TRX2A DDS Board Build

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TRX2A DDS Board Build

Postby KD1NA » 04 Jan 2013 02:05

In building the Juma TRX2A radio I decided to build the all band RF board first, Then the poly phase boards. Then I attacked the DDS board. I had already built the PA100-D earlier and found the DDS board on the linear and the TRX2A are similer and I had some problems with the PA100-D DDS board damaging one resistor and capacitor due to my poor handeling of the parts. When building the DDS board for the TRX2A I used solder paste and a small heat gun. I had much better luck with the solder paste and no component damage resulted. On the TRX2A I found a resistor (R25) that was 0 ohms and not listed in the main parts list. Later I discovered that when using the 30 MHZ chip IC12 You needed to install R25 over where IC6 would have been installed. This information is listed in the schematic of the DS PSU section of the schematic. When testing the DDS board I found the data displayed on the LCD display was garbled. In using a meter to check the circuit I discovered that the connection for signal DB1 between the CPU (Pin 55) and the LCD display (Pin 8) was open. The solder connections for the CPU and LCD display were good but the printed circuit board connection of this signal was open at a passthru connection on the board. I fixed the problem by running a 30 gauge insulated wire along the board bypassing the open connection. Now the data on the LCD is clear and all the buttions seem to work fine.

I am supplying this information to help anyone building the TRX2A. Even though you may be very careful in building the DDS board trouble may present itself by an open printed circuit board connection.

73
Dave KD1NA
KD1NA
 
Posts: 13
Joined: 25 Jul 2012 21:03
Location: USA

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