Ramsey Electronics FZ-146 Specifications download pdf (Page 71)

FX-146 • 71

STAGE A: DC POWER INPUT REGULATION & DISTRIBUTION and

PACKET RADIO I/O CONNECTOR (J1)

The "power supply" for your FX- transceiver is, basically, any "12-volt"

battery or well designed power supply operating from 120VAC or other

source. In theory, all "12V" sources should provide pure DC voltage to your

FX- transceiver DC input. In fact, there are many variations and

imperfections in common "12VDC" sources, ranging from weak batteries,

poorly filtered AC powered supplies, vehicle ignition noise, or just badly

made power supplies.

Stage "A" of your FX- Transceiver is designed to help your radio survive

quite a wide variety of imperfections. It's not a "power supply" in itself, but it

comes close, because it performs all the essential functions expected from a

good solid-state DC source. Just add 12-15VDC from a battery, vehicle or

bench supply.

Much of the circuitry operates on the regulated 8 volts supplied by voltage

regulator VR1. If you have already looked around the schematic diagram

and also seen "+8R" or "+8T", these are points where the regulated 8V

output is switched for Receive or Transmit by the PTT (push to talk) circuitry

(Q12, U4c, U4d, Q13, Q14) which we'll discuss in more detail when it's time

to build it in Stage M.

The Receiver IC (U1) and the digital frequency synthesis circuit is powered

by +5 volts regulated by VR2. The op amps used in the circuit (U4 and U5)

operate from this single supply through the use of voltage divider networks

at the respective IC's. The full 12-15 volt input is supplied to the transmitter

RF output section and to the receiver audio amplifier (U2).

The large 1500 uf capacitor (C42) and inductor L20 are installed at the DC

input to filter out ignition noise, etc. Fuse F1 is contained in the power cord

and the DC power switch is integral to the volume control. The DC negative

(black) wire is soldered directly to the PC board ground plane.

The Packet Connector

The Packet I/O Jack (J1) is not a "stage" or section of your transceiver in

itself. It is simply a convenient "port," to use computer terminology, which

gives a packet TNC (terminal node controller) convenient access to the

microphone and receiver audio circuits. We'll install J1 and its associated

bypass capacitors at the beginning -- because now is as good a time as any,

and it gets some parts on your PC board quickly and easily! Also, having J1

in place will give a little extra protection to other parts when you are working

on the solder-side of the board.

1 2 ... 66 67 68 69 70 71 72 73 74 75 76 ... 144 145

No comments

Ramsey Electronics FZ-146 Specifications Page 71