www.webx.dk Start page

MY little Radio Control page

Also see the video wireless page if you like.

Foreword:
The 1300MHz band also know as 23cm band is open more or less worldwide for radioamateurs.
Now small and cheap video transmitter equipment can be purchased and used legally with a radio amateurlicence.

The compleete set I got from rangevideo came with antennas also.

The receiver casing and controler board is identical to many 900MHz types.
this one is frequency stable, no tuning knob !, the 4 channels are selected with a slider switch.
The receiver is supplied with 10-14V DC center pin positive, using a standard 2.1mm DC jack, nice
There is a reverse polarity protection so nothing bad happens when you are unlucky with this.
Video and Audio connectors are phono so no need for them adapter cables that always get lost.
The internal circuit is running on 5V and 9V from two lineary regulators
both are mounted with good termal contact to the case, and can run for days on 13V DC without alarming heat problems.
The pin marked with RED is RSSI from 0-5V so you can use this analog signal to indicate signal level.
Sensitivity: -98dBm to -96dBm depending on channel, (-92 to -90dBm with TV signals) a bit better compared to 2.4G types
Supply Volt and Current : 12V 275mA

Receiver center frequency: measured with Agilent E4438C 3MHz dev 100kHz sine
CH1 1235MHz
CH2 1277MHz
CH3 1315MHz
CH4 1359MHz

The transmitter is small only 25 x 29 mm, 8mm thick, weight 11.9 gr
the antenna is a good stable quality, electrical length 9cm, weight 8.3gr
This transmitter run on 12V DC 118mA (so no problem for the tiny stepup psu from RV, if you only have 5V available)
Supply voltage and current and power out :
13V 130mA, 219mW 23.4dBm
12V 120mA, 180mW 23.4dBm
11V 100mA, 147mW 21.7dBm
10V 90mA, 118mW 20.7dBm
9V 70mA, 88mW 19.5dBm

center freq ch1: MHz
center freq ch2: 1320 MHz
center freq ch3: MHz
center freq ch4: MHz
Spurious Harmonics : not measured yet
Jamming close by GPS, EM406A: 180-200 cm distance then all is fine
Jamming close by GPS, EB85: 80-90 cm distance then all is fine
if you have many sats, then it is much better,
I started on purpose with a weak GPS signal and measured where I will get 0 sats in degrade.
the 2 sat degrade distance is much closer, and no problem with loosing 2 sats, if you started with 8-10 sats.

If used indoor for a long time with no air flow cooling it, this tx unit will get burning hot,
it is intented to be used on RC planes with plenty air flow or with a heatsink mounted to it.

Range test: alot better over 500mW 2.4GHz systems
Video picture looks just as good as a wire connection when I tested indoor
The video source drives my different monitors and googles well.
The nullings seems like less problem indoor, compared to 2.4GHz systems.

Antennas:

marked A

marked B
Both Antennas looks the same and was supplied with this video set, the coil in type B had 1 mm shorder length wire

The tuning and performance could have been made a bit better, but in real life no visible matter to anyone,
All users will normally be happy as long as return loss is 10dB or better.

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Thomas Scherrer OZ2CPU 2010 April