29 Sep 2012

Autumn Projects Update

About 6 weeks ago I listed a number of projects that I wanted to do this autumn. Here is a progress report.
  1. Finish the 472kHz transverter and write this up. DONE
  2. Simple 28MHz QRP WSPR transceiver to use with a netbook. DONE (but the TX only beacon is boxed)
  3. Stand alone 137kHz receiver (for use with PC).
  4. Semi-permanent E-field probe antenna and on-line 137kHz/472kHz grabbers
  5. More non line-of-sight light beam experiments (get better distances). 12W Phlatlight LEDs and more sensitive SRF213 detectors ordered
  6. Semi-permanent 481THz QRSS beacon for NLOS light beam tests.
  7. Alternative HF antennas - maybe re-erect my Par Electronics 40/20/10 end-fed.
  8. Further earth-mode (ground conduction) experiments - tests at around 30 and 73kHz as well as more tests at VLF aiming to improve best though ground DX (currently 6km with 5W). More permanent earth-mode "antenna" erected.
  9. Experiment with horizontal loop antenna on TX at VLF (maximising coupling into ground).
  10. Build some better LF/MF test gear such as resistive SWR bridge, 50W dummy load and a noise bridge.
So, the next project is probably going to be (3) a stand-alone 137kHz receiver combined with some E-field probe development. What I am hoping to do is make a 137kHz RX that can be run from home uploading to an on-line grabber and that can also be used in the car with a roof mounted E-field probe antenna. This will allow me to do some fairly accurate field strength measurements with various TX antennas. With a bit of care I should be able to make this work on various bands from 8.97kHz through to 500kHz.  What I am hoping to be able to do is have a car-mounted receiver with PC that can be used for "drive around" tests although this will depend a lot on the LF noise in the car when the engine is running. I may have to limit tests to static ones with the car electrics not running.

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