Tag Archives: Tufteln

Testing a new Tufteln knee board and antenna during this beautiful SOTA activation on Mount Mitchell

On the morning of November 4th, I woke up with one thought on my mind: “I need to activate Mount Mitchell before it’s too late!”

It’s not like Mount Mitchell was going to disappear, but I knew I was already on borrowed time since the long section of the Blue Ridge Parkway I use to drive to Mount Mitchell from Asheville typically closes in the early part of November for weeks at a time. The park itself will close to guests too–in fact, last year, it closed its gates as I drove out of the park! There are often other roads open to Mitchell in the winter, but they’re very much out of the way for me and frankly, weather can shift and the park close at the drop of a hat.

As the crow flies, Mount Mitchell is actually very close to my QTH. If I wanted, I could hike there directly from my home. I’ve yet to do this, however, because with the 3,000′ elevation change and the anything-but-direct trails that skirt the Asheville watershed, I’d need a full day or more to hike it one way. I will for sure do this sometime, but only when I can pack appropriately and reserve a campsite.

Morning drive

As soon as I surfaced that morning, I check the weather map. I noticed that the temp at Mount Mitchell was actually slightly higher than at my QTH. I looked out the kitchen window and could see fog in the valley. This meant one thing: inversion!

When we have inversion, the cold air is pushed down into the valley and warmer air can be found at higher elevations. The flip opposite of what you’d typically expect.

I ate a quick bite, grabbed come coffee, and hit the road.

As I drove past Warren Wilson College’s farm, it was absolutely gorgeous. I had to stop and take a photo or two [click images to enlarge].

The drive up to Mount Mitchell on the BRP was ideal: clear skies and quite warm!

Mount Mitchell State Park (W4C/CM-001 and K-2747)

In fact, I felt like I really struck it lucky that day. I didn’t even need a heavy jacket or gloves. Continue reading Testing a new Tufteln knee board and antenna during this beautiful SOTA activation on Mount Mitchell

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

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!

Joshua explores Unun insertion loss (efficiency) comparison testing

Many thanks to Joshua (KO4AWH) who shares the following guest post:


Unun Insertion Loss (Efficiency) Testing

by Joshua (KO4AWH)

A simple “side-by-side’ method can be deployed with the use of a Calibrated NanoVNA to read back “S21 Gain” which is, in this case, signal loss from the output of S11 back into S21 through the identical windings. The gain (loss) reading in negative dB gives us the total signal loss through the windings. We can then divide by 2 to get the loss through one winding and then convert with a bit of math to an efficiency number.

p = 10^(x/10) * 100 where p = percentage 0-100% and x = loss in dB

Example: -2dB reading on “S21 Gain” on the NanoVNA divide by 2 for a loss of -1dB on each winding would be 10^(-1/10) * 100 = 79.4%

We have a 50 ohm signal coming out on S11 of the NanoVNA through the first winding to some unknown exact impedance but that is then converted back through the second unun into the S21 port where the signal is measured. It is therefore necessary to use identical windings for each test to ideally match the impedance change.

I like to run the signal test with the top and bottom of each band, take the average of the two, and then convert to efficiency, 100% being perfect. I record these values to then chart each band’s efficiency for the winding pairs. The goal here is to compare the different windings. For example, with a 9:1 used for a long/random wire, compare toroid sizes, number of toroids and in some cases the number of windings. One nice advantage to a 9:1 Trifilar winding is that you can increase or decrease the winding count in multiples of 3 while maintaining a 3:1 winding ratio. Take the square of the windings ratio (3) to find the impedance ratio of 9:1.

Here is one example of two different windings compared. Both are Trifilar but one with a single T80-2 toroid and 9 sets of turns and the second with a Double T80-2 and 12 sets of turns. 100% would be zero signal loss through the windings, 0% would be full signal loss. -3dB (loss) per winding would equate to a 50% efficiency in either single winding.

The difference between these two windings across the Amature Bands was quite surprising to me. I assume typical, often used windings will be decent across the bands. Here we saw a large improvement in access to the bands by adding several extra turns.

When each component of the station induces loss to the radiated signal, or the ability to receive, you have to improve each area for the best transmit and receive capability. This test is not foolproof, it is not the most accurate way to measure efficiency and maybe not the easiest but it gives me a comparative analysis of various windings with the tools available to me. If I can increase the performance of my windings, I can increase the performance of my station. Time to wind some more transformers!

Joshua

KO4AWH

Tufteln Antennas

Tufteln.net

The Elecraft T1 Protection Case by Tufteln

Long-time QRPer.com reader and supporter, Joshua (KO4AWH), runs an Etsy store with a wide range of products primarily designed for field operators. Over the past few months, Joshua has sent me various prototypes for feedback and also to test in the field. You’ll see some of his antennas in upcoming field reports and activation videos. I’m very impressed with his designs.

If you’re an Elecraft T1 owner, you should be especially interested in his T1 Protection Case.

Joshua sent me an early version of this clip-on case several months ago and it immediately replaced the simple cover I printed from a Thingiverse file. (To be clear, the Thingiverse case served me well for a couple years, but I prefer this one since it doesn’t require a rubber band to hold it on the T1.)

The Elecraft T1 is a hearty little ATU and I don’t worry about damaging it while tucked away in my SOTA pack, but the little buttons on the front are prone to be pushed with any amount of applied pressure. This can result in unintentional operation which can accidentally place it in bypass mode or at least shorten the life of your 9V cell.

The Elecraft T1 is not an inexpensive station accessory and, at the moment, they’re about as rare as hen’s teeth. The lead time on new T1s is counted in months rather than weeks (at time of posting, this is due to vendor board issues).

The Tufteln Protection Case simply snaps on the Elecraft T1 and protects the BNC connectors, ground point, and the front panel buttons.

The case material is durable and adds very little to the bulk of the T1.

Of course, you can’t operate the T1 with the case around it because the BNC connectors are covered, but I have propped up my T1 on the case while using it on rough concrete picnic tables. I’d rather the case be scratched than my T1!

If you own an Elecraft T1 and don’t have a protective cover, I’d encourage you to either print one, or buy Joshua’s T1 case. For years, I simply removed or reversed the 9V battery to keep the T1 from engaging while packed, but that doesn’t protect the buttons and (frankly) it’s a pain to pop the battery out and flip it for each use (then to remember to flip it back when packing away).

The Tufteln case is a simple and affordable ($16.50) solution!

Thanks for sending this to me, Joshua. I dropped my T1 while setting up my TX-500 for Field Day and it protected my favorite little ATU!

Click here to check out the Elecraft T1 Protective Case on Etsy.