40m Pixie measurements

Pixie harmonic measurements

This afternoon I visited G6ALB to do some more accurate measurements of my completed 40m Pixie kit. Power out with the 12V battery was 400mW and with a fresh PP3 9V battery 200mW. On the 12V battery TX current is around 129mA and at 9V around 83mA. 2nd harmonic rejection was about 20dB. Even the 9V output is a useful level. Maybe the cased unit should include an internal 9V battery pack which is switched off when an external 12V pack is available?

Pixie on the bench

To be more useful, I should add a 7.030MHz crystal and have a switch to select this or the original 7.023MHz one. 7.030MHz is the QRP frequency. My experience is this can be quite busy.

I should also case the unit!  Drilling the case could be a challenge in my current state of health! Just doing the building and testing was exhausting.

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

One Response to “40m Pixie measurements”

  • Robert, VA3ROM:

    Hi Roger,

    I don’t know about England but in Canada, transmitters (regardless of power) built after 1 January 2012, harmonic or spurious emmissions must be reduced by at at least 43dBc PLUS 10log(P) and this has been adopted from the ITU standard. So, the rig’s simple filter needs to be replaced with at least a 5-pole Butterworth LPF or Cauer/Elliptic LPF to be legal in my part of the world.

    i.e. for a 5-watt transmitter to be legal, suprious emissions (2nd harmonic) must be reduced by at last 43dBc + 10log(5) = 43 + 6.99 = 49.99 dBc.

    http://life.itu.int/radioclub/rr/ap03.htm refers

    It’s a fairly new standard which Canada and the US has adopted and I would think that most ITU member nations have done the same, but I’d wager that the majority of Hams even die-hard QRPers don’t know about this. There are grandfather clause exemptions in the regs.

    What’s even more annoying is that my Industry Canada publishes or rather hides these kind of reg changes in the Canadian Gazetteer and I don’t remember anyone in our national organization mentioning this rule change in any publications. I stumbled across it looking for information on something else in the updated Canadian Amateur Radio Operating Procedures (which no one else seems to know about either 😉 )


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