Time to translate. Your sat box has an RGBHV output. It uses 10 of the 15 pins on the chassis mounted RGB connector. Your projector accepts RGBHV. It accepts via 5 BNC females chassis mounted on the projector. Pro type gear uses BNC connectors rather than VGA and RCA connectors because video cables are 75 ohm AC impedance and BNC connectors are 75 ohm. Since your source device outputs RGBHV and your display device inputs RGBHV no transcoder is necessary. You just have to use the right connectors at each end. Male BNCs at the projector end and a VGA at the set top box end. IF you have your existing RGBHV cable with males BNCs at both ends, use a breakout cable with 5 females BNCs at one end and a VGA connector at the other. Breakout cables are used to change the type of connector not the format of the transmissions.
Transcoders change RGBHV, RGBH/V, and RGB sync on green to component or component to RGBHV, RGBH/V, or RGB sync on green.
Without getting too carried away, both component and RGBHV may be available outs on your box. The native or best out on your box will be the component out because the box has a cheap and relatively poor quality transcoder built into it which transcodes the superior component signal from your box into an RGBHV signal. For the best possible RGBHV signal out of your box, you could add a high quality component to RGBHV transcoder to transcode the boxes already good component signal to the RGBHV signal you need for your projector. By in essence replacing the poor built in transcoder with an expensive but superior external converter (the MP is the only one I would use) you will have a superior RGBHV signal as well.