LF: 137.685kHz QRP QRSS3 tests with 20m earth-electrode antenna

[Roger Lapthorn <rogerlapthorn@gmail.com>]

This afternoon I restarted my QRP tests on the 137kHz band.

With 8W RF out from the crystal controlled beacon unit (ERP will be low uW level) sending QRSS3 feeding the 20m spaced earth electrodes, currently under 8cm of snow, I ventured forth in the car complete with an E-field probe built right into the bottom of a mag-mount antenna on the car roof. The E-field probe whip is about 12-15cm long only. It looks like a small UHF quarter wave, rather than an antenna for 2200m! 

Some excellent signals were received 8.2km away relatively in the line of the earth-electrodes (see image attached). Orthogonally at a range of 14km, the signal was not copyable at all. With the laptop on the passenger seat I could see the signal levels on Spectran as I drove along, stopping regularly to take a screenshot. Although no real copy at right angles to the TX antenna it was a very good signal in many places on the drive.

The receiver consists of the E-field probe with short whip on the mag-mount in the centre of the car roof, feeding the FT817 with IPO button pressed (improves sensitivity when ON at 137kHz) feeding the PC running Spectran at 0.34Hz resolution.

I do find it unbelievable that such a TX "antenna" buried under the snow with NOTHING in the air at all and with earth rods just 20m apart can put out a half decent signal on the 2200m band that can be detected so well on such a tiny little RX antenna on the car roof.

The TX frequency is currently around 137.685kHz (based on the crystal frequency divided down from 80m - it may be off somewhat) and this QRSS3 beacon will remain on overnight. I am hoping that stations out to around 100km will take a look for it.

Please, if you think you have any chance of copying, take a look for this QRP QRSS3 beacon which will be TXing now until lunch time Wednesday.

73s
Roger G3XBM

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