Revisions/Errata for Ensemble RXTX Project

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2/3/2015 Local Oscillator

Updated to specify that C55 should NOT be installed.

ATTENTION:An SMT capacitor on pin 1 of the Si570 needs to be removed to comply with the NO CONNECT for this pin for the Si570 supplied with the various kits. Having this capacitor mounted on the circuit board degrades the performance of the RXTX transceiver, especially the higher frequency builds of this kit.

6/23/2014 TX Mixer (QSE)

Extensive rewrite of the Theory section for the TX Mix stage, based upon input from Milt, W8NUE.

This should resolve the confusion alluded to in this topic on the reflector.

1/31/2013 Bill of Materials

Caveat on user-furnished 100k resistor (Rtest)

Added caveat on Project BOM listing concerning the 100k resistor that is NOT included in the kit but must be provided by the user if they are to perform the (optional) Functional test of the TX Opamps.

1/22/2013 Local Oscillator
RF I/O and Switching
TX Opamps
External Connections

Expanded Inductor Winding Instructions


I have modified the build instructions such that, in each step calling for the installation of an inductor, I print out a winding instruction.  For example, in the step calling for the installation of the T5 transformer in the RXTX Ensemble, the instruction is:
XFRMR: 0.6uH: 14T/2x7T bifilar #30 on T25-6 (yellow) 8"
Primary: Using approximately 9 inches of #30 wire, wind 14 turns on a T25-6 (yellow) ferrite.
Secondary: Using a total of 9 inches of #30 wire, wind 7 turns , bifilar, on the ferrite in the same direction as the primary winding. Inductance of the single winding (usually the primary) is 0.60 uH."
1/13/2013 Power Supply
USB Power Supply
Local Oscillator
RF I/O and Switching
RX Mixer (QSD)
RX Opamps and Output
TX Opamps
TX Mixer (QSE)

Added section between Completed Board photos and the testing section to provide a link to a view of the entire schematic, with the completed stages tinted yellow-ish and the stages left to be done tinted blue-ish and the current stage untinted.

This was per a suggestion from Alan, G4ZFQ, that we provide a "birds-eye, contextual" view of where we are in the build at any stage.

1/3/2013 Driver/PA

Component values for the 40/30/20m RXTX have changed after considerable discussion in this thread.

The new values have been updated to the documentation.  Here is a summary of the changes:

  • C24 and C26 each become 180pF
  • C25 becomes 390pF
  • L2 and L3 each become 0.6uH, 14 turns of #26 wire on T37-6 cores.
7/12/2012 RF I/O and Switching

Modified instructions for installation of T6 (Antenna Isolation Xfrmr).

For details refer to the excellent paper by Alan G4zfQ.