[RRDXA] RFI

[Franki ON5ZO]

For what it's worth, I ran a Microham MicroKeyer close to my antennas with 
1kW and never had a problem. I believe another friend of mine (OT1A) doesn't 
have any problems either.
Another friend of mine had to wind his mic cable through a ferrite core to 
get the modulation on 40m a bit cleaner and I soldered a 10nF bypass 
capacitor across his CW output because it was sticky. Like mine his antennas 
are very close to the shack.

Since last year I run SO2R with a MK2R+ without problems, but I had problems 
with the switching of my Dunestar BPF-600 bandpassfilter: clicking and 
rattling relays. I solved this with Draconian measures.

- I use a lot of ferrite. All antennas are choked on the coax 
(http://www.dx-wire.de/), again a choke at the rig and amplifier.

- Where the cable exits the device (keyboard / mouse end), I have wound it 
round a 2" length of ferrite rod and hold this in place with heath shrink 
tuning.

- Now I have routed both cables through the shield of a stripped 1/2" coax, 
that is grounded at the PC end. Not easy to fiddle the plugs through, but 
patience is said to be a virtue.

- At the PC side of the plugs, the cable is choked by winding it through a 
giant torroid.

- I bought self adhesive aluminum tape to completely fill the gaps around 
the main board receptacles.

- Where I use USB or PS/2 extension cords (because choking = reducing 
length): I taped the connection between both cables with this alu tape.

- Use a good ground with big fat wires to interconnect everything to a good 
ground system. Again I use the flattened 1/2" coax shield for low inductance 
/ ohm value. It didn't work with a short 2.5mm² lead from the central 
grounding point. All shielded control cables are grounded on both sides: 
shack end and 'outside' end.

QRO and antennas close to the shack is always a problem... But the Microham 
toys are really great!

73 de Franki ON5ZO / OQ5M