Preparing for some portable operation. Ogling an activation of POTA PA-0181 (2,5km / 1½ mile by bike) and/or PAFF-0079/PA-0180 (5,6km / 3½ miles), my wife PD4LYN and I decided to test the new equipment in the field.
Our /P setup under test
- TRX: ICOM IC-705;
- Battery: 13.2VDC 12Ah home-brew LiFePo4 pack;
- Antenna: Diamond RHM-10 with PL socket; mounted at the back of my bike with a SO239 gutter mount;
- Amp: 45W MX-P50M, when QRP is really impossible due to abysmal condx, trying to output about 25W at most; seldom used nonetheless;
- Keypad: for easy voice or cw-keying; simple, home-brew pad, needs some reworking;
- PC: Asus Transformer T100TA;
- Tuner: mAT-705, not needed, but you never know;
- Paddle: Pico Paddle;
- A couple of coaxial cables.
We noticed some heavy RFI originating from the USB between the IC-705 and the mini-notebook. Previously, with the microHAM USB III, I did not have this problem, so I (wrongly) assume this is a combination of transceiver, USB-cable and possibly some coaxial common mode going on. It messed up the RX and, as we later found out, RFI from the TRX also messed up USB. Quite predictable.
Next time I will try:
- a decent RF-choke;
- a variety of properly double shielded USB-A-to-micro-B cables of different lengths with ferrite core(s);
- a separate ferrite clamp of decent quality to run the USB-cable through;
- changing the position of the antenna relative to the transceiver;
- warmer weather! It was sunny, around 15ºC (60ºF), but a harsh wind in open land made it very uncomfortable.