-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
president grant mb8719 fc-390 hook up points
- Thread starter 689worldwide
- Start date
1. Unpack your frequency counter from it's box and set aside the
"pigtail" supplied to hardwire it to chassies without the plugin in
the back. Set this aside for later.
2. You'll have to make a very simple modification to the frequency
counter as to make it work on your Cobra/Uniden unit. Okay, remove the
four screws on the sides of the unit and open the thing up and open up
the metal box and take the time to read the pc number. It should read
EPT210014C ot EPT210014D. The (C) model has ONE jumper to soldier
together on the top of the PCB, however the newer (D) model had TWO
jumpers to soldier together on the bottem of the circuit board. You'll
have to unsoldier the metal case from the PCB to get to the its bottem.
3. Use a very small wire to bridge the jumpers on both models. NOTE:
on model EPT210014D you'll have to resoldier the metal box to it after
you are done. Re assemble the unit.
4. Wiring the unit to your set: (your radio already has the bottom and
the top off) Drill a 1/4 inch hole in the back of your radio for your
wires.
A. Get your pigtail now and inspect it for a co-ax, that is the VFO
wire. Okay find TP-1 and TP-2 that's your VFO output...find where the
test points are soldiered to the set's pc board. and mark it TP-1 and
TP-2...Get a 68Pf ceramic capacitor to soldier in series to the inner
wire of the VFO coax and TP-1. Now, soldier the shield to where TP-2 is.
B. Now look at your wires again for a BROWN one, that is
ground..soldier it to the ground foil on your pcb.
C. Find your RED wire and soldier it to pin #1 of your MB3756 chip
bolted to the right side of set it is a 8 pin sip chip. Please use a
VOM with the set turned on Pin #1 should read just over 8VDC.
D. (turn your radio on) Now find the ORANGE wire that's the USB B+
wire turn your set's AM USB USB selector switch to USB. There are two
wires coming from the selector switch a yellow one and a green one.
Check which one has voltage (just over 8VDC) and soldier your ORANGE
wire to the pcb where where the wire that showed voltage is connected to.
E. Now you are about done. You should have only a yellow wire left to
go. Switch your set to LSB and find the green or the yellow wire that
has voltage (8.0VDC) and connect your wire on the pcb where it is
soldered to.
in the grant/madison radios, TP1 is the point where L20 meets R106.
this is to the left rear of the PLL section if the radio is facing you component side up.
TP2 is right next to it, and its actually PC board ground.
they may be hard to see, but i think they should be labled on the PC board.
just for the record; i have this mod on file, but have never done it myself.
LC
"pigtail" supplied to hardwire it to chassies without the plugin in
the back. Set this aside for later.
2. You'll have to make a very simple modification to the frequency
counter as to make it work on your Cobra/Uniden unit. Okay, remove the
four screws on the sides of the unit and open the thing up and open up
the metal box and take the time to read the pc number. It should read
EPT210014C ot EPT210014D. The (C) model has ONE jumper to soldier
together on the top of the PCB, however the newer (D) model had TWO
jumpers to soldier together on the bottem of the circuit board. You'll
have to unsoldier the metal case from the PCB to get to the its bottem.
3. Use a very small wire to bridge the jumpers on both models. NOTE:
on model EPT210014D you'll have to resoldier the metal box to it after
you are done. Re assemble the unit.
4. Wiring the unit to your set: (your radio already has the bottom and
the top off) Drill a 1/4 inch hole in the back of your radio for your
wires.
A. Get your pigtail now and inspect it for a co-ax, that is the VFO
wire. Okay find TP-1 and TP-2 that's your VFO output...find where the
test points are soldiered to the set's pc board. and mark it TP-1 and
TP-2...Get a 68Pf ceramic capacitor to soldier in series to the inner
wire of the VFO coax and TP-1. Now, soldier the shield to where TP-2 is.
B. Now look at your wires again for a BROWN one, that is
ground..soldier it to the ground foil on your pcb.
C. Find your RED wire and soldier it to pin #1 of your MB3756 chip
bolted to the right side of set it is a 8 pin sip chip. Please use a
VOM with the set turned on Pin #1 should read just over 8VDC.
D. (turn your radio on) Now find the ORANGE wire that's the USB B+
wire turn your set's AM USB USB selector switch to USB. There are two
wires coming from the selector switch a yellow one and a green one.
Check which one has voltage (just over 8VDC) and soldier your ORANGE
wire to the pcb where where the wire that showed voltage is connected to.
E. Now you are about done. You should have only a yellow wire left to
go. Switch your set to LSB and find the green or the yellow wire that
has voltage (8.0VDC) and connect your wire on the pcb where it is
soldered to.
in the grant/madison radios, TP1 is the point where L20 meets R106.
this is to the left rear of the PLL section if the radio is facing you component side up.
TP2 is right next to it, and its actually PC board ground.
they may be hard to see, but i think they should be labled on the PC board.
just for the record; i have this mod on file, but have never done it myself.
LC