Elecraft K3 modifications

There aren't that many modifications that you can do to the Elecraft K3. This is very different from the K2 as in my list I now have 138 different modifications for it. But Elecraft does have a few K3 enhancements and mods on their home page and here are two additional modifications that I have done to my K3.

Plug-in roofing filters on
main RX board

The first one is to add a wideband LC-filter (roofing filter). The filter was inspired by ideas from W5DHM with three tuned sections at the IF frequency of 8.215 kHz. It is to the right in the image. It is not the best of filters, and probably compromises performance somewhat, most likely because of its low image rejection 30 kHz away. It has however served me well as a receiver filter for the latest version of K1JT's software WSJT-X. That software processes a 4 kHz band for both the JT65 and JT9 digital modes, and the LC-filter has demonstrated to me the utility of having a wide roofing filter for reception of those modes. The filter also works well for listening to broadcast AM which was what W5DHM designed it for in the first place.

Studies on Morse code recognition

Nice drawing of Morse key by Dutch
radio amateur Dick Kraayveld, PA3ALM
(http://www.morsecode.nl/pa3alm.html)

In the early 90's there were some interesting studies performed on Morse code recognition and the effects of pitch frequency, signal to noise ratio, and code speed. They were part of the PhD work of Peter Montnémery who is a medical doctor and also radio amateur SM7CMY. I reread these papers now since there was a discussion on the pitch frequency (CW pitch resolution) just recently on the Elecraft mailing list. This discussion comes up from time to time, as it did for instance in 2006 also (Sidetone questions -- copy speed vs sidetone pitch).

The two first papers are probably the most interesting ones for radio amateurs, so therefore I have posted their abstracts and a key figure from each of them also.

The simplest possible AM transmitter

Here's a design for a 1 MHz amplitude modulated (AM) transmitter. I've been looking a while for something like this, a simple short range AM transmitter for the medium wave band, as I needed something for demonstration of my collection of old radios.

The result is the AM transmitter shown here in an Altoids tin on top of a Radionette Kurér radio. This is a portable tube radio from the 1950's. Several hundred thousands were produced, and it was exported from Norway to 60 countries. It is still popular among collectors.

The transmitter is as simple as it gets. The heart of it is a 1 MHz crystal oscillator in a can. Its 5 Volt power is modulated via an audio transformer, one taken from the output of a transistor amplifier (primary 147 ohms - secondary 3 ohms). I drive the modulator from my cell phone into the low resistance side of the transformer and get good audio when the phone's volume is set to maximum.

Q codes from the streets of Paris

I had the privilege of living in Paris with my wife a few years ago. At that time, 2008/2009, the series for car license plates had just come to Q. That made it easy to find plates with many of the Q codes which are used as abbreviations in radio communications. What follows is the result of walking the streets of Paris, mostly between the 5. and the 13. arrondissement:

Here is a broadcast to all radio amateurs: 

What's in a name - radio societies all over the world

The IARU HF Championship took place this weekend. This is the contest where every country has national stations which exchange the abbreviation of the radio amateur society. Therefore it was an opportunity to reflect on what the names of the national societies mean. Many of the names in the IARU list portray the heritage of a hundred years. It is not so strange then that this may make some of them hard to understand and even a bit old-fashioned.

Starting with the ARRL - American Radio Relay League or NRRL (Norwegian ...) then this is about a network of stations relaying messages in a country with large distances. This is a bit 1920's to me. Looking at the ARRL web page it looks as if the the ARRL agrees and really would like to modernize the name to the National Association for Amateur Radio. The Portuguese may already have modernized it a bit by the use of network instead of relay: "Rede dos Emissores Portugueses"  (Network of Portuguese Transmitters), or perhaps it is just because this is the same word as "relay" in Portuguese?

The radio amateurs are coming! Oslo Mini Maker Faire

"Have you dreamt about sending radio signals via the ionosphere? Or what about studying moon bounced echoes? Visit the radio amateurs and you can learn about analog and digital radio communications, antennas and electronics. There are 5-6000 radio amateurs in Norway, and they probably represent the oldest maker hobby.”

This was the enthusiastic introduction that we were given on the web pages of Oslo Mini Maker Faire. It was arranged at Norwegian Museum of Science and Technology on April 6-7, 2013 in collaboration with the University of Oslo. There were close to 4000 visitors during the weekend and about 100 exhibitors. Our joint stand between the radio amateurs of the Asker/Bærum and Oslo clubs also had a constant stream of visitors.

Young operators in All Asian contest

The All Asian DX Contest is one of the more fun ones to participate in. One thing is the DX aspect of it, but I like it also because of the exchange of the age of the operators. In other contests one exchanges boring stuff like serial number 1, 2, 3, ... ; the CQ or IARU zone (14 and 18 for me); or the power output. But exchanging the age of the operators gives a little glimpse of the person behind the radio on the other side.

It also makes it possible to make a graph of the distribution of age. I had 62 contacts this weekend, of which 55 were unique. They were mainly in Asiatic Russia and Japan. The average age of the operators was 51.6 years - 7 years younger than me - and the graph shows the distribution. The bar for e.g. 54 is the percentage, 20 in this case, of operators in the bracket 50-54 years and so on.

The graph actually makes me quite optimistic concerning the future of ham radio. There are many young contest operators out there, at least in Asia. This resonates well with what others are saying also. Never before has there been so large activity on the bands as during contests these days.

Cosmetic K2 Upgrade

My Elecraft K2 which is now more than 11 years old (serial #2198) has served me well, even earning me QRP DXCC (100 countries with 5 Watts) some years ago. It is still cosmetically in mint condition, except for that single item which sticks out like a sore thumb: The tuning knob.

This became very clear to me a couple of months ago when LA8OKA's and my K2 were displayed side by side at our stand at Oslo Maker Faire. His is less than two years old, serial #7224, and they were similar except for the scratches in the faceplate of my tuning knob. If I am allowed to generalize from my knob only, it seems as if the faceplate had poor quality paint and has been replaced by a better quality version over the years.

Anyway I ordered a new one and paid the price which at present is $30.37 plus shipping. The difference is really striking and I feel like I have a new K2 now, well worth the price! The K2 now serves as my second rig, and I think it has many years of good service still to come.

Related posts:

• Elecraft K2 do's and don'ts
• Five LEDs in buttons for the Elecraft K2
• My Elecraft K2 Modifications