7 Nov 2008

Even simpler 80m micro-transceiver!

Just finishing off breadboarding a 12 parts QRP transceiver (plus hi-Z earpiece, xtal and key) for 80m CW. The name is the uu80b.

It is crystal controlled on both RX and TX and the inspiration was the Curumim rig from PY2OHH (see earlier post). TX output is 450mW. The xtal controlled regen RX seems to be quite sensitive too. Unlike my FETer, this rig is full break-in and needs no multi-way TX/RX switching. I have already seen and heard the TX part on the on-line Twente University SDR which is 150 miles away from here in Holland. The rig uses just two 2N3904 transistors and a handful of standard parts.

Currently it is on 3.579MHz but this will be moved to 3.560 as soon as I get another crystal next week. Skeds welcomed!

Isn't ultra-simple QRP construction


Anonymous said...

very pretty assembly,but currumim rig is Miguel Bartie,PY2OHH, project.


Alex PY4EU

G3XBM said...

Thanks Alex. I have corrected the blog to state Miguel's correct call.

The Curumim rig was certainly the idea that got me started on this "transistor-only" derivative.

dieter said...

Hi, You know that there is an extra Minimal Art Session (MAS) activity by the QRP community annually?


72, Dieter

John G8SEQ said...

Hi Roger, how were RFC1 & C3 determined? Was it by experiment? According to my calcs. rfc1 or C3 should be reduced to resonate at 3.6 MHz, as they are currently nearer 3.1 MHz.

de John G8SEQ.

PS. Currumia is a type of wren, but Miguel says his site shows the wrong picture!

John G8SEQ said...

My earlier posting, suggested that RFC1 & C3 resonated at 3.1 MHz. This was an error; their resonant frequency is more like 500 kHz.

If C3 is reduced to 500 pF then they resonate at about 3.6 MHz, which might offer an improvement, but it will depend on what is used for an antenna.

de John G8SEQ