9W2SVT

Saturday, April 17, 2021

Hermes-Lite 2.x

Hermes-Lite 2.x, a 3rd Generation SDR

In the month of Dec 2020, I was reading up on FPGA and wanted to know more about this topic. I was attracted to this YouTube https://www.youtube.com/watch?v=qlgq52IIUo8 titled Hermes-Lite: Amateur Radio SDR.

This Hermes-Lite 2.x is considered a Gen 3 SDR ( see below)

How is this different from other USB SDR dongle out there ? Here are some summary points :

Uses a low cost cable modem IC called AD9866 for ADC / DAC
No USB port , you get the SDR I/Q signals via Gigabit Ethernet / LAN
uses FPGA ( Field Programmer Grid Array ) to process the vast amount of I/Q signals
5W power amplifier
Remote control
Open Source

The most significant feature that caught my attention is the ability to view the entire HF spectrum from 0 to 38Mhz in ONE screen. Snapshot from video at 6:00

After watching this video, I did a quick search and found one of my supplier called makerfabs.com is currently doing a 2nd group buy for this SDR radio. https://www.makerfabs.com/hermes-lite-2.html

There are 3 parts for the order, the main hermes-lite 2 board, the N2ADR filter / relays and the enclosure with faceplates and all the necessary stuff.

I posted this "group buy" to a local ham radio fb group to get some interest check and got a few crazy ham people to join me for a group buy just before Chinese New Year 2021. As China closes for a long break during Chinese New Year festival, we need to get it shipped out before everyone closed down.

Really nice to see they recorded the video on how these boards are actually made.

https://www.makerfabs.cc/article/pcba-in-production-hermes-lite-2-0.html

After a short wait, a few units arrived. According to the instructions, we need to drill a hole and install a aluminium heatsink at the bottom.

Purchased this chamfer tool recently, so put it to good use. Once everything is done, install the latest PowerSDR and power it up.

How is this SDR radio different from the current SDR out there, firstly, it is connect to the software over the Local Area Network, means you can place the radio far away from noisy electrical items and do remote control.

I also loaded the HPSDR on RPI4 https://github.com/g0orx/pihpsdr with a 9.7" display that I plan to use a 7" pi display and add knobs and buttons to them like this picture below.

Here is a picture of a commercial product from ApacheLabs, Controller V2 that run PIHPSDR by John Melton.

Generations of SDR

Before we continue, let's explain about different generation of SDR radio out there, a really good youtube by Justin Giles-Clark VK7TW https://www.youtube.com/watch?v=2oKDxI09UkY . In the middle of the video, he also mentioned the Hermes board that the Hermes-Lite is based on.

Generation 1

Direct Conversion, HF to AF, 192kbps
Radios like Funcube, Flex3000, Elecraft KX3, RTL SDR
Relies on soundcard ADC
image rejection issues

Generation 2

ADC ( Digital Down Converter ) / DAC ( Digital Up Converter )
Direct sampling
Need powerful PC and fat pipes
Radios like SunSDR
FlexRadio's PowerSDR made open source

Generation 3

Processing in the radio
FPGA doing the processing
band pass filters, attenuator
hugh dynamic range
remote operations
Flex 6000, ANAN-200, HPSDR, Hermes-Lite

Generation 4

Gen 3 with knobs and buttons
Looks like an actual radio
Radios like SunSDR, Flex-6700, EG-ELAD, ApacheLabs

Summary Links :-

Main Site http://www.hermeslite.com/
Group Buy https://github.com/softerhardware/Hermes-Lite2/wiki/Group-Buy
Makerfabs https://www.makerfabs.com/hermes-lite-2.html
OpenHPSDR-PowerSDR https://github.com/mi0bot/OpenHPSDR-PowerSDR/releases/
pihpsdr https://github.com/g0orx/pihpsdr

Sunday, September 27, 2020

HFB01 Portable HF Antenna

Doing a short review and blog of my "Super Antenna MP1" clone from China with model name of HFB01. This antenna support from 3.5Mhz to 440Mhz, a really wide frequency range.

HFB01

For the installation, I made a L shape water pipes mounted to the balcony grill. The base of the antenna is clamp using U clamps. with this setup, it is easier to adjust the angle and easier for me to adjust the variable inductor easily.

Once eveything seems secured to the grill, I started to tune the antenna for 40m, 7.070Mhz by adjusting the variable antenna up and down and looking at the SWR of the MR100 Antenna Analyzer. This step was really easy compared to my previos JPC9 antenna by adjusting the length of the telescopic antenna.

MR100 SWR

Once I m satisfied with the antenna tuning, I fire up FT8 to do some receive and transmit tests.

FT8 Transmit Tests : I can only transmit to Japan and east coast of US but could not transmit to Europe side.

FT8 Receive Tests : I can only receive from nearby South East Asia and Japan only.

FT8 Rx & Tx

FT8 Rx

Overall, I am quite safisfied with this antenna with it easy to tuning and very light weight.

Saturday, December 8, 2018

DIY SVT MMDVM

SVT MMDVM first calls

The Digital Voice ( DV ) for the ham radio have started a few years ago but to build a hotspot ( a tiny personal half duplex repeater ), you will need some pricey equipments like DVStick with AMBE-3000 vocoder and USB interface plugged into a Raspberry Pi with an Arduino Mega to drive the UHF transceiver.

It all started around Sept 2017 when the price of DMR radio was getting below RM1,000 and a few of us purchased a TYT MD-2017, one of the more popular DMR radio at that time.

Secondly, without a DV hotspot, having a DMR radio is kinda useless unless you are within the range of a DMR repeater in your area.

MMDVM G4KLX

Thanks to Jonathan Naylor G4KLX ( https://github.com/g4klx/ ) (and many many people people) that created the MMDVM, a software that integrated multiple hardware ( teensy, Arduino DUE, STM32F1, STM32F4 ) and Raspberry Pi running pi-star ( https://www.pistar.uk/ ).

When I saw the hardware requirements, I noticed that I actually have ALL the hardware with me, STM32F103 red-pill, Raspberry Pi and they were also using a version of Arduino called stm32duino.

A few STM32 red-pill I purchased previously

The only missing piece was the UHF transceiver called RF7021SE module plus changing the TXCO to 14.7456Mhz. So I started doing my research on different board designs and immediately design a single board layer to test out my design.

MMDVM boards

Here is the first version after many iterations and because it was a single layer board, I had to place the SMD LED at the bottom of the board.

SVT MMDVM

SVT MMDVM 3D view

Once my designed was almost finalised, I bring it to Uncle Chow ( 9M2CF ) to convert my PCB design to a single layer PCB.

SVT MMDVM negative

SVT MMDVM etched

SVT MMDVM copper removed

After some UV exposure and chemical baths, I got the SVT MMDVM board ready to be soldered.

SVT MMDVM fully soldered

SVT MMDVM top side with red-pill

SVT MMDVM running

Fully connected to the RPI 1 and pi-star software loaded.

SVT MMDVM connected to RPI 1

Saturday, May 27, 2017

Measuring capacitance of variable capacitor (varicap)

This is just a short post of measuring the capacitance of the variable capacitor at maximum capacitance..

The first picture is the measurement taken at both the stators ( stationary plates), this is used for magnetic loop as per the diagram below.

Capacitance at both stators

Position of variable capacitor

The below picture measure the capacitance between the stator (stationary plates) rotor ( moving plates).

Wednesday, May 3, 2017

Variable Capacitor for ham radio

A short posting with pictures of variable capacitors made using a CNC machine by 9W2CEW. The CNC cut both the rotor (moving plates) and stator (stationary plates) in one go. Refer to the last picture below.

This design is usually found in loop antenna to change the capacitance value from the shaft.

Side view

Variable caps with laser cut cover

0.7 mm aluminium plates

Sunday, April 16, 2017

40m vertical balcony antenna using PAC-12 , adjustable coil and telescopic whip

Just want to share an updates on balcony antenna using the following setup :-

PAC-12, coil and whip antenna with mounting

PAC-12, coil and 5.6m telescopic whip

Adjustable coil

Equipments :-
Antenna Base : PAC-12
Coil : Adjustable coil ( max inductance is 23uH )
Antenna : 2.5m or 5.6m telescopic whip at 2.29m length
Frequency : 7.080Mhz ( near JT65 freq )

Telescopic whip ( either 2.5m or 5.6m length) at 7 1/2 feet ( 2.29m ) and the adjustable coil at 21.31uH.

This is the reading of the antenna analyzer at JT65 frequency, complex impedance of 25 + j0, SWR of 1.26:1, therefore I do not need to use any antenna matching tuner. When I transmit at 25W, the meter reads an output power of 20-22W going out to the antenna.

The antenna analyzer is a version of SARK100 called MR100. The details at summary links below.

MR100 showing the SWR

LC100A LC meter to measure the inductance.

LC meter show the coil henry readings

The below is the result of the short 40m balcony antenna, I am able to reach both Europe and USA using it.. In my condo, I am almost surrounded with highrise buildings and not much openings.

9W2SVT JT65