TANDEM MATCH 2kW SWR POWER meter protection RX-TX ANT A-B LDMOS MOSFET BLF188XR

Description

Board
OUT UNIT
designed for high power amplifiers
(up to
2kW
)
in HF band 1-50MHz.
This can be very useful as the core of a power meter, or as a component in an amplifier system.
Applies a variant of the well-published "Tandem Match", it can measure forward and reflected power at the same time, without having to throw a switch to do it.
It provides the ability to measure forward and reflected power levels; this is especially important in detecting high reflected power conditions, such as a damaged antenna, or when we forget to connect the coax to the output of an amplifier, etc
.
The signal of FOR (see scheme -
VD4 - U1:3) is used for measurement of power.
The signal of REF
(see scheme -
VD5 - U1:2)
is used for measurement and for system of protection against high REF value.
Components U1:4, VT3, VT5, VT6 create "
G_STOP", "
+ _ STOP"
signals for protection of the amplifier. Keys of signals of protection of G_STOP and + _ STOP with "latch" (VT4). I.e. signals G_STOP, +_STOP disappear only with the return of the amplifier in the RX mode.
Board
OUT Unit
includes:
1. Directional coupler TR1,
2. Amplifiers U1:2, U1:3 for SWR-POWER meter,
3. Protection - comparator U1:4,
4. Keys switching - VT3, VT4, VT5, VT6,
5. Relays RX-TX; ANT A - ANT B - K1,
K2
. VT1, VT2 control the operation of the relays,
6. U1:1, VD10, VD12 form a voltage of negative polarity to ALC protect the transceiver,
7. VD6, R37 - ALC voltage to the transceiver (
the voltage of the negative polarity)
,
8. VD1, RU1 - protection of static voltage from the antenna.
The size of the core TR1 10x20x15mm allows you to measure the power of at least
2000W
.
At the same time resistance of loading has to be 50 Ohms.
To manage protections of amplifier OUT Unit gives several options signals:
G_STOP -
Open drain up to 100mA, U<25V
+_STOP - output +12V up to 100mA
ALC – output to -10V
If SWR exceeds value (which you will choose as resistors R21, R29) - VT3 will open.
VT3 will stay open through VT4, while there is a voltage of +12V_TX.
When switching to RX mode - protect turns off.
A-B - switching the antenna A - antenna B. To switch to apply a voltage of +5-12V.
+12V_TX - Voltage +12V TX from the amplifier, which switches the amplifier from RX-mode to TX mode.
FOR – measurement of power
REF – measurement of SWR
Size PCB 90x71mm
The graph shows the dependence of the output voltage on the transmitted power.
You can build a similar chart yourself online - link to the resource - https://www.kontrolnaya-rabota.ru/s/grafik/tochka/
Enter the table -
0;0
0.82;10
1.35;20
1.80;30
2.12;40
2.42;50
2.69;60
2.96;70
3.24;80
3.43;90
3.56;100