- Four large front-panel meters displaying signal strength, RF power, SWR, and plate current.
- Built-in SWR calibration.
- Transmit/Standby switches to preserve the life of the vacuum tubes.
- Circuit Hybridization: Transistors and Integrated Circuits (ICs) handle low-power tasks like the receiver chain, intermediate frequency (IF) amplification, and Phase-Locked Loop (PLL) logic. Vacuum tubes drive the high-power RF final and driver stages.
- PLL Frequency Synthesizer: Frequency control is derived from a sealed, metal-shielded Phase-Locked Loop circuit using the Motorola MC145109 IC (or the closely related PLL02A in some iterations). This configuration stabilizes all 40 channels across the 26.965 MHz to 27.405 MHz band.
- Operating Modes: The Mark IX operates exclusively on AM (Amplitude Modulation). T
- Final Output Tube: Utilizes a 6L6GC beam power pentode valve (frequently manufactured by Samsung for these units) to handle power amplification.
- Driver Tube: Employs a 6W6GT or 6DG6GT vacuum tube to drive the final stage.
- Power Output: Standard legal parameters yield 4 watts of carrier power on AM (swinging up to 30 watts PEP depending on modulation and modification) and 12 watts PEP on Single Sideband modes.
- Transmit/Standby System: Features a front-panel toggle switch controlling the high-voltage plate line. In Standby, high voltage is removed from the tubes to prevent thermal stress and degradation during long monitoring periods. Filaments remain warm, ensuring immediate transmission capabilities when flipped to Transmit.
- Solid-State Receive Line: Dual-conversion superheterodyne configuration driven fully by 12V DC internal regulation.
- Signal Conditioning: Includes an integrated Automatic Gain Control (AGC) loop with select response speeds to stabilize audio fading, an Automatic Noise Limiter (ANL), and a dedicated RF Noise Blanker (NB) stage.
- Frequency Fine-Tuning: Employs a front-panel Delta Tune (Mark IX) or a Clarifier (Mark X) allowing local oscillator shifts of approximately ±600 Hz to clear up off-frequency signals.
- Input Voltage: Designed for a fixed 105–120V AC, 60Hz mains line power source.
- Internal Regulation: A split-rail primary power transformer steps down voltage to power the solid-state chassis (12V DC), while a separate secondary winding steps up voltage to service the tube plate grids (high-voltage AC rectified to DC).
- Physical Chassis: Massive 19" wide by 9" tall footprint providing a high volume of interior space for passive thermal dissipation without requiring cooling fans.
- Signal Strength (S-Meter): Measures relative incoming RF signal intensity.
- RF Power Meter: Monitors forward transmitter wattage output.
- SWR Meter / Calibrate: Tracks Standing Wave Ratio relative to 50-ohm load matching.
- Plate Current / Modulation: Monitors the milliamperage flowing directly through the vacuum tube plates (averaging ~15 mA under nominal resting state) alongside a modulation percentage index.
PROTECTIVE COVER Remove the chassis cover. Caution: There is live voltage when power is applied.
For this output power level tune up procedure, it is assumed that the PLL frequency synthesizer is functioning properly. The entire PLL circuitry (including two crystal oscillators, VCO, frequency dividers, low pass filters and the phase detector) is sealed in metal shield. The PLL section alignment procedure will be explained afterward. Power supply voltage is 1 17V 60 Hz A.C. Connect an R.F. wattmeter (50 ohm) to the antenna connector. Set transceiver to Channel 19 (27.185 MHz). Refer to interior parts location drawing in instruction book for the following adjustments. 1. Depress microphone button and adjust cores of L301, L302, L303, L304, L305, L306, L307, and L308 for maximum reading on the wattmeter. 2. Check output power on all channels. If not equal, readjust L302, L303, L304, and L402. 3. Adjust L307 and L308 for optimum maximum wattmeter output. 4. Adjust RV 603 for reading on transceiver power meter equal to indication on the wattmeter. 5. At factory C314 (nominal value of 82 pfd) is selected for maximum R.F. power level. 6. Located behind the P.C. board containing the VACCUM tubes is a shielded can containing the final R.F. amplifier tank circuit. There are two variable capacitors are mounted on top of tank coil. Peak these for maximum output. These capacitors interact so it will be necessary to adjust and readjust until maximum reading is obtained on R.F. output meter.
1. Set transceiver in Transmit mode. 2. Connect oscilloscope D.C. probe to T.P. 1 3. Adjust L403 and observe the D.C. level swing between zero volts to 8 VDC. Then set the level at 7VDC when channel selector is set at Channel 40, (Note when channel selector is switched to 1. the level will jump to about 3-4VDC.) 4. With frequency counter measure VCO frequency at P408 against the chart. As an example, the channel 1 Transmit VCO should be 16.543 MHz. When changed to channel 1 Receive mode, the VCO frequency will be 16.27 MHz.
Set volume to maximum. Selector to Channel 19. 455 KHz I.F. alignment 1. Connect A.C. VTVM to speaker terminals. 2. Connect signal generator to DRAIN of Q105 (Through about 0.01uF capacitor) 3. Set signal generator to 455KHz ± 0.5 KHz 4. Apply power to unit and adjust signal generator output to produce a reading of 0.5 volts on the A.C. VTVM. 5. Adjust L105, L106 and L107 for maximum output on VTVM. Note: Reduce output of signal generator as necessary to keep VTVM reading around 0.5 volts. I.F. 10.695 MHZ 1. Connect A.C. VTVM to speaker terminals. 2. Connect signal generator to the base of transistor Q102. 3. Set signal generator to 10.695 MHz (±1 KHz). 4. Adjust L103 and L104 for maximum output as read on VTVM. Reduce signal generator output as necessary to keep the VTVM reading around 0.5 volts.
1. Connect A.C. VTVM across speaker terminals. 2. Connect signal generator to antenna connector. 3. Set signal generator to 27.185 MHz, modulated 30% with a 1-KHz tone. Set signal generator output to 10uV. 4. Set transceiver to Channel 19 and vary signal generator frequency around 27.185 MHz to produce a maximum reading on the A.C. VTVM. Leave generator at this point. 5. Adjust L101, L102, and L401 to produce maximum output on A.C. VTVM. 6. Reduce generator output to approximately 1uV. Adjust L101, L102, L103, L104, L105, L106, L107 L107, and L401 for maximum reading on VTVM. Repeat until no further improvement noted. 7. Adjust RV102 for “S-9” reading on the transceiver meter with 100uV signal input. 8. Squelch Adjustment. Adjust input signal to 60 dB (1mV) from signal generator, and turn squelch control full clockwise; adjust RVlOl until signal just breaks through. |