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Wendymott 18th Jul 2021 5:47 pm

Yaesu FT290
Hi peeps. I acquired a Yaesu FT290 recently, and have done a few changes both on Rx and Tx stages.
However, I would like to add a speech processor / compressor in the Mike casing. I have plenty of SMD SSM2165 vogad devices, and I would prefer an electret mike module.
The problem is the Mike connector is a 7pin plug / socket.I need + V for the vogad / mike supply. I really do not want to change the socket to an 8 pin, have you seen it ?? Has any of our members done such a mod and how did they go about it ?
I could disable one of the push switches as in + /- channel change or the FST button, and it may come to that unless someone has a better idea.
Thanks in anticipation :D

G6Tanuki 18th Jul 2021 6:10 pm

Re: Yaesu FT290
Not sure about your particular circuit but in times-past I built a 1750Hz repeater-toneburst into a Pye "shaver"-style mic casing, using a CMOS chip for the crystal-osc/divider and powering it from a tiny wire-ended NiCd battery of the type intended for memory-backup.

Cunning trick: the battery was charged through a 1N4148-and-5K-resistor combination across the PTT switch; when the PTT was open there was 12V across it and 'stealing' a couple of milliamps to charge the battery was insufficient to cause any issues.

These days I'd use a 'supercapacitor' rather than a battery - either way it should be able to provide a few mA for your processor - just so long as your transmit:receive duty-cycle is sensible and gives the charge-storage-device enough time to refresh itself between 'overs'.

Restoration73 18th Jul 2021 8:40 pm

Re: Yaesu FT290
You might be able to isolate the pin which is normally connected to chassis and rely on the
chassis and the metal mic plug body as the signal ground.

Sparky67 18th Jul 2021 9:04 pm

Re: Yaesu FT290
Could you DC-block the mic wire with a cap behind the fixed connector in the radio and then feed +Ve volts up it to the mod in the mic itself? You might want to current-limit the voltage source to prevent any nasty happenings if a s/c occurs in the mic...!


SiriusHardware 18th Jul 2021 11:58 pm

Re: Yaesu FT290
There is a precedent for this in the form of the old K40 speech processor / compressor microphone which was originally designed for for the USA CB market, ie, for AM and SSB.

Since few CB transceivers had + supply available on the mike socket the solution was as outlined in some of the suggestions above - a small amount of power was drawn from the PTT rail during RX mode to charge a capacitor which provided the compressor IC with a power supply during TX.

I actually often considered connecting an original K40 microphone (which I still have) to my FT290R2, but for some reason never did get around to trying it.

One reason may have been that K40s sounded very harsh on FM which they were never designed for, so it would have made it necessary to carry the original microphone around as well, for FM operation.

Terry_VK5TM 19th Jul 2021 2:38 am

Re: Yaesu FT290
Wendy, if you replace C01 with a non electrolytic 1uF cap, you should be able to drop a current limited 12v on to the mic line without any problem :)

Wendymott 19th Jul 2021 2:56 pm

Re: Yaesu FT290
Well peeps.. you certainly came up trumps with several ideas...its too warm in the workshop at the moment to concentrate.. but I shall certainly be looking into the suggestions :D Thanks all :D

Jon_G4MDC 19th Jul 2021 3:00 pm

Re: Yaesu FT290
The best type of speech processor is generally reckoned to be an RF clipper.
This might be considered. I have built a couple but not put them to use yet so can't comment on how good they are.

Wendymott 20th Jul 2021 12:28 pm

Re: Yaesu FT290
Hi John. Very interesting !!.... another avenue to explore... Thanks :D

Wendymott 21st Jul 2021 8:04 pm

Re: Yaesu FT290
2 Attachment(s)
After a lot of poking and prodding... it seem there were two "spare" wires in the Mike lead. Thus I dont have to "Piggy back" the DC on the AF wire.
Apparently the FST button is there but has no function.... its not even mentioned in the I /B .
I am not going the RF compression route with this one..... however I will seriously look at it for my 2M SSB base station.
I attach the circuit I am going to use...the pcb fits into the old mike area.
The HARD part will be gaining access to the back of the Mike Connector, but a "faint heart never won a fair maiden" .

Wendymott 30th Jul 2021 9:15 pm

Re: Yaesu FT290
Hi Peeps...... HELP !!! Please
My first FT290 is now in a good place... as in.. it works well in both modes. However, there was one on Ebay which was a "reserve".. just in case my primary radio needed parts. It was bought as.. "Spares or repair". Well, as I had success with my first I decided that "repair" was a possibility.
The controls function and the display is in good condition. The 10.81 Mhz I.F strip on RX is comparable with Set one. What appears to be wrong is the VFO is operating at approx - 6 Mhz below carrier than -10.81 Mhz. And there is no frequency shift with the set frequency control.
I looked at the alignment procedure for the VFO and there is no change in the L/O frequency when adjusting the 18.74 Mhz oscillator as per the manual. Set one confirms a fault. I compared all the voltages on the connectors of both modules (front panel) and all seem ok.
Obviously the PLL is sick.... has anyone out there had any experience with the uPD2819 PLL going faulty.
Over to you :D :D

Terry_VK5TM 31st Jul 2021 1:17 am

Re: Yaesu FT290
UP2819 - is pin 7 high or putting out a pulse train (high = pll locked other = unlocked)

And is the 5.76MHz xtal working (pins 2 & 3).

And the obvious one (measured on the actual IC pins) - +5V (Pin 1) and GND (Pin 13)?

Is it receiving data from the MCU ? Pin16 = CLOCK, Pin 17 = DATA & Pin 18 = LATCH <- should be a positive pulse at the end of the word transfer.

Edit: There are also a lot of very low value electrolytic caps around the PLL ic and tuning voltage buffer that I would be suspicious of as well.

Radio Wrangler 31st Jul 2021 6:56 am

Re: Yaesu FT290
I have a funny feeling there is a scrap FT290 damaged by nicad leakage sitting around somewhere. It's been there for about 20 years with the intent of finding another for spares, which never happened. I'll see if I can dig it out.

I think the digital controller side of it got 12v or so in lots of wrong places via the conductive electrolyte shorting things.


Wendymott 31st Jul 2021 11:17 am

Re: Yaesu FT290
Hi David and Terry..... Terry... All points covered.....I have used the good one for comparisons and it all seems to check out. EXCEPT Pin 7..... will check that :D.

David.. can I PM you re some sort of acquisition :D

Wendymott 31st Jul 2021 1:15 pm

Re: Yaesu FT290
Well the good news is... The controller pcb module is fine :D Pin 7 of the loop IC is hunting.. as in pulsed...the VFO tunes to RF in - 10.81 I may look on ebay for a loop IC. Even though offers of a scrap FT290 is imminent .
The HARD part will be removing the Base plate screen ..BIG Iron needed.

Terry_VK5TM 31st Jul 2021 1:57 pm

Re: Yaesu FT290
Don't jump too fast - what do you get on pin 14?

Should be the product (I think) of 18.7414MHz (X02 & Q3009) and what ever Q3001, 002 & 003 is producing.

Edit: You should get a frequency between 2 & 5.99MHz at pin 14 as you tune across the band.

Wendymott 31st Jul 2021 2:36 pm

Re: Yaesu FT290
2 Attachment(s)
Hi Terry.
On the DUFF "Radio B" one.. I get two frequency carriers... one on say 134.23 and the other on 131.18... neither move when tuning is rotated.... on the Good one Radio "A" ..I get a lot of Hash / carriers... But they shift with the tuning pot.
See attached photo's

Terry_VK5TM 1st Aug 2021 12:26 am

Re: Yaesu FT290
1 Attachment(s)
Can you reach pin 10 of connector J02 on the CPU board?

Is the voltage varying somewhere between 0 & 5V when you tune?

The 131.19 frequency should vary as you tune - this does not come from the PLL chip but from the CPU.

Attached pdf is block diagram with the PLL and frequencies you are seeing lower left - sounds like Q3004 is not mixing.

You'll need to zoom to about 400% to see it clearly.

Radio Wrangler 3rd Aug 2021 11:34 am

Re: Yaesu FT290
Scrap FT290 found!


Wendymott 3rd Aug 2021 12:06 pm

Re: Yaesu FT290
EXCELLENT David :D Please pm me to arrange where and when :D

Wendymott 11th Aug 2021 4:28 pm

Re: Yaesu FT290
Well with the aid of Terry and David, I Now have two operational radio's. With the mods I made to radio 1... I can generate 5W FM into a 50R dummy load, however this has been backed off to 3.5W, as I dont want to over drive the PA in SSB mode.
Radio 2 was a bit more of a challenge, where David's scrapper came into its own. R2 had an iffy mode switch, very noisy, and after some "tail chasing" decided it needed replacing..its sealed thus no chance of getting any cleaner into it. So thanks to David, I did a switch swap. Plus a Dual gate fet replacement.............. Oh yes a TOTAL re alignment.... the person I bought it off stated.. "spares or repair"...he neglected to say.. EVERY coil, trimmer and preset had been "adjusted" when all that was wrong was the post amp of the PLL oscillator was duff. Ah well.. not much you can do...
One other mod I made to both was to rewire the DC input socket, which is wired at -V centre pin...As I dont want the internal battery set up, it was changed to + centre pin. This then cancels any confusion in the supply department.
One other point to note... due to the age of this radio.. it is all "Hairpin leaded" components.. packed so tight you wonder who designed it. Service wise a heat gun is essential to remove some components as the pcb is PTH "plated through hole". I replaced some components, that were impossible to relocate with SMD parts.

Terry_VK5TM 11th Aug 2021 11:24 pm

Re: Yaesu FT290
Re the power supply socket change - remember to grind off the markings on the the back underneath it - other wise uncertainty will remain if somebody else uses it.

Wendymott 12th Aug 2021 9:53 am

Re: Yaesu FT290
Good plan Terry... I had already marked it as such..... both workers are now modified :D

Wendymott 24th Aug 2021 9:49 pm

Re: Yaesu FT290
In the last couple of days, I have been dismantling one of the "poorly" 290's. And its quite a job. Who or whom ever designed the main pcb, must have had some sleepless nights..It is literally jammed with components.. not a spare mm2. To strip the pcb it is impossible without a heat gun. The PTH pads especially the ground pads really suck up the heat, and no matter what you use. All the leaded components are "hairpin" formed thus allowing such a compact assembly. This is where it gets virtually impossible to fault find. If you are working on one without another, to locate the actual component, it is near impossible, as I have not found any pcb component ident data, except for the alignment pages. showing the key adjustments..
Another discovery was...the amount of "interconnect" wires..... NO wire Links.. just pvc coated wires everywhere. This is where I have been going wrong... my pcb designs are based on T/C links to get power from A to B.....thus the pcb's are larger than need to be...neater yes...but space wasting. Lesson learnt.

Terry_VK5TM 25th Aug 2021 12:23 am

Re: Yaesu FT290
1 Attachment(s)
So something like this might be a help?;D

Wendymott 25th Aug 2021 1:45 pm

Re: Yaesu FT290
Thanks Terry......will be a BIG help with my next foray into the innards :D

Jon_G4MDC 25th Aug 2021 7:36 pm

Re: Yaesu FT290
Remember seeing in one of these and thinking "how do they build it and make any money from it ?".

SiriusHardware 25th Aug 2021 7:40 pm

Re: Yaesu FT290
My FT290-R2 cost me not much short of 500 when it was a current product. I don't think they did too badly out of us.

Wendymott 25th Aug 2021 10:04 pm

Re: Yaesu FT290
Jon... One wonders..... the number of inductors, Xtals and filters.... plus all the semi's.. may have been a "loss leader" to get into the market.

Terry_VK5TM 25th Aug 2021 11:34 pm

Re: Yaesu FT290
The amateur market was (and still is) too small to run "loss leaders".

They would have made money on each and every product they sold.

Radio Wrangler 26th Aug 2021 4:31 am

Re: Yaesu FT290
At the time the FT290 would have been Yaesu's biggest seller by some margin, and well ahead of the other makers.


Wendymott 26th Aug 2021 1:21 pm

Re: Yaesu FT290
So that theory has been well and truly shot to pieces :D

G0HZU_JMR 26th Aug 2021 4:59 pm

Re: Yaesu FT290
1 Attachment(s)
Rummaging in my stash of old and dusty 2m radios I still have a Standard C58 multimode and a Yaesu FT290R mk1. The C58 has similar features as the FT290R and is even smaller.

I think they both had a similar selling price in the magazine adverts way back in 1981.

G6Tanuki 26th Aug 2021 6:43 pm

Re: Yaesu FT290
It's interesting to note that the 'Standard' company palled-up with Vertex [who made a lot of professional/commercial two-way-radio gear] and eventually merged with.... Yaesu!

I've got a little "Yaesu" VX150 hand-held radio here, dating from the end of the last-century; it is the same chassis as was sold to the commercial market as the VS150, VS being "Vertex-Standard".

Terry_VK5TM 3rd Sep 2021 11:56 pm

Re: Yaesu FT290
Does anybody per chance have a paper copy of the schematics for the FT 290 and could either do or arrange for it to be scanned at 300dpi or more please in BMP or SVG format? Or even sell it on so I can scan it.

Even if it was scanned as seperate overlapped pages, I can join it together.

Along with Wendy, I now also have a '290 and although mine is fully working, it would be nice to have a really good copy - 'just in case'.

All the ones I have been able to track down on the 'net are either low quality or have a flaw of some sort right in a critical part of it.

G0HZU_JMR 4th Sep 2021 12:56 am

Re: Yaesu FT290
I did a similar thing many years ago and joined some scanned pages together to make up a huge image of the schematic. However, I only had access to someone else's scan and it wasn't good quality to start with.

I think I posted it onto the FT290R user group about 10 years ago but I'm not sure if it is still online. I had a quick look and couldn't find it. However I did upload it to the link below a while back but you have to click on the image to zoom in to see the best detail.

If I'd been given a decent set of scanned images it would have been a lot better in terms of quality. However, I did find it useful when I first bought my FT290 on ebay. In those days they could still be bought for sensible money. I paid 36 delivered for mine although I did have to sort out the s-meter circuit as the AGC/s-meter were stuck at full scale. I got fed up trying to navigate the FT290R schematic on separate pages so I stitched them together in a huge composite image.

Terry_VK5TM 4th Sep 2021 4:16 am

Re: Yaesu FT290
I got that one thanks Jeremy from an archive of the old Yahoo group (The Electric Handbag).

Unfortunately, as you say, once you zoom in it goes to :censored: and turns in to a blurred mess.

I also got a pdf (3 separate pages) which you can zoom in quite way and it stays mostly legible, but there are some spots where it is very indistinct, like where things on page folds tend to lose clarity.

I did try to join The Electric Handbag in it's new home on Groups IO but it looks like it has fallen by the wayside unfortunately as I didn't get any response to the request.

mickm3for 4th Sep 2021 12:30 pm

Re: Yaesu FT290
1 Attachment(s)
Hi this holds up well if you zoom in mick

Wendymott 4th Sep 2021 4:38 pm

Re: Yaesu FT290
Sorry Mick. Its the same one.... what we need is a member of Yaesu staff that worked on the thing and "borrowed" a copy.. until then... we struggle.

Restoration73 4th Sep 2021 4:48 pm

Re: Yaesu FT290
This version may be better

Terry_VK5TM 5th Sep 2021 1:05 am

Re: Yaesu FT290
Got those, by the time you extract the schematic as images and then stitch them together they lose clarity - well, they did when I tried it, I could have been doing something 'not quite right' :D

Pity there isn't (that I have seen) an 'app' that will work to stitch PDF pages together.

mickm3for 6th Sep 2021 3:09 pm

Re: Yaesu FT290
Hi just been in contact with Yaesu teck dpt (i know them quite well) and it seems there was never a paper manual for this set they have not got one listed in the Archives at head office, so we are limited with what we can find online Mick

SiriusHardware 6th Sep 2021 5:02 pm

Re: Yaesu FT290
It sounds like this is a circuit crying out to be reverse-engineered and redrawn in Kicad or something similar.

It does happen, I won't bore you with the examples, but people do sit down and redraw the entire circuit especially if the only known ones are quite poor.

The MK2 (FT290R2) does have a proper service manual - or in Yaesu Technical speak - 'Technical Supplement', which is a term always worth searching for if you are looking for a Yaesu service manual.

dsergeant 6th Sep 2021 6:01 pm

Re: Yaesu FT290

Originally Posted by mickm3for (Post 1404394)
Hi just been in contact with Yaesu teck dpt (i know them quite well) and it seems there was never a paper manual for this set they have not got one listed in the Archives at head office, so we are limited with what we can find online Mick

Really. I have a nice schematic in my FT290R user manual in my hands.... Just tried scanning it, unfortunately it is about twice the length of an A4 sheet and my auto feed scanner stalls when it reaches what would be the expected bottom of an A4 sheet with 'paper jam'. Would have to chop it in two and then stitch the two bits together which I am not prepared to do.

But a very clear schematic on a real piece of paper...


SiriusHardware 6th Sep 2021 6:54 pm

Re: Yaesu FT290
Would you consider taking clear, well lit overhead photos of each half or quarter and posting them here as attached .zips? (Don't attach them as images, the forum engine will destroy most of the useful detail by resizing them to what it considers an acceptable size).

I don't think folks will mind a diagram in two halves or four quarters with a bit of lens barrel distortion as long as everything on each half or quarter is completely readable.

Bazz4CQJ 6th Sep 2021 7:53 pm

Re: Yaesu FT290
I, for one, would be happy to contribute to raising whatever it would cost to get;
  1. the manual scanned on some professional kit (not requiring the use of scissors)
  2. nominating dsergeant for position of Saint-hood.


mickm3for 6th Sep 2021 8:27 pm

Re: Yaesu FT290
Hi i would contribute to the fund (i have a ft290r working at the moment ) and i like to have a manual for my rigs mick

Radio Wrangler 6th Sep 2021 9:15 pm

Re: Yaesu FT290
For larger than A4 digitising, I tape the master on a wall, position two soft-box lights, and put my camera on a tripod. I have a reprographic /macro lens that's pretty free of distortion and get whole things in one go with plenty of resolution (Nikon D6) Resolution is close to that of a good scanner.

But this is at the other end of the country. Anyone nearer got suitable gear?


Terry_VK5TM 6th Sep 2021 11:43 pm

Re: Yaesu FT290
I'm surprised that Yaesu don't have one in the archive, but they do exist.

I will probably go down the line of redrawing it in a cad program (and there is a lot of it).

Some of the pdf's online are reasonably good quality wise, but being in 3/4 seperate pages makes tracing signal/power lines across pages somewhat agonising, especially when you lose track of the one you were following.

dsergeant 7th Sep 2021 8:09 am

Re: Yaesu FT290
1 Attachment(s)
Ended up in chopping it into two...
Quick scan at 150dpi saved as a pdf. Looks quite readable, you will have to play with the stitching together.


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