Guest Post: “It Was Bound To Happen…”

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.

10 thoughts on “Guest Post: “It Was Bound To Happen…””

  1. It goes to show that when “The Radio Gods” are WITH you the world is your oyster! Who hasn’t had something like that happen to them? Isn’t this fun? This is the stuff we will talk about over coffee or a beer for years to come.

    Dave K8WPE

  2. Once, I also failed to switch my ZM-2 to the “operate” position on a SOTA summit, with the same results! . . . more or less LOL. QRP is truly amazing isn’t it?

  3. Thanks for sharing your most enjoyable story!

    The ZM-2 is my favorite manual tuner. The Elecraft T-1 is my favorite in the “automatic” class.

  4. Hi Matt. Just checked the ZM-2 schematic – yep, it’s using a variant of the N7VE absorption SWR bridge, which is basically a 50ohm wheatstone (I just built one of those for potential /P ops for my SW-3B). Your antenna was thus 1/4 of the wheatstone, and I believe you get a 6db attenuation to your signal 🙂 From your QCX-mini then, probably just over 1 watt? – to Japan – *Stunning* 🙂

  5. (Checks schematic on web page) I see now. Tune mode still goes to the antenna, but an extra circuit is in parallel, to measure SWR.

    My ZM-2 is due to arrive soon, good to know about this.

  6. ?Well done. I think 300mW qualifies as QRPp which gets an extra pat on the back.
    I don’t think you are the first to get caught by out leaving the SWR bridge on “tune”.

  7. That’s so fun! The three kids here and I head up to Mt. Davidson pretty frequently, and our first QSO from the mountain was also to JG0AWE. There must be something about the mountain, because we were also running QRPp that morning into a 20 meter RockMite.

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