The Paesano!

A Left Coast SSB Transceiver

 

Capsule Synopsis: Presented here is a QRP Level SSB transceiver that can be fitted to operate on either 40 or 20 Meters SSB. It is also FT-8 capable as evidenced that VFO #2 boots up on the FT-8 frequency.

I want to mention that for FT-8 you will need a second microphone jack that has a 0.1 Ufd blocking capacitor fitted in series with the input. Often homebrewers never read the manual.

The reason for the 2nd input is that for SSB the Paesano uses an electret microphone and there is normally a DC bias voltage on the input side of the microphone jack. Very likely that DC voltage would be incompatible (meaning you will smoke the digital adapter) with the output of what you using to interface the digital signals. Think of the 2nd jack as the Data Input Port! You have been warned!

 

 

It doesn't take to much to get me hooked on a project especially when I see something really innovative. Such was case of a project that showed up on the front cover of the Summer 2019 GQRP Club SPRAT publication. Adorning the front cover was a small single board SSB transceiver called "The Perigrino" which in Spanish means Pilgrim.

Here is a link to the original Perigrino Project --it is in Spanish...

http://www.qrp.cat/ea3ghs/Peregrino-Transceptor-QRP-SSB-2013OCT24.pdf

 

The key innovation of this project aside from having only 84 parts is that the whole crystal filter section was switched between transmit and receive. Now that was the very first time I had ever seen this done. Mind you this now marks yet another way for me to think of transceiver topology.

The Pilgrim is a brain child of two hams from EA land (Spain) and I believe was first launched in 2012. The project which appeared in the 2019 SPRAT was built by Nigel, G0EBQ who also provided additional commentary on his build such as changing the crystal filter frequency.

In looking at the The Pilgrim my thoughts focused on changing things -- not for just saying I changed something; but to make changes that suit my approach to building SSB Transceivers.

Basically The Perigrino operates on 17M, uses a homebrew four pole crystal filter at 3.392 MHz and uses a Super VXO for the LO. The power output is in the QRpp category having only a single 2N5109 in the output stage. The main topology consists of two SA602's with no Rx RF amp and includes a built in antenna tuner as the output is high impedance (no 50 Ohm direct feed). The LO is tuned with a Polyvaricon and supposedly covers most of the 17M band. The mic input uses an electret mic (no D104's here) and the audio stage is a 2N3904 driving an LM386. There is no volume control per se but a 1K pot ahead of the IF block adjusts the received signal level.

The real heart of The Perigrino is two NE602's (SA602 or SA612). The first NE602 is both the Receive and Transmit Mixer with the self excited VXO LO and the second NE602 is the Product Detector on receive and Balanced Modulator on transmit. It also has a self excited BFO. Thus by switching the signal path of the filter from Pins 1 and 4 on the two devices, it can be either a receiver or a transmitter. Now that is innovation. I use two NE602's in my Sudden Transceiver and can attest --They WORK and WORK WELL!

Essentially we have modified the Perigrino schematic as follows and it now becomes "The Paesano".

 

 

Rushing ahead we have the Paesano on the air...

 

 

Serving the dessert first ... The Paesano has been working initially on 40 Meters and is now on 20 Meters. DX has been worked on both bands with Chile on 40 Meters and Spain on 20 Meters. Great signal reports and some very nice comments on the audio -- must be my $1.50 homebrew electret microphone. True I was running some power (500-600 watts); but those are what the bands are today. The important issue -- the baisc rig does well and coupled with an amp can put you in a league with the Big Dogs!

 

I should mention that The Pilgrim is NOT a kit as such; but there are circuit boards available which should appeal to many would be builders who simply cannot undertake any project unless a PCB is available. Thus "The Paesano" will at least partially use The Perigrino PCB. Below is what will be used for The Paesano.

 

Why do I now call my project "The Paesano". Well for those of you who don't know I am Italian and the word Paesano, in Italian, means Friend, Buddy or Pal. It is in the context of being a Pal that I call my project The Paesano - A Left Coast SSB Transceiver.

So what would I consider changing to suit my build approach:

  • The first change would be the band of operation to 20 Meters as given the sunspots 17M is "kinda quiet". Then again in 2012 the 17M band was probably active since it was still at the higher end of the cycle
  • The Filter would be changed to a 9 MHz Commercial Filter which is a four pole unit available from INRAD known as Model #351. This filter was chosen since it can be directly fitted to the PCB with only two modifications of slightly increasing the hole size for some of the capacitors since several are used in parallel and the building of two matching transformers. The Pilgrim directly feeds the filter to either pins 1 or 4 via the DPDT relay. In my build I attempt to match the 200 Ohm Zin/out of the filter to the 1500 Ohms Zin/out of the NE602's. This is done by cutting two traces on the underside of the PCB and installing the small transformers that are made using the FT-23-43 cores. A 4 Turn to 11 Turn winding matches 200 to 1500 Ohms. 4^2 = 16 and 11^2 =121 . 121/16 = 7.5+ and 1500 / 200 = 7.5 -- a pretty close match. Connections to the relay center leafs from the transformers are made through a 10NF cap.

In the two photos above the first shows the two locations where traces are cut to install the matching transformers (black lines). The second shows the install of the transformers and the two coupling caps

  • The next major change is the use of the Arduino and Si5351 PLL for the LO and the BFO. An additional change under evaluation is the use of the 65K Color OLED's. These OLED's can be found for about $3.50 USD and that should enable building a $20 Digital VFO/BFO with a Color OLED. The Paesano will have two VFO's with a default start up frequency of VFO B on FT-8 (14.074 MHz). This is yet another reason for the changes --two VFO's. A "dummy" display is shown below and the effort so far is how to locate data on the screen face (less than 1 inch square) and how to change colors. This will take further development effort. But so far looking promising. As with my other projects when you invoke special functions such as the TUNE mode, the "USB" portion will change to "TUNE" in a different color. Once the 10 second TUNE cycle is over then the display will return to "USB".

The OLED Display SPI connections are as follows:

 

Pin Function
13 SCL
11 SDA
10 CS
9 DC
8 RES
Vcc + 5 VDC
GND Ground

NOTE: These Pin Numbers work for the Arduino UNO or Nano. You also need the Special Library called Ucglib available from Adafruit. Now this is one cool library as it contains drivers for about 10 different displays and you simply activate (un-null) the driver for your display. The above version is the SSD1331 --but I just received the ST7735 version which is also included in the Ucglib driver package. I have the code working with both versions.

But as we have all found out --- The shiny glittery stuff may not be gold. So while we got both OLED's to work, one version installed in The Paesano was so noisy that no signal could be heard. A second version (ST7735) which we received yesterday works perfect --no noise. So for the initial testing I used a 128X128 Color TFT. I had to fabricate an adapter plate to install the smaller color OLED in that rather large hole in the front panel. You can see that in the second photo below.

This is what we love-- no noise and no drama.

 

 

 

 

 

We now have the Nano, Si5351 and the Color OLED assembly built and working. There are two links below for the code with one being the 40 Meter code and the second the 20 Meter code. These sketches are for the basic ino but you will need the additional supporting libraries as there are "included files". Send me an email to craponthebench@gmail.com and I will email you a complete set of the sketches and the supporting libraries. Easier to do this way.

 

40 Meter Sketch Info

20 Meter Sketch Info

This now moves to the "how" to mate the Si5351 to the former Perigrino board. To Pin 6 on each NE602 (SA602, SA612 --all interchangeable) install a 10 NF capacitor -- there is a very convenient way to do this using the holes provided to originally install Crystals CR7 and CR2. There are other holes on the board that connect to CR2 and CR7 on the side of the Caps not connected to Pin 6 on the devices. Find a convenient ground point and solder the shield to this ground point. No connections are made to Pin 7. The two black dots on the underside of the board shown below show the capacitor install in the holes intedned for CR7 and CR2.

 

 

 

The Build Detail

Much of the Perigrino board is left undbuilt but there are a couple of additional Modifications are made before final wiring integration. BTW use color coded wire as it helps signal tracing troubleshooting. Any time you see an Orange wire it is associated with anything receive. Similarly anything yellow is transmit. When you see a red wore this means power is applied at all time. Twisted wire multicolor wire bundles are usually audio as in volume controls or audio output. Red and Black are power wiring! There are three sets of coax going to the board. One is the BPF connection and the other two are for the LO and BFO

The two modifications are now discussed.

Audio Gain Control

There is no audio gain control on the Perigrino and this modification involves installing a 10K Pot. The output from the NE602 is fed to Pin #3 on the LM386. From Pin #3 to ground is a 10K fixed resistor. That resistor is removed and the trace to Pin #3 is cut. In the location where the fixed resistor was installed the two ends of the pot are installed in its place. The Center wiper now connects to Pin #3. Be sure you connect the rigt end of the pot to ground so that the gain advances as you go CW

8 VDC Regulator

The NE602's should be supplied with no more than 8VDC. In the Perigrino, 12 VDC is fed through a 180 Ohm resistor to a 8 V Zener Diode. I didn't have a Zener but did have a 78L08 whihc is a TO-92 sized three terminal regulator. By removing the 180 Ohm resistor the three terminal regulator can be easily fitted to the board and you are good to go.

 

 

Final Wire Integration on the underside

 

Next we will cover the building of six major additional pieces to the Paesano. Many of these pieces have been used on other projects including the Sudden Transceiver built in 2018. In many cases we are simply repeating the building of those same circuits. The six pieces are: