Hi, welcome to a new voltlog, today we’re going to teardown something interesting. As you can see on my left I have this huge antenna / radio assembly which btw weighs approximately 25 Kg so it’s not easy to handle in my small lab, in fact it takes up most of my bench so I will probably do the teardown on the floor.
This antenna is called Gigabeam Wifiber and it’s manufactured by a company called Gigabeam Corporation that went bankrupt in 2010. The system is supposed to act like a transparent access point offering gigabit links over radio where fiber infrastructure is difficult to implement.
The radios operate in the 71-76 and 81-86 GHz radio spectrum bands and the modulation format is BiPhase Shift Key (BPSK). They have a transmit power of 20 dBm which translates to 100mW and that is not really a great deal of power but the antenna has a large gain of 50dB. The system takes a gigabit fiber input and on the other side from the receiving antenna you get a gigabit fiber output.
I have a pair of these, one of them is broken and I’m going to attempt to find the fault and maybe fix it. I’m hoping the problem is somewhere in the power section because that will be an easy fix because otherwise I don’t have a spectrum analyzer to take a look at the different RF stages.
Anyway In this video you are only going to see the teardown but that should interesting on its own because I expect to see lots of RF magic inside and interesting system design.
Also checkout the high res photos below:
Here is a list of the components I managed to identify inside the unit:
- SMT4004: integrated programmable voltage manager IC which can monitor and control up to 4 independent supplies.
- Texas Instruments OPA725: low noise, high speed, rail-to-rail op-amp.
- Analog Devices AD8604: quad rail-to-rail, input and output, single-supply amplifier.
- Maxim MAX4663: quad, SPST, CMOS analog switch.
- IDT ICS601: Low phase noise 1 to 5 clock multiplier.
- XCF04: Xilinx In-System Programmable 4 Mbit ROMs for Configuration of FPGAs.
- Sipex 3232 RS232 transceiver.
- Semtech LC03-3.3: transient voltage suppressor.
- Intel XT971ALE: Single-Chip 10/100Mbps Ethernet PHY Transceiver.
- Pericom PI49FCT3803: 1 to 7 clock buffer targeted at networking applications.
- Maxim DS1339C: Real Time Clock.
- TLK1201: gigabit ethernet transceivers.
- Xilinx XC3S1500: Spartan 3 FPGA with aproximately 30K logic cells inside.
- MPC8270: PowerQUICC II Processor with embedded communications processor module targeted for telecom applications.
- Analog Devices ADF4154: frequency synthesizer.
- Hittite HMC368LP4: frequency doubler with both an input and output amplifier.
- Hittite HMC441: GaAs PHEMT MMIC medium power amplifier.
Although the operating temperature of this LED might be up to 85 deg C, while looking through various datasheets, I couldn’t find a graph showing a plot of the expected life in hours vs temperature. If I were to guess I would say you need to run these at less than 50 degrees C to get some decent life out of them. There was a mention of a stress test in a datasheet and that meant for that particular led manufacturer running it at 60 degrees C full rated current for 1000 hours with no resulting damage.
If you have any info on these LED’s and what temperature they should be running at to get some decent life out of them, please leave a comment below.
So to finish up on this story I have to say that I learned some things about these LED strips. If I were to design something from scratch I would run some basic thermal calculations based on the figures from datasheets but in this case, with these chinese led strips, there is no datasheet, I can’t even easily compare to existing datasheet because these can’t be compared: the driving current is different, the LED only has one die in my case and so on.
The next thing I will try is to double my L shaped heatsink with another piece the same model and size this way I will be increasing my heatsink surface and hopefully cool the LED’s better, maybe shave another 5 degrees.
I will be posting an update with some measurements for comparison once I get the upgrade done. Links for the power supply, led dimmers as well as the light meter used in this video will be in the description of the video so do check them out.