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Thursday, 6 May 2010

ARCI QRP 72 part challange - Going to miss it.

I am trying to get the project rebuilt/boxed after reworking the PTO. Unfortunately tonight after 3 hours trying I cannot get the cw RX/TX mute to function as it did and the TX has some nasty spurs so I've bust it somehow, and as not boxed up yet got to face reality I am not going to make the deadline to get this to FDIM so will not be entering. It is my own fault I mixed the Dayton and Friedrichshafen dates up so lost 5 weeks. Frustrated, angry and embarrassed all in one...

My one IC wasn't anywhere in the RF part I used PIC keyer that also controlled the RX mute (FET on the AF).

Anyway, when the w/e is over I'll write it up.

My final part counts were:

Basically a VXO FET oscillator using an IRF510 followed buy a 3 pole LPF. Some pulling possible using a small trimmer cap. Built for 80m.

BPF, that shared the TX LPF, FET mute of the front end and the AF section. DBM mixer, M5 Brass bolt PTO, 2 8MHz crystal c580Hz filter, 8MHz BFO (J310), RF amp/product detector (J310), AF amp (3 NPN).

PIC + one resistor. I would have added a side tone too but needed one more component!

72 total.

The whole lot could do with a bit more decoupling and as planned on battery use no main voltage regulation except one zener in PTO. I build every module on a separate PCB, manhatten/ugly style.

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