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WSPR from the Car

At work, I park on the top of a huge multi-story steel-frame carpark. I often wondered about using it as a ground for a HF vertical (yes, I’m that much of a nerd). I hatched a plan to give it a try!

Using a 80m HF mobile whip (borrowed from Rob M0VFC) fixed to a large triple-magmount base on the roof of my car, I was able to connect a ground strap using some wire to the car body, and trim the HF whip in to resonance with my EU1KY Antenna Analyser (which is awesome!). The plan was to connect to the ground strap to the carpark frame when at work.

In previous projects, I had made a WSPR beacon in a small project box with an OLED display on the front. The beacon takes a GPS antenna on SMA and outputs WSPR transmissions on frequency for direct connection to a low-pass filter and antenna.

Over the course of a day, I left the WSPR MEPT transmitting from the car, parked on my driveway, and achieved some impressive distances considering how inefficient these antennas are. The transmitter was set to a power of 1W, and I wasn’t expecting great results considering the antenna compromise. The results were not bad for something less than 3 metres long on the vehicle roof!

The transmitter was powered from a 12V/12Ah sealed lead acid battery with a low-voltage cut-off relay.


A table of spots, sorted by distance can be found below:

TimestampMHzSNRGridReporterRGridkmaz# Spots
 2019-02-07 23:48  3.570109  -27  JO02  K9AN  EN50wc  6536  297  2 
 2019-02-08 04:14  3.570109  -28  JO02  W8AC  EN91jm  6004  294  5 
 2019-02-08 05:52  3.570108  -22  JO02  KD2OM  FN12gx  5664  293  29 
 2019-02-08 06:46  3.570109  -26  JO02  N2NOM  FN22bg  5615  291  3 
 2019-02-08 04:42  3.570113  -26  JO02  N2HQI  FN13sa  5598  292  24 
 2019-02-08 06:22  3.570110  -25  JO02  KK1D  FN31vi  5445  288  6 
 2019-02-08 04:02  3.570109  -25  JO02  WA9WTK  FN42fk  5327  288  2 
 2019-02-08 04:02  3.570106  -26  JO02  EA8DBU  IL18oe  3073  215  6 
 2019-02-08 05:52  3.570109  -20  JO02  EA8BFK  IL38bo  2923  211  64 
 2019-02-08 03:32  3.570110  -25  JO02  OH8GKP  KP24rt  1949  36  42 
 2019-02-08 05:52  3.570109  -26  JO02  LY2BGP  KO24ao  1536  72  26 
 2019-02-08 04:02  3.570109  -24  JO02  IZ6BYY  JN62wv  1435  133  42 
 2019-02-07 23:16  3.570111  -22  JO02  9A3ZI  JN86fj  1305  115  10 
 2019-02-08 17:22  3.570112  -20  JO02  OE6PJD  JN77uc  1213  114  10 
 2019-02-08 03:54  3.570110  -17  JO02  OE3GAS  JN88bn  1155  106  7 
 2019-02-07 20:22  3.570113  -13  JO02  F5OWL  JN33cc  1113  157  3 
 2019-02-08 03:26  3.570111  -25  JO02  IW2DMO  JN45uj  1013  138  44
Updated: 8 February 2019 — 6:06 pm

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