Using RUMlogNG for iOS with an Elecraft KX2 over Bluetooth [Part 2]


I finally found some spare time today; the weather was not so good outside, and I’m on vacation this week… that’s help a lot! 🙂 My main objective today was to build a functional prototype, a proof of concept.

Step 1 : Install and power the Bluetooth module on a breadboard using a small 5V power breadboard supply.

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Step 2 : First I used my logic analyzer probe with the software Logic from Saleae on MacOS to verify if all communication parameters were well set. Hooray! I transmitted the word “TEST” between the iPad Adafruit app running on the iPad Pro and the Bluetooth module.

Then I established a link between the Bluetooth module and RUMlogNG To Go iOS app running on my iPad Pro. The Bluetooth module needed to be recognized first before going further.


Step 3 : Another step was to install a MAX322 chip needed to «translate» the information using the RS-232 protocol between the Bluetooth module and the Elecraft KX2. Note the MAX322 must be powered at 3.3V. The Bluetooth module can provide such voltage output. But for this prototype, I  powered the chip using a 3.3V voltage line from the breadboard power supply.

Step 4 : Every components are now properly hookup. RUMlogNG To Go iOS app on the iPad Pro and the Elecraft KX2 are ready to establish a link. Note the baud rate must be set properly on the transceiver at 9600 bauds. As you can see in the picture below, I entered the CAT command IF; and the KX2 returned me the frequency on VFO A 14.210.


There is a short video below I captured from my iPad Pro with the Elecraft KX2 and RUMlogNG To Go controlled by the Bluetooth interface in action!

Note that I captured the initial footage with the new capture function available in iOS 11. Then I completely edited the video and did all effects with my iPad Pro using the iOS LumaFusion. A great app!

My goal still to build the project for under 35$ USD. I’m also planning to design my own PCB board and offer it as a kit; Fritzing is already running on my Macbook Pro.

More to come in my next post!

Meanwhile, do not forget to follow me on Twitter @VA2SS, and subscribe to my blog and my YouTube channel as well.

Have fun and stay tuned!


de Jeff | VA2SS

Using RUMlogNG for iOS with an Elecraft KX2 over Bluetooth [Part 1]

Hi everyone! It is not a surprise for people who knows me well, I am an addicted fan of all Apple products. I am also the kind of guy who is always searching for a way to get more of his gears and enhance the overall experience; especially for my iPad Pro!

My project is to build a Bluetooth interface and let me connect my Elecraft KX2 to my iPad Pro while using my favorite logger RUMlogNG To Go for iOS. At the moment, RUMlogNG To Go support only 2 methods to connect to a transceiver : Bluetooth or Piglet. (I know, this is a known iOS limitation to access external devices). 🙂

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I really do prefer a connection over Bluetooth for many reasons, but at first for energy efficiency. I like this logger app, even the MacOS version. It is a very powerful iOS app with a lot of nice add-on features like a versatile DX cluster, world map with grey zone, logbook import and export using Dropbox, and much more! The developper Thomas DL2RUM really pay attention for all feedbacks received from users. Cheers to Thomas! 🙂

I will use for my project the Adafruit Bluetooth LE interface. It is really a polyvalent  board, compatible with Apple iOS, that can be easily integrated inside all custom built projects. I bought mine at DIGIKEY store; their iOS app is also really cool! Everything is done using my iPad Pro. I am even writing this blog using exclusively my iPad Pro. Hi Hiiiiiiiiii ‼️🎉😜

I will also use a wide known and available MAX3323 chip for the serial communication between the Bluetooth board and the Elecraft KX2.

The project will cost under 35$ USD to build. I’m also planning to design my own PCB board and offer it as a kit. It will be almost a plug and play experience, easy to assemble to everybody!

More to come in my next post!

Meanwhile, do not forget to follow me on Twitter @VA2SS, and subscribe to my blog and my YouTube channel as well.

Have fun and stay tuned!


de Jeff | VA2SS

End-Fed antenna revisited… again!

podcastWell, I really hope all of you had a great summer so far? We had a great one here in Quebec this year. We had plenty of beautiful days with a lot of warm period to go out and play with our ham radio gears…. even also to renew with astronomy that I left behind since 2007! What a great summer!

I was searching for quite some time for references related to end-fed antenna. Not especially for much technical details, but more about experiences from users in the field. I happily found a short, but a great article from W1SFR Stephen wrote back in 2013.

20160216_191324206_iOSAn article I previously wrote about “end-fed antenna using an Un:Un 9:1”. End-Fed link

T68-2 (3 wires)
T68-2 (3 wires)

The main reason I was searching for such document it is because I am using this kind of antenna for portable use, and I really like the simplicity of this antenna for many aspects: fast to deploy, works on many bands, no antenna to tune, honestly effective for casual use, etc… Much of my argument is related to personal consideration of course…. like many other aspects in our lives.

Now back to the document from W1SFR. The document from Stephen was for me a way to bring field experiment results over technical details. And atop of that, he is using an Elecraft KX3, like I use an Elecraft KX2 myself since last May 2016. So I was also very pleased to find in his document a reference chart of wire lengths to use, and which “traps” to avoid when using such antenna.

The end-fed antenna he is using in his article is combined by the use of the same 9:1 Un-Un that I am using. So great! We are now comparing almost an apple with an apple! 🙂

I built my 9:1 Un-Un using the EARCHI documentation that can be found here… EARCHI document. We even use the same length of coax, but not the same type… I’m using the lossy RG-174… I prefer to keep everything smaller and lighter as possible. If I take a look at his comparison tests he presented in his chart using different antenna analyzers, I am also getting similar results on my side with mine.

My results using a RigExpert AA-600 using 25 feet of coax, 35 feet of wire atop of a 31 feet fiberglass mast.

I was reading recently many comments from people that were bored of the actual DX condition when doing outside operation; DX condition are not are their best, hard to operate QRP, etc….  But what the hell…. Hi!! Most of them also discovered that when using digital modes, even when we could find that the DX condition are not at their top, that many, many DX contacts could be easily done when QRP. Let me tell you that I had plenty of fun so far during my last summer! I even found that when using an end-fed antenna, running QRP and using digital modes…. I was able to reduce my power by half… so from a big 10W SSB :-), I used 5W or less when using PSK, RTTY or even JT…. and 1W or 2W was also very often possible. It is fun to try to use less power.. it is part of the hobby… the experimentation!

Well, back to the End-Fed antenna. It is fast to deploy and to have fun. Fairly efficient, especially when using CW or digital modes, compact, lightweight, etc… I prefer this antenna over many others that I actually own, and that I do not use very often for many reasons.

So, the article from W1SFR gave me another confirmation, another point of view, that the End-Fed antenna could be a well performer.

Give this antenna a try! It is a low cost antenna, that could be easily built, and could let you potentially renew with the fun of outdoor operation, in a minimalist way!!

I would like to thank W1SFR Stephen for his great article. Another link from W1SFR…. his antenna kit…

Meanwhile, do not forget to subscribe to my blog and my YouTube channel as well.

Have fun and stay tuned!


Jeff | VA2SS

Elecraft KX2 «Go Box» from Thomas OE2ATN

I recently found that Thomas OE2ATN recurred and built another great «Go Box», but this time for the Elecraft KX2. What a great addition for people who like to have something very neat and compact in a small enclosure.

I’m still impressed about all the details he takes care when he is building his project. Everything is well sharp, and nothing is left aside. It is like an «art project».


The project use a water tight «Peli 1050» brand enclosure, the European version of the «Pelican 1050» from the well known company Pelican in the USA. I never verified the quality of the European version, but I assume the quality is the same because they are both from the same company holding using the same quality standard.

More about the company relationship:

This kind of case is now very easy to find on the market. Elecraft KX2 deserves to have the best case! 🙂


There is 2 common questions people are asking him. More FAQ could be found on his website listed below at the of this post.

The right PowerPole is for charging the internal Battery. The original KX2 battery cable was connected to the switch and then runs back into the KX2.
So you can cut it from the KX2 and load the LiIo via the right PP. Of course on your own risk as Elecraft suggests to remove the battery while charging. My note on this solution: Do you remove your laptop / tablet / phone …. -battery while charging? Sure there might be different opinions now. In ON-position the right PP supplies the voltage of the internal battery – maybe for a little LED to have some light on the knobs or any other accessory.
The left PowerPole is connected to the 12V jack for an external supply on the KX2.

Heatsink and airflow I do not really care about heat because I´m not operating for longer periods (mostly on mountain tops) and I do no data modes. Just phonie and CW. Never had any heat problems with my old GoBox design, even when operating in direct sun for around half an hour.

I invite you to visit his personal website at the addresse below:

Thank you Thomas OE2ATN to share your project and idea with us!

Do not forget to subscribe to my blog and my YouTube channel as well.

Stay tuned!


Jeff | VA2SS

End-Fed antenna… a well performer!

As all of us know, there are plenty antenna solutions in books and on the market today. Many manufactures promise with unexpected and excellent results. But don’t be a fool and too much attracted with these results, from time to time, the simplest antenna setup could be well enough, and also cheap to build. A project, this is what amateur radio is all about!

The End-Fed antenna is well known to be a good antenna choice for a fair result you could expect from it. Many of us use it for it’s ease deployment. It is also very easy ton build. The heart of this antenna is the UNbalanced to UNbalanced adapter with a transformation ratio of 9:1, commonly called an UN-UN 9:1. Take a look at my previous post for more details on “How to build an Un-Un”.

Link :

So by example, you could expect to bring down an impedance of 450 Ohm to 50 Ohm very easily. I will not talk about the loss and other consideration…. just keep all this simple please. 🙂 My actual End-Fed antenna setup consist of 35 feet of wire, called the radiator, and 25 feet of coax cable. The Un-Un is just in between. This antenna setup will perform well on band higher than 20m, let say between 20m thru 6m.

The antenna can be easily deploy vertical or diagonal. Mine is held by a 31 feet high fiberglass mast. Easy to setup, easy to deploy. For the radiator, I choose a 26 AWG wire made silicon coating. Why silicon coating? It will still flexible even in winter at -25°C. The coax cable need to be simply laid on the ground. Avoid letting the coax cable as a coil. Here the results I obtained when doing some tests earlier this weekend.
As you can understand, I did not use any antenna tuner to get these results. The adding of an antenna tuner will be only to protect to transceiver. The antenna tuner will not work very hard! It is important to understand that this antenna is also very broad. It covers the entire bandwidth of all bands from 20m to 6m below a SWR of 2:1, let’s say with a small exception on 15m band. I use this antenna since 2 years now. And I had many good results with it. Even when running QRP SSB with 10 Watts or less. If you are a CW guy or a digital addict, this antenna will give you many joyful moment! Have fun and let me know about your results if you try this antenna.
Jeff | VA2SS

A tiny QRP Un-Un 9:1

As I would like to take the less space in my mobile arsenal in my next summer outdoor mobile operation, I decided to make a tiny Un-Un 9:1 for my End-Fed antenna based on the schematic published by the :

EARC Emergency Amateur Radio Club

The schematic can be found here

I only took a smaller T68-2 core and a smaller wire gauge…. a smaller of everything. The wire lenght I use for the antenna is 35 feet of 26 AWG flexible silicon coating wire and 25 feet of RG-174 coaxial line. Tiny Un-Un, tiny wire and tiny coaxial cable…. but not tiny results !! 🙂


Until now, this Un-Un 9:1 perform well as expected on 20m band and higher. A longer antenna wire will be tested later.

A very tiny Un-Un 9:1 that can handle QRP power less then 20W PEP.



For building instruction, I invite you to take a look at their schematic from the link I provided at the beginning of this blog.

All the credit goes to the EARC Emergency Amateur Radio Club.

Nice job guys !


More information will be provided later with further test results. I will do a comparaison between the original design and the tiny version. I will use a RigExpert AA-600 to plot a few graphs on how do they react between them.

Stay tuned !


Jeff | VA2SS