Linux Home Station Upgrade

  For some time now I've been thinking of streamlining my setup. Using a large and ageing tower PC with keyboard and everything else takes up quite a lot of space in my small 'shack'. I recently acquired a 64 bit laptop. The tower PC was running Windows 10 and was getting slower with each update. In addition to this, I was getting spurious lock-ups and crashes mid contact which wasn't very good. It seemed like a good time to change over to a Linux operating system. Because the laptop was a 64 bit machine, I figured it would have no problem supporting the latest that Linux had to offer. Because I have had some experience with Debian, I decided to install the latest Debian 12.5. Everything went pretty well, apart from a few slip-ups with registering Dialout and TTY in groups. This is required for setting up any USB control functions. A little Googling sorted out my problems. I then moved on to installing the requisite apps to control my rig and to operate on FT4 / 8 with WSJT-X. I also installed Gridtracker as I had before on 'Windoze'. I can't believe how much faster the response is using this system now. Start-up and shut-down times have been reduced to mere seconds.

Since I had been using MSHV for my FT4 / 8 work, it took me a little while to familiarise myself with WSJT-X, but now everything is flying. Just a shame the propagation is so bad at the moment.

End Fed Random Wire Antenna

With the demise of the EFHW,  I decided to revert back to an EFRW. I don't know why they call it a random wire because there are set lengths that you use to get the best results. I tend to just refer to it as a long wire. This would only need a wire length of 58 feet, which makes for an easy fit in the garden. No need to divert around trees and the like. It is a straight run from the apex of the roof to the support pole at the bottom of the garden. However, the transformer would have to be reworked from a 49:1 to a 9:1 ratio (above diagram). That was easy enough to achieve. The secondary windings were reduced from 14 to 6, sticking with the 2 turns on the primary. I removed the capacitor also. Two type 240-43 ferrite rings were used as before. This is no longer a resonant antenna on any band, unlike the EFHW which is resonant due to utilisation of the harmonics. Running a check on the VNA confirmed that this would be promising with regard to SWR readings on all bands from 1.8MHz up to 28MHz. A higher SWR was observed on the 7MHz band and the 24MHz band of around 2.5:1 but nothing the ATU in the rig couldn't handle. I found that a 1m long counterpoise wire was sufficient to reduce the SWR readings even further and hopefully help with common mode current flow. A common mode choke was also employed on the coax close to the feed point. 

Conclusions:

The antenna performs as expected. Several good DX contacts were achieved - even on 10W. I rarely run above 30W anyway because I use mostly digital modes. I find this to be sufficient for contacts all over the world. These contacts include USA, Canada, Brazil, Suriname, Ukraine, China and most of the European countries. I have noticed though that the noise level may be higher. Not sure why this is. It doesn't appear to be on all frequencies. Could just be the normal noise level on a particular day. Conditions haven't been the best recently anyway. Overall, I feel more confident with this antenna than the 'fickle' EFHW. 

EFHW Problems

I have recently been installing some reflective bubble-foil insulation in the loft and had to move my antenna so that all the wire is outside of the building. This meant losing a good few metres of wire as I am constrained with my available space. I had to run the wire vertically down the gable wall up to the level of the garage roof and then a horizontal run to the garden. This still wasn't enough space so I passed the wire around a tree at the top of the garden before heading for the support pole at the bottom of the garden. Major problems then ensued! I lost my decent SWR readings across all the bands except the 40m target band which was perfect. I then set about shortening the antenna and adding different counterpoises until I got something near workable. Still not very good. I think I have screwed everything up! What I can't understand is the near perfect match on 40m whilst the rest was a shambles!

So, decision made, I ordered a new 20m length of wire. I figured that if I start with a known quantity, I could work from there. I intend to 'steal' a few feet and put the supporting pole at the very extreme South East corner of the garden. (Hope the neighbours don't complain!)

Conclusions:

The new wire run did not improve things. This makes me think that the wire doesn't like the things it is coming into contact with, mainly, the wall. The wire is clipped to the wall vertically downwards. I am going to re-route this so it goes over the flat roof before going to the tree, keeping it mainly in free space. I am also going to lengthen the wire by about a metre or so. Looking at the VNA readings it looks like the wire is too short because the peaks and dips are low by about 1MHz on all bands, but I will do the re-route first and check again.

Update:

Nothing I was doing seemed to improve the situation. Although the EFHW still works, I have serious doubts about its efficiency and high SWR readings. My decision is to scrap the antenna altogether and start again with something different.