Saturday, July 20, 2024

Finally SuperHound


Heard a lot of complaints about the new superfox mode. Lots of trouble when there is QRM on the fox frequency. So far I did not hear K8R anywhere although I was very curious about this new superfox transmission. I got a tip from PB7Z today that K8R had a big signal on 15m. So I thought I give it a try. I quickly installed the newest WSJT-X beta version (rc6) and gave a couple of calls. You see, third time it was no problem at all. K8R indeed had a big signal here on the experimental squalo.

Sunday, July 7, 2024

3BMOX antenna overhaul (1)

 This 3 band "7 element" yagi has an important advantage. It has no coils or lineair loading. It is full size with a moxon as the 20m part.

This antenna would do quite good in my tower. However, I find it too big and too heavy (20kg). But I would like to see how things are constructed and do an overhaul because some parts seem to be damaged and/or worn. I started with cleaning everything today since the color of most of the parts were brown and green and that was no paint!

I quickly took this photo after the cleaning. It started to rain so no further progress was made. I found a heavily worn tube which I will replace. Like the previous EA VHF 3 band antenna I rebuilt there are parts made from POM which are getting brittle. Moxon isolators seems to be glasfiber which was not protected by tape, coating or paint, they seem to be usable but I wil certainly wrap them with tape. Hopefully the weather will improve a little this summer...

Wednesday, July 3, 2024

Reducing RFI from solar systems

  Reading this very useful and detailed post from fellow blogger KA7OEI.

I extended my solar energy production with 5 extra solarpanels a while ago. It really was a bargain getting these as I bought the 260Wp panels at a cost of €50 (€10 per panel) from a colleague. The inverter was searched for on the dutch internet marketplace and I bought one for another €50. Most of the costs were the mounting rails, wiring and the #31 ferrite to make shure no RFI would reach my antennas. The last items were an additional €300. 

The open line of the inverted-V doublet is just about 1,5 meter above the solarpanels. I even got a quarter wave CB antenna near the panels to listen to some chats on CB when in the garage. I really did take all precautions to make shure I would not have any RF coming from the inverter or the panels. On the pic at the right you see that I used big #31 FT240 ferrite rings in both AC and DC lines. The earth wire is fitted with a big #31 snap-on ferrite. DC wires are mostly fitted in earthed Alu tubes were possible. Everything is earthed to a central earth point, the tubes, the mounting frames and the inverter.

At the left a pic from the Alu tubing used. Yes, it is made of old antenna left overs. I always use what I have at hand. I seldom throw away scrap Alu tubing. Over the years I collected some ;-).

Well to keep a long story short I can recommend the page from FerriteShop about this subject. I followed most from their tips and used #31 snap-on ferrites below the panels. The only difference at my installation are the FT240 ferrite rings below the inverter.

For Dutch readers it could be interesting to read the Dutch Telecom recommendation:

Well, I don't have any RFI from my own solarsystems. I see QRM in the waterfall of my IC-7300 from my neighbours solarsystem on 50MHz. Just to be shure it isn't my own I checked when I switch my own systems off. Of course there was no change, the QRM stays there and is not from my property for shure. Luckily the QRM is only there when I turn my beam over their house.

The 5 solarpanels harvested 165 KWh in less then 2 months. Approx 3 Kwh average per day. It is not much but anything helps. The system can be extended easily when I find another 5 or 6 secondhand solarpanels.