Rohde & Schwarz

all-purpose SK1 transmitter triple

for 1 kW shortwave operation
in any mode

basement allocated and fully remoted

right:
driving exciter for the VK20 amplifier

 

 

 

 

 

 

 

 

Rohde & Schwarz

heavy duty shortwave
amplifier VK20

basement allocated and
fully remoted by the SK1

runs in combination with
the antenna matching device HS 9128

20 kW permanent output in any mode

 

 

 

 

 

 

 

 

 

 

RF Power, AF Response & Intermodulation
Measurements for Transmitter 20 kW, type SK 20/3904

Operational Data

  Ua (kV) Iao (A) Ug2 (V) Ug1 (V)
SK1 3,0 0,35 460 -40
VK20 8,2 2,6 1200 -160

 

Vacuum-Tubes:


RS 1072 C   Ser# 3445 (SK1)
RS 1082 CL  Ser# 234 (VK20)


For all measurement procedures the transmitter is terminated by dummy load RBN 60/60

 

RF Power Output operating in emission mode A1

Rated value: 20 kW

Measured @ power stage 'II' by vacuum-tube voltmeter URU with insertion head after automatic self-tuning:

 
f (mc) Pin (W) Uout (kV) Pout (kW) Ia (A)
1,5 220 1,11 20,5 5,2
2,1 240 1,09 20,0 5,2
3,5 215 1,12 21,0 5,2
5,4 240 1,07 19,0 5,2
8,3 205 1,09 20,0 5,4
10 250 1,08 19,5 5,3
13 280 1,09 20,0 5,3
16 390 1,11 20,5 5,4
20 350 1,08 19,5 5,2
24 280 1,09 20,0 5,2
30 180 1,07 19,0 5,1

 

Indicated Pmax with manual power setting @ decade exciter NO281 and adapting the anode overcurrent trip:

Pout = 30 kW @ 10mc for intermittent operation

 

 

Audio Frequency Response operating in emission
mode A3 with Pcarrier = 7,5 kW
f (kc) 0,1 0,5 1 2 4 6 8,4 16,8
Rated
value (dB)		 ≤ ±2,5 ≤ ±2 0 ≤ ±2 ≤ ±2 ≤ ±2,5 ≥ -20 ≥ -32
Measured
value (dB)		 -0,5 +1 0 +0,5 -1 -1 -60 > -70


Measured by RC Generator SRB & Millivoltmeter UVN

 

Spacing of intermodulation products 3rd & 5th order operating in emission mode A3J

Rated value: ≥ 41 dB vs. pep

Measurement procedure
The transmitter will be modulated by two audio signals with the same level which both @ a time drive the transmitter to 50% output.
After shifting down to the 10 kc stage the RF output signal will be recorded by the frequency spectrograph FNA.

 
f (mc) f1(kc) f2(kc) 2xf2-f1 2xf1-f2 3xf2-2xf1 3xf1-2xf2
      d3(dB) d3(dB) d5(dB) d5(dB)
5 1,21 3,6 45 46 67 69
20 1,21 3,6 42 41 57 60
30 1,21 3,6 42 41 58 60

 

detailed 3.6mc FNA spectrogram pdf (30 kB)

 

 

 

Siemens S97326

10 kW medium-wave
broadcast transmitter

PDM modulation

compact dimensions

high efficiency

 


 

 

 

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