Yaesu FT-847 Page & Mods

In the year 1998: “Yaesu proudly introduces the new FT-847 Satellite plus HF All-Mode Transceiver. Once again Yaesu has created the ultimate radio with cutting edge technology that includes all band performance.”

“New features include 100 Watt output on HF / 6-Meter bands, while 2-Meter and 430 MHz bands feature a full 50 watts power output. Additional features include: Cross-band Full Duplex Operation, Normal / Reverse Tracking, CTCSS and DCS encode/decode, High Resolution 0.1 Hz Tuning Steps for Ultra Smooth Tuning, DSP Filters (Notch, NR, BPF), Shuttle Jog Tuning Dial, Direct Keypad Frequency Entry, 1200/9600 bps Packet ready, Optional Voice Synthesizer and more!”

“With its high-tech design and revolutionary features, the FT-847 is truly the one radio that can do it all ! The new FT-847 will continue to distinguish Yaesu as the world leader in amateur radio products.” – info from old Yaesu website.

I recently acquired an FT-847 and decided to restore, align, and clean it. However, since it was already in excellent condition, only minor adjustments were needed.

Views and inside photos

My menu/alignment settings

After the reset I set the following menu items:

The menu items 8,20 and 22 may need some change after the volume fix.

Service and Alignment Menu

This radio has an alignment menu in addition to the user menu. To enter this alignment menu, you turn off the transceiver, press the UP, DWN, and FAST keys on the microphone together, while turning the transceiver on again.

In the alignment procedure, each alignment parameter is selected by rotating the SUB-TUNE dial. The alignment is performed by pressing the MCK/W key while injecting a signal of the required frequency and level. Pressing the MENU key after a setting is made stores the entry. To exit the alignment routine, press POWER to switch off the transceiver.

More information about the alignment menu can be found in the service manual and technical supplement.

Frequency calibration

To adjust the reference frequency change the TC1001, visible in the center of this picture. It is located on the bottom side.

Solution for the volume problem

I have found a relatively simple solution to the volume problem, which refers to the much too high minimum volume. It can be easily applied.

There is a small resistor on the back of the front panel PCB that is connected directly to the volume control between the maximum and the slider. This small resistor must be removed. Instead, a small trimmer with 20 kOhm is connected 1:1 (parallel) to the 3 pins of the volume control. The trimmer can then be used later to adjust the volume curve and set the lower start point of the volume knob.

The second step is to take another 3.3 kOhm trimmer and solder it on one side to pin 3 (ground) of the audio IC. Pin 1 of the IC is the audio input, which then goes directly to a small electrolytic capacitor, behind which you connect the second pin of the trimmer.

After all this, use the volume control to set the volume so that audio is just coming in (first level, as it is digitally controlled in steps). Then, use the trimmer on the audio IC to set the minimum volume you want. Just remember, that this also limits the maximum volume. The trimmer at the volume control is then used to set the desired curve, i.e. how the volume should change as the control itself is turned. It also controls the start point of the volume knob, which can be useful if the beginning of the pot is cracking. This allowed me to solve the well-known volume problem perfectly.

More info about the problem: Volume control issues

Solution for the loud fan problem

The small and loud rear fan can be simply disconnected, as the bigger and slower running front fan should be enough for cooling in the most cases.

More info about the problem: Fan disconnect fix

Features (from Yaesu website)

• Ideal for Satellite and HF Operation
• HF/50 MHz: 100 Watts, 144/430 MHz: 50 Watts
• Crossband Full Duplex Operation
• Normal / Reverse Tracking
• Dedicated Satellite Memories
• DSP Filters (Notch, NR, BPF)
• Low Noise VHF/UHF Preamps Built-in
• High Resolution 0.1 Hz Tuning Steps for Ultra Smooth Tuning
• Shuttle Jog Tuning Dial for fine or rapid tuning
• CW Sidetone and Pitch Control
• CTCSS Encode/Decode Built-in
• DCS (Digital Coded Squelch) Encode/Decode Built-in
• Direct Frequency Keypad Entry
• 1200/9600 bps Packet Ready
• Dimensions: W 10.2″ x H 3.4″ x D 10.6″

Some useful links I found:

OK2KKW: FT847 Supply Switch
EB5AGV’s Workbench: Yaesu FT-847 restoration
FAQ for Yaesu FT-847

Last updated on 2024:12:16 at 00:33 UTC