Almost there

  • Coax switching mess almost cleared around the microHAM relay box.
  • Yesterday the Big Yearly Total Thoroughly Cleansing of the shack. Found a few stacks of QSL cards which I’m not certain that I’ve processed yet. Plus a BIG box I definitely still need to process.
  • Let amp run dry and have XP install yet another bunch of updates.
  • Just tested all bands on the tower: 30m to 10m = all systems go!
  • Bought bits and pieces plus odds and ends to connect coax in outdoors cabinet.

So I finally could actually make a QSO soon. I’ve been reading the new G3SXW book. Fun reading, I might reread his other books one of these days.

I’m contemplating to get rid of the shack’s USB mouse and PS/2 keyboard. Replace with QRO-proof 2.4 GHz stuff? People recommend Logitec products. The problem is all the ferrite and shielding around the cables that are on the desk. Apart from the looks, it limits the operating comfort. I really took a lot of necessary RFI measures. I tamed that beast so I’m a bit reluctant to change things. Each new antenna makes me cross my fingers because you never know how its radiation pattern affects the PC. Here’s a copy of a post I did two years ago. It tells how I solved my RFI issues.

The relays were clapping to the rhythm of the CW being sent. The problem was worst on 40+30m. Double six, 2 band decoders, BPF-600 filter set and reduction interface. This was a severe problem that even damaged the decoder’s hardware! Tripping point was also far less than 100W, I couldn’t even use the amp.
I already had a good grounding system – or at least I thought so. There were TENS of ferrite clamps everywhere too. But it didn’t help.
The D6 switch is driven by the band decoder by means of two 10m long shielded (!!) cables. The shield was grounded in the shack and on the Double6 by means of the edge of the DB25 connector. That turned out not to be enough. On both ends of the control cable, I removed some of the outer insulation to expose the cable’s shield and clamped a grounding strap on the shield. This strap went straight to the grounding posts in the shack and at the antenna side.
Better grounding of the control cable was the answer here and solved 90% or more of the relay "clapping" problems up to 1kW. So make sure that every DB25 has its edge connected to one of the ground pins, and that all shields are properly grounded. For  grounding wire, I use the shield of RG-213 leftovers to keep the inductance low or at least lower than a 2.5mm² wire.
Other RFI issue:
I had some problems not affecting microHAM devices but the PC. If I launched a CQ on 15m, I would lose mouse and keyboard control, which is quite painful in a contest. Or the kbd would send commands to the PC and thus the rig all by itself. On 10m exceeding 500W, WinXP was so kind as to tell me that "the computer is now shutting down". Here’s how I solved it and cured the remaining 10% of the problems.

  • I took the shield of RG-217 (thick) coax and routed all mouse and keyboard cables with extensions cables through this. This makes a grounded shield for the PC control cables. A Faraday cage if you will. It was not easy to get the PS/2 or USB plugs through the lengthy shield but with some fiddling and harsh words, I managed to squeeze it through.
  • I bought self adhesive aluminum tape. Where PS/2 and USB extension cables get together, I taped this connection RF tight. I also used this aluminum tape to tape all connections to the PC’s main board, to close all RFI holes. The backside of the keyboard too was covered with this tape, which was then used to connect this shield to the grounding wire (coax shield) slipped over the cable.
  • The shielded mouse and kbd cables are then coiled up 2 to 3 times and I made a "binocular" core by means of ferrite clamp on cores. Where possible, I put ferrite clamps over all control cables. I use lots of ferrite chokes on the coax ( ). The PC’s case is also grounded to the RF ground. Most if not all of my RFI problems are now gone.

Hope this helps?
73 de Franki ON5ZO

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