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Tuesday, 24 October 2017

Two new 4sq 40m and 80m

Building two new 4 SQ.
One for 40m other for 80m.
Starting off with SJ2W's pcb and will go from there.

Relays are DPDT, 250VAC, 8A versions from Farnell Code 1629053 so far have been good to well over 400W so use for SDR RX and QRP TX shouldn't be a problem.

The torroids T225-2B I have already and several 500V SM caps, again over kill for QRP.

The SO239 were from a batch buy so decided to use all 10 in one go. Just tacked in place for now until I finalise the enclosures, I have several of same type used on E51KTA trip but not sure about UV stability, Might invest in some dicast or IP56 ones.

I'll add the rest of the components once I have the switch and dummy load/power meter sorted out, the signal I'll feed into an Arduino Uno or Nano I expect to do the power measurement.

These will be remote switched for the direction (the relays are not latching type so will need to have them energised for use) so I'll be using USB and Arduino to create the switching voltages.
I might add a sense so can sample the frequency, not sure what value that might be though.

Poles will separated by 1/4 wavelength and will support 1/4 wavelength 40m and 80m ground planes (Poles fibreglass 10m and 18m), wire elements 2mm I expect. Extensive radial matt. Will probably put the antennas up splitting the 4 points of the compass to get reasonable coverage.

I expect I might experiment with a 5th central GP and see what difference that makes.

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