Subject: TS-790A X-Band Repeat Mod
CROSS BAND REPEATER MOD
To operate the TS790A in the repeater cross band mode,diode D32 on the
control board must be opened.In addition,two resistors must be soldered
to a 13 pin din plug which will be connected to the ACC. 2 jack on the
back panel of the transceiver.
TO LOCATE AND OPEN D32
1 Disconnect the power supply and antenna from the radio.
2 Remove the 14 screws that secure the top and bottom covers.
3 Carefully remove the top and bottom covers.
4 Locate the control board. this is a vertically mounted board that is
positioned approximately 1 inch behind the front panel.
5 Locate diode d32 towards the top right side of the board.
6 Using a small pair of wire cutters,cut the lead of the diode. do not
pull on the lead or the diode as this may tear the foil on the other
side of the board.
7 assemble the radio by reversing steps 1-3.
13 PIN DIN PLUG CONFIGURATION.
1 Using a small flat blade screwdriver,lift up on the tab of the nylon
cover.
2 Once the tab clears the slot of the metal holder,pull the cover
off the plug.
3 Carefully separate the two metal holders and remove the pin assembly.
4 First tin pins 1,8 and 11 of the assembly so the resistors can easily
be soldered in place.
5 SOLDER A 100K ohm,1/4 watt resistor between pins 1 and 11 of the
assembly (the resistor leads should be cut and shaped before soldering).
6 Solder a 1.5K ohm,1/4 watt resistor between pin 8 and the lead of the
100K ohm resistor that is attached to pin 11.(the resistor leads
should be cut and shaped before soldering)
7 Wrap a small piece of electrical tape around the resistors.This will
insulate them from the metal holder after the plug is assembled.
8 Mount the pin assembly in the two metal holders.
9 Slide the cover over the plug until the tab engages in the slot.
The "U" shaped strain relief will not be used.
10 Plug the 13 pin din plug in the ACC2 jack on the back panel of the
radio.
OPERATING PROCEDURES
The repeater cross band operation allows the TS790A to receive on one
band and re-transmit the signal on the other band. Incoming signals
will automatically be switched to the sub band.The TS790A will then
re-transmit the signals from the main band. Each band may contain
offset and sub-audible tone information (an optional TSU-5 must be
installed in EACH BAND for decode).
1 Press the MAIN function swich to select the MAIN band.
2 Select the first operating frequency and mode (fm only).Select the
offset as required.
3 If the CH.Q is on,press the CH.Q switch to turn the function off.
4 Select the sub-audible tone as required .
5 Transfer the contents of the MAIN band to the SUB band.
6 Select the second operating frequency anf mode (FM ONLY) and turn
the CH.Q off.
7 Select the offset and sub-audible tone as required.
8 Adjust the MAIN and SUB band squelch controls to the threshold
point.The TS790A will transmit in the repeater crossband mode if
the squelch controls are set too low or a signal is received.
9 Adjust the power control to allow normal output power from the MAIN
band.
10 Adjust the sub band volume control to a normal listening level to
monitor incoming signals.
11 To place the radio in the repeater cross-band mode,press the F.
switch and then press the M.IN switch. An asterisk will light in the
MAIN band display for confirmation.
12 To cancel the operation,repeat step 11 and disconnect the DIN plug.
13. If the DIN plug is left in place after use,bleedover from the SUB
band audio if present will be mixed with any transmitted audio.
This will make your audio during a conversation hard to understand.
TSU-5 TONE UNIT
When the TSU-5 tone units are not installed,only the tone (encode)
function can be used.
If CTCSS is to be used it must be installed in both bands to function
with the cross-band repeater mode.
TX AUDIO ADJUSTMENT
The audio gain can be adjusted by variable resistor VR36 on the IF unit.
If the range of VR36 does not suffice for normal transmit audio,the
values of the resistors on the 13 pin din plug can be changed.
as an example,if the audio is too low,reduce the value of the 100K ohm
resistor and increase the value of the 1.5K ohm resistor.
TO ACCESS VR36
1 Remove the bottom cover of the radio to expose the IF unit.
2 locate VR36
3 Use a plastic alignment tool to adjust VR36 for normal TX audio.
4 After the audio is adjusted,install the bottom cover.
73 AND HAPPY MODING
CARL
packet:VE3ZCO
Internet:VE3ZCO
SOURCE: The QRZ Windows Ham Radio CDROM |
