Tweaking the K2 for digital modes

My Elecraft K2 which I assembled as a kit in 2001, has mainly been a CW rig, but now I wanted to use it more for digital modes like FT8 also. That required some tweaking:

1. Wider bandwidth in SSB filter, so I took it from 2.4 to 2.6 kHz (KI6WX)
2. More sensitive VOX (G3RXQ)
3. RF-filtering on audio input (G3RXQ)

All of these are modifications to the tighly packed KSB2 board shown above so it took some patience to implement them. The bandwidth modification consists in replacing six ceramic capacitors that were sitting between the crystals. The VOX sensitivity modification is done by adding a pot which can be seen in the image as it sits outside the PCB on the left-hand side. I was lucky to find a mini 5k slider pot in my junk box which fitted in. Finally the RF-filtering was done by adding an inductor of 2.5 mH (right below the 5k pot) and a decoupling capacitor.

Recognizing a CQ on the FT8 waterfall

A CQ is not so hard to recognize on an FT8 waterfall display as there is a charactaristic indendation from the right early in the 15 second period. This can be seen in the three circled traces in the figure.

They show a CQ at 711 Hz with SNR 11 dB, one at 899 Hz with SNR 16 dB where my receive cursor is placed, and one at 2003 Hz with SNR 6 dB. These are fairly strong signals so it is easy to see the indendation, but in my experience it works down to almost -10 dB also if the contrast is set correctly with the slider on the display. 

Look closely and you'll see one in the period before also, at 21:15:00 (SNR 12 dB). Try this the next time you run FT8 and I'm sure you'll recognize it too!

This post first appeared on the LA3ZA blog.

FT8 From My Garden With Chrome Remote Desktop

W3RW, J. Robert Wittmer wrote "Enjoy FT8 From Almost Anywhere" in the September issue of QST. He used Teamviewer for remote operation. I tried that and found what the article also said, that if the host PC's session was terminated one needed to get a new password in order for an Ipad to log on again. I also found that multiple screens was a bit cumbersome to access.

Then I read the blog of DM5HF, Christoph Steinert, and saw that Google's Chrome Remote Desktop could be a good alternative.

You have probably worked an FT8 robot

I was following the presentation of Joe Taylor, K1JT, from the recent German ham radio meeting in Friedrichshafen this year. He showed this slide of stations suspected of being robotic ones, due to them being seen on PSKReporter 24 hours a day, 7 days a week. His list is this:

I have worked many of these and most of them on multiple bands:
A41ZZ, A45XR, CN2MA, ES6DO
EW8W, HA1RB, HA7TM, IK4LZH
OG0C, OO6O
OO7B, RA9H, SQ9IWA, SV1EDY
SV5DKL

I only miss IK4LZH, KA1AQP, KW4SP, OO6O, OO7B, RA9H, SV1EDY, and W1KE.

In addition it wouldn't surprise me if MM0HVU also runs automatically from time to time judging from how often that call sign is seen on the bands.

Have you worked any of these stations? And are there others who are active on an almost 24/7 basis?

By the way, the presentation has title "WSJT-X FT8 and Beyond" and can be downloaded (images and sound) here. It is well worth listening too.



This blog post first appeared on the LA3ZA Radio & Electronics Blog.

Port sharing for WSJT-X

The program for FT8 and other digital modes, WSJT-X, requires control over the communications port of a rig like the Elecraft K3. But so does the log program. Fortunately there is a solution for sharing ports. I use LP_Bridge and DXLab Commander which are both freeware.

LP_Bridge works OK, although it does abort for mysterious reasons from time to time. The setup is here:

The active ports are COM16 which connects to the radio, COM14 which connects to Commander, and COM13 which is used for the logging program.

FT8 anomaly or long delayed echo?

My friend Alf, LA2NTA, has sent me these screenshots from when he has been operating FT8. The first image is when operating 10 meters and took place early in November.

Two of LA2NTA CQs being received by himself on 10 meter (in red)

It shows how his own CQ comes back to him at 10.54.00 and at 11.00.00 and is decoded in his own receiver. The echoes return at the time of transmission.