The Transceiver

The painting off aluminium plate is not easy, as you can see the colour drops. We will see if I can fix this later?

I have now run a few QSO with this transceiver on SSB. And this was the goal. It is not perfect but it works. In Rx the sensitivity is high enough with preamp on. On Tx it is from 10-15W out on all bands. I hope to test on 6m but for the moment is veary  quiet on this band.

As you can see from the display a lot has ben implemented in SW, RealTimeClock, Battery indicator, temperature, one VFO, vfo step size, Rx Rf gain or Atten, S-meter, Band select, mod set,  tune, power set 1- 15W and settings include touch screen calibration.

POWER and SWR  indication is not yet implemented in SW, hopefully ok in HW. Cw-keyer and CW decode is not implemented, same test has been made. I have separate code tested. Mic Compressor is not tested yet more qso and test is needed.

SD card is working. But not used to much. Can be used for settings and calibration. Touch screen is working but a bit slow, I hope to speed up it in a newer sw code?

The AF Filter CW/SSB has some strange behaviour so it is bypassed for now a MAX7400, I tested it before I do the schematic, murphy has been her.

As they say use the TRANSCIVER Make QSO, I haw new things to build (Digital versions, sty tuned)

73 de SM4HNG

 

TRX Board

This is a board from Dian Kurniawan (YD1OSC). BritX All Band HF Exciter with Audio BPF and 1 Watt TX preamplifier.  It is a design based on BITEX from Ashar Farhan.

I have take away the tx amplifier, I use my own design on the FrontEnd 02 board. Also take away the rx amplifier before mixer, then it works in/out to RF mixer.

Next mod is for CW I won’t sidton on audio if keying, so 12VTX to audio amplifier LM386 is taken from 12V to make it possible

I will son describe how I put all this together to a transceiver 1,8 – 52 MHz.

 

The Key

This is a key from Russia I bought in a ham market in Vårgårda 2019. Now mounted on a bit of  oak wood. Perfect for field operation. 

QRP Digital Board 01

                               KiCad

The Cad of this take some time, first try to put in CPU on the board didn’t  succeed , so the final is with the CPU module from . Same small mistakes is now fixed, and all function is verified. The result is a board with a lot of function.  Extra Dac for AGC , 8 i/o and one UART, 4 ADC channels this is for future use.  Tested and working is AREF analog reference for CPU module, RTC + EEPROM, VFO + BFO (Si5351), LP-Filter (CW/SSB), Input for CW key, MIC amplifier, MIC compressor, SD-CARD, TFT and Touch display, temp sensor, encoder and ton-generator for CW. Connection for the earlier done board PA, LP-Filter, Frontend 02. 

Next is a modified TRX board stay tuned!

QRP Frontend 02

QRP Frontend 02

Final test with the Arduino Mega controlling the i2C buss(select Filter and set attenuator Tx/Rx, turn Rx amplifier on/off.

QRP Frontend 02 is a BP filter board with RX preamplifier MAR-6 or a discreet PIN-diode attenuator, controlled by a dac. The same BP filter and the attenuator is used in Tx and is driving a amplifier SGA-3486Z as driver for the QRP PA earlier described. All BP filter is controlled from I2C bus. BP filter is from YU1LM i i think it is rely good result, no alignment.

I has started working on a front panel board, the latest before putting all this together to a QRP Transceiver. Stay tuned!

QRP LP filter and SWR board

QRP LP filter and SWR board

Here is the LP-Filter mounted on the earlier described PA.

QRP LP-SWR 01 is a LP filter board 1.8MHz - 52MHz and added SWR Meter, all relay for filter is controlled from I2C bus. The filter is design from GQRP Club Datasheet W3NQN, Filter PDF. I have rely problem to get low insertion loss, so I think it was the toroid was the problem. Now I know it is the capacitor I firs used has really bad Q value. I has change to SMD GC0 500V capacitor and they has much higher Q value than the hole mounted capacitor I bayed first. The SWR was presented in QRP-Quarterly January 2018, SWR Meter. I lock for different diodes then 1N60 and tried a few types and get god result with HSMS2800. Her is the result. 

Exemple 80m and 10m.

Backside off the filter.

Part off shematic

I have a few PCB left, e-mail if you ar intrested xxx@gmail.com.

Signal generator for short wave 0.1 – 30 MHz

I have an old test set Schlumberger 4022 I don’t need longer. This was one reason to build this generator. The generator is a kit from QRP Labs   it uses Si5131 from Silicon Labs. I used 2 attenuator  Weinschel  0-63.75 dB. The insertion loss @ 0dB atten was around 7 dB so I need a Amplifier and one more attenuator to compensate for that. I adjusted the attenuator to get 10 dBm output. A high isolation switch on output to turn on/off RF, typical 75dB isolation. A rotary encoder and Arduino mini pro drive the attenuator and isolator directly and one I2c OLED display, really simple solution, sw 100 row of code.