to get that capacitor back into place. Therefore, I grabbed a standard through hole .1uF cap and painstakingly got it connected in the right place, verified by lots of continuity testing.

Once finished with all the electronic components on the main board, I was feeling pretty cocky and also the completion of the project was more clearly in view. The cautious and methodical approach gave way to a faster build pace, which directly lead to the second “disaster.” While installing the headers that connect the main board to the display board, I failed to CAREFULLY READ THE ASSEMBLY MANUAL and soldered the male pin headers where I should have installed the female sockets!

This misstep might have ended the project right then and there if I had not at some point in the last year bought a proper desoldering tool. This is not an expensive automatic vacuum pump powered solder re-work stations, but rather a heating tip and manually actuated solder sucker built into one tool. Twenty-two unsoldered connections later, we were back on track. Continue reading QMX – From Kit to Field!

HRWB DC Distribution Panel Kits in stock at Digikey!

Many thanks to Mike (KG4MTN) who notes:

Good morning Thomas,

I did not know if you are aware, but Digikey has in stock about 67 HRWB 5-port dc power strip kits. I ordered one last night, they are $49.94 plus tax/shipping. Apparently these have been out of stock for some time, I am glad to see them available.

72 and God bless,
Mike Serio
KG4MTN

Thanks for the tip, Mike! These will sell out quickly, so grab one while you can, I say! I love mine.

Click here to purchase one via DigiKey!

Field Radio Kit Gallery: KD0FNR’s Rockmite 20 and Tuna Topper

Many thanks to Hamilton (KD0FNR) who shares the following article about his portable field radio kit which will be featured on our Field Kit Gallery page. If you would like to share your field kit with the QRPer community, read this post.


Rockmite 20 and Tuna Topper Pack QRP Punch

by Hamilton (KD0FNR)

Our ham radio field kit—in my mind—revolves around simplicity. I’ll walk you through a lot of details, because we have a blast with the field kit and I love talking about it. At the end of the day, it’s a kit radio and amplifier housed in a couple of cans with lengths of wire we bought at a hardware store for an antenna, a cell phone power brick, and a keyer glued together out of video game switches and an old battery case. We’ve thrown the kit into cloth shopping bags and backpacks with equal measures of success. We once patched an antenna connection using washi tape.

OK, I said ‘our’ and ‘we’, but who are we? I’m the dad of three kids—one of whom recently passed her Technician radio exam, KO6BTY—who are 12, 11, and 8 years old. Right now, they’re rarely on the radio—of course, that’s about to change—they help with most aspects of our radio outings.

Which brings up the question, what do our radio outings look like? Our outings are pretty equally divided between, camping and day trips. Our entire family has enjoyed camping—and done a lot of it—since long before I got back into ham radio. Each of the kids went on their first camping trip when they were a few weeks old.  Our camping trips range from local, public transit enabled outings—we take the bus to Pantol Campground, across the Golden Gate Bridge from San Francisco where there are two POTAs readily available: Mt. Tamalpais State Park and  Muir Woods. We also take multi-day/week trips: I grew up in New Mexico, so the kids and I frequently find ourselves back there activating or attempting to activate sites like Villa Nueva State Park, Organ Mountains National Monument, and Cibola National Forest, among others. These are the outings that have led to large-ish battery selections you’ll see below.

Our day trips are quick runs along various local bus, train, and ferry lines with a hike tacked on the end. Within the peninsula that encloses San Francisco, we have several POTA locations and two easily reachable SOTA locations. We pretty frequently bus to a spot, and then spend a few hours hanging out in a nice park getting some radio time.

Having said all of that, you might have guessed that our kit would be optimized for easy travel. You’d be right. Now, finally, let’s talk about the kit!

Radio Details:

All of our equipment is home-built. It’s evolved over the last year-and-a-half into he tidy kit you see above. Finally having a ‘typical’ kit picture is actually what inspired this article.

Equipment List:

[Please note: All Amazon links are affiliate and support QRPer.com.]

  • Rockmite 20
  • Tuna Topper
  • One 20 ounce can Dole Pineapple Slices (emptied—see support crew; and cleaned)
  • Two RJ-45 breakout boards
  • One spool butcher’s twine (two if you’re feeling bougie)
  • One Imuto power brick that supplies 15 V when funneled through:
  • One Adafruit USB Type C Power Delivery Dummy Breakout – I2C or Fixed – HUSB238
  • Two banana jack sockets (plus a few more for spares)
  • Forty feet 12 gauge insulated/stranded wire
  • Twenty-five feet (or so) RJ-45 Ethernet cable (scavenged from the parts bin at our local maker space)
  • One antenna launcher (scavenged from available fallen tree limbs onsite)
  • One donut Bag from your favorite donut store
  • One roll of washi tape

The Rockmite is a rock-locked radio with two available frequencies that are 500 Hz apart from each other. That makes our antenna design really simple; we’ve got a dipole that’s trimmed to be resonant at 14057.5 kHz. Project TouCans puts out a QRP maximum 5 Watts. Our field kit has evolved to that 5 Watts though. We started out with the Flying Rockmite at 250 mW, then we made a power bump to 750 mW, and then with the addition of a Tuna Topper amplifier and a lot of experimenting we finally achieved a QRP maximum 5 Watts output power.

The QRPp Rockmites–having so little power combined with lots of somewhat confusing reading about antenna matchers and coaxial cable and baluns–led to the original Flying Rockmite. “Do you know what makes you not have to discuss feed lines?” I reasoned, “Not having a feedline.” And so, the RockMite was inserted into the dipole. I brought the keyer controls down to me and sent the power up along an Ethernet cable. Continue reading Field Radio Kit Gallery: KD0FNR’s Rockmite 20 and Tuna Topper

NM0S introduces the NorCal 40B transceiver kit

Dave (NM0S) has updated the NorCal 40A transceiver kit. Here’s the information from NM0S’s website

NM0S Electronics has received permission from the Wayne Burdick N6KR to produce an updated version of the legendary NorCal 40A CW Transceiver.

The new ‘B’ version kit overcomes the issues with obsolete components that caused the original kit to end production.

The NorCal 40B follows the design of the original faithfully, while adding a rugged pre-drilled, silkscreened enclosure!

Click Here to order ($150 US)!

Are you prepared for Radio First Aid?

by Vince (VE6LK)

(As is Vince’s usual, this article has a bunch of links – click on as many as you wish for the full experience)

Before I go too far into this topic, I wish to first offer hearty congratulations to Thomas Witherspoon for having one thousand posts on QRPer.com! Woo-Hoo!

Do you pack a Radio Field First Aid kit?

On my recent trip to VE3-land I had a few opportunities to practice set-up with my gear–away from the safe place that is my truck–to ensure I’d brought everything for my trip to Hamvention and activations along the way. I did forget an audio cable, however a visit to a local dollar store solved that problem inexpensively.

So, unless you pack two of everything -because two is one and one is none– you should expect that something’s going to fail or break along the way. What you never know is when or how that’s going to happen. I wouldn’t be writing this story if it had not happened to me before.

This time it was on a Sunday outing to VE-1512, the McLaughlin Bay Reserve Wildlife Area in Oshawa Ontario and far away from the comforts of my shop at home. Tucked away not far off of the 401 Highway, this nature reserve is a calm and peaceful oasis just minutes from urban life. I saw kayakers, hikers and trail runners during my visit.

Setting up my Comet HFJ-350M, I added the jumper cable to set the antenna for 20m and then I started to push the antenna down into the ground onto the stake. And that’s when my hand slipped and I broke the jumper cable connector, busted off in the hole.

Broken pin that triggered my outward potty mouth

For the inquisitive among you, my inner potty mouth made a brief outward appearance, ahem. Continue reading Are you prepared for Radio First Aid?

POTA at Fort Dobbs: Testing a BCI filter and depleting a battery!

Friday, March 17, 2023 was a dreary, rainy day.

It was the sort of day made for reading a good book by the fireplace or…in my case…activating a park!

I don’t let rain stop me from playing radio in the field. I carry a rain fly in my car pretty much all of the time so if push comes to shove, I can create a dry space to play radio.

That said, a number of parks I frequent have large covered picnic shelters, so why not use what’s already there?

That particular Friday, I had one particular park and one particular goal in mind.

G106 + BCI Filter

As I mentioned in a post this weekend, I purchased and built a K9DP BCI Filter Kit.

If you’d like to see photos of the build, check out this post.

I built this BCI filter specifically to pair with the Xiegu G106 transceiver. Why? Because the G106 is prone to overload if you’re anywhere near an AM broadcaster.

The last time I visited Fort Dobbs State Historic Site (K-6839), a local AM broadcaster bled through the audio of the G106. I was able to complete the activation without any issues at all–in fact, it was a very successful activation (read the report here).

Still, I did feel that the receiver was a bit less sensitive due to the broadcaster overwhelming the front end of the radio.

That Friday, I wanted to pair my Xiegu G106 with the new in-line BCI filter to see if that might mitigate the interference I experienced before.

Fort Dobbs State Historic Site (K-6839)

After arriving at Fort Dobbs, and before taking my gear out of the car, I made my way to the park office (in the log cabin at the end of the sidewalk above) and asked for permission to use their picnic shelter. Continue reading POTA at Fort Dobbs: Testing a BCI filter and depleting a battery!

Video: Alan’s method for winding toroids

After posting my article about the K9DP BCI filter kit build, Alan (W2AEW) commented:

If you dislike winding toroids, the method I show in this video makes it a lot easier!

This is an excellent way to handle the toroid while winding. Check out his video below:

Click here to view on YouTube. 

Alan has a massive library of instructional videos on YouTube. If you haven’t already, subscribe to his channel!

Assembling a K9DP BCI Filter Kit (Photos)


If you own a Xiegu G106, X6100, or any other radio that is prone to overloading when in the presence of an AM broadcaster, you should consider building an in-line BCI filter!

As many of you know, I’ve been testing the Xiegu G106 over the past couple of months for a review that will be published in the May 2023 issue of The Spectrum Monitor magazine.

One criticism of the G106 is that its front-end overloads when there’s an AM broadcaster within a few miles of where you choose to operate. The Xiegu X6100 is identical in this regard.

One quick way to remedy this is to build or buy a BCI filter. We’ve mentioned in the past how you can homebrew them and I planned to do so. After checking my parts drawer, though, I realized I needed to buy a capacitor, toroids and at least one of the two BNC connectors needed if I wanted an in-line filter in a small project box.

I decided it would be much easier to simply buy a kit and, based on a tip from a reader here on QRPer.com, I purchased one from Dan (K9DP). Continue reading Assembling a K9DP BCI Filter Kit (Photos)

From idea to kit: Adam introduces the Arduino Digital Modes HF QRP Transceiver (ADX-S) kit

Many thanks to Adam (BD6CR) who shares the following guest post about his latest project:


From Open Source Project ADX to Kit ADX-S

by Adam (BD6CR)

BD6CR @ CRKits.COM

Original Design: WB2CBA

Modification and Kitting: BD6CR

I knew Barb, WB2CBA from his uSDX design a few years ago and I introduced both DL2MAN and his designs in my blog. So, when I came across the ADX – Arduino Digital Xcvr a few months ago, I immediately ordered both the ADX (through hole) and the ADX UNO (surface mount) PCB samples.

I started building the ADX UNO and put it in a dental floss case and made a few contacts on park bench. However, the soldering is too much for my eyesight. So, I turned back to the ADX because I don’t need to solder any SMD parts, since both the M328P and SI5351 are module based. I could build the project in 3 hours and it worked the first time.

However, I felt unsatisfied with the strong BCI since the CD2003 radio receiver chip was connected as a direct conversion receiver. JE1RAV mentioned in his QP-7C modification project that he tried JA9TTT’s idea to build a superhet SSB receiver with the TA2003 or CD2003, so I tried and it worked very well. I have decided to name the new circuit as ADX-S, where S stands for Superhet.

I shared the great news with Barb and he encouraged me to carry the flag to make it a kit, since my design D4D was his first digital radio and he loved it.

You can refer to Barb’s page on ADX here.

My hardware modification can be outlined in this schematic. I have added an FL1, PFB455JR ceramic filter by Murata and a C25 coupling capacitor from CLK2 of SI5351 module. The RX audio comes from pin 11 instead of pin 4.

I modified it by cutting two traces on the ADX PCB and it looked ugly, so I redrew the PCB. Continue reading From idea to kit: Adam introduces the Arduino Digital Modes HF QRP Transceiver (ADX-S) kit