Hi Jim, most of that seem sto make sense, I will be back on them next Tuesday, as that will be my first available day back at the bench. I will see how it all goes and let you know if I run into trouble. I did get them switched, and powered it up, receiver works just fine, I have not goe to the transmitter section as of yet.
There is a 3 pin cord on the PA on the back of the radio, do you know what this was for? And does it need to be reconnected. Thanks.
Mathew
Jim Brown <[EMAIL PROTECTED]> wrote:
>
>
>Now here is
>> where I got lost, how do I tie them so that when a signal is heard on
>> two meters, it keys the 440 transmitter and sends the audio out to the
>> transmitter. You mention that I need to take a voltage to the to the
>> receiver oscillator, can you point me in the right direction, from
>> where should I take the voltage, and where should it goto on the
>> receiver board.
>>
>> Then what should I do with the mic audio to get it to the receiver?
>
1. Remove the multifreq board if it is present. It would be between the
transmitter exciter and the receiver on top of the chassis.
2. Jumper pins 4 and 10 on the exposed connector (where the multifreq
board plugged in) extending up from the board on the bottom of the
chassis. This puts regulated +10 VDC to the receive oscillator to keep
the receiver alive when the transmitter is key down. Looking at the
front of the unit this would be the first and seventh pins from left to
right.
3. Remove the large connector on the front of the radio that connects to
the control head. Unplug the connector to the board underneath the
chassis that is connected to the front panel connector. This assembly
comes out as a module leaving the exposed pins from the board under the
chassis that went to the front panel connector.
4. You should see the pin functions printed on the chassis beside each
pin now exposed.
5. Ground the F1 pin.
6. Put +12 VDC to the pins marked A+ and Tx Enable A+. Put +12 VDC on
the wires leading to the amplifier through a connector. I removed the
two wires from the front panel connector assembly and used them with the
amplifier connector already installed.
7. Connect a volume control pot (10K will work) between the three pins
on the connector marked Volume HI, Volume Arm, and Volume Low.
8. Jumper terminal labeled Volume HI to Sq Monitor terminal.
9. Connect a 15K resistor from Volume HI to a .22 capacitor. Connect
the other end of the capacitor to ground. Connect a 1 mFd cap between
the junction of the 15K resistor and the capacitor and the pin labeled
Mic HI (plus side to the Mic HI pin). The deviation will be adjusted
with the only pot on the transmitter exciter board. The capacitor and
resistor serve to de-emphasize the receiver audio. If the Mic input
loads this circuit too heavily, an emitter follower transistor can be
inserted between the cap/resistor junction and the Mic input 1 mFd cap.
Use a 1K emitter resistor if this is necessary.
10. Connect a 15K resistor from the terminal marked CAS to the base of a
low power NPN switching transistor. Connect the collector of this
transistor to +12 VDC. Connect the emitter of this transistor to the
base of a higher power NPN transistor (TO-220 size). Connect the
emitter of the TO-220 transistor to ground. Connect the collector of
the TO-220 transistor to the pin marked Push To Talk. A Darlington
transistor could be substituted for the transistor pair if it is
available. Do not lower the series resistor from CAS below 15K.
11. A monitor speaker can be connected to the Speaker HI and Speaker Low
pins. Adjusting the volume control will not change the audio level
going to the transmitter exciter.
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