RAT5 Manual version 1.2.0
RAT5 Information Manual version 1.2.0 © GW4GTE 2010
Page 5 of 29
1.1 Modification Record
Changes to the information manual
This manual is Version 1.2.0. The previous manual was version 1.1.4
•
A drawing error was reported in the previous circuit diagrams figure 2.1 and
Appendix 2 : VR1 was drawn as fed from the C13 side of R2. It should be
connected to the C28 side. This is now corrected.
•
FL1 in the circuit diagrams of figure 2.1 and appendix 2 is now annotated as
ALFY455GT to reflect the part change (see below)
•
Appendix 3 (PCB layout) incorporates the track changes detailed below.
Changes to the PCB
The PCB to which this manual refers is version 1.2. The previous PCB was version 1.1.
New IF filter
PCB Version 1.2 incorporates a different 455kHz filter. We have now managed to
source a slightly narrower filter while keeping the kit price the same. The new filter is
+/- 4.5 Khz wide at -6dB, previously it was +/- 6kHz wide at -6dB. The filter pinout is
slightly different, requiring a modification to the PCB layout. If existing kit owners wish
to try the new filter and are happy to adapt the previous PCB the new filter can be
supplied as an upgrade. No other circuit changes are required.
Track modification
The PCB track around the pins of RV1, RV2 and RV3 have been thickened to provide
more strength when using the potentiometer fixing threads to support the PCB.
