Tag Archives: Matt (W6CSN)

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QMX – From Kit to Field!

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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! →

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

Matt’s Weekend POTA Roundup!

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Many thanks to Matt (W6CSN) who shares the following post from his blog at W6CSN.Blog:

Weekend POTA Roundup

by Matt (W6CSN)

It’s been a stormy past several days here in Northern California, but if anything, the weather only amplifies my motivation to go outside and get on the air.

Rather than do a separate writeup for each, this post is a roundup of my last four POTA activations, from Friday, February 2nd through Sunday, the 4th.

A faint rainbow splashes down in front of Angel Island

Thursday and Friday had been wet, with one storm in a series moving across the Bay Area. However, by Friday evening the cold front had passed and there was a break in the rain. This was a perfect opportunity to try an after work activation at the Presidio of SF (K-7889).

I hadn’t used the QCX-Mini in a while, and this activation reminded me why. I believe what is happening is that being so close to the antenna, RF interference causes clicking while keying, nearly to the point of distraction. I need to experiment with RF chokes on the key and audio lines to see if that improves the situation.

Fed up with the RFI on the QCX-Mini, I switched over to the MTR-4B which doesn’t seem to suffer the same issue. I wrapped up the activation after netting 21 QSOs in the cold west wind.

All QSO maps in this post are from http://tools.adventureradio.de/analyzer/

The next bout of rain wasn’t due to arrive until later Saturday afternoon. This was a change in the forecast that subsequently altered my plan to stay in Saturday soldering on my QMX Hi-Bander project.

Initially I went to Fort Point (K-0819) in the hopes of changing it up from my usual activation park but there were just too many people there. So seeking relief from crowds, I crossed the Golden Gate Bridge and went up on the slopes of Mt. Tamalpais.

I parked at Trojan Point at an elevation of approximately 1800 feet. See this post for more views from this location. The temperature was in the mid-40s, which is cold for us coastal Californians. Besides, the winds were picking up ahead of the next storm so I operated from the comfort of my vehicle using the Gabil 7350T base loaded vertical antenna on 15m and 20m.

This activation used the FT-818 and yielded 23 contacts, including JH1MXV from northwest of Tokyo, Japan coming in fairly strong on 21 MHz.

Driving back to San Francisco takes me right through the Presidio of SF (K-7889) and noticing that it was after 00:00 UTC, I made the last second decision to divert to East Beach to see if I could work in another activation before the anticipated rain.

At my usual spot for activating this park, it took only moments to raise the MFJ-1979 20m quarter wave and do a quick deployment of the MTR-4B on the trunk of the car. The wind was picking up, but not nearly as strong as it was up on the mountain.

After seven QSOs, the skies began spitting raindrops, this was going to be close! I closed the cover of the Maxpedition pouch to protect the radio and battery while the Bencher paddles could tolerate a little bit of moisture.

I was happy to have a Rite-In-The-Rain notepad for logging [Amazon affiliate link], because now I was certainly writing in the rain! Three more contacts and the activation was concluded with a hunt of Jim, WB0RLJ, in K-4011. Continue reading Matt’s Weekend POTA Roundup! →

Field Reports, Guest Posts, News, POTA, QRP

Matt’s Rainy Day POTA Activation

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Many thanks to Matt (W6CSN) who shares the following post  from his blog at W6CSN.Blog:

Rainy Day Activation

by  Matt (W6CSN)

It’s late December and one of a series of winter storms is driving into northern and central California. The previous day, my plans for a combined Summits On The Air and Parks On The Air activation fell apart due to weather. Today most of the UTC day had passed with only light drizzle, and itching to get on the air, I hatched a plan for an activation at my nearby park reference K-7889, the Presidio of San Francisco.

Typically when activating at this park from the “East Beach” area, I will back into a parking space, setup the radio on the trunk lid and run the coax a short distance to a 17 foot vertical telescoping whip antenna which is clamped to a short steel post.

Today however, I chose to operate from inside the vehicle so both myself and the radio equipment would stay dry. Not wanting to leave the coax unsupervised where someone could trip over it, I deployed the Gabil GRA-7350T antenna with a triple mag-mount on the roof of the car.

The CW Morse paddles mounted to a steel clipboard on the center console.

The GRA antenna is a short, loaded vertical with the whip portion maxing out at about 8 feet in length. It works well on 20 meters, but it’s less of a compromise on higher frequencies. On 18 MHz, only a small amount of the loading coil is needed to achieve an acceptable SWR, so with the bands in pretty good shape I brought the Yaesu FT-818 so I could get on 17 meters.

There weren’t many spots for 17m on the POTA web site, but I posted my spot anyway and started calling CQ. It wasn’t long before KX0Y responded, followed by more hunters from across North America and Alaska. The Golden Gate Bridge was visible from my vantage point at the start of the activation, but as the rain intensified the bridge became enshrouded by the incoming weather front.

With 00 UTC approaching, the rain now coming down harder, and 13 QSOs in the log I called QRT. Rather than carefully stowing the antenna and mag-mount, I simply broke it down as quickly as possible and tossed it all the back seat since I would have to bring it inside to dry anyway.

The following equipment was used in this activation:

[Note: All Amazon and CW Morse links are affiliate links that support QRPer.com at no cost to you.]

Thanks to all the hunters that responded and made the activation a success.

73 de W6CSN.

Field Reports, News, Portable, POTA, QRP

W6CSN Activates Fort Baker in the Golden Gate National Recreation Area

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Many thanks to Matt (W6CSN) who shares the following post  from his blog at W6CSN.Blog:

Fort Baker On The Air

by Matt (W6CSN)

Fort Baker is a former U.S. Army post situated at the north of side of the Golden Gate, opposite Fort Point and adjacent the town of Sausalito, California. The post is now part of the sprawling Golden Gate National Recreation Area (GGNRA) which is also known as K-0647 for POTA.

Many of the good POTA spots in the GGNRA are heavily used for recreation and sightseeing on weekend days such as this, but Cavallo Point is out of the way enough that there was still ample, free parking today. This location offers spectacular views of the Golden Gate Bridge, the city of San Francisco, and Alcatraz and Angel Islands at anchor in San Francisco Bay.

Today the “pull of POTA” was strong as I wanted to get another activation done before the arrival of an anticipated solar storm as well as rains predicted for the coming week.

During the week leading up to this activation the Bay Area has experienced fine weather with mild daytime temperatures and light winds, but driving in, the sound of rigging slapping loudly against the aluminum masts of the sailboats docked in the Presidio Yacht Club marina told me that it was windy down here.

A short series of wooden staircases lead up from the parking area to Battery Yates, named for Captain George Yates of the U.S. Cavalry who fell in the Battle of Little Big Horn in 1876.

The gun battery is a reinforced concrete structure which once sported six rifles that fired a three inch caliber cartridge to provide for naval defense inside of San Francisco Bay. The guns were manned through the middle of World War Two when, by 1943, they had been moved to more strategic locations.

Today I had hoped to use the same steel pipe which supported a fiberglass mast and EFHW in an earlier activation from this spot, but unfortunately the pipe was too thick to get the jaw mount securely attached.

I went with plan B which was to use the pipe railing at the back edge of the gun pit. Being unsure whether or not the galvanized steel railing made any electrical connection to what surely must be rebar embedded in the concrete, I deployed the 17 foot vertical whip with three radials just in case.

Whatever was serving as a counterpoise, it was doing a great job, providing an SWR reading of 1.0 to 1 on the Mountaintopper MTR-4B. This was probably the third activation on this Lithium-Ion battery pack, so the power was down to 3.7 watts, still plenty for a CW activation with a resonant antenna.

The activation was scheduled ahead of time on the POTA web application so all I had to do was just start calling CQ POTA and let the RBN do the spotting. I soon heard from KG6HM from right across the Bay, followed by stations from Washington, Idaho, Utah, Arizona, and New Mexico.

I was starting to think it would be only western states calling in, but the band opened up a bit, bringing N3RT from Delaware. Now we had a proper coast-to-coast activation, and, I bagged a hard-to-get state needed for an informal CW “Worked-All-States” achievement.

By this time, the wind really started to pick up and with the sun so low in the western sky, it was becoming chilly. Satisfied with the 14 QSOs in the log, we packed up, made our way back down the pathway to the car, and then to a fancy coffee house in Sausalito for a nice warm cup.

Equipment Used

73 de W6CSN

Articles, Guest Posts, News, Skills

Guest Post: Watch Your Tone

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Many thanks to Matt (W6CSN) who shares the following post  from his blog at W6CSN.Blog:

Watch Your Tone

by Matt (W6CSN)

In this modern era of radio technology, where even analog radio is largely digital, we amateurs are accustomed to perfect signal quality all the time.

Nevermind the perfunctory 599s that are handed out during contests, for activities like Parks On The Air and Summits On The Air I believe most of us like to send and receive an honest RST report.

R-S-T from the 1938 edition of the ARRL Handbook

Although subjective, readability (R) and signal strength (S) are pretty well understood quantities. But what about tone, the T in R-S-T ? When was the last time you sent or received a tone value other than “9” (the highest value) ?

Last evening, at the end of one of my frequent activations of the Presidio of San Francisco (K-7889), I struggled to pull a barely readable and very weak signal out of the noise. For what it’s worth, the natural noise floor was very low, with the geomagnetic field listed as “Inactive” on qrz.com.

One of these stations had a distorted signal ?

What made the signal particularly difficult was that it sounded quite distorted. The problem I faced was how to tell the OM that it sounded like his signal had been through a blender. The numbers in the Tone scale go from 1 to 9 but I did not have any understanding of the specific defects encoded by the scale. I needed to send a report, and quick, so I dashed out a “225” followed by “DISTORTED.” But I was unhappy that I needed to send an extra, unexpected word to explain the reason for the “5” tone.

Tone

1–Sixty cycle a.c or less, very rough and broad.
2–Very rough a.c., very harsh and broad.
3–Rough a.c. tone, rectified but not filtered.
4–Rough note, some trace of filtering.
5–Filtered rectified a.c. but strongly ripple-modulated.
6–Filtered tone, definite trace of ripple modulation.
7–Near pure tone, trace of ripple modulation.
8–Near perfect tone, slight trace of modulation.
9–Perfect tone, no trace of ripple or modulation of any kind.

http://arrl.org/quick-reference-operating-aids

When I got home I resolved to refresh my knowledge on the R-S-T system so that I could have it at my disposal while operating and on the rare occasion when a tone value other than 9 is warranted.

May your signals always be strong and pure.

73 de W6CSN

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

Matt’s “Crackadawn POTA” Field Report

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Many thanks to Matt (W6CSN) who shares the following post  from his blog at W6CSN.Blog:

Crackadawn POTA

by Matt (W6CSN)

This is the weekend in October that features the U.S. Navy’s Blue Angels taking to the skies over the Bay Area. The air show takes place over the Bay waters, which means the beaches and shorelines around San Francisco will be packed with people and traffic. Since my usual POTA operating location is right by East Beach, I had pretty much given up on the idea of activating K-7889 this weekend.

Lights of the Golden Gate Bridge reflecting off the still Bay waters.

The airshow is on Saturday and Sunday, but the Blue Angles practice on Thursday and Friday, weather permitting. So here I was on Friday morning, awake at 5AM watching K4SWL on YouTube doing POTA when the idea of getting out for an early activation got into my head.

It was still dark when I tossed my backpack, which was already loaded for POTA from the previous activation, into the car and headed down to the East Beach in the Presidio of San Francisco National Historic Site (K-7889).

The sky getting lighter in the East before sunrise.

Given the early hour and low light conditions I didn’t relish the idea of doing my usual picnic table and tripod antenna setup. Not long ago I had acquired one of those “mirror” antenna mounts with the jaw clamp arrangement, and this was a great opportunity to try it out. Between the parking lot and the beachfront promenade there is low fence constructed of short steel posts and strands of stainless cable. The fence post was a perfect place to attach the clamp and the MFJ-1979 17 foot telescopic whip, which is a quarter wave on 14 MHz.

Close up of the MFJ-1979 whip antenna clamped to steel fencing.

I was ready to string some radials out to give the antenna a ground plane to work against, but wondered if the post, being sunk into the ground by the Bay and the steel fencing cables might provide enough of a counterpoise. A quick check of the SWR on the meter built into the MTR-4B showed a 1.2 to 1 – no need to even bother with radials with an SWR like that right out of the box.

Low SWR on the quarter wave vertical as the Bay wakes up.

The other advantage of this antenna setup was that it is right next to the car. However, I don’t really like operating from my vehicle as it’s not very sporting nor is it comfortable. Instead, I simply set the station on the trunk lid and completed the activation from a standing position. The other advantage of this arrangement was that I could closely guard the RG-316 coax going from the radio to the antenna to keep any humans or canines from getting entangled. Continue reading Matt’s “Crackadawn POTA” Field Report →

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

Matt’s Low-Profile POTA Activation at the San Francisco Maritime National Historic Park

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Many thanks to Matt (W6CSN) who shares the following post  from his blog at W6CSN.Blog:

SF Maritime NHP POTA Activation

by Matt (W6CSN)

There are several Parks On The Air eligible parks in San Francisco and the northern tip of the peninsula of the same name. One would expect that a POTA activator that calls this city home, would have logged activations from all of these parks, but so far this one has eluded me.

Muni Pier (closed) across Aquatic Cove

The San Francisco Maritime National Historic Park (K-0757) sits at the northern edge of the city, right next to the Fisherman’s Wharf area that is so popular with tourists visiting San Francisco.

NPS Map of SF Maritime NHP

The National Park encompasses an area that includes the municipal pier, aquatic cove with its small public beach, the art deco style Maritime Museum, and Hyde Street Pier with its floating collection of historic ships.

The historic ships alongside Hyde Street Pier

For various schedule and logistical reasons, K-0757 was the one park in the city that I had not yet activated. So today, when my daughter wanted to visit the ships, I made sure to have my lightweight POTA “go” pack with me in case I found an opportunity to attempt an activation.

I’d say the main attraction at Hyde Street Pier is the Balclutha, a steel hulled, square rigged, cargo ship built near Glasgow, Scotland and launched in 1886.

Balclutha – a survivor from the Age of Sail

Balclutha is continually undergoing restoration and maintenance by the Park Service and skilled volunteers. Her many careers on the world’s oceans are documented with numerous interpretive stations and exhibits, both topside and below decks.

We wrapped up our tour of the vessels on the pier by exploring C.A. Thayer, a 219 foot long sailing schooner built in 1895 near Eureka, California to serve the coastal timber trade.

Eureka is a steam powered ferry that served on SF bay.

I was thinking about where to activate and not really looking forward to setting up on or around the public beach. Between the Aquatic Cove swimmers, people enjoying the beach, and tourists going to and fro, there wasn’t really an “out of the way” location to setup even a small station.

Hyde Street Pier itself was actually pretty quiet, but I wasn’t about to set up my station there without prior approval of park staff. Just as we were about disembark from Thayer I noticed an NPS employee near the gangway, and so I took the opportunity to inquire about setting up my low impact, leave no trace, POTA station.

It turns out the person I talked to on the deck of C.A. Thayer was the supervisor of the SF Maritime National Historic Park! He is keenly interested in radio and was even aware of recent solar activities that have given us amateurs a mixed bag of propagation conditions. He agreed to my request to set up at the end of the pier, past Balclutha’s gangway.

Is Balclutha’s steel hull a reflector of radio waves?

I used the Gabil GRA-3750T antenna with its stock telescopic whip tuned for 20 meters. This is the most low profile antenna I can field for HF. Yes, it’s a compromised antenna system but as you’ll see it works good enough. Continue reading Matt’s Low-Profile POTA Activation at the San Francisco Maritime National Historic Park →

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

Matt’s Summer Vacation Mountain POTA

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Many thanks to Matt (W6CSN) who shares the following post  from his blog at W6CSN.Blog:

Summer Vacation Mountain POTA

by Matt (W6CSN)

Our family regularly enjoys a summer vacation in the mountains. There is no shortage of mountains along the Pacific Coast, but if you refer to “The Mountains” around our house everybody knows you are talking about 5500 feet up the western slopes of the Sierra Nevada along Highway 4 near the town of Arnold.

Summer Cabin

Last year’s trip to “the mountains” was my first foray into portable QRP operating and I successfully hunted a few Parks On The Air stations. In the year since, I’ve become much more involved with (some would say addicted to) POTA, especially as an activator.

The cabin sits on a small lake.

For the “base” operation of hunting other stations, I set up the FT-818 with an EFHW strung between the deck and some trees adjacent the nearby lake. The 26 ga polystealth wire antenna literally disappeared into the trees, the only giveaways being the 64:1 transformer floating in space off the deck rail and, more likely, the the bright orange arborist line used for the downhaul at the far end.

I made a few hunter QSOs during the morning hours from the cabin, but this location wasn’t hearing particularly well. Signals weren’t strong and I sent more than a few 229 reports. However, this “hunter mode”operation was secondary to my main objective of activating some new to me parks while on this trip.

Hunter QSOs from the cabin

On the first full day in the mountains we headed back down the hill a ways to visit Railtown State Historic Park in Jamestown, CA. After riding the excursion train and enjoying lunch by the roundhouse, I brought up the possibility of an activation. However, with the July heat well into the triple digits, the family wasn’t in the mood for dads radio obsession. Quite frankly, I wasn’t too excited about setting up the station in the heat, so it was an easy choice to put this one off for another time.

No activation attempt at Railtown this time

The next POTA activation opportunity came when we had made plans to head up for a day at Lake Alpine. We chose to go up to the lake around 10AM on Monday, hoping for smaller crowds. Also, we had plans to visit Calaveras Big Trees SP the following day.

This gave me an idea: I could make the short drive from the cabin up to Calaveras Big Trees (K-1134) in the morning while everyone was sleeping in and try to get the activation done before heading to Lake Alpine. This way the family visit to Big Trees wouldn’t be interrupted by dad playing radio. Continue reading Matt’s Summer Vacation Mountain POTA →

Field Reports, Guest Posts, News, Portable, QRP, QRPp, SOTA

Guest Post: “It Was Bound To Happen…”

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Many thanks to Matt (W6CSN) who shares the following post  from his blog at W6CSN.Blog:

It Was Bound To Happen…

by Matt (W6CSN)

You’d be safe to guess that Mt. Davidson would have been my first SOTA activation seeing as it’s the closest SOTA summit to my home QTH. However, it actually took me a little while to get around to heading up W6/NC-423.

The trail begins near the corner of Dalewood and Lansdale.

Today was the day! I dropped my hiking buddy off at work at 8 AM then drove up Market Street, over Portola Drive and wound my way around Mt. Davidson, finding easy parking on Dalewood Way near Lansdale Ave.

The easy trail up Mt. Davidson.

From the trailhead near the bus stop, it a short and easy hike up to the activation zone. On this route you reach the east end of the summit, opposite the large cross, which is a well known landmark.

Except for the occasional exercise enthusiast, I had the place to myself this morning. Not wanting to lug the fiberglass mast up the hill, I deployed the Gabil Radio tripod and loading coil, using a 3 meter collapsible whip antenna. This is an easy setup and not too much of a compromise on 20 meters.

While I can do a lot of back and forth the get the loading coil set just right for a good match, I find it easier just to get the coil close enough and touch it up with a tuner for a low SWR reading.

I sent a spot via Sotamāt and started calling CQ SOTA on 14.058 using the QCX-Mini. My first call was from JG0AWE from Nagano City, Japan. This was followed quickly by several more stateside calls and I was able to gather the four QSOs needed within a span of five minutes.

QCX-Mini on 20 meters.

I continued working stations and chasing some Summit-to-Summit contacts for another half hour. It was at that point I noticed that I failed to throw the switch to the “Operate” position on the ZM-2 tuner. This whole time I had been operating in “Tune” mode with the 50 ohm absorptive bridge in circuit! It was almost like using a dummy load for an antenna!

Oops! I left the ZM-2 in the “tune” position!

Later, at home, I measured this tuner configuration with this radio using an actual 50 ohm load instead of an antenna and found that I was most likely operating with an effective power to the antenna of only 300 milliwatts!

Despite this extremely low power I was able, using CW, to complete the activation with no difficulty. This is a testament to the effectiveness of the CW mode, and not so much this operators skill.

Sutro Tower and Twin Peaks to the North.

After logging 10 contacts, I called it quits, packed up the station and headed back down for some breakfast. Next time I’ll try to remember to set the switch correctly after tuning up, but I make no promises. I’m guessing pretty much everybody that has a ZM-2 has at one point or other forgot to switch into “operate” mode, It was bound to happen.