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Dec 22, 2012, 02:01 AM
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Pre-amp rework

Another day of soldering & the preamp once again emerged undefeated. This was the 1st rework since the M.M. era. It was an attempt to reduce noise by running it on 5V from a linear regulator. The regulator should smooth out low frequency noise, but this idea failed. It still needs a separate battery. The next idea still remanes an isolation transformer.

Now the diagram of how to convert the preamp to different voltages.

The preamp finally got a 2nd channel installed, for whenever a 2nd microphone arrives. The price of the CAD GLX-2400 increased $10 since last year, typical for fiat money.

The 2nd microphone was supposed to arrive whenever the final Delta IV heavy launched from Vandenburger. That was supposed to happen by now but never did.

Once again, a small encloser makes life unnecessarily hard. Having everything on a single board, in a rack enclosure would be a lot easier. The key components are the 5V regulator for the preamps, the 48V phantom power regulator, & the preamps.

In other news, it occurred to me that hardly any RC pilots using 1W video transmitters actually have the required license. They've gotten so ubiquitous & the unlicensed power level has been increased over the years so no-one cares about a license anymore. Anything under 1W seems to be unlicensed, nowadays. Rangevideo no longer offers a 1W 900Mhz transmitter.

The best of the best Spektrum radios still dick around in the 100mW power level of 2007. There are no consumer video transmitters licensed or unlicensed above 1W.

Any UAV work at 100mW is just playing. It can't go very far or transmit a useful amount of data without falling over. It's especially painful for a fixed wing, which can just do circuits in a field.

The great task for outdoor flight has always been developing a bulletproof connection capable of going beyond line of sight, carrying video & data over 1Mbit, so a fixed wing can actually do straight line flying. Ideas from optical communication to repeaters to highly directional antennas have come to mind, using the standard sub 1W radios.

The rules are convoluted, but it seems a technician class license gets you 200W in the 900Mhz & 2.4Ghz bands for transmitting data & the bandwidth might be a lot higher than the unlicensed usage, quite an improvement over the standard RC experience.
Last edited by Jack Crossfire; Dec 22, 2012 at 02:37 AM.
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