Lafayette Model HA-460 6-Meter Amateur Transceiver

SPECIFICATIONS

RECEIVER

• SENSITIVITY: Less than 1 μV for 10 dB s/n
• SELECTIVITY: ±3 Kc at 6 dB down, less than ±12 Kc at 50 dB down
• INPUT IMPEDANCE: 50 ohms (unbalanced)
• OUTPUT IMPEDANCE: 6 ohms
• TUNING RANGE: 50.0 Mc to 52.0 Mc
• IF FREQUENCIES: 1st: 5745 Kc; 2nd: 455 Kc
• AUDIO OUTPUT: 4 watts

TRANSMITTER

• POWER INPUT: 20 watts
• TUNING RANGE: 50.0 Mc to 52.0 Mc
• CRYSTAL FREQUENCIES: 8.334 Mc to 8.666 Mc
• MICROPHONE: High impedance ceramic with push-to-talk switch
• OUTPUT IMPEDANCE: 50 ohms (unbalanced)
• TRANSMISSION MODE: Type A3 emission (AM)

GENERAL

• AC POWER REQUIREMENTS: 117 volts, 60 cps, 160 watts (maximum)
• DC POWER REQUIREMENTS: 12 volts DC at 14 amperes (maximum)
• DIMENSIONS: 12-1/8" W x 5-1/8" H x 9-1/4" D
• WEIGHT: 19 lbs

GENERAL DESCRIPTION

INTRODUCTION

The Lafayette Model HA-460 is a compact, self-contained 6-meter radio station. Its compact size, ease of mounting, and universal power supply make this unit ideally suitable for operation as a 12 volt DC mobile unit or fixed station operation from a 117 volt, 60 cycle AC power source. The HA-460 covers the most popular lower portion of the 6 meter band (50-52 Mc). It is supplied complete with a push-to-talk microphone, power cables for AC and DC operation, and a mobile mounting bracket.

NOTE

An FCC amateur license is required by anyone operating this equipment.

FEATURES

Built-in solid-state universal power supply. Operates from 117 volts AC or 12 volts DC. Crystal-controlled or VFO transmitter operation. Built-in TVI filter. Spot switch. 5-meter/Relative power indicator. 6CW4 Low-Noise RF amplifier; Crystal-controlled dual conversion IF system. Built-in speaker.

TUBE AND TRANSISTOR COMPLEMENT

DIODE COMPLEMENT

INSTALLATION

LOCATION

The HA-460 may be placed in any location that will permit free air circulation through the ventilation holes and openings in the cabinet. In fixed-station use, avoid excessively warm locations such as those near radiators and heating vents. Also, avoid direct blasts of air from circulating fans, etc. Do not place any object on the cabinet cover that will impair natural ventilation. In mobile installations, avoid direct air blasts from heaters or air conditioning units. See Figure 1 for mounting procedure.

CONNECTION TO POWER SOURCE

The HA-460 may be used for 117 volt, 60 cycle AC operation or 12 volt DC operation by selecting the correct power cord and plug assembly. In fixed installations where a 117 volt AC source will be used, the power cord with the standard two-contact plug on one end is used. In mobile installations the power lead with the in-line fuseholder is used. It is recommended that the bare end of this wire be connected directly to the battery terminal. Connection of this lead to other points may cause reduced voltage, increased ignition interference, etc. If additional length is required, wire no smaller than No. 14 AWG should be used.

The DC power cable must be connected in the following manner. The red (fused) lead should always be connected to the battery terminal which serves as the "hot" side of the system. This means that in a negative ground vehicle, the red fused lead must be connected to the positive battery terminal. In a positive ground vehicle, the red fused lead must be connected to the negative battery terminal. In each case the battery ground switch on the transceiver must be set for the type of ground employed in the vehicle.

NOTE: Make sure the BATTERY GROUND switch is set for the ground polarity of the vehicle in which the HA-460 is to be installed. The HA-460 will not operate unless this switch is in the proper position.

ANTENNAS

The HA-460 is designed for 50-ohm termination; therefore, any 4-meter antenna providing 50-ohm termination may be used. Antenna polarization is very important at these frequencies and should be considered when choosing an antenna. Generally speaking, the antenna polarization should be compatible with that of the stations you will normally be in contact with. The antenna should be connected to the antenna receptacle on the back of the unit using 1/4" (RG-8/U is recommended for lengths in excess of 100 feet). It is important that the antenna be adjusted for the lowest possible VSWR at your normal operating frequency. Additional information on antennas may be found in the ARRL Handbook or in the ARRL Antenna Manual.

HEADPHONES

The headphone jack, located in the lower right corner, is wired so that the internal speaker is automatically disabled when the headphone plug is inserted.

OPERATION

CONTROLS, INDICATORS AND CONNECTORS

The controls, indicators and connectors necessary for the operation of the HA-460 are listed in Table 1.

RECEIVER OPERATION

To operate the receiver portion of the HA-460 Transceiver, proceed as follows:

1. Connect a 6-meter 50-ohm antenna to the ANT receptacle located on the rear of the chassis.
2. Connect either the AC or DC power cord supplied with the unit to the eleven pin POWER connector located on the rear of the chassis, and an appropriate power source.
3. Set the POWER switch to ON. The dial window should become illuminated indicating power is applied to the transceiver.
4. Adjust the VOL control for the desired audio level.
5. Rotate the RCVR tuning control to the desired frequency.

NOTE: If desired, headphones may be used in place of the internal speaker. To use headphones, simply plug them into the PHONES jack on the front panel. This will automatically silence the internal speaker.

TRANSMITTER OPERATION

To operate the transmitter portion of the HA-460 Transceiver, proceed as follows:

1. Connect antenna and power source.
2. Connect microphone to MIC receptacle on front panel.
3. Set XTAL-VFO switch to the desired mode of operation. For crystal mode of operation, insert crystal in front panel XTAL socket. The frequency of transmission is six times the crystal frequency. Since the driver stage and VFO tuning condensers are ganged, tune VFO to the approximate frequency of operation to obtain maximum excitation to the final RF amplifier.
4. If the VFO mode of operation is chosen, tune the VFO tuning control to the desired frequency.
5. Pre-set the PLATE TUNE and ANT LOAD controls to mid rotation (black line up).
6. Set POWER switch to ON. The dial window should become illuminated indicating power is applied to the transceiver.
7. With microphone push-to-talk button depressed adjust PLATE TUNING and ANT. LOAD controls for maximum meter indication. Repeat adjustments until no further increase in meter reading is obtainable.

NOTE: Any time the operating frequency is changed, the PLATE TUNE and ANT. LOAD controls must be readjusted for maximum output.

8. The transmitter is now ready for transmission. To transmit press the push-to-talk switch on the microphone and talk into the microphone.
9. To locate the frequency of transmission on the receiver dial, set the SPOT switch to ON and tune the receiver until a strong unmodulated signal is heard. Then, return the SPOT switch to OFF and proceed with operation of transceiver.

NOTE: Transmitter will not operate with the spot switch in the ON position.

TRANSMITTER CRYSTALS

Crystals are available from Lafayette Radio, or any of the well-known crystal manufacturers. To order crystals proceed as follows:

1. Divide the desired operating frequency by 6 to determine the crystal frequency. Example: The desired operating frequency is 50.0 Mc
   $$ \frac{50.0}{6} = 8.333 \, \text{Mc (crystal frequency)} $$
2. The crystal order to the manufacturer should contain the following information:
   
   • Crystal Type ............ FT 243
   • Crystal Frequency ...... Determined by formula in step 1.

THEORY OF OPERATION

INTRODUCTION

The following discussion of the theory of operation for the HA-460 Transceiver is divided into four parts. The first part discusses the theory of operation for the receiver portion of the transceiver. The second part discusses the theory of operation for the transmitter portion of the transceiver. The third part discusses the power supply. The fourth part discusses the S-Meter/Relative power indicator.

RECEIVER

Refer to the receiver block diagram, Figure 4, while reading the following discussion. If greater detail is desired at any point, refer to the schematic diagram.

When an RF signal is applied to the antenna of the transceiver, it is fed through the harmonics filter and the change over relay K1 to the input of the 6CW4 RF amplifier. The 6CW4 RF amplifier is a low-noise Nuviator stage. After amplification by the 6CW4 RF amplifier stage the RF Signal is fed to the grid of the 6GHB 1st Mixer stage. The 6GHB 1st Mixer stage is the pentode portion of the 6GHB tube. The triode section of this tube is variable local oscillator 1. The frequency of the local oscillator is determined by the setting of the TUNING control and it can be varied from 44.255 to 46.255 Mc. The output of local oscillator 1 is fed to the grid of the pentode portion of the 6GHB tube where it mixes with the incoming RF Signal. The output of the 1st mixer stage is tuned to the first intermediate frequency which is the frequency difference between the two signals applied to its input.

The output of the first mixer V2 is fed to the grid of the pentode portion of the 2nd mixer (V3). The triode portion of V3 is a 6.2 Mc crystal oscillator. The output of the 6.2 Mc crystal oscillator is fed to the grid of the pentode portion of the 2nd mixer V3 where it combines with the 5745 Kc signal fed from the 1st mixer V2. The output of the 2nd mixer V3 is tuned to 455 Kc which is the second intermediate frequency.

The output of the 2nd mixer stage V3 is fed through two stages of IF amplification (V4 and V5) and then to a 1N60 diode detector. The 1N60 diode detector rectifies the IF signal to produce the audio signal and the AVC voltage.

After filtering the AVC voltage is applied to both 455 Kc IF amplifiers, the second mixer, and the Nuvistor RF amplifier to provide automatic volume control. After filtering the audio signal is fed through a self-adjusting automatic noise limiter to the VOL control. From the volume control the signal is fed to the input of the first audio amplifier V7. After amplification the audio signal is fed to the grid of the triode section of the phase inverter (V6). The phase inverter processes the audio signal and feeds it to the grids of the pentode sections of two tubes (V6 and V7) which operate as push-pull power amplifiers. The output of the push-pull power amplifier is fed to the primary of the output transformer (T5). The secondary of the output transformer (T5) has two windings. One winding is used to drive the receiver speaker. The second winding is used to modulate the transmitter when relay K3 is in the proper position.

TRANSMITTER

Refer to the transmitter block diagram Figure 5 while reading the following. If greater detail is desired at any point, refer to the schematic diagram.

The transmitter signal is generated in the pentode section of the oscillator/buffer stage V10. The oscillator may be either crystal-controlled or used as a VFO. The triode section of the oscillator/buffer stage V10 is a buffer amplifier used to isolate the oscillator from undesirable effects which might be caused by the loading of the following circuitry. The output of the buffer amplifier V10 is fed to the input of the first frequency doubler/tripler stage, triode section of V8. In VFO mode of operation the fundamental frequency of the VFO is doubled. In crystal mode, the fundamental frequency of the crystal is tripled. The output is then fed into the input of the second frequency doubler stage, pentode section of V8. The second frequency doubler stage doubles the frequency again. The frequency produced at the output of the second frequency doubler stage V8 is four times the VFO oscillator frequency and six times that of the crystal frequency. The output of the second frequency doubler is fed to the grid of the RF power output stage V9.

The RF power output stage V9 amplifies the signal further and supplies RF power to the antenna through a pi matching network and a harmonic filter.

To modulate the transmitter, an audio signal must be introduced into the microphone. When an audio signal is introduced into the microphone, it is amplified by the triode section of the microphone preamplifier V4. The output of the microphone preamplifier is fed to the triode section of the second preamplifier V6 where it is further amplified. The output of the second preamplifier is fed to the triode section of the phase inverter V7 where two 180° out-of-phase signals are produced to feed the push-pull power output tubes (V6 and V7). The output of the phase inverter is fed to the grids of the pentode sections of the power amplifiers (V6 and V7) which provides the power necessary for high level plate modulation. The output of the push-pull power amplifiers is used to modulate the RF power output stage V9.

POWER SUPPLY

The power supply of the HA-460 is a universal type capable of operating from 117 volts AC or 12 volts DC power sources. When operating from 117 volts AC power source, the power supply functions in the usual manner with the AC being applied to the power transformer and rectified by a full wave rectifier and its associated filter network (see schematic diagram). When operating from a 12 volt DC source, four 2SB425 transistors are used to convert the DC to AC. The AC is then stepped up by the power transformer and rectified to produce the B-f voltage. A polarity reversing switch S1 (see schematic diagram) is furnished so that the power supply may be used on vehicles having either a positive or negative ground.

S-METER/RELATIVE POWER INDICATOR

A unique meter circuit is used to provide indication of operation in both the receive and transmit modes. In the receive mode, the screen current of the AVC controlled IF amplifier (V5) is measured by the meter. The indication is proportional to the AVC voltage (or incoming signal strength). The meter is calibrated in "S" units to 9 and in decibels above S-9. In transmit, a small portion of the RF output signal is rectified and filtered. This rectified voltage is measured by the meter and gives an indication of the relative output of the transmitter.

TROUBLE SHOOTING HINTS

INTRODUCTION

In case a malfunction should develop in the HA-460, the trouble-shooting hints given in Table 2 can be used as a general procedure for locating the defective section of the transceiver. Once the defective section has been located, the voltage measurements given in Table 3 can be used as a reference to further localize the malfunction.

TABLE 3-VOLTAGE MEASUREMENTS

NDV: No detectable voltage.

RETURNING THE UNIT FOR REPAIRS

In the event that repair is necessary (either in or out of warranty), Lafayette recommends that you return the transceiver to the Lafayette store from which it was purchased. If the unit is to be shipped to their main office for service, please read the instructions which follow.

SHIPPING INSTRUCTIONS

Pack the unit very carefully to avoid damage in transit, preferably in its original carton. If the original carton is not available, use a sturdy carton with at least 3 inches of shredded paper or excelsior around the unit. In the latter case, wrap the unit in paper first to avoid particles of packing material getting into it. Include with the unit a letter explaining exactly what difficulties you have encountered (remember to add an extra 5¢ postage and indicate on the outside of the carton that First Class Mail is enclosed). Ship by prepaid express if possible and mark ELECTRONIC EQUIPMENT - FRAGILE. Clearly address the carton as follows:

SERVICE DIVISION
LAFAYETTE RADIO ELECTRONICS CORP.
111 JERICHO TURNPIKE
SYOSSET, L.I., N.Y. 11791

ALIGNMENT

RECEIVER

To align the receiver portion of the HA-460 obtain the test equipment listed below and proceed as directed in Table 4.

Test Equipment Required: 1. Calibrated signal generator 2. AC VTVM 3. Non-metallic alignment tool

TRANSMITTER

To align the transmitter portion of the HA-460 obtain the equipment listed below and proceed as directed in Table 5. Equipment Required: 1. Milliammeter (Simpson Model 260 or equivalent) 2. 8.5 Mc crystal. Note: Any crystal which will produce an output frequency between 50.0 and 52.0 Mc may be used. The proper adjustments must be made in Table 5 to compensate for using a crystal with a frequency other than 8.5 Mc 3. Non-metallic alignment tool 4. Ten watt dummy load 5. TV Receiver

* NOTE: When L10 and L11 are properly adjusted, the grid drive to the 2E26 RF output tube will be somewhat lower on either end of the band as opposed to the middle (i.e.: Lower at 50.0 and 52.0 Mc as opposed to 51.0 Mc).

SCHEMATIC DIAGRAM CHANGE MODELS HA-410 & HA-460 AMATEUR TRANSCEIVERS

There has been an error in printing the schematic diagram of the power socket connections on the above mentioned units. The diagram below shows the power socket connections as it should appear. It will be noted on the corrected diagram below that pins 4 and 5 of the power socket are reversed from that shown on the original schematic diagram.