with RTL-SDR and LNA receive cubesats

The last days I’am active with the modifications of the RTL-SDR dongle to receive the Cubesats.
In short I had used the next mods (1st test fase);

* 10 meter RG58 in coil arround the RTL-dongle to reduce noise and grounded to the USB.
* removed the metal part on the USB connector.
* added a ring-coil arround the small cable to reduce noise.
* added the LNA from lna4all (ln4all.blogspot.nl)

I’ve tested a few SDR applications, but the best results I getwas with the SDR-Console v2.1 beta software and for the RTL dongle the Ezcap USB 2.0 driver. The OS is Windows XP (now Windows 7 Pro) and running on a portable/fixed computer.
The next days I will bring the SDR-dongle together with the LNA in a metal box, to reduce more unwanted noise (shown on the last photo).

The picture(s) below will give you a nice view how I made it together.
If you need more technical information, pse send me a request (see contact page).
ASAP I will make more information available with weblinks,(sound) files and screendumps.

(pic 1. The mods)     (pic 2. Delfi-n3xt)      (Pic 3. SDR mod RF closed box)


Receive CQ from ISS Space Centre

Today I received the ISS ‘loud and clear’ – 59+ on the 145.800 Mhz.
I have tried to make contact back, but the TX was active on the wrong frequency, it should be 145.200 Mhz. If you want to listen to it, click on the sound-link.

Recorded CQ from ISS dd:311013 (wav-file)

RTL-SDR dongle and Raspberry Pi 512 Mb

Today finished the soft- and hardware solution with the RTL-SDR and RPi.
The main idea is to use the low-cost ($25) RTL-SDR dongle on the RPi and connect the RPi with a portable computer, with the SDR-client software on it.
The test antenna is the 3-element HB9CV antenna only for 144-146 Mhz.
This means that for ‘satcomm’ we can only follow the 2m oriented sats.
The RPi is the 512 Mb internal memory ‘hardware’, this should be fast enough to handle the RTL_TCP server software.
In the download section you can find the (english / dutch) manual to install the correct software on the RPi and the PC with minimum OS, Windows XP.
The pictures will show the first tests and the basic hardware.

SDR software, main screenServer (CLI) screen on Raspberry - connected to the SDR client

Building the Taurus case

In the next pictures you can see the result of the new Taurus case.
You can find the case at ‘Otto schubert GMBH‘ (click on the name), and use the Art. Nr. 228.
On the same shop you will find adds to make the box complete.
First I started with the front, this is made from pbx-board (copper on both side’s).
Next I started to make the bridge for the potmeters (picture soon).

For the results see the pictures .. soon I will place the design with the figures to use.

Meantime case update

Photo 30-05-13 18 30 09

Photo 30-05-13 18 29 48

Motorola GM950 small RS232 Interface

Today I have finished the small RS232 interface to manage the Motorola GM950 UHF/VHF transceiver.
This small interface will cost you about 10 Euro, and will give you much fun !
I had made the PCB layout on the test board, the design is so small that you can easy do this (see picture).

The yellow line’s on the back of the PCB, will show the line cuts needed to place the parts right on the board.
In the green circle you see the small modification on pin 9 and 8 of the 9 PINS RS232 connector.
in the schema you can see that the use of a 9 Volt battery will be oke, but when you make a stable 5 Volt on the PCB the communication will go to be stable to connect to the transceiver.

Back of PCB Motorola

The software you can get from the website in the UK (see ‘Ham links’)

The original design is made by IK5BZH, so that OM must have the credits to find out this small interface !

I have learned that it will be best worked with short RS232 cables and full wired, no crossing cables or what else.
For the connection to the RJ45 (Microphone) connector you have to pay attention, this is 180 degrees rotated – PIN 8 is on the left of the RJ45 !!

Both GM950 ( UHF and VHF) transceivers can be handled with this interface, the best software to use is version r2.00.00.

Motorola PCB 2Motorola PCBSchema RS232 interface Motorola







If you double click on the pictures you can see more !

Repaired new bulb in FC-757AT

Today I have ‘repaired’ the small bulb lamps in the FC-757AT of Yaesu.
But the result is a little bad.
The bulb’s should be ready for about 12 V, but the bridness is not good!
If you have the correct bulb’s for the FC-757AT, please contact me !

On the pictures you can see the result, while opening the cover.

Bulb for the FC-757ATThe broken one's







The broken one’s



The replaced bulb will fit in the blue tube (on top of the picture)

LED bar S-meter

The small project, LED bar S-meter, is active.

I found the schema at the website from F6BQU.

The schema is very easy and the result is nice (see the pictures) I’ve used to test the LED bar with the signal generator (function generator).

The next I have to connect the LED bar S-meter on the receiver part of the Taurus 20 or Bitx 20.
See the next pictures.

LED Bar S-meter LED bar S-meterSchema LED-bar