K6JCA has analyzed the needed components values for matching a load while moving on a constant reflection coefficient circle. The plot below shows that in case you select the high-pass configuration for your tuner, certain angles of the reflection coefficient will give you skyrocketing component values.
Component values for the highpass and lowpass configurations
Above you can see that the LsCp &CpLs configuration keeps the max component values quite flat. LsCp and CpLS are therefore the best engineering choices based on cost and realistic component values.
European Grid Locator map (western Europe). Credit to PA2HJS for making the map.
I have made a repeaterlist for the Oslo area in Norway. This list can be saved as CSV from Excel and is then after saving as CSV compatible with Chirp.
Make sure to check that the CSV files uses commas (,) as separators and NOT semicolon (;). This can be set in the meny you see below. Goto Start menu and type locale. Click the change date, time, number format.
Thanks to Alf LA2NTA for the data I used in this list. See another posting for the direct link to Alf’s list that is located in the cloud. My list here will not be frequently updated, but per April 2017 it should give a good starting point.
I updated my MD-390 with the modified firmware. This fw. gives among others, these new functions:
- Promiscuous mode. Listen to all voice groups on one timeslot. Even if you havent programmed the VG in a channel.
- See last heard on the display on all VGs on the time slot you have assigned to the channel regardless if you have enabled that VG
- VU meter for TX audio
- Updated contact list database
- Display dimming timer and intensity adjustable
- Lower beep audio on transmit not allowed etc
- List of last heard
- Channel info on display: tx freq, rx freq, timeslot, TG, sender ID, repeater ID etc
Alf LA2NTA has made an excellent repeaterlist covering norwegian repeater that are updated quite frequently.
Alf edits the document straight at Google Drive. You can check out the most updated version on this link: https://docs.google.com/spreadsheets/d/1tPHd2HDnkHOPJrQkDUpCRH00zhCIOoMiAMqaustzqsk/edit#gid=1
To set up GPS on the TYT-390, make an own contact with name GPS and call ID 5057
Then set up Destination ID: GPS under GPS settings. Set the interval to 60s or more. (Not too often as GPS packets take repeater capacity)
Now select “GPS system 1” under the channels you want GPS enabled on. I have made a set of channels with GPS on and a set of channels with GPS off.
In Brandmeister dashboard, go to Services/Self Care and select chinese radio. Check that your call and your name looks OK (you need an account at Brandmeister).
Then program your radio with the codeplug with the radio settings above.
Set your radio outside for several minutes to achieve GPS lock (can take quite some time).
You should see a globe symbol show up without the red ring (red ring means no GPS lock).
Then you can check aprs.fi for your callsign.
The Red Pitaya SDR board is based on the Xilinx Zync SOC and has 14 bit external A/D converters. However, for SDR usage on the HF bands from 0.1-30 MHz (and for that matter up to 50 MHz) the Red Pitaya is a bit “deaf” in the stock configuration. I have made a broadband amplifier that has a fairly high gain and very good IIP3 properties. Below I have posed some pictures of the prototype amplifier.
This is the prototype amplifier. I inserted a ferrite ring on the input lead to roll off the VHF / UHF sensitivity to reduce problems with nearby broadcasters etc. There is a also a PI network attenuator on the ouput and I have inserted a couple of beads in that as well to roll of the outpu response when frequency increases. The other components in the lower part is a input pi attenuator I used when I did some VNA frequency response measurements. This as well as the RCA plus is not used (RCA plugs are surprisingly good for low level RF signal routing in the HF bands and nice to use in the lab). I used a more professional attenuator with a large attenuation range and flat response to determine the proper attenuation level after the preamp into the Red Pitaya. Reducing gain after the first amplifier has very little effect on the noise figure. Reducing it before the first amplifier directly adds to the noise figure. I added some protection diodes over the input to reduce the risk of strong RF signals or static voltage build up damaging the input. Below I am measuring the response of the attenuator with the DG8SAQ VNA. It was flat from 0-1,3 GHz.
The Red Pitaya hardware is the first low cost RX / TX capable SDR hw to come onto the market that is open source and can match the Ettus Research USRP periperhal. It has a combined CPU and FPGA signal chain with two channels 14 bit 125 MSPS A/D and D/A. It also has a Dual core ARM Cortex A9+ FPGA (Xilinx Zynq 7010 system on chip). Only a few years ago this caliber of hardware had to be custom designed and was typically used in radar antijamming systems, radar signature classification systems, ultrasound, sonar and in high end vibration analysis tools (as examples). The ARM CPU on board can run Linux and it has GNU-Radio support. For fast data transfer there is a GBE (Gibabit Ethernet) interface to other host systems. With a a RTOS on the ARM core or a zero copy IP stack under Linux it should be possible to approach fairly close to 1 Gbit/sek transfer rates to host systems (if needed).