Another project was added: PPM to Analog Converter
This hardware will convert a standard RC PPM signal into an analog voltage of 0-5V. Mainly intended to convert the RSSI and Link Quality of the EzUHF receiver but can be used for other purposes as well.
Got a GPS-GSM tracker today which I ordered some days ago at eBay.
http://www.ebay.com/itm/320762016759
I plan to use the tracker in my biggest FPV plane for location in case of a long range crash.
The housing is a way bulky and heavy even for a big plane. So could not resist to disassemble the tracker to check if size and weight can be reduced.
Here is the outcome:
Some notes about the hardware:
[Update]
I have added a picture which show two pads for the microcontrollers serial interface.
Parameters are 19200 Baud 8N1. After power up (without SIM card) there is a loop transmission of AT+CREG.
For testing purpose I ordered a OSRAM SFH4236 IR LED. I did some test in my backyard to see how it performs.
Setup:
600TVL Camera with Hitachi chipset http://www.securitycamera2000.com/products/Hitachi-DSP-Wide-Dynamic-Frame-Integral-Sony-CCD-4mm-Board-Camera.html
IR filter removed on the cameras sensor!
SFH4236 http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=475-2911-1-ND
Ledwarrior01 current source to power the LED @ 1.36V/700mA
Results:
Of course radiation is invisible to human eyes, so one must be very careful while operating the LED!
The above video was taken while operating the plain LED.
Exchanged the white LED on a starboard with the IR LED. The starboard is equiped with a 10° optical lense:
In a previous post I described how to control the internal tuner module of a common 1.2GHz FPV receiver by a PC.
Since this setup was only for general tests I put some more efforts and put an AVR tiny44 in control.
On a 4 channel receiver I removed the original micro-controller and replace it by a AVR tiny44, running on internal 8MHz oscillator.
The tiny44 takes inputs from the 4 DIP switches and controls the tuner by I2C and the LED.
Attached to this post is the source code for the tiny44, written for WinAVR compiler.
With this code you have the following functionality:
| DIP1 | DIP2 | DIP3 | DIP4 | Function |
| ON | OFF | OFF | OFF | Favorite frequency 1, default 1240MHz |
| OFF | ON | OFF | OFF | Favorite frequency 2, default 1280MHz |
| ON | ON | OFF | OFF | Favorite frequency 3, default 1276MHz |
| OFF | OFF | ON short | OFF | Manual tune, 1MHz up |
| OFF | OFF | OFF | ON short | Manual tune, 1MHz down |
| OFF | OFF | ON long | OFF | Auto tune, 1MHz up every 100ms |
| OFF | OFF | OFF | ON long | Auto tune, 1MHz down every 100ms |
For DIP3 and DIP4 a long press will be >1 second.
The frequency set using DIP3 and DIP4 will be stored in EEPROM 5 seconds after last tuning action (DIP switch used).
After power cycle this frequency will be the start for new tuning.
Frequency range for manual/auto tuning is 850MHz to 2200MHz in 1MHz steps.
Wiring is given in the source code, header of main.c.
Recently I got a 0.9GHz 500mW video transmitter for repair. The owner just connected power reverse polarized and the transmitter went up in smoke. 
I took the transmitter apart and after a quick voltage check I found the voltage regulator to be defective.
Just replaced the 78M08 linear voltage regulator on the lower side of the PCB, the part circled in red.
Took also some quick RF measurements to check the transmitter:
| DIP1 | DIP2 | TX Frequency | RF Power |
| 0 | 0 | 1040 MHz | 27,0dBm |
| 0 | 1 | 1010 MHz | 27,2dBm |
| 1 | 0 | 980 MHz | 27,3dBm |
| 1 | 1 | 910 MHz | 27,5dBm |
RF Harmonics for 910MHz, 27.44dBm TX:
1280MHz = -20.6 dBc
2730MHz = -14.8 dBc
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