Monday, March 10, 2014

Minima Bidirectional IF Amplifier

I had some time today to work on my Farhan's Minima Transceiver Bidirectional IF Amplifier Module as previously posted for the layout and design.

Because of the density and the desire to put as much ground plane on both sides of the PCB, I decided to layout the Input, Output and Power traces on the back side, which meant that via's would be necessary. Normally I avoid double sided Homebrew PCB, but sometimes they are necessary. The via's are 40 mil pads with 12 mil holes.

Homebrew PCB via's are not fun to drill or install at this scale, there are ten via's which were the last thing that I installed.

As with all of my Experimental Minima Modules, this module was created with the Homebrew PCB Toner Transfer Method on .032 board material with 1/2 oz copper clad.

Minima's Bidirectional IF Amplifier
0.8 x 1.4 Inche PCB
The upper string of components are used for Transmit (signal flow is left to right), and the lower components are for Receive (signal flow is right to left), which for simplicity sake, is the same orientation as the schematic.

The Backside
The Backside clearly shows the 10 vias that were necessary for the circuit layout. Maybe it could have been a single sided board, but the front side copper pour (ground plane) would have been broken into islands with poor conductivity between major sections and the SMA connectors. The vias are 40 mil pads with 15 mil holes. Small wire-wrap wire was used to make the via connections.

The circuit powers up, and amplifies a 20MHz low level signal in both direction depending on the power connection. Actual performance numbers will be measured later in conjunction with the rest of my Minima Test Modules. According to chatter on the Minima Reflector, the gain of this stage is not anything great, but I do not remember it's expected gain.

The power connector center pin is ground, therefore moving a two pin power connector is all that is necessary to change direction for testing

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