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9cm Transverter

Shown here to the right of the 1296 and 2304 gear is a 50-watt transverter I cobbled together for 3456 MHz.

Designed for portable operation, it runs on 12v, and has an OCXO-based local oscillator.

For the innards, I used a Down East Microwave low-power transverter kit, which I modified to mate up with a 50w Toshiba amplifier module and my own t/r control board, L.O. and I.F. interface.

The transverter can be driven with as little as 10 mw, but it does provide ALC feedback to the driving radio, and has a 14db input attenuator so that it can be used with just about any transceiver.

The ALC is used as a safety measure to prevent overdriving and damage to the interface.
The rear panel has the usual connections, plus a few extras I found useful, such as an L.O. sampling port, an "L.O. only" power connection, and a crystal oven temperature trimmer (useful for discovering the most stable crystal temperature).
On the inside, I tried to remember everything I should have done when building other things; so what I did was modularize with connectors on the major assemblies like the power amp, transverter board, local oscillator, t/r relay, etc.

The LO compartment is at the lower right. It's contained in the mini-box shown, wrapped with insulation on the inside. Within that insulation is the oven controller, L.O. and band-pass filter assemblies.

The three boards mounted above the L.O. are the t/r interface, sequencer and 28v boost converter (for the 28v antenna relay).

The 50w amp is located on the other side of the center separator wall, in it's own airtight compartment.

Worthy of mentioning is the accessibility of the adjustment trimmers. All of them can be adjusted by simply removing the top cover of the transverter, including the L.O. frequency netting trimmer visible in the previous photo.
 

Here's a peek inside the transverter module, showing the basic transverter board and it's connections.

When I assembled this, I used different values for the MMIC bias resistors to match up with my control board (8v for the L.O. and 12.5v for the others). I also did not install the last MMIC in the transmit chain; it was not necessary, as the Toshiba PA only needed 1mw drive for full output.
 

Inside the amplifier compartment, the 50w Toshiba amp mounts to a beefy heat sink, and is secured to the chassis with the brackets shown. This is a class A amplifier, drawing 20A continuous during xmit, and must be able to dissipate up to 270w.

The fan is mounted so that it draws air from the outside and forces it forward through the heat sink to the front panel, where it then flows up, back and out through the top vent holes in the rear panel.

This fan comes on during transmit, but will also run if the heat sink warms above 35C. There is a thermistor connected to that blue wire at the top right, providing feedback to the fan controller, which is located on the t/r control board in the other compartment.

Block diagrams and other schematics follow below.

Next, the TCLO:

This last drawing is the t/r control board: