VFO Sync board for Yaesu FT1000MP Mark V Field

Enhance your listening experience with help of a small stealth control board

Yaesu FT1000MP series transceivers have two receivers that can work on a same frequency band. Additionally, if to set the main and sub receivers to a same frequency, pseudo stereo reception becomes available. A stock FT1000MP MarkV/Field can synchronize Sub VFO tuning with the Main VFO if to switch it to the "Dual" mode, press the "A->B" button to write the Main VFO frequency to the Sub VFO, then press and hold the Main VFO "Lock" button. After that rotating the main dial will change both VFOs synchronously, and the audio from the main and sub receiver creates a pseudo stereo effect.

This feature however is inconvenient for practical use. First, the operator has to hold the main VFO "Lock" button while rotating the main dial. Both operator's hands become busy with this, and losing grip on the "Lock" button means losing the frequency sync. This quickly becomes tiring experience. Second, when doing this, the transceiver front panel becomes unresponsive until the operator releases the "Lock" button and exits the VFO sync mode. Because of that the operator can not do anything else when sync-ing the VFOs and listening for the dual channel audio. If you ever tried this feature, you know what I am talking about.

I found the 2-channel reception producing interesting deep audio resembling the stereo effect, which is produced in this case because of using two receivers (further in this article for simplicity I will be referring to it as "stereo reception"). However, that "Lock" button thing renders the feature useless. But I still wanted to experiment with stereo reception, so I pulled the schematics, analyzed it, and as the result, a small add-on board was born which is presented here - the "Sync" board for Yaesu FT1000MP series radios.

The add-on board described here was designed to overcome these limitations. The board has a Microchip microcontroller that samples the main/sub VFO encoder signals and a control signal from the keypad controller, and on a command from the operator locks and unlocks the main dial to the Sub VFO one. The board therefore frees the operator from constantly holding the "Lock" button when receiving in stereo mode, and all front panel buttons/controls continue working. The operator can easily switch modes at any time, his hands stay free and all front panel keys work as usual, which is a huge improvement over the dual VFO tracking method offered by Yaesu as described on p.63 of the MarkV Field Operating Manual. Now the operator can enjoy listening to stereo audio constantly, when surfing the bands. Countless combinations of the filters, noise reduction settings, clarifier, IDBT and EDSP controls in stereo mode bring new listening experience to the stock transceiver. I found all generic CW,SSB,and AM mode audio benefiting from it.

The Sync board works on all three the base FT1000MP, FT1000MP MarkV, and MP1000MP MarkV Field radios.

Fig. 1. The Sync board for the Dual VFO tracking.

The Sync board is sized 2.5x0.25'' (65x15mm) and easily installs inside the transceiver. It has only a few components and consumes very little power. The microcontroller does not require a clock crystal, and generates no detectable RFI.

To start listening to stereo audio, activate the sub receiver by pressing the "Dual" button and write the Main VFO value to the Sub VFO with the "A->B" button. Now to start sync-ing press and hold the main VFO "Lock" button and momentarily press the "Dual" button. The Sync board captures this 2-button keystroke every time it is sent, and switches the sync circuit on or off, activating or deactivating the sync mode. An audible beep is produced as indication of a state change.

A big advantage of the Sync board is that there is no need to sacrifice any of the front panel buttons to control it - everything is done using the existing buttons and no normal front panel functionality is lost. The operator can easily switch modes, his hands stay free and all front panel keys continue working, which is a big improvement over the dual VFO tracking method offered by Yaesu, p.63 of the MarkV Field Operating Manual.

The board memorizes the state it was on when the operator turns off the power, and when the radio is turned back on, the last state is restored automatically. Because the board works by processing only the main dial encoder signals, it can not follow frequency changes commanded by the radio's frequency synthesizer, such as fast frequency change with "Up/Down" buttons or with the jog shuttle, when calling the previously stored frequencies from the memory, or when changing the bands or making direct frequency entry using the keypad, or when the transceiver is controlled by a software via a COM port. However, it is very easy to re-sync after making such changes - the operator simply needs to press "A->B" button to write the new main VFO value to the sub VFO, and both VFOs will start changing in sync again.

The board outline was designed to fit into the available mounting space and requires only 2 or 3 wires to solder as illustrated in the following picture.

Fig.2. The transceiver bottom view. The Sync board is shown mounted in the top left corner of the picture, by the front panel.

The Yaesu MarkV operating manual calls this mode the "diversity reception", but I would call it "stereo reception", because for a true diversity reception two completely identical receivers with phase locked VFOs are needed. This is not the case with either of FT1000 line transceiver, where the sub receiver differs from the main one in schematics and filtering, though their VFOs seem to be referenced from a single frequency source and as appear to be phase locked. Regardless, the stereo mode opens big field for experimenting with 2-channel reception, from a basic audio base enhancement for casual surfing the bands to sophisticated combination of filters/EDSP/sideband settings to produce new enjoyable listening experience. The best effect is produced if to turn the clarifier on and move the main VFO just 1 unit (the actual frequency shift depends on the menu 1-9 setting) away from the sub VFO. This small frequency shift makes the audio sound very interesting in CW/SSB mode, and is still noticeable in AM mode.

Beside producing better audio in casual bands surfing, two-channel receive may prove useful in contests when using the headphones, because it produces separate audio for each ear, and the "flat" signals become distinctive as if they would come from different directions, especially with the clarifier introduced light shift between the VFOs. Additionally, the 4-8 menu allows for different audio mixing options from the main and sub receiver channels.

The Sync board is now being used with my FT1000MP MarkV Field transceiver which I have as the base station. Timo OH5KW confirmed the board works on his FT1000MP MarkV (non-Field model), and Ingemar SM5AJV got it working with his base FT1000MP. Therefore, the Sync board works with all FT1000MP models, only the flat cable connector markings seem to differ. Ingemar SM5AJV experimented with diversity reception using the Sync board and wrote an article for the Swedish national amateur radio magazine QTC and placed a few audio snippets on his Blog page here. With Ingemar's permission a copy of the article (in Swedish) can be found here.

Another useful application for this Sync board can be for a spectrum scope/panadapter that uses the Sub VFO channel tuned in sync with the Main channel. The input into the panadapter can be either from the Sub VFO IF circuit or audio circuit depending on the bandwidth requirements. Using the Sub audio for this purpose gives a advantage that the signal bandwidth into the panadapter will remain independent from the Main receiver which can be set to use CW and SSB filters, EDSP, and IF controls to the operator's liking. Say, when the operator selects a 200Hz filter on the Main receiver, the panadapter will still show the full few kHz spectrum with the bandwidth defined by the Sub receiver channel. Check Jeff F6AOJ's web page here (translated from French) for information about his project using the Sync board for his panadapter.

Kits and Documentation

If you wish to order a Sync board kit please click here.
A document with Installation instructions is available here.

In case you have questions, please feel free to email me at the address below.

Contact: miv@makarov.ca