Category Archives: Antennas

Accessories, Antenna Tuners, Antennas, News, QRP

Joshua’s ATU-10 review update after new firmware upgrades

2 Comments

Many thanks to Joshua (KO4AWH) who shares the following update to his previous guest review of the ATU-10 automatic antenna tuner:

Update on the ATU-10: new firmware released

by Joshua (KO4AWH)

The short story is that David N7DDC has a Firmware update with a new tuning algorithm that seems to fix the previously seen failure to find a decent match. As noted earlier in comparison with the Elecraft T1, the ATU-10 still does not necessarily get as close a match to 1:1 SWR but it now does indeed find a good match making this tuner my go to for use with my IC-705.

Not previously mentioned, the ATU-10 is also designed to work with the IC-705 for tuning commands when connected with a TRS 3.5mm cable, not just as an auto tuner when given a signal. And, in practice it works just as it should. I actually took the IC-705 and the ATU-10 and worked a SOTA/POTA with the beta version of this new firmware. I ran a 35’ wire and it worked great allowing me to work 40m, 20m, 15m and 6m for a total of 26 contacts. As a followup to my previous testing with the prior firmware 1.4, below are my results with the current new 1.5 firmware.

Testing on August 20th, 2022

The only difference from the original testing is the 31.5’ radiator was replaced with a 35’ and I did not tune and record results with the T1.

Conclusion on the ATU-10

I now feel very comfortable recommending this ATU. newdiytech.com has a great price and the build quality seems just fine. With the new algorithm update, a good match is found. The ATU-10 works great stand alone and also works fully automatically when used with a IC-705. This configuration means you can put the ATU at the antenna feed point and run a control cable back to the IC-705 and have a 50 ohm across the coax to help minimize loss, making for a nice portable setup with great band hopping flexibility.

Of course, if interested, I sell a protection cover for the ATU-10 just as I do for the T1.

If your curiosity is strong, here is some testing I did for David as he was updating the Algorithm now used in firmware 1.5.

UPDATE August 3rd 2022:

David Fainitski N7DDC has released a test firmware with a new tuning Algorithm with some promising initial results. A quick test on each band in the table has been added to reflect the new algorithm. This is not a firmware update yet but I suspect it will be soon. Results are great as tested. I hope to see this in a new FW soon.

August 6th, 2022

A second test firmware from David Fainitski N7DDC with the ability to increase or decrease the L and C manually allowed me to verify if a better match could be made. Turns out in a few cases it could. After testing again with a Tufteln 9:1 T80-2X2 on a 41ft sloping radiator I was able to achieve much better results than with the current version 1.4. In two cases I was able to find a better match manually. I realized later that if I were to tune a second time the ATU-10 would find the same, better match, on its own. Again, not a full firmware update, i.e. you have to flash back to 1.4 if you want to be able to turn off the turner.

(Click to enlarge.)

August 7th, 2022

Another test firmware David asked me to check. This version seemed more likely to find the best match. I did have the ATU go to L0, C0 twice but then find a match on a second try. This happened once on 40m and once on 10m. Almost like it faulted but there was some switching/clicking involved before stopping, it just landed at a 3:1 or higher with 0 for L and C. A second tune however straightened it out. I did not record those two cases. Below are the results. I was able to find a slightly better match twice but I am sure one would never notice the difference during normal use. The improvement both times was within the error of SWR across the three device measurements.

(Click to enlarge.)
Accessories, Antennas, News, Portable

Arborist throw lines: Ideal lengths, weights, and packs for field radio

19 Comments

Many thanks to Barry (WD4MSM) who writes:

Thomas,

I thoroughly enjoy the website and movies!

Could you answer one question?

How much arborist throw line do you take into the field? 150’ – 100’ – less?

Thanks for taking the time to answer.

Barry WD4MSM

Great question, Barry!

I basically have four variations of throw line kits.

You’ve asked about line lengths, but I’m also asked frequently about the throw weight sizes and throw line bags as well.

First, let’s take a look at my kit variations, then I’ll share my thoughts on throw line lengths, weights, and bags. Note that many of these products are Amazon so there are affiliate links:

Throw Line with folding cube

One is my original Weaver throw line kit made up of two parts:

The line length is 150 feet (45.72 meters).

I tend to use this throw line when I’m doing a POTA activation very close to my vehicle. It’s lightweight, but a bit bulky to take on a long hike.

Compact Arborist Throw Line Kit

This kit is identical to my large folding cube kit above, but the throw weight is 12 oz and I store it in a small Weaver stuff sack.

Continue reading Arborist throw lines: Ideal lengths, weights, and packs for field radio →

Antennas, Articles, Guest Posts, How To, News

Steve’s Homebrew Vertical Antenna for POTA

15 Comments

Many thanks to Steve (KM4FLF/VA3FLF) for sharing the following guest post:

A Great Homebrew Vertical Antenna

by Steve (KM4FLF/VA3FLF)

Last spring, I was going through my many boxes of ham “stuff” looking for items to sell at our club tail gate sale. I came across a couple of Hustler SM Series Resonators (20 /40 Meters) that I had acquired. I am not sure where I obtained them, but I decided they were keepers.  That decision turned out to be the first step in a year long process that has given me an awesome homebrew vertical antenna.

After doing a little research I found the resonators and accessories at most of the online ham dealers. They are used primarily as mobile and marine antennas. I had seen where a ham had used these on a ground stake as a portable antenna as well. I ordered a Hustler MO1 mast which is 54 inches tall and thought I would attempt to make a portable POTA antenna.

Antenna base

I had a couple of small aluminum plates that I drilled out a few holes. I cut out a notch to put a SO-239 Stud Mount on the plate as my antenna base. I now had a ground plate, connector, and antenna with resonator. By putting a stake in the bottom of the plate, I was able to get the antenna to stand up. The Hustler resonators have a hex screw for tuning that can be loosened. The antenna can be adjusted for resonance by lengthening or shortening the radiator length. After adjusting the radiator my SWR was still horrible on the two bands.

Antenna base close-up

I had some 14-gauge wire laying around and attached it to the plate using carriage bolts and nuts for my ground radials. I didn’t think about the length of the wires at this point but went with three or four lines around 20 to 30 ft. I was able to use my vertical a few times with moderate success. My SWR on 20 and 40 Meters was around 2:0 to 1 at best. It was bulky and very delicate. Sometimes screwing in or unscrewing the MO1 the SO239 would slide off the edge of the aluminum plate. I put away my contraption for the winter and decided to move on to something else.

In April of this year, I wanted to revisit my project. Continue reading Steve’s Homebrew Vertical Antenna for POTA →

Antennas, Articles, How To, News

Joshua explores Unun insertion loss (efficiency) comparison testing

5 Comments

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

Accessories, Antenna Tuners, Antennas, News, Reviews

Joshua tests the ATU-10 portable automatic antenna tuner

19 Comments
ATU-10 with TufteIn protection case

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

UPDATE: Please check out Joshua’s most recent review after updating the ATU-10 with new firmware. The results have improved dramatically.

ATU-10 Random Wire Testing

by Joshua (KO4AWH)

I had a bit of time to do some field tests and I recently acquired an ATU-10. So I jumped right in and did some ATU-10 Random Wire Testing. The testing was completed with a Tufteln 9:1 QRP Antenna configured with an elevated feed point sloper and a counterpoise hanging straight down. The coax feed was RG316 17′ with the ATU at the radio with a short jumper. Several different radiator lengths are used as mentioned below. The ATU-10 was sourced from newdiytech.com, price was $120.24 shipped to me in GA USA, Ordered June 25, delivered July 8th.

A quick list of ATU-10 Features:

  • 0.91″ OLED Display that shows Power, SWR and internal battery remaining.
  • USB-C Rechargeable LiPo 1.7Ah
  • Grounding Lug
  • Bypass Mode (When I set to this mode however it would tune anyways)
  • Latching Relays (No power needed to keep in position. Hold tune with ATU off)
  • Input port for communication with IC705 (and potentially others)
  • 7 Inductors, 7 capacitors
    • (Elecraft QRP)
      • C array, pF 10, 20, 39, 82, 160, 330, 660
      • L array, uH 0.05, 0.11, 0.22, 0.45, 0.95, 1.9, 3.8
    • ATU-10
      • C array, pF 22, 47, 100, 220, 470, 1000, 2220
      • L array, uH 0.1, 0.22, 0.45, 1.0, 2.2, 4.5, 10.0
  • USB-C firmware update (ATU shows up as a drive, simply copy the new firmware file to the device and it will automatically update)
  • Weight 232g (8.1oz)
    • Tufteln Case adds 23g (.8oz) for a Total of 255g (8.9oz)
    • Compared to the T1 with cover for a total weight of 187g (6.5oz)

SWR measured with a RigExpert RigStick 320, Lab599 Discovery TX-500 and the ATU-10

The test process was to first check the SWR on the antenna with no tuner. SWR values recorded from the TX500 and RigExpert Stick 320. Values recorded in the 2 columns under the “No Tuner” section. This was completed for each of the Bands listed in the table rows (see below). SWR values were the lowest in the band range for all recorded numbers. Continue reading Joshua tests the ATU-10 portable automatic antenna tuner →

Accessories, Antennas, News, POTA, SOTA

The arborist throw line is an invaluable field radio kit tool

19 Comments

Two days ago, I activated Parc national des Grands-Jardins (VE-0499)–a stunning national park here in the Charlevoix region of Québec, Canada.

As soon as we drove up to the activation site I had researched in advance, I surveyed the picnic area and mentally noted the best spot to deploy an end-fed half-wave using my trusty arborist throw line.

With the throw line’s assistance, I had an antenna deployed within a couple of minutes max.

It hit me then just how invaluable a tool the arborist throw line has become for the types of park and summit activations I do.

Pre-Throw Line Activations

During NPOTA (National Parks On The Air) in 2016, I wasn’t aware of arborist throw lines and had been using some high test monofilament fishing line attached to a weight.

The fishing line was strong enough to support my QRP antennas and I could typically reuse the same length of line for 2-3 activations. Eventually, the line stretches and weakens thus it must be cut off and discarded.

Never again

I’m a big Leave No Trace kind of guy, so am embarrassed to admit that during one activation, my fishing line snagged high up in a tree and left a bundle of broken monofilament in a spot where I could not retrieve it. This was deep in a forest and although I doubt anyone will ever see it, I know it’s there. It bugs me to this day and if I ever sort out a way to remove it, I certainly will.

This occurrence was one of the catalysts for purchasing my first arborist throw line kit.

That throw line kit absolutely revolutionized my antenna deployments by:

  • increasing the speed deployment,
  • increasing accuracy,
  • allowing me to re-use the same line hundreds of times,
  • and being orders of magnitude more reliable and stronger than fishing line.

It changed everything and I’ve never looked back.

Since that first throw line kit (which I’ve lent to a newly-minted active ham), I’ve built four more throw line kits.

Compact Weaver Throw Bag

In early 2021, I purchased a second throw line and 12oz weight (identical to my first) for backpacking along with this compact Weaver Leather throw line storage bag (affiliate links).

I was searching for a more SOTA-friendly/backpack-able solution than the arborist throw line cube.

I was very skeptical about how easily this bag would work in the field. One of the reasons my throw line storage cube works so well is because the opening is large allowing the line to deploy without tangling. Packing up is fast because the line can be flaked back into the cube in a matter of seconds. Continue reading The arborist throw line is an invaluable field radio kit tool →

Antennas, News

Scott builds a compact random wire antenna with 9:1 Unun

8 Comments

Many thanks to Scott (KK4Z) who writes:

Hello Thomas,

I just finished an antenna project using an antenna I got from you. I call it my K4SWL antenna. I added an UnUn to it:

K4SWL Antenna Plus

Recently, I have had the desire to try my hand at winding toroids. They have always been a mystery to me. Today’s project is winding a toroid for 40-10 meters. My target antenna is one I learned from Thomas, K4SWL. It is a random wire antenna that is 29.5 long with a 17 foot counterpoise. It is a great antenna and works well at park campsites. I either string it up in a tree or I use my 20′ B&M fishing pole.

[Continue reading on KK4Z’s website…]

Scott KK4Z

Thank you for sharing this, Scott. I’ll be the first to admit that I can hardly take credit for the antenna design as it’s been out there for ages, but I do love this simple antenna and it has become an invaluable member of my field antenna arsenal.

I, too, have been planning to build a 9:1 UNUN and pair it with the speaker wire antenna just to make that match a little easier. 

Thanks so much for sharing this and your excellent build notes!

Antennas, Field Reports, News, Portable, QRP

QRP POTA at Fort Dobbs: No antenna? No problem!

15 Comments

I’m a pretty organized field radio guy if I do say so myself.

In all of the hundreds of field activations I’ve attempted since the days of the National Parks On The Air (NPOTA) program, I’ve only arrived on site two or three times and discovered I was missing a key component of my field kit.  Out of those times, only once do I remember that the missing component prevented my activation (it was hard to power my radio without a battery and power cable). The other times, I was able to improvise.

As I mentioned in this two-parter series, I tend to build two different types of field kits:

  • one that’s fully self-contained (like the MTR-3B kit),
  • or one that’s modular, where component families (transceiver, antenna, power, etc) are in their own packs and can be moved from pack to pack.

I always prefer having dedicated field kits, but they’re pricey because they require a dedicated antenna, battery, radio, key/mic, earphones, pack, connectors, and sometimes even their own throw line.

I assemble modular kits around a particular radio and antenna system prior to leaving the QTH to go on an activation. I have a method for doing this which prevents me from leaving stuff behind.

Save this time…

On Thursday, April 7, 2022, before leaving the house for a quick overnight trip, I grabbed my SOTA pack and disconnected my Elecraft KX3 from the KXPA100 amp in the shack.

My pre-side rails KX3 in the shack.

My KX3 is used a lot in the shack–along with the Mission RGO One and Ten-Tec Argonaut V–it’s one of my staple rigs at the QTH. I didn’t think I would have time to complete an activation on this quick trip, but if I did, I wanted to use the KX3. I also grabbed one of my pouches that contained a 12V battery, distribution panel, and power cord.

Also inside the pack was my Elecraft KX2 kit. It was in there from a previous activation, so I just left it in the bag.

When a window of opportunity for a quick activation opened on Friday, April 8, 2022, I grabbed it. I didn’t have time to go far afield, so I chose to activate the closest park to where I was running errands that day.

Fort Dobbs State Historic Site (K-6839)

As I was driving to the site on I-40, it dawned on my that I might have forgotten to pack an antenna.

Not a good feeling, but I was only 10 minutes from the park, so there was no turning back.

You see, a couple days beforehand, I did a bit of an antenna inventory at the QTH–I took all of my antennas out of their packs, checked them over carefully for any damage or fault points and  made notes.

I normally keep a 20M EFHW antenna in my KX2 field kit, but I remembered that also I removed it during the inventory.

Once I arrived at Fort Dobbs, I opened my SOTA pack and confirmed that I had no antenna. Not a one.

I kept a clear head and realized that if I wanted to complete the activation, I needed to do one of two things:

  1. Search the car in case, somehow, I had a spare antenna floating around in there. Unlikely, but I’d feel like a fool if I aborted an activation with an antenna in the car.
  2. Go to a nearby hardware or dollar store and find some cheap wire.  The KX3 has a brilliant internal ATU to match pretty much any wire I connect to it.

So, I searched the car. Continue reading QRP POTA at Fort Dobbs: No antenna? No problem! →

Antennas, Hams, Morse Code, QRP

Bob’s new stainless key and stealthy speaker wire that snags serious QRP DX !

4 Comments

Many thanks to Bob (WD4EWZ) who writes:

Thomas,

Let there be no doubt that your speaker wire antenna is awesome! I have been licensed for 46 years but was inactive during much of that time. I finally pulled the trigger, largely on your reviews, on a new Icom IC-705, AH-705 and PowerWerx PS.

I live in a very HOA restricted area so antennas were my bane. I built your speaker wire antenna not expecting much, and for the first few days I got nada. The bands were terrible and the antenna was looped around my lanai.

On Friday I had an inspiration. I made a throw line, moved an unused bird feeder anchor post and got the antenna about 40 feet up into a tree. The wire is invisible from the street, and we have more latitude in the backyard. My wife likes it so much she wants me to just leave it there, and make another for POTA/SOTA.

Does it work? Oh my goodness… Last night I nailed 9K2BM in Kuwait on 20m SSB, and this morning the JAs were melting the face off my IC-705.

This antenna is a wonder. As is the 705, after a week of learning how to optimize the settings.

Joe, at HRO in Winter Springs warned me that the 705 had a learning curve, and I foolishly said ‘yeah, sure.’ I do this (computer science/IT/data science) for a living. Don’t worry about me.’ Wrong! A huge learning curve, but I’m getting there.

Also, my new paddles recently arrived. I love this little stainless paddle — the magnets are strong enough to hoist a car, and the price is amazing… $69 on Amazon [affiliate link]!

I am using a 4″ square steel forging plate I had from my days of making metal jewelry. (Too many hobbies). It works a treat.

Thanks so much for your writings and 73.

Bob (WD4EWZ)

Thank you for sharing this, Bob! Loads of readers have asked me about those stainless paddles, so it’s great to get a report on them. 

I also love how you’ve implemented the speaker wire antenna in such a stealthy way! And the DX you’ve snagged? Simply amazing.

Thanks again for sharing!

Antenna Tuners, Antennas, News

Norm recommends the MFJ-212 Matchmaker for effortless tuning

4 Comments

Many thanks to Norm (VE3WNS & M0CEL) who writes:

Hi Thomas,

[…]At my condo QTH in downtown Toronto I’ve been using a balcony tripod mounted MFJ 1886 along with my Icom 7300. I heard about the MFJ-212 Matchmaker and decided to try it out. It worked brilliantly. What it does is put out a signal in the form of hash and you can see the resonant point moving along the band scope on the radio as you tune the antenna. Once the hash is centered you are on frequency without ever transmitting.

I’m back at my QTH in Manchester where I have a pretty respectable station, you can see both on QRZ. Anyway, your videos are responsible in a large part for getting me interested in POTA so I’ve purchased an ICOM 705 and a Chameleon F Loop 3.0. I decided to purchase another MFJ 212 Matchmaker and again, it works brilliantly. No transmitting required as the antenna can be tuned visually on the 705 band scope. The 212 can be powered externally or, as in my case, I’m using the 9 volt battery option. I figure the battery will last for ages.

[…]I have to say the MFJ Matchmaker has made working with a hi Q loop a pleasure, especially one that tunes as smoothly and finely as the Chameleon F Loop.

73

Thank you for sharing this, Norm and for the kind comments! I had no idea such a product existed. I love the concept, though–this could be especially useful tuning antennas like loops with high Q and thus narrow bandwidth. 

Click here to check out the MFJ-212 Matchmaker at MFJ ($149).

Update: A number of you have pointed out that the MFJ-212 is a noise bridge! I think it’s so cool that, in a sense, this accessory is even more useful when paired with a transceiver with spectrum display. Thanks for the comments!