Tech -relay SW

Transmitters for LP AM broadcasting  or  occasionally relay service on shortwave



Out of order:                                            Classic transmitters (60’s & 70’s)

Rohde & Schwarz SK050 (0,5 kW) Telefunken S2525/3  (1 kW)




Latest mosfet TX  technology:




Step size:1Hz,10Hz,100Hz,1KHz,10KHz,100KHz.
Audio response: 50hz-10khz +- 1.5db.
Audio input:  XLR balanced 600ohm at 1V rms.
A limiter and negative peak limiter is provided.
Carrier level:  set by the user
Output power: 0-400+ Watt  (carrier)
Modulation up to  pos. 125+
Antenna connector:  UHF SO239
The transmitter includes protection for excessively SWR and protection for excessively heat.  Watt meter, P.T.T switch, SWR meter and modulation meter is included.

Interested in a 400+  watt / 1600+watt pep  mosfet power transmitter shortwave or (400 watt / 1 kW mediumwave?  Mail for info:                             


  • Dipole antenna (one system)  for broadcasting :














 L = 2 x 50 meter

 h  = 20+  meter centre  

In real the arms of the dipole are constructed under a  corner.  The polarization of this  antenna is in general horizontal (upwards/skywave).


Audio line for broadcasting  AM:  

Audio-processor:   BW Broadcast DSPX – AM    for the best radio audio performance

AM  audioprocessor

“the  soul of the station sound”




Accurate  AM audio control on negative  & possitive  modulation peaks .

     Mike Radio engineers are frequently  experimenting  to obtain the ultimate sound experience.


SDR audio picture: to make audio visible. Made by  Nicolas living near Paris (France) using  ‘Airspy HF’,   freq.  4895 kHz,  on 8th april 2021 around 18.30 UTC (= 20.30 CET local time).


Here below you can hear the audiofile from Nicolas that belongs ‘to the picture’ above:

This is the average reception quality @ the afternoon/evening,  which can be expected on 60 / 52 meter meter band, at a distance like Paris, London, Berlin and  Copenhagen.