Category Archives: Articles

Articles, Guest Posts, News, POTA

VE6LK’s #POTAThon1231: The RAC Portable Operating Challenge

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Many thanks to Vince (VE6LK) who shares the following POTA field report:

Canmore Nordic Centre VE-1167, Alberta

#POTAThon1231 – The RAC Portable Operating Challenge

by Vince (VE6LK)

It’s the final day of December 2022 and I find myself, a non-hiking non-climbing city kid, trudging around in the snow on a nature preserve not far from my home. I’m in shape -round- and it’s not helping me much. I’m not really dressed for this but I’m not far from the warmth of my truck. My goal is to do an activation and move on, for I’m in the middle of the final day this month of a set of #POTAThons and I still have one more park to get to.

#POTAThon is what I call it when I plan on getting to more than one park in a day. Usually these things aren’t thought of for weeks in advance, they are more like a “tomorrow morning” kind of thing. Opportunistic, if you will. Please feel free to adopt the hashtag on social media as it is free from all royalties and encumbrances.

VE-3477, British Columbia

But, before I tell you the story of how I happened to be trudging through the snow, let me tell you that someone said something to me that set me off on the journey that had me trudging through snow on that day and hefting a wire into a tree.

Revelstoke National Park VE-0061, British Columbia

I do public service events throughout the year, and in December I travelled from my home in Alberta one province westwards to Kelowna B.C. to the Big White Winter Rally. RallySport is fun to get involved with as a ham radio operator, and is especially trying -for all the right reasons, as you’ll see in this clip from 2015– in Net Control where we run logistics for the event. You’ll be able to read that story in the March-April edition of The Canadian Amateur magazine.

In Net Control, set up and ready to run the race. 6 people will be in here. (Click to enlarge)

Anyway, I’m to the point in my life where a long one day drive is no longer enjoyable, thus along the way to BWWR, I planned to activate parks and take two days to make the trip each way. A week off to play radio sounds like a great vacation to me at any time! Thus, the plan was struck to do this and have fun. This means that multiple #POTAThons would be required! Continue reading VE6LK’s #POTAThon1231: The RAC Portable Operating Challenge →

Articles, News, QRP Radios

If Yaesu designed an FT-818 replacement…what would you like to see?

74 Comments

We hams can be quite opinionated when it comes to our radios.

After Yaesu announced last week that it was discontinuing production of the FT-818ND, hams across the globe expressed their opinions about this pint-sized rig.

It seemed to me that the majority who posted messages in email groups and on social media had high praise for the FT-817/818. Indeed, many of those same people purchased an FT-818ND the same day of the announcement. The rush of FT-818ND purchases wiped out new inventory at most US retailers overnight.

Not everyone had praise for the FT-817/818 series, though. Many felt the ‘818 was a relic of the past and irrelevant in 2023. Some even posted long “good riddance” rants about the FT-818.

Let’s face it…

Our love of radios is highly subjective

What one person loves, someone else might hate. This is especially the case in the incredibly diverse ham radio world where radios are used in different parts of the spectrum, with different modes, for different activities, and in different operating environments. Continue reading If Yaesu designed an FT-818 replacement…what would you like to see? →

Articles, Morse Code, NPOTA, People

BBC Radio 4 – Lights Out: Call Signs

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My dear friend, Volodymyr Gurtovy (US7IGN), has been featured in another brilliant documentary on BBC Radio 4 called Call Signs.

This documentary was produced by the talented Cicely Fell with Falling Tree productions for BBC Radio 4. Note that Cicely also produced a BBC Radio 4 Short Cuts earlier this year featuring Vlad as well. Enjoy:

BBC Radio 4 Lights Out: Call Signs

A man, a Mouse and a morse key: the story of a radio amateur in Kyiv as the Russian invasion unfolds.

When his wife and two children flee Kyiv to escape the war, Volodymyr Gurtovy (call sign US7IGN) stays behind in their apartment with only his radios and the family hamster, Mouse, for company.

Before the war, he used to go deep into the pine forests, spinning intricate webs of treetop antennas using a fishing rod, catching signals from radio amateurs in distant countries.

Prohibited by martial law from sending messages, he becomes a listener, intercepting conversations of Russian pilots and warning his neighbours to hide in shelters well before the sirens sound. After three months of silence, he begins transmitting again. Switching his lawyer’s suit for a soldering iron, he runs a radio surgery for his friends and neighbours, dusting off old shortwave receivers and bringing them back to life.

During air raids, he hides behind the thickest wall in his apartment, close to his radios, their flickering amber lights opening a window to another world. A story of sending and receiving signals from within the darkness of the Kyiv blackout.

Music: Ollie Chubb (8ctavius)
Producer: Cicely Fell
A Falling Tree production for BBC Radio 4

Listen to Call Signs on BBC Sounds by clicking here, or via the embedded player below:

 

Articles, News, QRP

The spirit of QRP

63 Comments

Here we are, on the morning of Christmas Eve, and I find this quote from Teddy Roosevelt  floating around in my head:

“Do what you can, with what you have, where you are.”

                                    –– Teddy Roosevelt

Perhaps I’m thinking about these words because they sort of fly in the face of all of the consumerism that often surrounds the holiday season…?

Well, I’m not sure of the reason.  What I do know is, I feel like this quote speaks to me as a QRPer. Part of the appeal of low-power operations is making do with less. With just a faint breath of power, I can reach across the globe to connect with others, and have just as much fun doing it as the guy with the tall backyard tower.  Yes, I have to admit, there’s a certain satisfaction in that.

You might not know this, reading QRPer.com, where we often talk gear, discussing its various shortcomings and merits, but I’m actually a fan of simplicity.  Outside of the world of radios and packs––and even in it, to a degree!––I try not to own too many things.

In my little QRP world I feel incredibly fortunate to be able to beta test, review, and evaluate a wide variety of radios and gear. Since I do purchase almost all of my review radios––except for the few that are loaned to me––I’ve accumulated a lot of them over time. I know I can sell the ones I don’t often use, and I frequently do, but it’s fun to take them out for a spin now and again; you may notice that I rotate them out regularly.

Yet because of this, I do worry that people read my posts (and those of others in the ham community) and reflect with despair along these lines: “I can’t activate in the field…I need a lot of new expensive gear to do that!”

But this couldn’t be further from the truth.

For four years, when I lived in Germany and the UK, I only owned one radio–a Yaesu FT-817. And, know what?  I had so much fun with that single radio and a limited number of home-brew antennas.

To which I might add, this past year, some of my most memorable activations have been with radios I purchased for under $200:

I could easily activate all of the parks and summits I wish, only using one of these little radios, coupled with a key, a home-brew wire antenna, and a battery.  That’s it~!

So, you really don’t need a lot of gear to enjoy field radio.  This is true especially if you’re a CW operator.  But even just starting out, you really can have fun with a simple field kit.

Even if you’re new to ham radio, don’t wait to hit the field until you’ve assembled the “perfect” or the largest, finest field radio kit. Instead, take Teddy Roosevelt’s advice,  and just do what you can with what you have…right where you are.  

Here’s wishing everyone

A Very Happy Holiday Season! 

Articles, Morse Code, News, Portable, POTA, QRP, QRP Radios, Reviews, SOTA

A review of the LnR Precision Mountain Topper MTR-4B ultra-portable QRP transceiver

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The following article originally appeared in the November  2022 issue of The Spectrum Monitor magazine:

A Review of the LnR Precision Mountain Topper MTR-4B V2

by Thomas (K4SWL)

I confess, there is something that I’ve come to believe is almost a rite of passage in the SOTA (Summits On The Air) community. And, no, I’m not talking about activating an All Time New One (ATNO) summit, or completing a particularly challenging activation on a snow-capped peak.

I’m talking about owning one of the iterations of the amazing “Mountain Topper” pocket-sized QRP CW transceivers designed by Steve Weber (KD1JV).

This little radio first caught my attention at a Four Days In May (FDIM) QRP conference over a decade ago: a ham friend in the SOTA community proudly showed me a very early version of the Mountain Topper that he built from a kit. The first thing that struck me was how impossibly small and extraordinarily lightweight it was. But when he showed me the 9-volt battery he used to power it––a power supply not only small, but convenient––I was mesmerized.

Over the years, the Mountain Topper has evolved.  There have been many models, ranging from two bands to five. To my knowledge, they’re no longer offered in kit form, but LnR Precision manufactures and tests these in North Carolina, and they’re better than ever in terms of features and performance.

At present, the MTR-4B V2––the second version of the four-band Mountain Topper––is the only model in production, and if you’re hoping to acquire one, due to supply chain issues (at time of publishing) there’s a rather long wait time. They retail new for $350 US, and frankly, the used ones I’ve seen posted in ham radio classifieds ads have been equal to, or even over, the listed price for a new rig.  Obviously, demand for these radios is much higher than supply.

So, how could it be that this minuscule QRP radio performs well enough to produce some serious DX from a remote summit…so well, in fact, that people are willing to wait in line for one?

Magic or method?

As any CW operator will tell you, the magic is in the mode. CW is such an efficacious mode that it cuts through the ether like a knife, even when conditions are less than favorable.

Obviously, pint-size radios like the Mountain Topper are QRP––low power––so designing them around such a simple mode is a very smart choice. CW transceivers are much less complex than a similar SSB transceiver, thus have less components, less mass, and are in general more affordable (when compared to those with similar receiver performance).

My comprehensive MTR-4B field kit (the MTR-4B is in the mesh pocket).

In addition, the Mountain Topper is designed with the field activator in mind:  specifically, SOTA activators, but of course, POTA (Parks On The Air), WWFF (World Wide Flora and Fauna), IOTA (Islands On The Air), or any other popular “-OTA” field activity. As a field activator in one of these programs, you are the DX. This means chasers and hunters are actively seeking your signal, and thus you are not competing with blowtorch stations to punch through a pileup.

I can also assure you that standing on a tall summit also gives you a brilliant starting point for your QRP signal. Some of the best DX I’ve ever worked has been from a summit.

So, for the average CW SOTA activator, QRP is preferred because QRO simply isn’t necessary––indeed,  in my opinion it’s a bit of an overkill. At least that’s been my experience now with my few hundred SOTA, POTA, NPOTA, SOTA, and even one Lighthouse On The Air activations.

So this brings us back to the wee Mountain Topper series and the model being reviewed here in the pages of TSM: The Mountain Topper MTR-4B. Continue reading A review of the LnR Precision Mountain Topper MTR-4B ultra-portable QRP transceiver →

Accessories, Antennas, Articles, Morse Code, News, QRP, Reviews

A Few Field Radio Gift Ideas for Less Than $100!

28 Comments

I received an email from a reader’s spouse asking about gift ideas for the holidays and beyond; ideas that could not only be used this month, but also tucked away for the future. They weren’t looking for the obvious things like a transceiver–they were looking for accessories that might enhance their significant others’ field radio fun.

Being the enabler I am, I was happy to oblige and, in fact, decided to turn my reply into a post (since it quickly turned into a very long email) with their permission. For obvious reasons, I’m keeping their ID secret! 🙂

Here’s a rather random sampling of things that came to mind. I tried to limit this to items that retail for less than $100 US. Note that some of these product links are affiliate links:

A quality LiFePO4 battery

Being a QRPer, I don’t need a large battery to enjoy hours of radio fun per charge. My favorite battery chemistry is LiFePO4 due to its weight, safety, shelf life, and recharge cycles (which is in the thousands as opposed to hundreds).

For me, a 3Ah battery is more than enough capacity to keep my QRP radios on the air for 3-5 activations per charge (depending on length of activation, etc.).

I’m a big fan of Bioenno batteries. Their customer support is excellent. You can purchase their 3Ah 12V battery for $64.99 US including the charger. If you already have a charger, the battery alone is $49.99. Click here to check it out.

If your significant other likes to push 100 watts, consider a larger capacity battery. I also have a 15Ah Bioenno battery for this purpose, though it exceeds the $100 gift price threshold). Click here to check it out.

A very affordable Li-Ion rechargeable battery


One of the most affordable rechargeable battery packs for the QRPer in your life is the TalentCell Rechargeable 12V 3000mAh Battery Pack. This pack typically costs around $30 US and is sometimes even less expensive.

This little pack is great because it will not only output 5V to recharge USB devices, but it also outputs 12 volts which is brilliant for QRP radios like the Elecraft KX series, TX-500, FT-817/818, Mountain Toppers, Penntek TR-35,  Venus SW-3B, and many others. I actually now pair this with my QCX-Mini. The battery comes with the charger and standard barrel connectors on the included DC cord which fits Elecraft and Penntek field radios among others.

This is a small battery, so can only be paired with efficient QRP radios.

While I don’t consider this a high-quality solution like a Bioenno battery, it is insanely useful and affordable. Click here to check it out.

Morse Code Keys!

I could easily write a series of articles about Morse Code keys. That’s not what you’re looking for, though, right? You want some quick suggestions. Here is a sampling of some of my sub $100 favorites listed in alphabetical order.

If your budget is flexible, you might also consider these paddles which are still less than $200:

Okay, so if you don’t mind pushing more than $200, I highly recommend any key made by the amazing Begali family. Their Simplex paddle was my first set of paddles and I still use them today. I plan to buy their Traveler next year. They’ve a massive selection of models and styles. Continue reading A Few Field Radio Gift Ideas for Less Than $100! →

Antennas, Articles, How To, Mobile, News

Dave sorts out vehicle-mounted antenna SWR issues

9 Comments
Photo by Katie Musial.

Many thanks to Dave (K1SWL) who writes:

Comments on vehicle-mounted antennas

by Dave Benson (K1SWL)

As with Rand’s recent post about his effective vehicle setup, I and others also use a small operating table inside the vehicle.  I’ve tried a number of approaches to antennas.  Without elaborating on those schemes, I’ll note that winter is now closing in here in NH. As a result, I’m now operating exclusively from my truck. My interest is now in minimizing setup and tear-down times.  Barry (WD4MSM)

also commented about the improvement in vehicle-mounted antennas with an added ground.  I’d like to quantify that.

I’d recently ordered a number of Hustler Mobile antenna components. They’re used as a stationary-portable setup using that company’s high-quality mag-mount. As I first evaluated the antenna, I was disappointed to find the minimum SWRs to be on the high side.

These results were related to the ‘floating’ coax shield, which serves as a counterpoise with the mag-mount setup.  Worse yet, these results were inconsistent. Touching the coax connector shell at the antenna analyzer caused the SWR to jump up, as did just changing the way I held the analyzer. Bad juju! It means RF inside the vehicle, with the potential for RF-‘hot’ symptoms at the rig..  Adding a 1:1 balun inline eliminated the stray RF at the rig, but didn’t do much for the SWR. It’s also just one more gadget to bring along.

A better fix was a custom bracket that bolted to the truck frame. I first confirmed that there was low-resistance continuity between a target location and the vehicle’s cigarette lighter shell.  This was something of a ‘comedy of errors’. I had a sheet-metal angle bracket on hand and went to work enlarging a hole in it. This had the usual outcome: a drill bit grabbed the workpiece and spun it. The bracket itself was buckled beyond redemption and my finger’s now healing well.  A length of 1-1/2 inch aluminum angle bracket was just the ticket.   Note that the mounting hole needs to be offset from the coax fitting mount. This avoids an interference between the mounting bolt and coax connector shell. Ask me how I know.  The bracket assembly uses a specialty coax fitting from DX Engineering. It’s their part number DXE-UHF-FDFB.

This bracket is bolted down on one of the corners of the Tacoma’s passenger seat assemblies.  It’s the closest location to the antenna I found without drilling holes and cutting the coax.  For this vehicle, it’s a 10mm bolt and was paint-coated for appearance reasons. I replaced it with a stainless-steel bolt from a hardware store. It’s important to include a split-lockwasher between the bolt and the bracket. This’ll keep the conductivity to the frame good over time. The bracket is deburred and its corners rounded to preclude injury to passengers.

In any event, it’s out of the way of the seat’s legroom space. A 3-foot coax cable assembly brings the coax nicely up behind the rig atop the operating surface.

So- how’d it work? It’s like the difference between night and day!  The broad SWR curves vanished – replaced by typical characteristics for monoband antennas. The sensitivity to handling the coax has vanished.  (A representative curve at right.) The curves are narrower, and that’s actually a good sign- it means that unwanted resistances have been reduced. 

With this fix in place, here are the SWR minima:

Frequency    SWR

14060        1.04:1

21060        1.05:1

28060        1.16:1

I took advantage of the CQ Worldwide CW Contest this past weekend. I was able to work 101 stations on 10M, 15M and 20M with this setup.  That was from a State Park 5 minutes away.  The attraction was a large and sunny parking lot, and solar gain was such that I needed to leave the truck door open several times.  This area is kept plowed out in winter, and I may try for the POTA ‘kilo’ award from there at the 1000-contact benchmark.  

We’ll see….   73, K1SWL

Articles, News, Portable, POTA, QRP, QRP Radios, Reviews, SOTA

The enduring Yaesu FT-817 and FT-818 series transceivers

54 Comments

The following article originally appeared in the October 2022 issue of The Spectrum Monitor magazine:

The enduring Yaesu FT-817 and FT-818 series transceivers

by Thomas (K4SWL)

Last April, our family went on a camping trip at New River State Park in Ashe County, North Carolina; we had an absolutely brilliant time.

Naturally, as with any camping trip or extended travel, I’d put a lot of thought into choosing the portable transceiver and field kit to take along.

The great thing about camping at a state park is that I can “activate” that park via the “Parks On The Air” (POTA) or “Worldwide Flora and Fauna” (WWFF) programs pretty much anytime: early morning, late afternoon, or even in a late shift well into the night. Or, of course, all of the above.  Since my activation site is also where I’m eating and sleeping, my radio usually gets heavy use.

Before leaving on that April camping trip, I knew what radio I wanted to operate the bulk of the time: my Yaesu FT-817ND. For a lot of reasons which  I’ll delve into later, I think the FT-817ND (or its latest iteration, the FT-818ND) is an amazing QRP field radio.

Despite unstable propagation and a little campground QRM that moved in over the weekend––no doubt from a neighboring RV, chock full of noisy switching power supplies––I found the FT-817ND activation to be a most enjoyable experience. I posted a few field reports and activation videos from my New River activations on QRPer.com. 

The thing is, each time I publish a field report using the FT-817ND, I receive a string of questions from subscribers and readers. Questions such as…

  • Should I buy a new FT-818 or a used FT-817?
  • Why do you like the FT-817ND so much?
  • What’s the difference between the 817 and 818?
  • How does the FT-817/818 compare with _____ radio?

Most queries, however, are a version of this comment from reader David:

“We have such a wide array of QRP rigs available to us these days, I’m curious what brings you back to the Yaesu for activations? It’s bigger than our more modern radios, with no ATU and more current draw.   I’m just wondering if there is something that you find it does particularly well, or if it’s just ‘because I like to use it,’ which to me is an entirely valid reason, too! My 897 served me well, as does my 891; I’ve had Yaesu handhelds forever, so I’m certainly a fan. I don’t own an 817/8 but they have a devoted following so I just wanted to get your perspective on it.”

Or as another subscriber distilled the question:

“Why choose a legacy design like the 817/818 when newer QRP transceivers have better overall field specs and features?”

Of course, these types of questions are simple enough when it comes to asking, but when it comes to answering, much more complex.

Of course, as I said in my recent TSM article about choosing a field radio, one’s love of a particular radio is by definition quite subjective, and this certainly applies to my response…we all have our own personal preferences.  But behind these preferences are objective facts, such as product’s unique features, specifications, and form factor; let’s take a look at these.

Continue reading The enduring Yaesu FT-817 and FT-818 series transceivers →

Articles, Field Reports, Guest Posts, News, Portable, POTA, QRP Radios

Mark’s first POTA activation with the Penntek TR-45L

14 Comments

Many thanks to Mark (W8EWH) who shares the following field report:

An Afternoon POTA Activation with the PENNTEK TL-45L

by Mark (W8EWH)

I have a hard time resisting new QRP radios, and I have an equally hard time resisting getting outdoors when late October brings 70F (21C) temps to Michigan.  Days like these are especially sweet given we saw the first snow here last week (no accumulation – but still…). For me there was no better way to enjoy this unexpected weather gift than with an early afternoon POTA activation with my newest QRP radio, the PENNTEK TL-45L.

The TL-45L is the latest radio from WA3RNC, joining the TR-35 and TR-25 in his online store.  It’s a 5-band, 5-watt CW transceiver covering the 80, 40-, 30-, 20- and 17-meter bands.  That in and of itself is not particularly noteworthy.  But when you look at this radio, you’ll immediately see what makes it different.

The retro look for me is unlike anything I have seen in a modern QRP radio.  It frankly looks like it was removed from an Apollo Command Module.  From the front meter to every knob and switch, this radio just begs to be fiddled with.  And each knob and switch serve a function that means no longer needing to dig through menu after menu to find where the narrow filter is switched in because of nearby QRM, or so I can slow down when my CQ POTA is responded to by a slower CW call.

The speaker is located on the (left) side of the radio, a feature many smaller QRP radios don’t have, though headphones can be used via a front mounted jack.  The radio sounds great – I think the radio’s case provides a nice sound chamber.

The TR-45L comes with a couple of options, neither of which I chose to add to my order.  One is a built-in rechargeable battery (5200 mAh), and the other an antenna tuner.  I have plenty of batteries, and normally use resonant antennas.

With the Monday late morning temperature approaching 70 I packed the car with radio gear, and my wife, and we headed out to Island Lake State Recreation Area (POTA K-3315) to activate this park with the TR-45L for the first time.  My wife is not a ham but often comes with me to POTA activations.  While I set up, activate, and then pack up, she enjoys the outdoors with a magazine and crossword puzzle, and sometimes, like today, a light lunch.  Usually, once the activation is complete, we’ll go for a hike on park trails.

Island Lake is about a 20-minute drive from my house.  Its 4000 acres is a mix of open fields and hardwood forests surrounding Kent Lake and the Huron River.  Today it was warm enough that someone was using a paddle board on the lake.

I have found a set of picnic shelters on elevated ground overlooking Kent Lake as a great place from which to activate.  I worked North Pole Alaska from this location on 20M CW using my IC-705 with 10W into an EFHW last May.

Once at the shelter I set up my EFHW (KM4ACK kit) in a sloped configuration using a conveniently located mature tree and my throw line.  It was roughly in an East/West orientation. Over the preceding weekend, I added PowerPole connectors to the provided power cord, and programed both internal CW keyer memory slots.  These are activated using either dit or dah paddle when I toggle Play using the provided switch.   Of course, I did a little POTA hunting using the home antenna to familiarize myself with the TR-45L’s operation.  The learning curve is short with nothing hidden deep behind any menus.

With the radio and antenna ready to go, I set up HAMRS on my iPad, spotted myself on the POTA website, and started calling CQ POTA on 14.0615.  Over the course of the next 35 minutes, I worked a total of 30 stations on 20M and 40M (most on 20M) at which point I basically ran out of hunters.  Not bad for a weekday afternoon.  I packed up and went on a couple mile hike with my wife.

The TR-45L is an absolute joy to use.

I forgot to put it in CW Narrow mode at first, and when nearby QRM popped up, I was able to add this in with the throw if one switch. QRM gone.  (Note, this setting – wide vs. narrow filtering – must not be retained after the power is shut off or the battery is disconnected.)

It sounds wonderful.  I used the side speaker the whole time as my wife doesn’t seem to mind, although the random guy who wandered in with a laptop to get some work done on a warm fall day decided to find somewhere else to work.  There are front mounted jacks for headphones, paddles and a straight key.  Even a rear mounted jack for an external speaker.  The built-in speaker can be turned off and on via a toggle switch.  The two CW memory slots are easy to fill using your paddle.  The front meter can show power output or SWR based on toggle switch position, and you are alerted to high SWR via a front mounted red LED.

I waited a while to get this radio.  Recent supply chain issues caused unexpected delays, but it’s available for order now in factory-built form and most definitely worth the wait.  Kits will eventually be available.  Check out all the TR-45L details here.

Mark Yergin

W8EWH

Articles, Guest Posts, Homebrew, How To, Morse Code, News, Portable, QRP

Sam builds a compact external speaker and 200 Hz filter for the Penntek TR-35

21 Comments

Many thanks to Sam (WN5C) for sharing the following guest post:

A Compact CW Filter and Speaker Build for the TR-35

by Sam Duwe, WN5C

I recently built a Penntek TR-35 and, like seemingly everyone, I love it.

Once the rig passed the smoke test I was having too much fun and wasn’t quite ready to put away the soldering station. I had two non-essential wants for this project: a narrower CW filter for listening comfort, and an external speaker. Here’s a quick description of how I crammed both of those into an Altoids tin. Nothing is new or groundbreaking here, but it has been a fun and useful project for me and hopefully will give some inspiration for others.

The Hi-Per-Mite

The heart of the project is a Hi-Per-Mite 200 Hz CW filter, designed by David Cripe NM0S, and sold as a nice kit for $28 by Four State QRP Group. Hans Summers G0UPL uses the circuit in the QCX so many will be familiar with the filter’s sound. It’s nice and narrow with no ringing, and makes using my base station (a Kenwood TS-520 with the 500 Hz crystal filter) a joy.

To be clear, the existing narrow filter in the TR-35 is great, but I like the option of going narrow(er). It’s a Pixie-level build difficulty so it should come together in an easy couple of hours. I originally built mine in an Altoids tin using inspiration from Phillip Cala-Lazar K9PL’s review and it worked very well. It sips current and is powered by a 9-volt battery. With a DPDT throw switch connected to both the audio path and the power you can easily switch the filter on and off.

The Speaker

A neat aspect of the TR-35 is that there is a lot of audio gain so you can drive a non-amplified speaker. I have a little Bluetooth speaker that does this trick when I want to use CW to annoy people, but I figured if I’m already hauling an Altoids tin to the field maybe I could get it to talk, too. I looked around my junk box and found a broken Baofeng speaker mic and salvaged the speaker. It works really well: a robust but comfortable volume.

I’m sure any little speaker would do the trick… nothing fancy here, it gets hot glued it to the lid of a mint tin after all.

The Build

After I built the Hi-Per-Mite here’s what I did: first I ate a tin of Altoids and felt a little sick. Then I drilled some holes. The one on the left is for the audio input, the one on the bottom for the headphones (both of these are 1/8” stereo jacks), and two on the right for two mini DPDT switches. I also drilled holes in the lid for the speaker sound to come through. I gave the tin a good sanding and tried to remove sharp edges, and then sprayed the lot with black primer and spray paint.

Continue reading Sam builds a compact external speaker and 200 Hz filter for the Penntek TR-35 →