A Note from Nigel, G0EBQ
MY POOR MANS PAESANO
Nigel Flatman G0EBQ 3375
I had built the excellent Peregrino, as featured in the Autumn Sprat, but its main problem is that /p operation isnt very conducive to the British climate, as well as 17m being pretty much just white noise at the moment. So the plan was to make a 20m version to work into a 50 ohm load and to drive a linear.
I built a 20m version on breadboard with a 3.20 Mhz IF and 11mhz vxo using cheap club crystals. The receiver worked fine though vxo shift was minimal-I have corresponded with another builder who believes that is due to the particular zener used to drop the voltage to the ICs though we have no idea why! My attempts to make the existing circuitry work into a 50ohm load were a miserable failure and I put it aside “for further investigation at a later date”.
I was able to obtain pcbs from EA-QRP for the Peregrino project and amongst those who contacted me was Pete Juliano N6QW; the result was Petes brilliant article called the “Paesano”in the last Sprat. Pete has been incredibly helpful and as a result of exchanging emails I have my simplified version up and running.
I dont have an electronics background and don't understand “new” technology such as Arduinos so have used “old school” technology. So I used the vfo from Farhan Ashars original BITX design (1) which is my standard vfo design and is stable and always works for me, adjusting the turns on the coil L4, a T50/6,and the value of the capacitor in series with the bandset trimmer for a 5 Mhz output. I took the output from the buffer transistor marked Q6 via a 10nf capacitor to pin 6 of the mixer U1; however the output was 800mv which was too much for the mixer so had to increase the value of the 4.7k resistor between the two transistors to 27k to reduce the output to about 300mv which was perfect.
The Imrad filter that Pete specified is still quite pricey so I used the club 9mhz one.With this though the impedance is 500ohm so as suggested by Pete I used matching transformers of 7t on an FT37-43, tapped at 4t, which worked perfectly. Mine is built on perfboard but if you are using the Peregrino pcbs you will need to adapt the pcb to suit.
I retained the existing Peregrino bfo circuit and the P switch for tuneup and changeover is just a simple relay and switch. Other than that I replaced the zener with an 8v regulator as recommended, and used Petes receive rf amp, bandpass filter, low pass filter and tx driver stages with a GQRP club freeby 2N3866 equivalent giving 600mw peak out, these are all superb designs and worked first time. My final remains a work in progress but with just the 600mw I have worked Slovenia and Sweden.The receiver is really hot-the rf amp makes a huge difference-and I have heard Saudi Arabia, Ivory Coast, Asiatic Russia and can hear East Coast Americans most days at good strength.
Many thanks again to Pete N6QW for his help and advice
References (1) www.phonestack.com/farhan/bitx
This is Nigel's completed Rig. Bravo G0EBQ!!!!