99 Responses to “The German SEM-25 Transceiver”

1. 

   Klaus says:

   2017/05/07 at 03:48

   Hello Dimitris !
   The cable #51 is only neccessary if you are operating 2 sets SEM 52 together (for example as a relay-station), the cable #10 connects the antenna-tuner-unit sem 25 (AGAT) to the transceiver sem 25. From time to time this cable #10 is available at http://www.helmut-singer.de and/or http://www.bw-schmitti.de .
   73,
   Klaus, DL4FCY
2. 

   Dimitris says:

   2017/05/07 at 07:48

   Many thanks Klaus,

   I m looking for buying these cabkes.
   Any help?
3. 

   giovanni says:

   2017/08/27 at 10:45

   Good evening at All SEM25 fans.
   My name is Giovanni and I have a SEM25 and a EM25 with a AGAT.
   I need help from those who are more experienced than me.
   I connect everything according to schema, the SEM engine works but the AGAT stays motionless.
   Turning on the transmitter, the AGAT rotates in full scale and does not move anymore.
   The transmitter works, verified with its ros-meter, and the loudspeaker on some frequencies receives signals.
   I checked the connection cables with the tester and they are all working.
   Can someone help me?
   Thank you from Milano
   Giovanni
4. 

   klaus says:

   2017/08/28 at 02:28

   Hi Giovanni !
   When changing the kHz- frequency on the control-box only, then the frequency displayed on the AGAT will not change. If the frequency on the control-box is changed in MHz-steps, then the AGAT-Display should Change. If not, please check the cable #10 which connects the AGAT with the Transceiver-unit.
   73,
   Klaus, DL4FCY
5. 

   Giovanni says:

   2017/08/28 at 06:46

   Hi Klaus,
   thanks for your answer.
   Unfortunately, the AGAT does not change both the kHz and the MHz controls.
   If you manually rotate the circular frequency scale in the AGAT by switching on the transmitter, the scale will rotate to full scale and stop.
   I’ll check pin to pin cable # 10.
   Greetings
   Giovanni
6. 

   erwin van steenacker says:

   2017/08/28 at 09:35

   Has anybody an idea on which frequencys transmittions is done usually.

   I have an old Wollys Nekaf with a build on SEM 25 but I have idea on which frequentie to check. As I’m living in Belgium, I have neither an idea how far the transmittion will work and who I might contact, but it is just for fun. My sem25 should work, but I only hear some static.

   Kind regards,, Erwin
7. 

   Giovanni says:

   2017/08/29 at 01:34

   Hi Erwin,
   In Europe the amateur bands that can be used with SEM are:
   10 meters (28,000 to 29,700 kHz);
   6 meters (50,000 – 52,000 MHz) – also called 50 MHz band.

   However, check the Belgium frequency plan and if you need some license.

   73
   Giovanni IW2BZO
8. 

   Giovanni says:

   2017/08/31 at 10:04

   Hi Klaus,
   Thanks to your instructions I checked all the cables.
   Cable no. 3 did not make good contact.
   Disassembled, cleaned and reassembled, everything works perfectly.

   Shortly, I set up the equipment on a MUNGA and I will try to calibrate the AGAT.
   Thank you
   73
   Giovanni IW2BZO

   • 

     Trond Gustavsen says:

     2019/10/24 at 12:49

     Giovanni! When serving in the Norwegian army , I used the SEM-25. IF something did not work, we checked and cleaned the cables. Especially earth-conections were checked (Bad climate). After that, everything was ok. Once a Leopard 1a was drowned in a bog. After 48hours, the tank was saved and the cleaning-work started. I remember that the radios (SEM-25 X2) still worked flawlessly!!!!
9. 

   Klaus, DL4FCY says:

   2017/09/07 at 11:11

   Hi Giovanni !
   Thanks for the info !!! For the alignment of the AGAT you need special tools which are included to the Antenna check Box (in German: Antennen-Prüfgerät). Without them it will be very difficult to adjust the “C” and the “L”-Pins.
   73,
   Klaus, DL4FCY
10. 

    giovanni says:

    2017/09/08 at 00:48

    Hi Klaus,
    I have the tool, but I have no instructions.
    I assume that for each step I have to act on the adjusting screws, until you get the lowest reflection.
    Then, hope that there is someone listening…………
    73
    Giovanni IW2BZO
11. 

    Klaus, DL4FCY says:

    2017/09/08 at 04:48

    Ciao Giovanni !
    Here are the instructions: Connect the antenna testing instrument or a swr-meter between SEM 25 and AGAT. Select the frequency you want to tune on the control-box of the transceiver. In the display of the AGAT the frequency (MHz) should be the same (for example: selected Frequency on the control-box SEM 25: 29,60 MHz., displayed frequency on the AGAT-display: 29 MHz). Then press the PTT an read the swr. If it is to high, open the 2 screws which are marked “L” and “C”. For ever MHz-Position there are 1 Aligning Pin “L” (= inductance tuning) and 1 Alingning Pin “C” (= Capacitance Tuning). Now hold the PTT pressed and insert the aligning tools in both holes and turn the tools alternating until the swr is low (or the reflected power has reached a minimum). This procedure must be repeated in every MHz-position you like to work. When I was in the Army many years ago, this was a job for a complete day… 26-69 MHz are 43 positions…
    I hope I could help you.
    73,
    Klaus, DL4FCY
12. 

    giovanni says:

    2017/09/08 at 06:02

    Thanks Klaus for the information.
    I think I will have to take it very calmly and patiently!
    At the end, also I put in the EM25 function to check if the SEM transmits ……. and I’ll let you know.
    73
    Giovanni IW2BZO
13. 

    Klaus, DL4FCY says:

    2017/09/23 at 15:50

    Hi Giovanni !
    I’m looking forward for your informations !
    I don’t know on which frequencies you want to use the sem 25, but I think on 10m. There are only a low number of channels which can be used. If the conditions are good, you will receive some stations on 29,50 or 29,60 MHz. I use my SEM 25 on these frequencies as a monitor – if there are stations, the condx are good, so it makes sense to look for other stations on 10m on the ssb or cw-segments as well as FM. I use a indoor antenna for 10m with my SEM 25 with a manual Tuner (YAESU FC-700), so the tuning procedure is much easier and quicker than with the AGAT.
    73,
    Klaus, DL4FCY
14. 

    giovanni says:

    2017/09/28 at 04:06

    Hi Klaus,
    thanks for the information.
    73
    Giovanni, IW2BZO
15. 

    Baudouin says:

    2017/11/24 at 03:09

    Hello, I have two sem25 and two sem35, one with its base for vehicle!

    I also have the antenna base with its box coupling but I no longer have antenna strands MS116, MS117, MS118. Can you tell me where to get them?

    thank you

    Baudouin

    ON2BJ
16. 

    klaus says:

    2017/11/24 at 04:25

    Hello Baudouin !
    Please refer http://www.helmut-singer.de and/or http://www.bw-schmitti.de
    From time to time they’re offering these parts.
    73,
    Klaus, DL4FCY