The Bitx3b/3c construction manual is being updated and will be available very soon, we are making some corrections to it, also some mods have been done on the exciter and pa for both versions.
The main mod being oscillation in PA caused by feedback. We have used a diode switching arrangement to cut of the RX antenna on Transmit, the mods were required on both exciter and pa board.
The new schematic for bitx3b/3c and pa can be download from this link.
https://drive.google.com/folderview?id=0B6TiQJ3zQGGlNWRIcl80RE9WUVU&usp=sharing
The new kits that will be sold now will have these mods done, how ever these mods can also be taken up in the existing pcb's you may have purchased.
The following files will been found with the download link.
1. Bitx3B Exciter Sch, with mod done to disconnect of Exciter RX Ant on Transmit.
2. Bitx3C Exciter Sch, with mod done to disconnect of Exciter RX Ant on Transmit.
2. New PA Sch with mod done to:
Disconnection of RX Antenna on Transmit at P5.
Selection of 12 or 24 Volts for Final.
0.01 Capacitors across all four IN4007 diodes
IN4007 diodes across both relays.
New Printed Circuit Boards of Bitx3B, Bitx3C Exciter And PA will have these mods done. The earlier Bitx 3B/3C PA boards can be modified as with above details. The earlier boards can also use relay instead of the diode cut off switch for the Rx antenna as per one's wish as both systems work.
The main mod being oscillation in PA caused by feedback. We have used a diode switching arrangement to cut of the RX antenna on Transmit, the mods were required on both exciter and pa board.
The new schematic for bitx3b/3c and pa can be download from this link.
https://drive.google.com/folderview?id=0B6TiQJ3zQGGlNWRIcl80RE9WUVU&usp=sharing
The new kits that will be sold now will have these mods done, how ever these mods can also be taken up in the existing pcb's you may have purchased.
The following files will been found with the download link.
1. Bitx3B Exciter Sch, with mod done to disconnect of Exciter RX Ant on Transmit.
2. Bitx3C Exciter Sch, with mod done to disconnect of Exciter RX Ant on Transmit.
2. New PA Sch with mod done to:
Disconnection of RX Antenna on Transmit at P5.
Selection of 12 or 24 Volts for Final.
0.01 Capacitors across all four IN4007 diodes
IN4007 diodes across both relays.
New Printed Circuit Boards of Bitx3B, Bitx3C Exciter And PA will have these mods done. The earlier Bitx 3B/3C PA boards can be modified as with above details. The earlier boards can also use relay instead of the diode cut off switch for the Rx antenna as per one's wish as both systems work.
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