Yaesu FT-857 Six meter transmitter oscillation.

[Shockwave]

If you own an early non "D" version of this radio and tried to use it on 6 meters, you may have found it to be useless there. These things oscillate so badly in this band they can form a full power carrier in the SSB mode! For years people have been chasing this problem around thinking it was loose grounding screws with no help at all from Yaesu. The problem is this company knows they messed up and sold thousands of radios that would never pass FCC inspection if tested on 6 meters.

They had to go back and fix the problem they made in the 857D but will never post a service bulletin or admit they screwed up. They will be happy to charge you to fix their mistake. Problem is Ham's don't like being forced into the role of debugging new equipment and then being charged to fix a manufacturers mistake once spotted. Yaesu has refused to comment on this problem or elaborate on what they did in the "D" version to correct the problem.

It all comes down to a piece of conductive shielding tape being placed over the pre-driver stage to stop it from coupling to the final stage. If this company had any ethics (long since lost) they would be mailing everyone they screwed a piece of tape with a photo showing where to put it. But no, they want you to waste shipping and pay them to do the job they should have done the first time.

Look at an internal photo of the 857D and notice towards the right hand side there is a piece of silver colored, conductive tape over the pre-driver and RF transformer in this area. That is the fix they charge you for. Another issue with these radios is the LCD display is not suitable for use in vehicles where the temperature could exceed 100 degrees. The connections to the LCD driver will fail one line at a time from temperature changes and the only fix is to replace it with the same junk.

 

[Captain Kilowatt]

If that was the only reason it should have been not working out of the box instead of taking months or even years to fail. There was an issue with running DC thru a filter as well which caused problems. I had a non D version that had that issue and it started on 6m and eventually spread to 10,12 ,and sometimes 15m. It started on 6m with garbled audio then the carrier on SSB then the other bands. It took a couple years to show up on 6m. So far so good on the D version.

 

[kopcicle]

So far so good on the D version.

The only two issues I still have are loosing auto repeater splits when modded GC and I hate listening to it .
Otherwise it's a capable shack in the box.

 

[Shockwave]

If that was the only reason it should have been not working out of the box instead of taking months or even years to fail. There was an issue with running DC thru a filter as well which caused problems. I had a non D version that had that issue and it started on 6m and eventually spread to 10,12 ,and sometimes 15m. It started on 6m with garbled audio then the carrier on SSB then the other bands. It took a couple years to show up on 6m. So far so good on the D version.

The thing with this problem is many non D versions are right on the verge of self oscillation. Anything from temperature change, frequency or VSWR could throw it into or out of oscillation. Stands to reason that component value drift over time could make the problem worse since the slightest change in gain could bring it out. Just taking the screws out of the cover and lifting it an 1/8 inch off the radio stopped my oscillation. That's when I knew that the cover was reflecting RF back into another sensitive stage. I assure you that just shielding over that pre-driver and RF transformer eliminates any trace of this problem.

 

[W4KVW]

I had an 857D several years ago & you may read my review on eHam.It was by far the worst transceiver I have EVER used or owned.You could not give me another one for FREE if I am required to keep & use it.I replaced it with an ICOM 7000 & it was the happiest day of my radio life.ZEBRA lines are the new big issue with them & the $300 repair bill for that makes it useless to me since I found the radio worthless as it was without any lines.

SIX-SHOOTER

 

[Shockwave]

I had an 857D several years ago & you may read my review on eHam.It was by far the worst transceiver I have EVER used or owned.You could not give me another one for FREE if I am required to keep & use it.I replaced it with an ICOM 7000 & it was the happiest day of my radio life.ZEBRA lines are the new big issue with them & the $300 repair bill for that makes it useless to me since I found the radio worthless as it was without any lines.

SIX-SHOOTER

My last two new Yaesu purchases were the FT-857 and a VX-7R and I will never buy another new Yaesu product again. No quality control at all and they don't give a damn about selling new stuff that doesn't work correctly. The VX-7R had a PL tone generator that put out a square wave that could not be filtered out in any receiver. You already know the FT-857 is an oscillator. Needless to say they won't get another chance for strike 3 from me.

 

[bob85]

Shockwave could be right about the case, its worth testing it with the case removed,

i have a ft100d well known for oscillation & vswr icon issues,
yaesu did some half assed mods with various grounding straps & copper tape most of which don't work at all, just looks a mess,

when mine started playing up i pulled the lid & everything worked fine, replace lid & off it went high throwing a tantrum & vswr icon would be on,

lifting the lid just a little stopped the oscillation,

i looked at how the case was grounded, measuring the inner coating with the fluke showed yaesu's coating does not conduct electricity,

the only grounding was capicitive through one small strip of copper tape at the rear of the radio & some tiny value of capacitance between the small areas around the case screw holes where the chassis touched the case,
cleaning the one piece of tape that was doing something fixed the issue for months then it started again,

there were other small strips of tape down the sides & across the middle of the case doing nothing at all because they don't make contact with the chassis,

i pulled the small tape out & replaced it with 3x wider & longer copper tape so that all the strips of tape contacted the raised chassis areas around all the screw holes greatly improving the rf grounding of the case, no more high vswr icon crazyness.

 

[Captain Kilowatt]

The thing with this problem is many non D versions are right on the verge of self oscillation. Anything from temperature change, frequency or VSWR could throw it into or out of oscillation. Stands to reason that component value drift over time could make the problem worse since the slightest change in gain could bring it out. Just taking the screws out of the cover and lifting it an 1/8 inch off the radio stopped my oscillation. That's when I knew that the cover was reflecting RF back into another sensitive stage. I assure you that just shielding over that pre-driver and RF transformer eliminates any trace of this problem.

I had an 857D several years ago & you may read my review on eHam.It was by far the worst transceiver I have EVER used or owned.You could not give me another one for FREE if I am required to keep & use it.I replaced it with an ICOM 7000 & it was the happiest day of my radio life.ZEBRA lines are the new big issue with them & the $300 repair bill for that makes it useless to me since I found the radio worthless as it was without any lines.

SIX-SHOOTER

I only got the FT-857 because I wanted a compact all band mobile radio as I used to spend a LOT of time on the road. It served me well and continues to do so so far. I agree it is not a great radio but with anything that small it is a compromise. A for oscillations in the RF section it appears that there have been many complaints about the IC-7000 doing so as well. Many people reported a blown driver section due to RF feedback/oscillations. https://www.pc5e.nl/downloads/ic7000/Mods/4517_IC_7000%20driver%20amp%20cure_UPDAT.pdf so the FT-857 is not alone in that regard. Any super compact all in one radio is going to have poorer performance that a higher end radio as you can only cram so much stuff in a box and have it all work. It's no coincidence that the higher end better performing radios are NOT all in one mobile radios.

 

[Shockwave]

The reason I give Yaesu such a bad rating today is there is 100% proof they knew about this RF feedback oscillation long before the first board was even manufactured. There are silver traces on the board that outline shielding boxes that were never installed. That means the person who designed the board knew shielding was required and the person who decided what would be installed on that board, cut corners.

Then consider the zebra striped display. How much money did Yaesu save by conductive gluing the LCD driver onto a plastic ribbon cable? Would it have cost $100 to install a PC board and solder the chip to the board? Probably not but it can cost the owner $400 to go back and get it fixed now and the problem will repeat itself if the radio is subjected to the same temperature changes again. In other words they never fixed it and will sell the same defective part again.

Then the FM squelch is so "choppy" that you have to go back in and try to install an electrolytic cap onto the surface mount board to smooth it out. Years of working at a service center that was both Yaesu and Kenwood authorized for warranty work showed a stark difference between companies. Yaesu runs like the world is on fire away from their own problems and Kenwood went out of their way to assist regardless of who or what was at fault.

 

[W4KVW]

I only got the FT-857 because I wanted a compact all band mobile radio as I used to spend a LOT of time on the road. It served me well and continues to do so so far. I agree it is not a great radio but with anything that small it is a compromise. A for oscillations in the RF section it appears that there have been many complaints about the IC-7000 doing so as well. Many people reported a blown driver section due to RF feedback/oscillations. https://www.pc5e.nl/downloads/ic7000/Mods/4517_IC_7000%20driver%20amp%20cure_UPDAT.pdf so the FT-857 is not alone in that regard. Any super compact all in one radio is going to have poorer performance that a higher end radio as you can only cram so much stuff in a box and have it all work. It's no coincidence that the higher end better performing radios are NOT all in one mobile radios.

I used my ICOM 7000 side by side in my shack with the ICOM 756 PRO II and it was every bit as good as the PRO II on HF & 6 meters. I did not see it as a compromise but that was not the case with the 857D. The 857D was Terrible on both HF & 6 meters because the filtering was Terrible on it.Yaesu should be ashamed of the 857 but as usual they feed the BS knowing that most people won’t own both radios so they can see how pathetic their radio is Again. It really was the WORST transceiver I have ever owned or used. In truth it SUCKED on its best day and I really would not own another even for FREE because it just made me angry that a radio that got so much hype could be such a huge POS . It made me miserable using it and radio is supposed to be FUN.

SIX-SHOOTER

 

[EA1AWY]

Initially a breakdown occurred probably due to the reckless increase in transmission power parameters.
After changing the failed Q1006 & 1007 mosfet drivers from some 2SK2975 to some RD07MVS1, the transceiver recovered the output power, except for the 70cm band where it did not exceed 3W. By eliminating C1039, the equipment could be adjusted to 20W in UHF, but a powerful oscillation (60W!!) appeared over 425MHz when transmitting in that band. This only happened when putting the covers on the equipment. I was able to eliminate it by soldering a 10pF capacitor in place of C1039 and adding antistatic conductive semiconductor packaging about the area of the driver and pre driver amplifiers . Specifically, one that was about 10kohm when measured with the multimeter. Both measures stopped the oscillation, so I implemented both for greater safety. In case it might be useful to someone. Greetings

 

[Shockwave]

As a side note, mine blew up the drivers again about 2 years ago and I won't even consider fixing this piece of garbage again. The original drivers used in the non D version, are absolute garbage. No wonder why they abandoned this part on the newer version. The problem is, when you send the old radio in to have them replace these parts soldered to the copper spreader, of course they put the same old junk back in rather than the new part. Another F minus grade for Yaesu.