Receiving antennas open a new DX world. To connect and experiment with RX antennas, you need to figure out how to connect such an antenna to the TRX. The more expensive TRXs have a direct RX ANT input. Smaller TRXs do not provide this option. One option is some more complex RX system that also has RX ANT switching. The other option is this small box that allows you to connect RX ANT to the TRX via proper protections, switching control during transmitting, manual switching between RX and TX/RX antenna, PTT splitter, etc.

PTT can also be connected to YAESU TRX that do not have RCA connector. With the mini DIN TUNER connector you get the PTT signal and this box allows you to connect other external devices (PA) to the classic RCA connector (PTT OUT).

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Parameters
Blog diagram
Connection
LED indication
RX ANT control
Measurements
Product details

Parameters

Frequency range 0.1 MHz to 30 MHz
RF power up to 250 W
RX ANT input high pass 100 kHz
RX ANT GDT and Neon lamp surge protection
High isolation: TRX - RX ANT over 100 dB
High isolation: TRX - TX ANT over 80 dB @ 7 MHz
Low insertion loss: 0.8 dB @ 7 MHz
RX ANT connector: SMA
TRX and TX/RX ANT: SO-239 female
DC IN 13.8 V and 0.3 A
DC IN: green connector or YAESU TUNER
RX/TX controlled by PTT
PTT IN: RCA and mini DIN
PTT OUT: RCA
PTT IN current typ. 15 mA
PTT OUT: FET with 0.5 A polyfuse
PTT OUT: max. 60 V DC open
PTT IN and OUT: optocoupler isolators
LED: ON (Y), RX ANT (G), PTT (R)
Control switch: small toggle switch
1m long cables for DC and toggle switch

Block diagram

There is the block diagram of the switch. The transmit signal is switched by a double contact power relay, due to the relay configuration minimal crosstalk from the TX antenna is achieved when using the RX ANT.

The PTT includes optical decoupling. An RCA connector labeled PTT IN or a mini DIN YAESU labeled TUNER can be used as the PTT IN signal. The box also contains PTT OUT. This is not delayed in any way, the box does not contain a sequencer. PTT OUT is via a FET transistor with a reversible fuse and 0.5A protection.

Power to the switch can be supplied from the YAESU TRX using a mini DIN cable or via a two-line connection on the green connector.

The RX ANT can be selected using the toggle switch. This is at the end of a 1m long cable and can be positioned to your liking.

Connection

This is an example of linking with YAESU. The power supply and PTT signal is taken from the TUNER mini DIN connector. PTT OUT can be used to connect a PA.

LED indication

Yellow LED ON - DC power ON indicator
Green LED RX ANT - RX ANT is selected
Red LED PTT - Transmitting, RX ANT disconnected, TRX connected to TX/RX ANT

RX ANT control

When the box is turned off the TRX is connected to the TX/RX port. It is possible to listen and transmit (to, from TX/RX ANT), but PTT OUT does not work. When DC power is connected, the box is controlled by two signals. One is PTT, where when transmitting the TRX is always connected to the TX/RX connector. The other control is on the green screw terminal. The connected switch allows you to select between RX ANT and TX/RX ANT inputs. This switches the signal source for the receiver. Transmission is always to the TX/RX port.

This control is possible by using the supplied small toggle switch or by replacing it with a larger one or by using a relay contact - for example Remote Control

Measurements

SWR TRX - TX ANT

Isolation TRX - TX ANT while using RX ANT

Isolation TRX to RX ANT while transmitting