Category Archives: Guest Posts

Antennas, Guest Posts, Morse Code, News, Portable, QRP

Rich re-activates Santa Fe Prairie State Park with QRM-busting in mind

4 Comments

Many thanks to Rich (KQ9L) for sharing the following field report:


Field Report: Testing a horizontally-polarized antenna at a high QRM POTA site

by Rich (KQ9L)

I wanted to give a quick follow up report from Santa Fe Prairie State Park (K-7839).

As you may recall I wrote up my POTA activation from this park on Oct 23, 2022. I made 15 Q’s that day but deep down felt I could do better. The setting of the park is quite industrial and consequently the man made noise is bad. Reflecting back on this activation, I feel that the limited the number of QSO’s I made that day was due to this QRM.

I resolved to try again but this time my objective was to figure out a solution to mitigate the effects of the QRM on my QSO count. Thinking about the problem, I recalled than manmade noise typically is vertically polarized and therefore for my second attempt, I decided to test this and use a horizontal antenna.

As luck may have it, here in Chicago we continue to experiencing unseasonably warm weather and my work schedule wasn’t too busy on Thursday, November 3, 2022, so it seemed like a great chance to put my theory to the test.

For the antenna, I decided to use one which I have owned for awhile, but have never used. I had purchased a RadioWaves Double bazooka from an online retailer some time back when they were on sale and planned to set up it a flattop dipole.

If you recall from my description of the Santa Fe Prairie State Park, there is a scenic overlook which has a tree mounted pulley system perfectly spaced to mount a 20m dipole. Although this would be the first time I used the system, it turned out to be a well designed and intuitive hoisting solution to use.

The “pulley” is actually an eyelet with paracord running through the eyelet. The paracord is in a continuous loop just like rope on a flag pole. By employing a simple overhand knot I secured the end of the antenna to the paracord and hoisted the antenna up into the tree about 20ft. It literally took a few minutes and I was ready to go.

Antenna was fed with my RG-316 feedline with built in common mode choke. Since a dipole is a balanced antenna system, it really doesn’t need the choke, but it was the coax that I had packed with me and I figured it wouldn’t cause any harm or negatively affect my test. I was QRV by 3:20pm, and anxious to get on the air. Continue reading Rich re-activates Santa Fe Prairie State Park with QRM-busting in mind →

Field Reports, Guest Posts, Hams, Morse Code, News, Portable, POTA, QRP

Jay discovered that his first CW POTA activation wasn’t scary at all!

20 Comments

Many thanks to Jay (W1ASP) who, last week, sent me a note about his first POTA CW activation. I asked if he’d consider writing up a short field report about his experience to share with others and he was happy to do so. Thank you, Jay.

Halloween POTA

by Jay (W1ASP)

Halloween doesn’t have to be scary.

I set out to Bear Brook State Park (K-2643) for my first CW POTA activation.

Bear Brook is relatively close by, its the largest state park in New Hampshire with over 10,000 acres. There’s camping, hiking and biking trails along with an archery course and plenty of swimming and fishing areas.

I didn’t give it much thought about what day it was, just that I had the time to do an activation and it was nice out, what a perfect opportunity to break in the newly assembled kit.

I decided on a spot next to the water and as luck would have it there was a picnic table right there. I took out my gear, set up and proceeded to tune around and listen. The band seemed pretty quiet. I wasn’t sure if I’d get enough QSO’s in to make it an official activation. I decided on 14.038 MHz, I sent QRL? I then held down the memory button, took a deep breath and hit it again to transmit: CQ POTA DE W1ASP

I waited a second or two and used the memory keyer once more, again nothing. I went to the POTA website on my phone and added my activation.

The memory keyer was used for a third time, I noticed a message pop up on my logging app, the Reverse Beacon Network spotted me. It wasn’t too long after, the first call came back to me!

I was nervous and fumbled a bit here and there but once I took my time I was fine, sending their call back and TU UR 599 599 NH BK. I cheated a little and left the CW decoder enabled. I wanted to be sure I had the call correct as I logged my 13 QSO’s. (I swear the 13 wasn’t intentional.) for my first CW park activation! I only realized that it was Halloween while walking back to my truck.

I thought to myself, “that wasn’t scary at all.”

Once I decided that, as an activator I’m in charge of the QSO, I relaxed and it was a lot of fun. I may have made a few mistakes but everyone was patient with me. I later received an email from another Ham in Delaware. He was using the same radio, and referred to them as the perfect “picnic portable radio” we emailed back and forth a few times and I look forward to hearing him on the air again soon.

 

The week before, I finished building my second QCX Mini. The first kit I built was for the 30 meter band around this time last year, this second one is a 20 meter version. I love these little radios, there’s something about these little transceivers that I just can’t seem to put them down.

I took my time making sure it was working properly, I hooked it up in my shack and I had my first QSO with another POTO activator in Maryland just over 400 miles away.  To say I was excited is an understatement!

I planned on putting together a kit about a month ago for POTA and eventually SOTA with the QCX Mini as the radio. I decided on using a small pack, I wanted it to be a self contained kit that had everything I needed to do an activation and nothing extra.

I keep the wire and radios together,  and depending what band I choose to operate on is the one I pack. I’m considering a third kit; maybe a 10m version? I threw the EFHW matching transformer in the bag along with a notebook, mechanical pencil and a battery pack I put together using four 3.2v LifePo batteries. The paddle I’m currently using is a stainless paddle I found on online with a mini CW paddle for backup and set of folding headphones.

I’m looking forward to my next park, this was a great experience. I wanted to learn CW since I became a Ham in 2016, that’s another story of what got me into Ham Radio in the first place.

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

Rich’s Triple Activation Day!

4 Comments

Many thanks to Rich (KQ9L) for sharing the following field report:

Triple Activation Day

by Rich (KQ9L)

I decided to build on the momentum and lessons learned from my last two POTA outings and yesterday [October 29, 2022] completed x3 Activations in one day— a first for me. I wrote a brief description of the day and I hope you enjoy reading about the activations.

Well the weather has been pretty good here in Chicago and Old Man Winter hasn’t made it around to these parts yet and being on a POTA kick lately, I decided see if I could complete several activations in one day. Previously I had completed x2 in one day, but felt that after all that I learned from my last couple activations, I should practice what I learned and go for three.

In my area, there are several POTA sites, but one area to the south of me seemed to be the best location to accomplish my goal. The area has a unique geographic feature and historically interesting landmark which added to the lure of the area. The region centers around the Illinois and Michigan Canal.

Here is a quick history lesson courtesy of Wikipedia:

The Illinois and Michigan canal was build in 1848 and served as a connection between the Great Lakes and the Mississippi River. Running 96 miles, it connects Bridgeport in Chicago to LaSalle-Peru. Why was this important? This connect helped establish Chicago as the transportation hub of the US and linked by water the East coast to the Mississippi River and from there the Gulf of Mexico. Before the railroad era in the US, this water way dominated transportation.

Pretty cool!

Along the canal are numerous little hamlets and one in particular, Morris, Illinois had x3 State Parks all within about a 5 mile radius. Perfect!

First stop was Gebhard Woods State Part (K-0995). The park is only 30 acres, but affords activities for hikers, fisherman, campers and picnickers. There is even an eBike rental facility so the park has broad appeal to many people, including hams!

I arrived pretty much right after sunrise and was greeted by fog and a thin layer of frost on the grass and picnic tables. Though beautiful this frost and fog, did not make for a fun activation. Temps were in the upper 30’s F, but with the fog the air felt damp and overall much cooler.

I hurriedly set up my PackTenna 9:1 antenna on my collapsible mast and leaned it up against a nearby tree. I had a separate counterpoise and feed line with a choke built into it…more on this later.

Continue reading Rich’s Triple Activation Day! →

Guest Posts, News, QRO, QRP

Guest Post: “Why I Quit QRP (and maybe shouldn’t have)”

16 Comments

Many thanks to John (VA3KOT) who shares the following guest post which was originally published on his Ham Radio Outside the Box blog:

Why I Quit QRP (and maybe shouldn’t have)

by John (VA3KOT)

For many years I was a dedicated QRP operator. I even took my “Portable QRP Operation” show-and-tell out on the road for presentation at ham clubs in my area. Then along came the dark, gloomy depths of the solar cycle minimum. My forays out into the Big Blue Sky Shack became a series of disappointments. Maybe the odd QSO here and there, but most often I came home with nothing but a few RBN spots after multiple CQ calls. Something had to change.

“Why QRP?“

I began to ask myself “why QRP?”. It’s a valid enough question. Just what is so magical about an output power of 5 watts? Why not 1 watt, 3 watts, or 20 watts? It has often been said that 5 watts of CW is equivalent to 100 watts of SSB. There is a mathematical proof but I won’t repeat it here. So shouldn’t 100 watts of SSB be considered QRP?

QRP has a cult-like following. There are several online organizations dedicated to it. I am a member of some of them. QRP certainly has an appeal for those of us who like to operate in the great outdoors. Perhaps the greatest advantage is that an entire station can be stuffed into a couple of pockets – antenna and all. And a QRP rig sips battery power so slowly that some can be powered all day on a 9-volt alkaline battery.

I laid the blame for my lack of portable QRP QSOs on poor propagation. Maybe my signal just wasn’t making the trip. The propagation demons in the sky were swallowing my signals, burping and grinning down at me with a smug, malicious gleam in their eyes. QRP-’til-I-die operators shrug that off as “the fun of QRP”. Not getting any QSOs is fun?

In hindsight, there could have been another explanation. The Reverse Beacon Network was constantly reaffirming that my puny emissions were making it up to the ionosphere and being refracted back down to the Earth. So why were so very few people responding to my CQs? I have a theory about that. Maybe, back then, random CQs only appealed to a small number of people. I asked myself how often I responded to random CQs. Hmmm, not too often!

Anyway, images of QRO rigs were dancing around my head whispering sweet messages of temptation in my ear. “Yes” I said to myself; “that’s the answer. Maybe I just need to blow more watts into the air and I will fill up my logbook!” But first a roadblock. I had to persuade “senior management” that I should invest in a new radio. Continue reading Guest Post: “Why I Quit QRP (and maybe shouldn’t have)” →

Guest Posts, How To, Radio Field Craft

Radio Field Craft: Rand explores the handy Prusik Knot

11 Comments

Many thanks to Rand (W7UDT) who shares the following guest post:

The Prusik Knot… strain relief for Wire Antennas and Coax.

By W7UDT, Randall ‘Rand’ Tom

The Prusik knot is a simple, yet effective means to provide needed strain relief to wire antennas and coax, while deployed. It’s comprised of a simple loop or length of suitable cordage (of smaller diameter than the shank, Coax or Wire, it secures).

The link below, is from our friends at Animated Knots…. It’s a brief video tutorial on how best to tie the Prusik knot. Having the Prusik in your ‘bag of tricks,’ will help make your next field deployment be a successful one.

https://www.animatedknots.com/Prusik-knot

As seen in the instructional video, the knot is comprised of a simple loop of cordage, sufficient in length for the task, which is fine, but, I would recommend NOT making a loop. Rather, keeping tag ends for easier anchoring. These tag ends should be at least 12” in length. This is called an open-ended Prusik. Either way, both have utility.

To do this, fold a 24” of cordage in half, to make a ‘bite.’ Lay the bite over the shank of the coax or wire, and feed the tag ends inside the bite loop. This forms a larks-head knot. Wrap two additional turns around and through, then dress and test the knot to form the Prusik. Simple. Anchor (tie) the tag ends at a point where strain relief is best positioned. Then adjust (slide) it to load.

After deployment, I would also recommend leaving the Prusik attached. It comes in handy, when coiling your feed lines or elements later for proper storage.

The Prusik allows it to slide along the wire or coax while free of tension, yet it holds fast under load. Much like a monkey’s fist hanging onto a vine. The tag ends, can then be affixed to suitable anchor where needed. The key here, is using a smaller diameter cordage, than the wire or coax itself.

The Prusik, along with similar ‘Friction Hitches’, can be used in any number of applications in Ham Radio. e.g. Anchoring coax, joining linked antenna elements, power cords, and adjustable guying. The list is long, wherever strain relief is needed.

I would encourage you to tie it, try it, test it, and judge for yourselves. As well, I would encourage you to check out other useful climbing friction hitches… YouTube is a great place to start. I hope you find this useful afield, and to hear you ‘On the Air!’

73! de W7UDT (dit dit)

W7UDT, ‘Rand’, lives and operates near Boise Idaho, with his lovely wife Stacy. Portable QRP operations, along with his Jeep and Harley are his ‘vices.’ Your comments and questions are welcomed. My email is [email protected].

Antennas, Guest Posts, Homebrew, How To, News, Portable, QRP

Sam builds a tiny tabletop HF antenna

18 Comments

Many thanks to Sam Duwe (WN5C) who shares the following guest post:

A (surprisingly good) tabletop HF antenna

by Sam Duwe, WN5C

I recently built a tabletop QRP HF antenna for 17 and 20 meters, in the spirit of the Elecraft AX-1, so I could operate at lunchtime on the campus where I teach. My wants were something small, that would fit in my work bag, that didn’t require a tuner, and could work on a couple of different bands. But on a lark I decided to attempt a POTA activation at Lake Thunderbird State Park (K-2792) pairing this antenna with my Penntek TR-35 QRP CW transceiver. I figured I’d maybe get one or two QSOs and then switch to a long wire in a tree. But what happened amazed me.

I talked to seemingly everyone. Beginning at 9:00 AM September 26th I worked both 17 and 20 meters for an hour and a half and made 37 contacts from across the country. I even had a Swiss guy call me back on 17 but he faded before we could finish. This antenna, at least as a CW POTA activator, works. Granted conditions were very good, but I’ve replicated this multiple times in the past few weeks, just recently at a picnic table in the parking lot of the Route 66 Museum (K-8644) in Clinton, OK (there is quite a thrill in urban activations).

It has also reasonably low profile and very quick to setup and take down. It is also quite a conversation piece when I set it up at school. I elevated the counterpoise by attaching it to a nearby oak and an interested undergrad sheepishly asked if I was listening to the tree!

The build is pretty simple. Physically the antenna consists of a small painters pole from Walmart and an old tabletop camera tripod. I found a nut that fit the screw portion of the tripod and hot glued it into the orange connecting section of the pole. That way the tripod can then be screwed onto the pole. The RF parts of the antenna consist of a 38” telescoping whip that I scavenged from the rabbit ears antenna that came with my RTL-SDR. It connects using the original connector which was hot-glued into a hole I drilled into the top of the painters pole. I found similar small 3 or 4-foot whips from AliExpress for cheap and these would probably work fine.

I then soldered a long length of speaker wire that was wound into two coils: the top for 17 meters (24 turns) and the bottom for 20 meters (25 turns plus the former 24-turn coil). The speaker wire was the soldered to the center of a BNC connector which I hot glued and taped to the pole. I soldered a short piece of wire from the shield of the BNC for the counterpoise and added an automotive spade connector to attach to a 17-foot length of wire. I also included a switch between the coils and the BNC connector to select either just the top coil (17 meters) or both coils (20 meters) using solder, hot glue, and tape.  I then covered my shame in silicone tape.

The most time-consuming aspect of the project was tuning the antenna. It required trial and error to first tune the number of turns on the 17-meter coil and then the 20-meters coil. I extended the counterpoise (for me it’s best when slightly elevated) and the telescoping whip. I performed the tuning with the whip not fully extended to give room to tune in the field. Using a nanoVNA was useful here, as was soldering a pin to the wire to poke through the wire at various parts of the coil to find the best SWR.

In use, the antenna can be affected by both body capacitance and how the counterpoise is situated, so I found that an in-line SWR meter was helpful in making sure all was well. Once set up it is easy to fine tune by just adjusting the whip length. 1.5:1 SWR is about how well I can tune on average. Obviously if you have a tuner you would just have to get it close.

There are a million variation on a small base-loaded vertical antenna, and you can definitely improve upon this design. And, besides the super well-built and elegant AX-1, QRP Guys sells an interesting looking kit, and there are some good 3D printed designs I might want to try out. But regardless how you go about it, it might be worth giving a tiny antenna a shot.

72, Sam WN5C

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

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

Rich activates the very POTA-friendly Santa Fe Prairie State Nature Preserve (K-7839)

2 Comments

Many thanks to Rich (KQ9L) for sharing the following field report:

Activating K-7839 with lessons learned from my last portable POTA activation

by Rich (KQ9L)

Here in Chicago, we have been blessed with unseasonably warm weather these past two days. I decided to build on my last successful POTA activation and apply some of the lessons I learned from that activation while working this one.

Close to my home is Park K-7839, the Santa Fe Prairie State Nature Preserve (K-7839) in Cook County, IL.

The preserve was established in 1997 and is staffed and maintained solely by volunteers. The park’s mission is to preserve a section of land for people to observe and admire the natural Illinois Prairie Landscape before it was altered by man.


The park itself is a thin sliver of land west of Chicago and is boarded by the Des Plaines River to the south and the rail yard / industrial park on the other there sides. If you look carefully in the second picture below, you can see some Sante Fe trains in the distance.

The park is easy to reach by car and right off the main park road are several picnic tables which I’m sure a ham in a wheel chair can easily access.

There are a number of features of the park which facilitate a POTA activation.

For example, in the picnic area, a Boy Scout Eagle Scout project resulted in the building of a 22ft flagpole. The flags are long gone, but the sturdy pole has been made available to hams for the hoisting of antennas. There are pulleys and easy tie down points to erect and inverted vee antenna.

To the east most section of the park is a lookout deck and at the east and west of the deck are trees with pulleys and lines permanently mounted. I’ve been told by the staff that the distance between the trees is a perfect fit for a 20m dipole. Continue reading Rich activates the very POTA-friendly Santa Fe Prairie State Nature Preserve (K-7839) →

Guest Posts, Hams, News, Portable, POTA, QRP

Rich packs the KX2 field kit for air travel and a POTA activation!

7 Comments

Many thanks to Rich (KQ9L) for sharing the following field report:

Field Report and Lessons from Torrey Pines State Beach (K-3580)

by Rich (KQ9L)

As you can tell from my call sign, I am a W9er, but recently had the opportunity to travel to California and specifically to the San Diego area. I thought it would be fun to try to activate a park near my hotel. I consulted the POTA website and found one park which was within 5 miles of my hotel, perfect!

While planning for the trip, I carefully chose and packed my gear to minimize added weight and bulk of my carry-on luggage. Because on this requirement, I chose my Elecraft KX2 with built in battery, my KXPD3 paddles, a K6ARK end-fed half-wave and the telescoping fishing pole from the PackTenna portable mast system.

Everything fit perfectly into a Lowepro CS40 case and Tom Bihn HLT. I did not bring the tripod from the PackTenna system to cut down on weight and bulk.


The hardest part of traveling with this setup was the fishing pole as I could not fit it diagonally in my carry-on legal luggage and I ended up having it sticking out the top of my soft side Patagonia MLC carryon backpack / travel luggage.

I received a few odd looks from passengers and airline personal but to my relief I did not get hassled for the odd looking thing sticking out of my luggage. To minimize the space my luggage occupied in the overhead storage, I simply pulled the pole out of the luggage and stowed it in the bottom of the overhead bin. Easy! Everything made it safely to my destination and no the got destroyed.

This morning [October 15, 2022] I decided to go out early to activate Torrey Pines K-3580 which is just north of San Diego.

I ran into a problem which I guess I should’ve anticipated. Being from the central time zone and normally a 5 AM riser, I found myself ready to go by 3 AM Pacific time. I dillydallied for a few hours and watched a few of your YouTube videos to get me psyched up and ready for the activation.

I got out to the site right at sunrise and set up without much difficulty. I found the vegetation to be conducive to setting up the fishing pole by leaning it up against some of the shrubbery. Continue reading Rich packs the KX2 field kit for air travel and a POTA activation! →

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 →