Thankful for you video ! Purchased a 857D radio that was acting oddly. I went into the service menu and found values very out of spec Most at 0 !! I am glad I did not have to go that deep in the radio !!
Mr Carlson's Lab Hi Paul thanks a lot for watching the adventure :-) So do I while watching your videos. Can't wait until your next expedition into electronics :-)
Hello there Peter once more. Thank you for another very interesting video in the successful repair of the Yaesu FT_857. I do not know how I have missed this one from over three years since you carried out the work. Anyhow well done and I look forward to seeing more of your work on video. 73 de John - G0WXU.
Thank you very much for your repair video. I have replaced a filter in the receive section in the past so I have been inside a FT-857D before. Now I have confidence to fix blown finals if the need arises. Thank you again.
Always nice to see that the new parts fix the main problem, right? Also, nice to see the new parts work as intended, instead of getting bogus parts from the supplier, which will drive the tech almost crazy. Another fine video Mr. Peter. Thank you.
Terrific teaching video....learned an amazing amount about the 857D, radio theory and practice. Particularly helpful to have the advice on heat dissipation and any attempt to 'stress' the radio by seeking to increase TX power. Thanks very much. AC2UQ
Still watching your videos. Keep 'em coming, Peter. I really enjoy watching a very good tech doing his magic on various radios. I sold all my test equipment years ago when I quit modifying CB radios for folks. I would open up a JC Penny's CB 40 channel CB so it would go above 40 channels, i.e., 27.405.00MHz and above. I drilled a hole in the top of my JC Penny 6241 SSB and inserted a plastic tuning wand into the frequency oscillator so I could swing it up + for going above 27.405.00MHz. PLL chips are really easy to re-program; you just cut a trace, add a resistor and either remove 5 volts or add 5 volts. I used to charge $20.00 per radio for the mods. I got my start into ham radio by first becoming involved in CB radios in the mid 70's. W Rusty Lane K9POW in eastern Tennessee
Good work. Like your methodical approach to troubleshooting. Very helpful. I'm repairing an FT-450 that was transmitted into. Looks like both driver and final MOSFETs are bad in my case. Thanks & 73.
Brilliant video and troubleshooting steps, I learned a lot, am grateful. However, I came here to compare my FT-857 to any other one to see what the DSP-2 module looked like, in case it was included. (I do not have a DSP-2 and wish I did.) To my surprise, this radio looks NOTHING like the PCB in my radio, not even close. I looked again from the beginning and at 8 seconds hear it identified as an FT-857D, not the previous plain "857" model. So I conclude that the _headline_ is in error as the all-important "D" was omitted, FYI. These two versions appear to be hugely different from each other. I'm tempted to go back inside mine and take the board out and look at the other side too, but I probably won't any time soon.
RD7MVS1is a somewhat fragile MOSFET device, but if not 'abused' will provide excellent service life. Vertex and Kenwood commercial portables use this device as a P.A transistor. Vertex(Vertex/Standard) which is now Motorola.
I have a Vertex VX-1700 and I haven't checked , but I do wonder if it uses the same final transistors as the 857D. I believe that 2879 finals can withstand more abuse, but if you think these Yaesu/Vertex finals are durable then this puts my mind at ease.
Great video as always Peter, thank you :) I think I can see a solder splash between the B and E tabs at 36:01 ;) which is giving the short circuit reading on that one. The 'scope showed you had DC bias of a volt or more on the bases which is more characteristic of open circuit B-E junctions. Your advice to change both is very sound. These RF power transistors often have 4 or more junctions in parallel inside them, and one or more junctions can fail open circuit. The device will still test okay with a DC meter, but obviously not work properly at RF. It's also worth pointing out that these devices contain beryllium oxide which is very toxic- don't try to open them up; and as you say always screw them down first before soldering or you will very likely break the case open and release the berylliuym- not to mention the magic smoke!
Alan Cordwell Hi Alan, you are right looks really like a solder splash. But also tested with DMM and sure that the trani is dead :-) Thanks for all your additional hints sure it is a valuable information for the audience.
My rig went dead today. I first thought I had this problem too, but I only have no TX power on AM. SSB is still working fine. AM does not work on VHF/UFH as well. I am not sure what the problem in my rig is, I will have to look into it on sunday. Anyways, thanks for this detailed repair walk-through! There's not a lot of people out there that would go through all this effort and show the whole repair including how to isolate / find the error.
I hope they are a matched pair. If not, one device might be driven properly, and the other, might be 'coasting' and not equally excited with the split signal from the input matching transformer. The HFe should be equalized to balance drive/output power.
I had an 2014 spec radio with the filter problem resolved by the factory. I opened the radio for 27 MHZ but the FM and AM modulation was so weak , especially on AM. I performed various modifications on the AF to improve the modulation....
My brother say to heat the two screws very hot, then to screw them down to torque, saying that when they cool, they are pre-stressed and help to hold the chassis to the device much tighter, thus heat transfer does not come loose or strain the thread.
when you noticed the smaller lead length on that second output transistor i thought about a carlsons lab video where he replaced the same parts and then explained how to spot counterfeit copies . The smaller lead length was one way hopefully you will not be seeing the same radio back too soon.
+iron man Hi, fake transistors are always a problem these days you never know what you get. The problem is that all DC parameters are identical but the dynamic parameters not. That means that this transistors do not have enough gain over the entire frequency range. Example on 80m full 100W output. on 20m only 50W and on 10m only 10W. In this repair the new transistors are working over the entire frequency range so no problem what so ever. Thanks for asking.
when testing a possibly blown final, the current drain gives a good clue too. If nothing gets out and it drains 20 Amps, generally you know the final is OK but there's a problem in the next stages (filter, switches...) ; if changing the bias voltage doesn't change the current, the transistors are dead and it saves time ;-)
You'd think drawing heavy current with no output would be a shorted final hands down? OK, open relay or circuit connection on LPF board or something between the finals and antenna but ..... well, I'd keep your pointer in mind but have never seen it on about a dozen final repairs I've had to do over the years. Biggest problem is finding and paying for the !@#%! transistors! hihi
@@sputnik4216 yes, a final shorted to the ground (in this case the current will be constant : won't vary with bias) and I've seen a couple of times some trouble caused by an incorrect switching in the output filter units (cold joint, cracked cap, open relay, filter switched to the wrong band and stuck...) those radio always imagine something new to put us into trouble ;-)
Many thanks for your videos. I especially appreciate that you're distinctly speaking, to help foreigners to understand. I read several owners of FT897 and FT587d complaining that these TRX haven't really 100W in SSB mode. They see that the meter is showing RF low levels in this mode, too in France a seller is disparaging these devices. I got both (897 and 857) and I wondered if these transceivers are only showing average power, or if they are really poorly designed in the AM/SSB mode, as I read. What do you think about this claim ?
Thank you. No I have not seen a 857 or 897 which is not able to deliver 100W PEP. The problem often is that many watt meters are only able to display avg...73
I am really surprised Peter didn't check the gain on the push pull transistors to make sure they were close to being a matched pair form the factory. Surely he must have done that first before installation. I know I would have checked them first before even applying the thermal compound to the transistors. Plus you need to tighten the screws down first before the soldering is done to make sure there is no stress on the legs of the transistors in the circuit, then solder them in.
You are absolutely right those transistors have to be matched . We buy this transistors as matched pair so that is already done. And it is true that the screws have to be tighten before you solder the transistors in. Thanks for the valuable contribution to our community when I have missed it to tell.
i have this 857d in my car i have to look at the settings. but it works just fine. only issue is the vfo is really lose i have to keep it locked if i'm mobile in the car. i also have the 897d. i went into the settings in it find it was nearly all wrong i had to set 85% of the radio to spec. it works great now :) i dont have the tool to take the knob off the 857 to look at it and fix it... so it stays as is for now 73's k7sce
Not watt vatt!! Either way great video and have had the same radio great radio after having it for a year. Mine is also mars modded and I haven't had any problems with it. Also think it is just nature of the beast with these new radios, they are not the greatest on am, also have a ft-991 I just acquired, and it is the same on am, audio not that great. Think these new radios are mostly designed to work on the ssb modes, and fm and am is just a secondary thing.
Hi, I have an FT857 (no D), 50mhz, vhf, uhf work fine, low or no power out on 1-30mhz. I assume since 50mhz is full power that the HF finals are ok. I do have a blown Q3006, part of the ATAS short circuit sensing circuit. Do you think this could be causing the issue? Any help in further diagnosing this would be appreciated.
I have a Question: My SWR is 1.2 however I've got a clicking relay delay on CW, even if I set the delay on FULL, the clicking is normal, but with use of about 3 min the clicking gets more and more scrambled. I've done a full factory re-set and it solves the problem for a few min of use, then the scrambled clicking noise comes back again. I've also put an in-line 1.1. Balun to try solve the problem IF RF is making it back down the antenna. Any suggestions ? It's almost like the radio builds up capacitance somewhere, then gets confused during CW transmissions
Very interesting, and worrying since I just got a 857D which appears to transmit no power on HF (I did not test the U/VHF yet)... I hope this is nothing like this (It should not since it is supposed to be new)... fingers crossed.
I like how methodical you are in diagnosing a problem. You test as far as can be tested, before replacing a component. I believe this is the best way to teach. Thank you.
I would replace the pot with a multi turn pot if it will fit in. Manufacturers cut costs by using single turn pots when a multi turn would be better. Also I have seen pots fail due to under sizing their ratings and in the end they wind up with a bad spot on the resistance trace.
Enjoyed the video as always but I sure would like to see how you solder and de-solder those finals. I have never done it before and would like to lean. Thanks from Dave, WB8VQV
wb8vqv Hi David, ah okay will show it in a future video, it is a bit tricky. To get finals out is a combination of desoldering gun, normal soldering iron and hot air. Thanks for feed-back 73's BTW, nice tower you have :-)
TRXBench Yes I too would like to see the actual de-soldering and solder job on the finals. Also a little more on the setting of bias (locationof probes procedure) are there 2 posts that have a jumper across them that is removed 1st?
Michael Swindal Hi Michael, thanks for feed back! No it is not really required but is sometimes a good idea as you can't really predict ESD voltage levels...
Hello Peter! I was wondering if check the power in from the driver, and power out from the PA via an oscilloscope is not an option. Does the oscilloscope load down the PA, and could cause damage to the PA? Thanks for all your videos! Regards...Dan
+Beretta96Dan Hi Dan, well the respective stage was always terminated as off course needed. The driver was terminated into the PA input broadband transformer and the power output of the PA was terminates into a 50Ohm dummy load so not problem at all. 73's
Herbert Susmann Hi Herbert, yes of course this is a radio with one single bias control for both finals so you need a matched pair. A radio will never ever leave my lab without TX IP3 , harmonic and spurious test after PA repair. Thanks for watching and asking 73
sehr geniales video! dein englisch ist klasse. ich glaube ich kann noch viel von dir lernen als angehender ham. eine frage... warum das blaue armband ab minute 48:00 ??? um statische aufladung zu unterbinden? 73!
Natureman Hi, vielen Dank für das positive feed-back. Ja, absolut richtig, das Armband ist dazu da, um vorsorglich jegliche mögliche Aufladung abzuleiten, damit empfindliche Bauteile nicht beschädigt werden können. Viel Spaß auf dem dem Weg zum HAM. 73
Peter having looked at this repair I wonder why they have 1 censer on 1 of Transistors and not on both maybe this would protect the radio from serious damage just a suggestion would a 2nd heat censer fitted to the other transistor help to protect the radio?
TRXBench good morning, my name is Antonio and I followed with pleasure his illustration, if you could please let know the Yaesu entered the famous "blocking capacitors" on three capacitors that were once signed TOKO? I hope for a response, the greeting cordially
My FT857 works BUT all of a sudden I can't change BAND! The BAND switches UP/DN just ignores me. Tried to remove the head but it seems stuck and doesn't want to pull off. Don't want to break it. Does anyone know what I did wrong this time? The only things plugged in are MICROPHONE, ANTENNA, POWER and EXT SPKR. Anyone have any clues for me? AF4K Bry
