Radiometrix Ltd

QPX1 Data Sheet

page 3

6. This is a 2 watt output product. Good grounding , good quality aerials, properly mounted, and a

low impedence power supply are required if full performance is to be reliably obtained.

Be aware of the effect that the strong RF fields generated by this device (and it's aerial) can

have upon other adjacent circuitry if this is not properly screened, filtered or otherwise protected.

Regulators, sensitive analogue circuitry, and microprocessors seem especially interference

prone.

Two watts of RF at VHF can cause an unpleasant and painful burn. Be careful.

7. Caution:. The TXD and P1-P3 inputs are not high voltage tolerant. Low voltage logic, or

switches to ground, are required.

8. A simple RS232 voltage tolerant transistor inverter connects pin 14 to PGM

9. Depending on the firmware, some versions use P0-P3 as parallel select. Others use P0 as a

programming input only, and P1-P3 as parallel inputs. Refer to tech support for details.

10. Enable pin (4) may be tied to +Vin

11. Overall thermal power dissipation in normal use is around 4 watts, rising to 6-7 watts under

aerial fault conditions.

12. This design uses the SMX1 mk2 transceiver RF board as an internal component

13. For visual reference, this unit uses an Evatron-type REAS120 extrusion

User interface: Modem mode

The 'modem' mentioned is a 1200 baud RS232 semi-intelligent unit (Transmit keyed when valid serial data is

present, so no separate TX control needed. Coding in the datastream also permits the receiver to ignore

noise and only output valid serial data) This is a half duplex unit, so collisions between transmitted and

received packets must be dealt with by the user.

Pin

Name

Function

1

NC

Leave open

2

TXE

Open = normal modem operation. Low = constant TX (for test). 10K pullup to 5v

3

NC

Leave open

4

ENABLE

Overall unit 'on' (high active, high voltage tolerant)

5

RSSI

DC level between 0.5v and 2.5v. 60dB dynamic range

6

AF out

200mV p-p audio. DC coupled, approx 1v bias. Muted by squelch

7

NC

Leave open

8

NC

Leave open

9

0V

Ground

10

(tba)

Leave open

11

MOD RXD

inverted "RS232" data out (to inverting buffer like MAX232)

12

MOD TXD

RS232 data input (true). 10K pullups to 5v

13

PGM

inverted version of pin 14

14

PGM

Serial programming/control input (true RS232)

15

Vcc

12V DC supply (11-15V). 550mA typ. current drain