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Yaesu FT857/897 Static Crashes / Design fault


#1

Hi All,

I have searched the reflector & not seen this mentioned before, so as many of us have either an FT857 or FT897 I think it is worth sharing.

Last weekend I noticed that my FT897D was hearing static crashes, even with no antenna connected. After eliminating any possible external source within the shack, I deduced that this was coming from within the radio itself. I took the radio apart & checked for any obviously failing components & did not find any.

I then turned to Google & found the answer pretty much straight away.

Apparently, during the design stages of certain versions of the FT857 & FT897, two 0.01uf DC blocking capacitors were omitted in error from either side of the Toko 455KHz AM filter. This eventually leads the the symptoms described above & can lead to the filter failing completely & possibly damaging other filters or components close by.

Not wishing to risk further damage I stopped using the radio until I could look at either repairing it myself or sending it away to be repaired.

Thanks to some very useful & detailed instructions / diagrams / photos on the net I opted to have a go at this myself, although I opted to use normal size components rather than Surface Mount Devices which are far too fiddly! Hi!

I spent this morning nervously cutting some very narrow tracks & trying to solder without dislodging any SMD components & I am very glad to say that my FT897D is functioning normally again :slight_smile:

My sincere thanks to those who have shared the detailed info on this mod, without whom I would probably still be scratching my head wondering what was causing the problem.

A photo of my version of this mod using “normal” size capacitors is below. It does say in the set of instructions I used that this is not for the faint-hearted, & I would certainly agree. It is not a complicated mod, but the very small size of the tracks & components involved does make it quite tricky if you are not used to SMD work.

If you find that your FT857/FT897 has developed this fault, & you are not 100% confident in your soldering skills then I believe most dealers with repair facilities will do this repair for a quite reasonable fee. I also believe some Kenwood radio’s are also affected.

My repair cost me about 10p, but it could have been much more expensive if I had made a mistake!

A photo of the underside of the main board of my FT897D with the capacitors added is below. Pardon my sloppy soldering, but it was extremely fiddly. Hi!

Any person attempting this repair does so at their own risk.

Thanks & best 73,

Mark G0VOF


#2

In reply to G0VOF:
When I noticed this was happening I contacted the vendor.
They contacted Vertex UK (YAESU) who fixed it outside warranty (charge was one way carriage).

Roger G4OWG


#3

In reply to G4OWG:

Hi Roger,

That is excellent & hopefully others who experience this fault will be able to do the same. As it is a design fault, it should really be repaired at Yaesu’s expense, regardless of whether it is in or out of warranty. I have to be honest though, I did have “I am a Radio Ham, I should be able to do this” running through my head when I looked at what was involved. Until I saw the size of the components. HI!

That said, it looks like you got a pretty good deal & our radios are both OK now :slight_smile:

Thanks & 73,

Mark G0VOF