Measurement of coil saturation and inductance

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A nice document that describes the measurement of saturation current of coils and calculating the inductance can be found here:

Attention !! This is an external link, i am not responsible for the content !
http://staff.ltam.lu/feljc/electronics/messtechnik/messung_ferritspulen.pdf

Jean-Paul Feltes wrote a very nice description about how to do it and what needs to be considered. Unfortunately it is in german language only.
This is a picture of a measurement of a selfmade coile with a ferrite core purchased from a big german distributor.
Unfortunately the exact parameters of the core and the air-gap are unknown. Since i have some problems with the saturation of the core in a switched power supply i tried to measure.
The inductance matches what i measured with the network analyzer. The saturation of 2A appears to be quite low. Probably the inductance is choosen too high.
In the picture you can clearly see the point where the coil gets nonlinear because of decreasing inductance when saturating.
Be careful not to switch on the transistor for a too long time and care about sufficient time to get the coil voltage to 0.

Saettigungsstrom

saturation current and switch signal for the transistor

TQ2SA relais for RF switching

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I tried a cheap TQ2SA SMD relais for RF switching. The circuit was using the 2 switches as one SPDT switch with the unused output connected to ground.
Find some pictures attached. For low power it should be possible to use the relais up to 70cm (ok, 30dB isolation only). On 2m and below it works with good results…

relais side

relais side

connector side

connector side

TQ2SA-5V_SPDT_insertion_loss

TQ2SA-5V_SPDT_insertion_loss

TQ2SA-5V_SPDT_short_crosscoupling

TQ2SA-5V_SPDT_short_crosscoupling

Windows-free V/U/SHF Contest

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During V/U/SHF contests we use the logging software VUSC from OK1DIX. Is is a multi-operator network based log designed for contest operation. Since my last windows installation got destroyed by a stupid trojan i decided not to install windows anymore. So i tried VUSC under the Wine API emulator and it works very well.
Just download the binary here (current version is 6.32): http://www.ok2kkw.com/vusc4win_eng.htm
Install the binary. It should create a start icon on your desktop which is quite unusual for Linux. You can also start it directly from the Wine directory which is /home//.wine/drive_c/VUSC/
Please refer to the manual from Lada to see how it works.
The only thing that currently does not work is the export of EDI Log files from the internal used .DIX database. The reason is that the windows “copy” commandline tool is used to put some files together. This does not work with Wine for some reason. If you want to export your logs you have still to use Windows or a Windows in a virtual machine. If you find a different way just let me know ;)
VUSC features some very good SSB and CW contest keyer. In order to use this with Wine you need to do some adjustments. You need a serial port with access out of Wine.
I use a USB-serial converter for example. This shows up as /dev/ttyUSB0. Now create a symlink in the directory /home//.wine/dosdevices with the command “ln -s /dev/ttyUSB0 com1”.
This makes a reference for Wine that it should refer to ttyUSB0 if com1 is selected. Take care that your user is in the group “dialout” in order to access the serial port.
Now you may do some settings to select the correct pins and ports for PTT and Key.

VUSC SSB/CW Keyer settings


A paddle that is connected to the paddle input pins can be used together with the keyer functionality of VUSC. This works very well. But first try to get the PTT keyed if you press F1 in mode SSB and CW.
One thing you might experience is that the CW keying is weird and the timing of the dashes and dots is completely rubbish. In this case switch off the VUSC internal monitoring tone in the CW/SSB/Packet menue by unselecting “Toggle monitor”. Now the CW from VUSC should be fine.
One more hint: At my PC the PCMCIA-serial adapter from D-Link i usually use did not work. Probably the driver does not support pin toggling although i do not understand why. The USB-serial adapter works fine…

VUSC and KST2Me running under Ubuntu 12.04

HiQSDR as VNA

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Since today the HiQSDR or the original N2ADR frontend might be used as a vector network analyzer for the shortwave range.
Jim wrote a simple tool that displays amplitude and phase between TX port and RX port and can handle some calibration.
Currently it is quite simple and i do not have provisions to measure reflections yet, so i can just measure S21 at the moment.
But for the future it will be a nice feature to have the antenna analyzer built into the transceiver itself.
The picture below shows a simple ugly-style lowpass filter.

HiQSDR as VNA

HiQSDR as VNA

3m EME mesh dish by DG0CN

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Gert, DG0CN has send me a picture of the new 3m mesh dish design for EME usage he recently made.
It can be splitted into 6 parts for easy transport. Pretty giant antenna ;)

EDIT 2017/06/28: i got the information that Gert passed away weeks ago. His business will most probably not be continued. The webpage already has gone. RIP.