Only added provision for self "TEST", that is; the switch disconnects the terminals and connect internally to know resistor values via rotary switch (minimum 2 Ohm since had nothing smaller at the time). Also add zeroing via a pot on R24 place.
One youtube video by VK3YE was enough to get me started building, after all, the meter that I was using before was not behaving correctly (latter found the problem).
The outcome was this:
(scale on the left switch is wrongly printed, where is x2 should be x0.5/divide by 2)
During build:
Making the scale:
The scale on the meter was changed from the original 0-50 to 0-100, the easiest way was to scan the original face-place and then edit on a image editor.
To calibrate I used a 68pF and 27pF capacitor, the idea was not to have highest precision possible only to be in a position of having certain about unmarked capacitors.
I used different Ge diodes and the 10K pot was changed for 2 of 5K in series to give better adjustment range. The Zener was changed to 6.8v. Ranges like this:
Had this build for some time, now it's time to show.
I was doing some experiments on the 10Ghz band and wanted a way of looking at the signals. Because the spectrum analyser I have only good to 1.5Ghz had to find a cheap way of doing it to get this:
Here looking at the third harmonic from an ADF4351 on 3.3Ghz after a pipe cap 10Ghz filter experiment.
The diagram explanation: a dbm mixer (Watkins-Johnson M80LCA) with a local oscillator based on a FVC99 10Ghz oscillator module (cheapest VCO I could find for 10Ghz). Some preamps on the input and output using 2Ghz preamp modules and replacing the MMIC amplifiers for the ones like Corvo NLB300 or ERA-1 that are good to 10Ghz.
The basic design:
To this diagram I added a 6db directional coupler inline with the FVC99 VCO (used a Omni Spectra PN2023, good from 8 12.4Ghz) so I could measure the LO frequency and PLL it.
There is no stability control on the FVC99 oscillator, still working on a PLL system (maybe one of these days) but in my case I have two select positions, one: VCO is controlled by a single pot (like on the diagram) and the other position controlled by an EIP371 frequency counter (from the Lo Out via directional coupler) that makes the PLL loop. With EIP371 and since the output voltage of the loop is very small the control range seats near 9.5Ghz, there is an option of extending the range like on the EIP manual:
Or with a similar diagram, a multiply by 10 of the PLL voltage out of the EIP371, that would be enough to use the full range of the FVC99.
For now I use 9.5 Ghz if using the EIP371 for more stability and around 10Ghz set by the pot ("Flo" on the panel) if it's just a quick test.
Here the EIP working as external PLL controling the FVC99 so the LO gets more stable.
On the Rigol DSA815 spectrum analyser you can set the input offset to get the display right on the band of interest
Displaying here a 10Ghz signal using the 9.5Ghz Lo frequency
If you want to just check if the signal is around there, no need to use external PLL control to the FVC99, the "stability" with a simple potentiomenter is enough.
Inside view:
The VCO adjust pot (top right in blue) is glued directly to the front panel
Some other images during prototype development:
Here one of the firsts tests, just an input amplifier, the mixer, the VCO and VCO amplifier and the mixer IF output directly to the spectrum analyser.
Testing during early days of the prototype with a 10Ghz homemade flange to SMA adapter and a pipe cap filter:
Anyhow, not a measuring device but it serves the purpose of checking if you have any signal around the 10Ghz band and for experiments, still very happy with the outcome and sensitivity.
Nothing major here, needed a small signal generator to test in the 10Ghz range (using harmonics from 3.3Ghz), decided to go with the ADF4351 module available everywhere. This is an improvement over the previous iteration here.
After the initial testing on 3.3Ghz made some changes on the software in order to set some common frequencies for future testing with QO-100 satellite equipment and also added provision to sweep around the frequency currently set in order to test some filters.
Output on 3.4Ghz:
And testing the third harmonic:
The Rigol is not a 10Ghz version, I'm using a down converter before the input, that will be another post...
The diagram, at this stage I still didn't added the two extra buttons (look on code for mode and band), to change band and to change mode between set frequency and sweep.
Inside on the almost final interaction (waiting SMA's to connect to front pannel):
And the front panel view working:
The code on the current version, keep in mind might still have some bugs, reach me for latest version if there is one:
If blogger breaks formatting ask me a copy by email.
/*! ADF4351 signal generator
CT2GQV 2020 v1.4
Based on code from: ADF4351 example program https://github.com/dfannin/adf4351
VFO with 100Khz steps starting from a predifined frquency (UL frequencia) using 2 buttons for up and down. Display on 16x2 I2C LCD of the frequency set and the third harmonic value Also serial output of the main frequency set. Possibility to sweep for filter testing. */
vfo.ChanStep = steps[4] ; ///< change to 100 kHz }
void loop() { int buttonState0 = analogRead(button0); // mode int buttonState3 = analogRead(button3); // band
int buttonState1 = analogRead(button1); // up int buttonState2 = analogRead(button2); // down // serial debug for the button for +/- frequency // Serial.print("B1,B2:"); Serial.print(buttonState1); Serial.print(","); Serial.println(buttonState2);
// band / start/stop sweep // button pin is puled down to ground...or close to it (100) as long as lower than 2049 if (buttonState3 <= 100) { {
if (opmode == 1 ){ /////// start stop start procedure if(tempopmode == 1) // started { lcd.clear(); lcd.setCursor(0, 0); lcd.print("SWEEPING starded "); lcd.setCursor(0, 1); lcd.print("Stop----------> "); tempopmode = 255; maxfrequencia=frequencia+10000000; //compute the max frequency so we start from the one now and 100Mhz down and up minfrequencia=frequencia-10000000; //compute the min frequency so we start from the one now and 100Mhz down and up delay(150); } else // is stoped { lcd.clear(); lcd.setCursor(0, 0); lcd.print("SWEEPING stoped "); lcd.setCursor(0, 1); lcd.print("Start---------->"); tempopmode = 1; delay(150); } };
// we are in band mode if (opmode == 0 ){ Serial.print ("BAND: "); band++; if (band > 4){band=0;}; if(band == 0){ frequencia=3496500000UL; vfo.setf(frequencia); lcd.clear(); lcd.setCursor(0, 0); lcd.print("F :"); lcd.print(frequencia/1000); lcd.setCursor(0, 1); lcd.print("F(3):"); lcd.print((frequencia/1000)*3); };
// if we are sweeping if (opmode==1 && tempopmode == 255){lcd.print(" .");}; if (opmode==1 && tempopmode == 255){lcd.print(" o");}; if (opmode==1 && tempopmode == 255){lcd.print(" O");};
if (opmode==1 && tempopmode == 255){ frequencia += vfo.ChanStep; // increase frquency by step if (frequencia >= maxfrequencia){frequencia=minfrequencia;}; // if we are on the limit then go to lower value vfo.setf(frequencia); Serial.print ("F:"); Serial.println(frequencia) ; };
// up frequency // button pin is puled down to ground...or close to it (100) as long as lower than 2049 if (buttonState1 <= 100) { frequencia += vfo.ChanStep; if ( vfo.setf(frequencia) == 0 ) { Serial.print ("VFO.SET: "); Serial.println(vfo.cfreq) ; lcd.clear(); lcd.setCursor(0, 0); lcd.print("F :"); lcd.print(frequencia/1000); if (band == 0 ){lcd.setCursor(0, 1); lcd.print("F(3):"); lcd.print((frequencia/1000)*3);}; } } // end up frequency
// down frequency if (buttonState2 <= 100) { frequencia -= vfo.ChanStep; if ( vfo.setf(frequencia) == 0 ) { Serial.print ("VFO.SET: "); Serial.println(vfo.cfreq) ; lcd.clear(); lcd.setCursor(0, 0); lcd.print("F :"); lcd.print(frequencia/1000); if (band == 0 ){lcd.setCursor(0, 1); lcd.print("F(3):"); lcd.print((frequencia/1000)*3);}; } } // end down frequency
// button software debounce if we are not sweeping if (opmode == 0) { delay(150); };
Not much here, just a simple signal generator based on ADF4351 module from "fleebay". PS: there is an improvement over this code at this new post.
I just needed to generate one single frequency that can go up or down in 100Khz steps via two push buttons. Added an optional LCD to display the main frequency and the third harmonic since I'm using it to verify some equipment on 10Ghz.
Test board:
On the frequency counter:
Schematic based on an Arduino Nano controler:
Spectrum output on lower frequencies (414Mhz) and output level at "0" (add 20db attenuation at the spectrum input):
and the third harmonic:
Power at "3" (second harmonic now visible)
3rd harmonic as seen on a 10Ghz adapter for a 1.5Ghz spectrum analyzer: (not calibrated):
Code:
/// code start /*! ADF4351 signal generator
CT2GQV 2020 v1.3
Based on code from: ADF4351 example program https://github.com/dfannin/adf4351
VFO with 100Khz steps starting from a predifined frquency (UL frequencia) using 2 buttons for up and down. Display on 16x2 I2C LCD of the frequency set and the third harmonic value Also serial output of the main frequency set. */
// buttons for up/down in frequency, puleed up from 5v with a 10K resistor, analog pin will be short to ground for button press int button1 = 1; int button2 = 2;
vfo.ChanStep = steps[4] ; ///< change to 100 kHz }
void loop() { int buttonState1 = analogRead(button1); int buttonState2 = analogRead(button2); // serial debug for the button for +/- frequency // Serial.print("B1,B2:"); Serial.print(buttonState1); Serial.print(","); Serial.println(buttonState2);
// up frequency // button pin is puled down to ground...or close to it (100) as long as lower than 2049 if (buttonState1 <= 100) { frequencia += vfo.ChanStep; if ( vfo.setf(frequencia) == 0 ) { Serial.print ("VFO.SET: "); Serial.println(vfo.cfreq) ; lcd.setCursor(0, 0); lcd.print("F :"); lcd.print(frequencia/1000); lcd.setCursor(0, 1); lcd.print("F(3):"); lcd.print((frequencia/1000)*3); } } // end up frequency
// down frequency if (buttonState2 <= 100) { frequencia -= vfo.ChanStep; if ( vfo.setf(frequencia) == 0 ) { Serial.print ("VFO.SET: "); Serial.println(vfo.cfreq) ; lcd.setCursor(0, 0); lcd.print("F :"); lcd.print(frequencia/1000); lcd.setCursor(0, 1); lcd.print("F(3):"); lcd.print((frequencia/1000)*3); } } // end down frequency
// button software debounce delay(150); } /// code end
Some other signal generators based on similar modules and also the ADF4355: http://f6kbf.free.fr/html/ADF4351%20and%20Arduino_Fr_Gb.htm https://pa0rwe.nl/?page_id=1345 (for the ADF4355)
Login
The "Speaky" HF SSB transceiver and other homebrew projects
