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Palstar HF-AUTO Automatic Antenna Tuner

Technical Manual

Product Overview

Palstar products are designed by Hams for Hams, carrying on the Palstar tradition for high-quality products designed and manufactured in Ohio, USA.

The HF-AUTO is a high-performance automatic antenna tuner designed for use across the HF spectrum.

Specifications Summary

HF-AUTO Specifications

HF-AUTO Power Cable

The HF-AUTO DC Power Cord connects to a 12-13.8V Power Supply and features a 3-pin Amphenol type plug with ferrite beads.

Theory of Operation

The HF-AUTO is a complete stand-alone RF Tuneable Auto T Network tuner. It operates independently of external data sources for frequency tracking. It uses an RF Coupler to provide voltage and current information from 1.8 MHz to 54 MHz. This information is processed to determine accurate phase-oriented forward and reflected values, which are used by Tl processors to calculate SWR. The unit can detect frequency and SWR at low levels (typically 2 watts) and scales up to 1800 watts. Tuning thresholds are established by processors, initiating a tuning sequence when necessary. A preset voltage system, utilizing a mechanical sprocket and kevlar belt system, determines the positions of the variable differential capacitor and roller inductor for precise tuning. The system samples DC voltage and compares it to the intended frequency band, adjusting L & C to achieve minimum SWR, typically better than 1.2:1, often 1.05:1.

Maintenance Requirements

Mechanical issues are the most common maintenance concerns:

Repair or Replacement Modules

Screen Display on Power-Up

Upon initial power-up, the display shows the software revision level and Palstar copyright information. The display typically shows:

AUTO Ant#1 F=
C=126 L= 370
PPK= 0
SWR=1.00

Controls include MODE, TUNE-SELECT, and ANTENNA buttons, along with PRESS MODE, PRESS TUNE KNOB, and PRESS ANTENNA buttons for operation.

How-To Update Software

Downloading HF-AUTO Firmware

  1. Create a folder on your computer's hard drive (e.g., HF_AUTOUPGRADE).
  2. Download the Firmware file (Zip format) from the Palstar website: http://www.palstar.com/en/hf-auto/. Look for the file named "HF-AUTO Firmware 1.x".
  3. Save the file to the created folder.
  4. Right-click the Zip file and select "Extract All", following the on-screen instructions.

Installing the Firmware Upgrade

  1. Turn OFF the HF-AUTO.
  2. Connect the RS-232 cable to the rear panel and your computer (Com 1).
  3. Turn ON the HF-AUTO.
  4. Set the switch at the rear of the HF-AUTO to "PROGRAM". The "PROGRAM MODE" LED on the front panel will illuminate.
  5. Double-click "LOAD_HF_9600" from your HF_AUTOUPGRADE folder.
  6. Wait for the DOS window to close (approximately 1 minute).
  7. Turn the "PROGRAM" switch back to "NORMAL".
  8. Remove the RS-232 cable.
  9. Turn the HF-AUTO OFF and then ON again.
  10. Check the HF-AUTO display for the new REV level in the top-right corner upon startup.

Note: The HF-AUTO ships with a DB9 serial cable. A USB to DB9 serial cable can be ordered from Palstar for computers without a DB9 port.

HF-AUTO Firmware Summary

This section details firmware updates and their corresponding changes:

Setup Mode

The Setup Mode allows configuration of various tuner parameters:

Controls for Setup Mode include PRESS TUNE KNOB to SELECT MENU, PRESS RED BUTTONS to ADJUST VALUES, and PRESS & ADJUST with TUNE KNOB.

Tuner Operation

To place the tuner in AUTO MODE:

  1. Connect the transceiver to the RF INPUT chassis connector at the rear.
  2. Connect a dummy load to one of the coax outputs or your desired antenna.
  3. Apply a single tone level greater than 5 watts (typically 5 to 50 watts using FM MODE).
  4. The display will indicate Frequency, Power Level, SWR, and numerical values for C and L.

Note: To execute a tune sequence at another band or frequency, lower the transceiver's power output and change frequency. The tuner will automatically adjust. Alternatively, press the PTT button on your microphone in FM MODE to accomplish this at the lowest power level.

Tuning the HF-AUTO

A short burst of single tone power allows the tuner to pretune to a memory segment. A subsequent application of RF power is needed to complete the final tune condition, especially at high power. Continuous single tone power can also be used until the final tune cycle is complete. Tuning at high power without completing the final tune condition could damage the tuner.

Saving Memory Locations

  1. Tune the HF-AUTO using a low power FM or CW signal.
  2. Manually tune L&C for best SWR while power is applied.
  3. While power is still applied, push and hold the red button to the right of the tuning knob for 2 seconds or more until the display shows "SETTINGS CHANGED".
  4. Remove power and release the red button. The frequency is now saved.
  5. To return to AUTO MODE, push the left red button.

Divisions in the Frequency Bands for Settings

FREQUENCY IN MHZ # OF SETTINGS SPACED
1.8 MHz to 20 MHz 51 4 Khz
3.5 MHz to 4.0 MHz 51 10 Khz
7.0 MHz to 7.3 MHz 36 50 Khz
10.1 MHz to 10.150 MHz 2 50 Khz
14.0 MHz to 14.350 MHz 18 40 Khz
18.068 MHz to 18.168 MHz 3 50 Khz
21.0 MHz to 21.450 MHz 5 100 Khz
24.890 MHz to 24.990 MHz 1 500 Khz
28.0 MHz to 29.70 MHz 51 500 Khz
50.0 MHz to 54.0 MHz 101 40 Khz
MARS FREQUENCY 707 4 Khz to 500 Khz

For all tunable frequencies from 1.8 - 30 MHz, 40 MHz through 41 MHz and 50 MHz to 54 MHz, there are 1193 subdivisions or memory positions.

Rear Panel of HF-AUTO

The rear panel features:

Inside View of HF-AUTO

A detailed view of the internal components, including the roller inductor, pulley/belt system, variable capacitor, stepper motor, and various PCBs.

HF-AUTO Schematic

The schematic illustrates the connections between the main PCBs:

The schematic details the various connectors (J1-J7, P1-P11) and their pin configurations, including SO-239 connectors, DE-9 Female for RS-232, RCA Phono Female, DC male connector, AMP mate-N-lok, and various 0.1" spacing pin headers.

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