JUMA PA100 F-sense Board Module description,  Last update 2008-11-30 OH7SV

Refer to the
schematics page

F-sense board

F-sense board installation

The F-sense module is used only in digital model PA100-D. The board has three functions.

1. Frequency sensing
The board provides clipped RF signal at suitable level for the digital control module for automatic band detection. The transformer T1 is used to pick up the exciter RF signal. The diodes D1...D4 with the resistors R1 and R2 are keeping the F-sense RF signal at proper level for the digital control board.

2. RS232 connection
The jack type socket J2 provides RS232 connection for JUMA TRX2 or PC connection for firmware programming. There are two jumper blocks which are used to select between straight
and cross connected TXD and RXD wiring. The jumper selection allows to use commercial jack - jack audio cable for TRX2 RS232 connection. This jumper position is marked "NORMAL" on the board. When the RS232 connections is used to update the firmware with a PC, the "PROGRAM" jumper position should be selected. This way the JUMA TRX2 PC cable can be used. See the PC cable wiring.

3. Band DC voltage input
The jack type socket J3 provides Yaesu FT-817 (or similar) type DC band selection input. The DC voltage is connected into the jack tip terminal.

Yaesu FT-817 band data DC voltage levels (nominal values)

1.8 MHz    0.33 V
3.5 MHz    0.67 V
  7 MHz    1.00 V
 10 MHz    1.33 V
 14 MHz    1.67 V
 18 MHz    2.00 V
 21 MHz    2.33 V
 24 MHz    2.67 V
 28 MHz    3.00 V

Voltage tolerance for JUMA PA100 is ± 0.10 V.

Band voltage levels below 0.23 V and over 3.10 V are not valid band data for PA100-D.