Installing those new relays in your FT-102


For those who have bought the FT-102 relay kits. Here are some hints to do the job.  Please do not consider these to be step by step instructions, however my notes may help you do the job.

Basically replacing the FT-102 relays is not a difficult job to do except for one relay that sits under the band switch, RL05 on the RF Unit.
My advice on doing the job is TAKE YOUR TIME, DON'T be in a rush. Do the RL01 in the PA compartment one evening.
Loosen up the screws on the rear panel that hold the rear panel to the chassis. This will allow you to pull the panel out
about 1/4 to 1/2 inch. This gives you some room. Needles to say remove all the covers for first, then the PA tubes
and set them all aside. There is one yellow wire at the bottom of the Relay board if you want you can unsolder the
yellow wire and this will allow you to pull the board up some so you can work on it, don't pull on the wires any more then you have to.

Replace RL01 T/R relay and then reverse the process. Take your time and only do that one relay part of the job then set it aside until you
get the time to come back, don't try and do it all at once. Reassemble everything and test the rig after you change
RL01 on the Relay unit (antenna T/R relay) test the rig and if all is a go, then take a break or proceed to the RF Unit.

    New Fujitsu RL02 Installed (See optional RL02 installation suggestion)

RF Unit.... You get to the bottom of this board by carefully folding the AF board back.  I recommend you take a small plastic Ty-wrap and secure the board in a laid back position when installing your new relays on the RF unit, this way the board will not be flopping around while your working in the transceiver.  Use one of the screw mounting holes on the audio board, slip the Ty-wrap through one of the existing holes and secure it to the bundled package of wiring in the set, this will keep the audio board out of your work space while doing your relay replacements.   I work with the rig flat on the bench, when I put in a relay I chose to hold it in place with my finger, put a small piece of solder near the relay leg and tack solder one leg in first. Push up on the relay and then solder it again, then do the rest of the leads.  DO NOT bend the relay legs to keep it in place. This will make it very difficult if you ever have to replace them down the line
and will ruin the board if you have to take one out again some time in the future.   More so recently:  Instead of using a finger to hold the relay in place during the soldering process, I tried  using a piece of cellophane tape to hold the relays in place from the top of the RF unit.  This worked out nicely, then I flip the rig back over one time and solder all the connections.  Removing all the relays at one time letting them fall to the bench really sped up the process.  I let all the relays drop to the bench, flipped the rig over. Pushed in all the new relays into the clean holes, using cellophane tape to hold all of them in place I only had to turn the rig over one more time and I soldered all the relays at once.

For more info on replacing FT-102 relays visit Jose's web page for more ideas as to how do the relay replacements,  Jose has some good pictures on his site as to how he did his installation.

  New RL05 Installed directly to the circuit board .

As for RL05 under the band switch. I've heard of different ways of getting this relay in and out. All agree that you
have to unsolder each leg on the front two band wafers on the band switch. I personally don't mind doing a little
extra work and taking my time doing so in order to do a job right. I disconnect the loading shaft and pulled it out, also disconnected the plate shaft and pulled it loose from the front. Then I removed the three screws on the front panel right side, this will allow you to pull the front of the radio forward about 1/4 to 1/2 of an inch. For the few extra minutes in doing this, it gives you a lot more room to work with from the front of the rig.
put the band switch straight up on 18 MHz and mark the band switch before you pull the panel forward.
In case you have a brain fart and some how the band switch moves, you will know
where it goes back together. If you do it my way and pull the front panel forward a 1/4 to 1/2 inch
Put all screws and parts in a container and don't loose them when you work.

I talked to Malcolm about this process for replacement of RL05.  Mal said NOT to pull the panel. It's up to you. Mal told me that he unsolders
the two wafers from the RF Unit and lifts up on the band switch wafers about a 1/4 of an inch and puts the relay on double sided stick tape attached to a pen or something. The he some how pushes it in. This may work for him but it's tight getting in to the front of the rig there with the front panel so close and you risk bending a pin on the small relay if it does not fit into the holes exactly right. So you have a choice, try Malcolm's way and maybe have to fight with it. Or pull the front my way and still fight with it, but hopefully less of a fight getting RL05 installed.  One other thing you might like to make note of at this time as this has been an area of discussion time and time again. There is a 12 VDC / 24 VDC modification that puts both RL-04 and RL05 in series. You might check and see if this modification has been done to your rig. We will discuss this further after you have completed your relay installation.  If you would like to jump to the section where we discuss the 12/24 VDC mod click here.

Remember what I said in the second sentence at the top. TAKE YOUR TIME.

Most hams have more then one rig in the shack today, so don't get in a big rush to do this job.

NOTE; RF AMP Protection Mod: See this pdf file.

  New RL01 & RL02 Installed on to the RF Unit.   

I was in no rush and even with pulling the front panel loose the whole process of replacing every relay on the RF Unit
took me a little over an hour, maybe an hour and a half to do the entire RF Unit relay replacement job.
You can do it how you please, but I feel by pulling the loading shaft allowed me to get my fingers into the area of
RL01 / RL02 on the RF unit much more easily.

  New RL03 and RL04 Installed

RL03 and RL04 are fairly straight forward and easily enough to replace.
Make sure when removing the old relays your soldering iron is hot enough to melt the solder
but not so dammed hot you destroy the circuit board traces when removing the relays.
Use SOLDER WICK to suck up the excess solder. DO NOT USE A SOLDER SUCKER. When the relay is out
use the solder wick again to make sure the hole is completely clean before attempting to put in the new
relay in place.

OPTIONAL RL02 Installation procedure (RF Unit)

An interesting idea that I have seen in several FT-102s I've serviced had this neat little modification done to the RF unit by Malcolm (NC4L) is to modify a 14 pin I.C. socket and  mount RLO2 on the socket.  The following pictures were sent to us from WA3URR David Hartwick.

Typical 14 Pin I.C. Socket 

Remove unused pins from socket leaving only those required to make contact to RLO2

Take your new socket in hand, with a good pair of cutters trim the edge of the socket so that the relay will fit firmly against the socket when installed

Install your new socket in place where this relay resides.

Plug in RL02 and away you go!   Nice mod Mal!  I did this same modification on the last couple of rigs I worked on and it was every bit as quick and easy as installing the relay to the board itself, I highly recommend you pick up a couple of 14 pin IC. sockets and do this modification if you're planning on replacing your relays at anytime in the near future.


By the time you get this far, you have completed the hard part and will have installed six out of eight relays included in the Fox Tango relay package.

FT-102 IF Unit     FT-102 Control Unit

You will install one more small Omron relay on the FT-102 I.F. Unit and one on the Control unit. Since there is only one relay on each of these boards, this should be pretty much self explanatory.  After replacing these relays you are finished with the relay modification for you rig, with the one exception noted below.


The FT-102 has one more relay on the RF Unit.

This is the board that resides directly under the final amplifier tubes that has the three tube sockets.

We did not include this relay in the kit. The reason for this is the best thing to do if this relay becomes intermittent is just to remove it.

Your FT-102 will either have the relay on the board you see to the far left, or it will be attached to PB2356A as an add on board.  When you remove the board move cut and insulate the white / blue wire so it will not touch anything, or pull it out all the way out removing it.  Move the white / orange wire to the place shown in the picture to the below, this wire will carry be your screen voltage.  Study page 63 of your FT-102 technical supplement (Final Unit Parts Layout.)  You will note there is also diode D02 that delivers the screen voltage to the tube, use DO2 from the small circuit board PB-2356A and mount it with the (+) cathode end facing the tube.  In this case the anode of the diode is soldered to the white / orange wire and mounted in a piece of heat shrink tubing. Lastly the small thin brown wire that was attached to the (28 MHz) point to activate the relay can be cut off or totally removed from your transceiver, on most transceivers you will more often then not find this wire has already been cut on the Local Unit at diode D-36.

When the relay is removed and the wiring completed, it should look like this.

Final Unit, PB-2355 why remove RL01?

Here is a little more info on RL01 on the Final Unit (The board with the 3 tube sockets) RL01 should drop the screen voltage from 210v to 160v when the transceiver is switched to 10m. The circuit on the Final Unit can bee see on page 63 of the technical supplement in the lower right hand corner see L07, R06, Q01 transistor switch (2Sc1815) which then goes to the coil of RL01. How is this supposed to be done? In the lower right hand corner of the Final Unit you see a contact at L07 Labeled 28 MHz. There is a brown wire on this corner of the board. That brown wire if you're willing to take the time and trace it back goes all the way back to the Local Unit PB-2345. How do I know, I followed it back. It's tack soldered on to the Local unit at the Cathode end of D36 (It could be on D35/36/37/or/38) as all the cathodes of these diodes are tied together on the local unit. The other end of these diodes goes to P40/J01, which then goes to the band switch 10-meter positions. 

RL01 of the PA board should be bypassed. Yaesu initially placed it there to switch the screen voltage to a lower value when on ten meters for better efficiency. The relay was inconstant and gave them troubles so they just left it in the radio without switching it on or off. Since they didn't make the radio with RL01 active for regular production they took it out of the schematic so you will not see it although it is most certainly there. It was easier to erase it from the schematic than alter and redesign the boards.

So just take the orange and white wire and place it on the other side of the relay so there can be no problems.

Finally One last thing regarding the 12v / 24v relay modification on the RF Unit. This modification will only have an effect on two of the relays on your RF unit. (Rl04 and RL05) This modification put RL04 and RL05 in series with a 12vdc voltage drop across each relay.  Most likely this has already been done in your transceiver, if not check out the PDF file below, print it and follow the performance modification.  My photos should help you complete this modification.  To see what it is we are talking about here, down load and print out the following PDF for your files.  See RF Unit 12volt Vs. 24volt relay modification RL04 and RL05  Our suggestion to you regarding this modification is if you have this modification installed in the rig and it is working leave it alone, go ahead and replace your relays with all 12 VDC relays and leave the modification in the rig.   Basically speaking if it works don't fix it.  More so recently I have come to the conclusion that this modification may be more necessary then first thought.  I recently received an FT-102 back on the bench several months after all it was returned to the customer.  At the time initial repairs were done all of the relays were replaced on the RF unit using the 12 VDC relays supplied in the Fox Tango Relay Package.  When the rig came back to me after several months in operation, it had a catastrophic failure in the 24 VDC power supply and a defective 15 VDC regulator on the rectifier "B" unit under the transceiver.  The receive was basically inoperative due to failure of the power supply board.  Now it's hard to say if the parts on the power supply board just gave out on their own or if it had something to do with the new relay installation, one will never know for sure.  After repairing the 24 VDC supply and replacing the 15 volt three leg regulator things started to come back to life in the transceiver.  However the receiver was still rather erratic and would come and go.  A slight push on the RF unit and the receive would pop back in. I wasn't sure at the time if we had an intermittent connection or some other problem,  at the same time I also noticed that RL05 was very warm,  being concerned about this and not wanting to see a second failure of the rectifier "B" power supply unit I decided to check the voltage on RL05.  It was nearly 21 VDC, far more then I would have cared to see at this point.  So I decided to go through with the Yaesu suggested 12 / 24 VDC modification as noted in the link above.  It basically very simple modification that boils down to putting RL04 and RL05 in series on the 24 VDC rail.  You will isolate two points on your RF unit circuit board then run a wire between both of those points.  Having done this it seems to have helped considerably and the relays were both at room temperature when completed.  I would recommend you look into this modification as a last step to your rely installation.  See pictures attached below for guidance in doing this modification if it is not already installed in your transceiver.  An alternative way to do this would be to install two 24 VDC relays in place of RL04 and RL05.  If you purchase the relay pack from Fox Tango, you will received all 12 VDC relays because this is what the FT-102 was sold with in it's original production and the modification is not all that difficult to do as noted in the pictures below.

I hope this helps you out a bit.
If you have any problems please feel free to drop me a note.
Carol W4CLM



Trouble shooting problems during relay installation

Many Fox Tango members have written to me telling me how much they appreciate the Fox Tango relay package for their FT-102.  I'm really glad to hear this and I thank you for writing. I had only a couple of folks write back with problems, so I would like to take a moment and try to address these issues.

While not highly technical in nature, the replacement of the FT-102 relays should be pretty well straightforward, remove the old, pop in the new, RIGHT? Well yes and no.  Let me caution you again

#1) Never be in a rush when you're working on your rig. If your tired, put the damned thing down and come back to it tomorrow.

#2)Check your work. This means not only to check your soldering and what you are doing in regards to installing the relay at that moment. You need to work slowly and it's wise to check the operation of the transceiver in sections. I highly recommend this. In other words if you change your RL01 in the PA cage, the T/R relay. Put the rig back together and test it after you install that relay. Make sure it all works as before (be it good or bad) just make sure the symptoms have not changed from that of what you started with prior to doing your relay installation job. Then move on to the next board.

#3) Again Check your work. Lets assume you move on to your RF Unit and start replacing relays on this board. All the relays go in great! Works looks great and you did a fantastic soldering job.
But you turn on the rig and you have a whole new world of hurt and new problems. Could it be your relay job? Possibly... But let me caution you all of the wiring in the FT-102 is very thin and can be brittle at the solder joint where connected.  In the photo below we see a good example of the wiring at the terminal strip that resides right next to the audio board.

When you lift the audio board to get into the bottom of the RF unit. It is very possible that you might break a tiny wire that is tied to the terminal strip right along side the audio board. Thus your symptoms have changed, you think maybe the relay installation job was at fault when indeed you only broke a wire some place. SO USE CAUTION, PROCEED SLOWLY, ALWAYS CHECK THE LAST PLACE YOU WERE WORKING IN SHOULD THE RIG GO HAY-WIRE AND THE SYMPTOMS CHANGE! I can't tell you how many wires and problems I have had to go back and troubleshoot due to my own carelessness, but it happens.

Working on an FT-102 this past week I had to replace the DELAY control on the front panel. You talk about a job. The control was working, but the spring mechanism inside the switch went Wacko and the button would not stay in when pushed. I had the front pulled off slightly to the left side finally got the row of controls out and did the job. You would think all would be great! Not so. When I tested the rig last night I could not get power out in the tune position. I could tune up the rig in AM mode and with a whistle in SSB mode everything looked great, but no TUNE. Upon inspection of the mode switch, more time and more work. I found I broke one tiny glass diode on the mode switch. Replaced the diode and everything is back to normal.

So the whole point in writing to you today is to remind you over and over again, take your time and check your work. Problems can pop up even for the best technician, if a tech tells you they never mucked up something you know they are not being truthful. It happens to everyone and it can and will happen to you! Be careful and always, always go back to the last place you were working in the rig if the symptoms should change. In this case working with the Yaesu FT-102 it's really very easy to break small wires when removing circuit boards or while doing even a very minor repair.

Lastly, we have all heard it before. For goodness sake! Discharge the H.V. caps in this rig before you work on it. The FT-102 will usually show about 900 Volts D.C. on the plate of the final. The H.V. caps under the rig will pack a real wallop and wake you up if you forget to discharge these things. With an AC shock you can get killed with relatively low voltage 120 VAC or what ever, because you can't let go of the current! In the case of DC, it's not the amount of DC that will kill you. It's that sudden stop when you fall off your stool and your head hits the deck!

Best Regards
Carol W4CLM





Updated 4/20/2013


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