Company: Art Tech
(BACK)

Art Tech ATRXD01 DUAL conversion 35MHz PPM
Receiver system: DUAL converting 31136G with LM393 and counter 74ACH164
IF1 =10.7MHz, ceramic filter (first osc the xtal is -10.7 from the rx frequency)
IF2 =455kHz, ceramic filter
FM decoder: ceramic resonator
RX frequency was accurate within 700Hz using: Original Art Tech yellow label crystal

Antenna wire desoldered (94cm long) and 50 Ohm RF test generator attached.
modulation: 1kHz sine and 2.5kHz deviation.

The demodulated audio signal was found on a test point.
Sensitivity -93.7dBm (4.5uV) at 10dB SINAD, this is 4dB better than their specifications (only 7uV) with -70dBm input level, the IF frequency width is measured to = 15.7kHz
with -50dBm input level, the IF frequency width is measured to = 20.1kHz

Sensitivity to injected noise on the power line
I inject a sine wave signal via a 400uH coil and transfer capacitor 100nF,
directly into the power supply connector of the receiver board.
This simulates a bad motor regulator BEC or Servo current pulse, or noise picked up on long power or servo wires
35MHz RF input signal level at -90dBm this gives us 15dB SINAD
Noise frequency with worst interference = 455KHz due to the IF frequency.
Input noise voltage level when the wanted signal is 5dB SINAD (Demodulated signal drops 10dB SINAD)
Measured to : 2.2Vpp, so that is really good!
you will newer see any problems from electric planes

Mirror frequency and other issues:
Since this is a DOUBLE conversion receiver we will expect to see mirror rejection
so at 13.7MHz rx frequency-(2x10.7MHz) we have -23dBm sensitivity this is 71dB rejection, quite impressive

NOTES
GROUND black wire on power and servos is UP
Need more channels ?? the 7th and 8th signal is available inside it:
carefully solder a wire to pin 12 and pin 13 of the ACH164 chip !

 Feb 6 2008, Thomas Scherrer

Top


Right


Bottom


Left


both boards opened