HF103 rc1

HF103 is a HF only prototype of BBRF103 that started at the end of 2019. Thanks to Andrew G4XZL for ideas, test reports and advice.  Here after the modifications.

Hardware:

- It is designed for LW-MW-HF band only: 0-30MHz.

- A Low Noise Amplifies has been added to improve NF of receiver.

- The Clock reference used is a low noise xtal oscillator with lower phase noise and spurs than Si5351a.    

- The RF attenuator of HF103 uses  DAT-31-SP+ 

- The PCB has been made larger 100x100 mm to increase spatial separation between components' groups (COVID style) 

Here the scheme and PCB layout.

Some pictures of hardware

Case 

ADC and RF layout
        

                                                LNA, filter, attenuator and xtal oscillator

Software (still in evolution):

- The reference clock oscillator, that is the ADC sampling frequency has accuracy error. The error is compensated with a software trimming value into the ExtIO.dll's user interface dialog.

- The ExtIO.dll will be compiled in Visual Studio 2019 and will not use pthreads library.

- The FX3 firmware will be modified to use the new IOs


Results :


The receiver 32MHz bandwidth with a 50 Ohm dummy antenna. The only spurs are the noise of FX3 board switching regulator of 1.2 V at 1.36 MHz and harmonics at 2.72, 4.08, 5.44, 6.80 MHz.  There is a noticeable tone at 20.550 MHz. No other signals with 20 dB LNA and without attenuation.

Comments

  1. RadoMSeptember 14, 2020 at 1:11 AM

    Its strongly needed FPGA between ADC and FX3 for buffering, synchronization and performance improving. Direct connection to FX cannot give guaranteed bandwidth on USB3 with nonReal time operating system like windows or linux. This mean that you can drop from time to time samples or group of samples. Think about adding FPGA between ADC and FX3.Yes, it will raise cost and complexity of the board, but there are no free lunch nor full happiness.

    ReplyDelete
    Replies
    1. ik1xpvSeptember 14, 2020 at 2:12 PM

      I agree that non-real-time operating systems require intelligent programming to process the broadband signal as a full HF band with low latency. However, this is not related to the stability of the super speed USB3.0 transfer. My programming of FX3 is naive, however it shows continuous transfer. Here a video "HF103 : HF spectrum accelerated elapsed time, 24 hours in 2:30 minutes" (https://www.youtube.com/watch?v=2jvBGXheA0M&ab_channel=ik1xpv).

      Delete
  2. Atul SrivastavaJuly 2, 2021 at 7:37 AM

    I appreciate your article. You truly share relevant and extraordinary knowledge. Thank you for keep sharing these valuable thoughts.

    OSCILLATOR : 141AN : ALCATEL-LUCENT
    PACK MICCD CKT
    Network Supply : FILTER : 1040A : ALCATEL-LUCENT

    ReplyDelete
  3. cozycactusMay 27, 2023 at 3:52 AM

    Hello!
    In the datasheet of SC189 used as switching regulator in fx3 kit mentioned that it uses 2.5MHz as the switching frequency, but you see spurs at different frequencies..

    ReplyDelete

Post a Comment

Popular posts from this blog

A look into the RX-888 mkII

Image
  The RX-888 mkII designed by Justin Peng and Howard Su  arrived!   It is an evolution of the first RX888. The curiosity won out and I opened it. Be careful if you decide to open your device because two heat pads are used to carry the heat from the R828D and the LTC2208 to the aluminium case. I managed to slide them out without damaging them by moving the PCB very gently. A plastic wide stick may help to push out the pads and after to reassemble the radio. The PCB layout is similar to RX888 In HF the input attenuator is a  PE4312   covering a 31.5 dB attenuation range. This replaces the 0, -10 ,-20 dB attenuator of RX888.  It is followed by the low pass filter at 64 MHz.  Then two switches PE4259   select the HF input or the VHF tuner R828D produced by Rafael Micro that replaces the R820T2. The added transformer connects in a balanced way to the R828D IF outputs. An AD8370  digitally controlled variable gain amplifier (VGA) provides precision gain control, high IP3, and low noise figur
Read more

RX888

Image
Yesterday I received the RX888 designed by Justin Peng and Howard Su.  The first impression in o pening the shipping package  is that it is very small.    It is as big as the Cypress fx3 superspeed explorer kit ! Thanks to Guy Atkins'  SWLing post  I was able to resist the desire to open it right away to see the interior.   I started looking at HF. I connected it to my old I7-3770 pc and to the 10 meters wire antenna that I have on the balcony of my house.   My city is Turin and here the local transmitter in MW has frequency 999000 Hz synchronized to a high precision reference. I tuned this station and without calibration of the internal oscillator of R888 I measured an accuracy better than 1 ppm. This is not obvious after a transport of more than 10000 Km. In case there is the internal trimmer that allows you to calibrate the reference oscillator when you have a reliable reference. Frequency calibration test The ExtIO_RX888.dll v0.4 has the gain scale calibrated without subtractin
Read more