Midland 13-505 VHF Amateur Band Transceiver

Federal Communications Commission Requirements

Your new Midland 13-505 is a combination receiver-transmitter designed and built for licensed VHF Amateur Band operation, as designated by the Federal Communications Commission. You are required to read and understand Part 97 of the F.C.C. rules and regulations prior to operating this unit.

NOTE: The technical information, diagrams, and charts provided in this manual are supplied for the use of a qualified holder of an Amateur Band license in servicing this transceiver. It is the user's responsibility to ensure that this unit is operating at all times in accordance with the F.C.C. Rules and Regulations.

If you install or service your own transceiver, do not attempt to make any transmitter tuning adjustments. Transmitter adjustments are prohibited by the F.C.C. unless you hold an Amateur Band license or are in the presence of a person holding the license.

Midland Communications Company hereby certifies that this unit has been designed and manufactured in accordance with Part 97 of the current F.C.C. Rules and Regulations as of the date of manufacture.

Owner's Guide

The Midland 13-505 is a versatile, all solid-state, professional quality transceiver providing 12 crystal-controlled transmit and receive channels on the VHF Amateur Band of 144 to 148 MHz. This transceiver is designed for installation aboard cars or pleasure boats and will provide years of reliable service with ordinary care.

The transceiver features include a separate transmit and receive channel control system, a modulation quality monitor system, provision for tone burst signal input, a discrimeter, an S/RF-power/SWR meter, and a high and low transmitting power switching facility.

It also features RF power protection circuitry that protects the expensive RF power transistors from possible damage due to short or open antenna circuit conditions or the use of an improper antenna system that could cause excessive mismatching, making the transceiver very easy to use and reliable.

We strongly suggest reading this Owner's Guide carefully before operation to receive the full benefit from this transceiver.

Operating Controls and Functions

OFF/VOLUME

This control turns the set on or off and adjusts the sound output from the speaker during reception. The VOLUME control does not affect transmitting output.

SQUELCH

Quiets the receiver when no signals are being received, allowing for quiet standby operation. It functions only in the receive mode and does not affect the receiver volume when signals are being received. To adjust: When no signals are present, rotate the squelch control clockwise until the receiver is quieted. Incoming signals will automatically release the squelch. Careful adjustment is necessary, as settings too far to the right may prevent weaker signals from releasing the squelch.

"RX/COM" CHANNEL SELECTOR

This controls both transmitter and receiver frequencies simultaneously if the "COM-SEP" switch is placed in the "COM" position. If the "COM-SEP" switch is in the "SEP" position, it does not control the transmitter frequency, and the channel selector can only control the receive frequency.

"TX" CHANNEL SELECTOR

This selects one of 12 transmit channels, regardless of the "RX/COM" channel selector setting, if the "COM-SEP" switch is placed in the "SEP" position. No receive channel can be controlled with this selector switch.

RF-SWR PUSH SWITCH

With this switch in the out position, the transmitting RF power output can be checked on the power meter scale. To check the SWR of your antenna system, depress the switch, and the SWR will be indicated on the lower SWR meter scale. The recommended SWR value is less than 1.5; a value of 2 or less will provide satisfactory results in practical transceiver operation.

PRIORITY SWITCH

When depressed, this switch selects both transmit and receive frequencies determined by the crystals inserted in the "A" channel sockets, regardless of the channel selector switches. In this model, the transmitter frequency of 146.34 MHz and the receiver frequency of 146.94 MHz will be automatically selected unless the crystals in the "A" channel crystal sockets are changed.

TEST SWITCH

When depressed, this switch cuts off the transmitter's final power stage and operates the receiver circuit, even if the push-to-talk switch is depressed. Therefore, by depressing this switch, you can receive your own transmitter's sending signal with your transceiver, allowing monitoring or checking of transmitting characteristics such as modulation, sound quality, and tone burst-modulated sound (if a tone burst signal is connected to the rear jack).

To perform this:

1. Depress the TEST switch.
2. Place the COM-SEP switch in the SEP position.
3. Set both RX/COM and TX channel selectors to have the same transmitting and receiving frequency. For example: Place the RX/COM channel dial (separate receiver channel dial) in the "A" channel (146.94 MHz) position and the TX channel dial (separate transmitter dial) in the "C" channel (146.94 MHz) position.
4. Press the Push-to-Talk switch and speak into the microphone. The receiver section of the transceiver will receive your transmitter's sending signal (your voice).

HI-LO SWITCH

This switch selects either 30W or 5W transmitting power. With the switch in the released (out) position, the transceiver produces full rated transmit power for longer communication range. The depressed (in) position produces 5W power for local or short-range communications.

TX LIGHT

This light illuminates while the Push-to-Talk switch on the microphone is being depressed.

PRI LIGHT

This light illuminates when the "PRI" switch is depressed.

CHANNEL DIAL LIGHTS

With the COM-SEP switch in the COM position, the RX/COM channel dial light illuminates and indicates the selected channel. If a channel without crystals in its sockets is selected, its dial light will not illuminate.

When the COM-SEP switch is placed in the SEP position, the RX/COM channel dial light illuminates in normal brightness, but the TX channel dial light grows dimly, indicating that the TX channel is ready to be operated. When the Push-to-Talk switch is depressed, the TX channel dial light grows brightly, and the RX/COM channel dial light turns off.

DISCRI-METER

This is a center-of-meter that indicates the receiving condition in terms of frequency shift. A pointer at the center position indicates that your receiver is exactly tuned to the received signal.

This meter can also be used as a simple frequency calibration null indicator. For example, tune the receiver to a known channel center frequency or a reliable station emitting a known frequency and observe the meter pointer. If the pointer shifts from the center position of the meter scale, tune your receiver by adjusting the appropriate local oscillator trimmer so that the meter pointer indicates the exact center on the scale. This allows your receiver to be easily calibrated.

The transmitter frequency of your transceiver can also be calibrated similarly. Follow these steps:

1. First, calibrate the receiver section of the transceiver as described above.
2. Depress the TEST switch and place the COM-SEP switch in the SEP position.
3. Set the TX channel selector to the channel with the same frequency as the receiver channel already calibrated.
4. Press the Push-to-Talk switch and observe the DISCRI-METER pointer.
5. If the pointer is not in the center position, adjust the transmitter oscillator trimmer so that the meter pointer reads the exact center on the meter scale.

S/RF/SWR METER

This meter is used in three ways:

1. Signal Strength Meter: The upper scale (numbered 1, 2, ..., 9, 30) functions as an "S" meter, indicating relative signal strength of received signals.
2. RF Power Meter: The middle scale indicates RF transmitting power. The center of the left separate scale indicates 5W, and the center of the right separate scale indicates 30W.
3. SWR Meter: The lower scale is used for checking the SWR of your antenna system connected to the transceiver. Refer to the description under "RF-SWR SWITCH".

NOTE: The three scales are calibrated to provide correct indications when a 50-ohm resistive antenna is connected to the ANT jack on the rear panel.

MIC JACK

Used for Push-to-Talk microphone connection.

ANT JACK

Used for antenna connection.

EXT. SP JACK

An external speaker (4-8 ohm) or a standard 1/4" two-circuit phone plug can be connected. When the plug is inserted, the built-in speaker is automatically disconnected.

TONE BURST CONNECTOR

This rear panel connector provides for tone burst signal connection. The details of the 4-pin TONE BURST connector are as follows:

• No. 1 PIN: Tone burst signal connection. Your transceiver is designed to produce 10 KHz frequency deviation when a 100 mV, 2 KHz tone burst signal is applied to this PIN.
• No. 2 PIN: Ground lead from a tone burst generator.
• No. 3 PIN: Regulated DC voltage (+10 V, 30 mA capacity) supplied while the Push-to-talk switch is depressed; no voltage is obtained during reception. NOTE: Do not short-circuit this voltage line, as it may seriously damage the transceiver's regulated power circuit.
• No. 4 PIN: NC (Not Connected).

Figure 1. Tone Burst Connector

Antenna Connection

Connect a VHF antenna to the coaxial antenna connector on the rear panel using a 50-ohm coaxial cable with PL-259 male and female coaxial connectors.

A 50-ohm VHF antenna is recommended for maximum efficiency, as this unit is designed to match 50-ohm loads. For more information on antenna systems for your specific needs, consult your dealer. Mount the antenna as high as possible for longer communication range.

IMPORTANT: DO NOT ATTEMPT TO TRANSMIT WITH NO ANTENNA OR AN IMPROPER ANTENNA CONNECTED. SIGNIFICANT ANTENNA REFLECTION LOSSES WILL OCCUR, POTENTIALLY AFFECTING THE RF POWER TRANSISTORS, EVEN THOUGH THEY ARE DESIGNED FOR AUTOMATIC PROTECTION.

Power Connection

The 13-505 is designed for use with a 12-volt DC negative ground system only. If unsure of your system's polarity, consult your dealer or a local service center.

Connect the supplied power cable to the Power Connector on the rear panel. The red wire from the unit is positive and connects to the positive (+) battery terminal, a fuse block, or ignition switch. The black wire is negative (ground) and connects to a metal part of the car frame or body, or the negative (-) battery terminal. For proper operation, ensure the radiotelephone and mounting bracket are securely attached to the boat to obtain a good ground connection.

Addition of New Channels

The crystals for three transmit channels [A-CH: 146.34 MHz, B-CH: 146.16 MHz & C-CH: 146.94 MHz] and two receive channels [A-CH: 146.94 MHz & B-CH: 146.76 MHz] are pre-installed for immediate operation.

Additional channels can be added by installing two crystals for each desired channel. When installing new crystals, the unit must be aligned for the exact reception and transmit channel frequencies. This must be performed by an authorized person, a holder of an Amateur Band license, or equivalent.

Receive and transmit crystal frequencies can be calculated using the following formulas:

• Receive Crystal (MHz) = (Operating Freq. (MHz) - 10.7 MHz) / 9
• Transmit Crystal (MHz) = Operating Freq. (MHz) / 12

NOTE: Use HC-25U type crystals with a load capacity of 30 pF at fundamental frequency.

To install new crystals, remove the sleeve-type cover of the unit by unscrewing the four screws on the rear cabinet. The transmit and receive crystal sockets are located on the front chassis, as shown in Figure 2. Each crystal position is marked relative to the symbols on the channel selector dial [A, B, ... L]. Insert the new crystals into the proper sockets.

Figure 2. Correlation between Crystal Socket Position

Operating Instructions

1. Plug in the Microphone and ensure the antenna and power cables are properly connected.
2. CAUTION: Do not transmit until an antenna or suitable dummy load is connected to the coax antenna jack.
3. Turn the set on and adjust the volume to the desired level.
4. Place the COM-SEP switch to the desired position.
5. Set the channel selector(s) to the desired channel(s).
6. Adjust the squelch control.
7. To transmit, press and hold the push-to-talk switch on the microphone. Hold the microphone 2 to 3 inches from your mouth and speak in a normal tone of voice. To receive, release the push-to-talk switch.

Parts Layout

Diagrams showing the front and back views of the circuit board with component labels are provided.

Warranty Policy

Midland Electronics Company warrants each new Midland product to be free from defects in material and workmanship under normal use and service for a period of 90 days after delivery to the ultimate user. Midland will replace or repair the product at its option, at no charge, if examination reveals it to be defective and under warranty.

This warranty does not apply to products subjected to misuse, neglect, accident, incorrect wiring not performed by Midland, or use in violation of furnished instructions. It also does not extend to units that have been repaired or altered outside of the Midland factory.

The warranty does not cover carrying cases, earphones, batteries, antennas, broken or cracked cabinets, or other accessories used with the product.

This warranty is in lieu of all other warranties, expressed or implied. No representative or person is authorized to assume any other liability in connection with the sale of Midland products.

A sales receipt must accompany the product to validate the date of purchase.

Midland Communications Company
110 W. 12th Avenue
North Kansas City, Missouri 64116

Copyright 1973 Midland Electronics Company
North Kansas City, Missouri 64116 U.S.A.
Made Exclusively for Midland Electronics Co. in Japan

Specifications

Receiver Section

• Frequency Range: 144 - 148 MHz
• Sensitivity: Better than 0.5µV (-20 dB quieting)
• Selectivity: 60 dB at ±25 KHz (EIA SINAD)
• Frequency Stability: Within ±0.001%, from -20°C to +60°C
• Spurious & Image Rejection: More than 70 dB
• Threshold Squelch Sensitivity: Less than 10 dB noise quieting level
• Tight Squelch Sensitivity: Less than 2µV
• IF Frequencies: 1st IF: 10.7 MHz, 2nd IF: 455 KHz
• Channels: 12
• Hum and Noise Level: Better than 50 dB, at 60 dB RF input, Mod. 1000 Hz, 2/3 rated system deviation
• Audio Output: 4 watts into a 4 ohm load, 10% distortion
• Audio Response: 300 Hz to 3000 Hz, referred to +1, -8 dB of 6 dB/octave de-emphasis curve
• Current Drain: About 0.8A at 13.8V, at maximum power output

Transmitter Section

• Frequency Range: 144 - 148 MHz
• Channels: 12
• Modulation: 16F3: ±10 KHz set, ±15 KHz adjustable, for 100% at 1000 Hz
• RF Power Output (Switchable): Hi Power: 30W, Lo Power: 5W
• Frequency Stability: Within ±0.001% from -20°C to +60°C
• Frequency Multiplication: 12 times
• Hum and Noise: Better than -45 dB, 2/3 system deviation at 1000 Hz
• Antenna Impedance: 50 ohms
• Spurious & Harmonic Emission: Spurious emission: more than 80 dB below carrier; Harmonic emission: more than 60 dB below carrier (Per EIA Spec, RS152B, para. 5)
• Microphone: 300 ohm to 2000 ohms
• Audio Frequency Response: 300 to 3000 Hz, referred to +1, -8 dB of 6 dB/octave de-emphasis curve
• Audio Distortion: Less than 7% at 1000 Hz, 2/3 system deviation
• Current Drain: High power: About 6A (13.8V); Low power: About 2A

Schematic Diagram

A schematic diagram of the 13-505 transceiver is included, showing the internal circuitry and component layout.