472kHz – improvements?

Using the strapped feeder to my Par 10/20/40m as my 472kHz antenna rather than my 2m/70cm feeder, the antenna current has nearly doubled with the antenna current meter now showing 30-33uA whereas it was 18uA before. This suggests ERP has increased by around 4-5dB (ERP proportional to I^^2), but we’ll see later. The Par antenna itself is lower than the 2m/70cm antenna and runs horizontally to a tree. Average height is around 3-4m AGL. The losses may be greater.

The picture shows the 472kHz coil used (a ferrite rod would be fine but since moving it is “lost”), the 472kHz homebrew transverter (left) and the 3C90 matching coil between transverter and antenna (towards centre, LHS of coil). The small meter measures antenna current and registered 18uA last night and 30-33uA now with the Par antenna with strapped feeders.

UPDATE 1420z: G8HUH (250km) is copying in daylight a full 8dB S/N better than last night. Encouraging.

UPDATE 1448z:  M0PPP (182km) seems to be coming in stronger than last night too and in broad daylight.

UPDATE 1700z:  M0PPP  is now spotting me at 1456z, 1538z and 1620z i.e. in daylight.   He was not copying me at all last night, so I think my signal IS stronger.

Roger Lapthorn, G3XBM, is a regular contributor to AmateurRadio.com and writes from Cambridge, England.

One Response to “472kHz – improvements?”

  • Glenn W9IQ:

    Roger,

    Wouldn’t the measured current be dependent on the SWR and the location on the feedline where you are measuring the current?

    – Glenn

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