Yaesu FT-450 Grounding Problem - Fixed.

If there's one thing that I will always be glad I did, it's buying an FT-450.  It was a second hand, first production run (pre-'D') model, in mint, unused condition. After tens of thousands of QSOs, it's proven itself to be a rugged unit that can take whatever punishment you throw at it.  You can send digital signals all day with the FT-450, and the crystal won't drift a jot.

However, from time to time - and I mean very infrequently - some ops (usually when there is a solid, strong signal both ways) will report a high-pitched tone on the audio.  Some have asked me if I'm in an aircraft!  I've always put it down to a noisy fridge compressor that sits behind me in the kitchen.

This week, I've been connecting-up a boom microphone, so today was the time to test it out.  To ensure the new mic wouldn't sound horrendous before I started operating in earnest, I got to grips with the transmission audio monitoring function on the FT-450, transmitting on a rather dead 15m band.

This proved very enlightening!  I could immediately hear the distinct high-pitched noise that does indeed render the audio as though it comes from the cockpit of an Airbus!  On selecting high mic gain, the noise was unacceptably distracting.

Before you worry, remember that maybe less than 1% of my contacts have reported actually hearing the sound.  It's much more common to get good audio reports, in fact.

I did some online searching, and found a useful discussion, identifying the source as poor ground bonding between the front control panel and the main body of the rig.  You can find the discussion here.

Now, I'm not very good with electronics, but this basic stuff did seem within my skill set, so I opened up the case to see if fixing this would remove the noise.

And there they were!  Three springy strips of copper that, as you might expect after a few years, were lightly tarnished.  On testing the quality of the connection between circuit and the spring metal, even a simple multimeter was enough to tell me, through its intermittent buzzer sputtering, that the ground connection was poor.

Removing the front panel.

Now, I have to agree with some of the comments online that this inadequate design for the grounding of the front panel is really unacceptable for a major maker like Yaesu.  I have no idea at all why a proper, soldered connection was not provided, but simplicity of assembly might be the answer.

Two of the three copper grounding spring strips.  They make for a poor connection.

The solution to this problem is very easy.  You just need to solder a thinnish wire to the solder base that fixes one of the metal springs, and then run this through the 'bulkhead' - there are only a couple of possible passages - to connect to one of the circuit board mounting screws, which have a good connection to the chassis.

Remember to solder to the front panel first, because doing it the other way around - like I did - means you have to try and solder a short wire to the front panel very close to the rig body (d'oh!)

Step 1.  Pass a thin wire through the ribbon wire slot. Ignore the red tag connection already made for now - I did things the wrong way round in my attempt...

Step 2. Now wiggle the wire to emerge through the lower right corner hole (from front)

Step 3.  Solder the wire to the solder base of one of the copper strips (use the nearest one to the hole in the chassis), and replace the front panel onto the rig.

Step 4.  Cut the wire to the right length, and secure it with a soldered ring connector fixed on the nearest available circuit mounting screw, which attaches to the chassis as a good grounding point.

Job done!

And the result?  Switched on - radio still working (phew!) - and no noise at all.  Just like the comment on the forum said, this fix resolves the noise issue completely.

But what a stupid design error!