Modifications for the Yaesu FT-290

Modification of tuning range


There are 4 possible jumpers in the FT-290R close to the CPU on the second small board from the rear.

Numbers are 1 - 4 from the bottom (the most hidden one).

The indicated combination is perhaps the most usable in Europe because the repeater shift is +/- 600 kHz, the steps on FM tunes to X00, X25, X50 and X75 standard frequencies and at the same time it gives a larger tuning range.

But please note that it is not legal to transmit on frequencies outside the ham band. Even by misstake.

In some countries it is not legal to have a reciever that can be tuned outside the ham bands. Plese check local regulatins.

Frequency     Repeater   Step       1 2 3 4
Not usable                          0 0 0 0
144   - 148        600    25 12.5   0 0 0 1
140   - 150      1.600   100 25     0 0 1 0
144   - 146        600    10 10     0 0 1 1
Not usable                          0 1 0 0
144   - 148        600    10  5     0 1 0 1
140   - 150      8.000   100 10     0 1 1 0
144   - 148        600    10  5     0 1 1 1
Not usable                          1 0 0 0
144   - 146        600    25 12.5   1 0 0 1  Standard in Europe
140   - 150      5.000   100 25     1 0 1 0
143.5 - 148.5      600    10  5     1 0 1 1  Probably most usable
140   - 150      7.600   100 25     1 1 0 0
140   - 150        600    20 10     1 1 0 1
140   - 144      1.000    20 10     1 1 1 1


Yaesu FT290R for TXV use


Once in a while I see questions about the use of an FT290R for transverter use.

I have an Yaesu FT-290R, about 12 years old. The look-alike rig for 70 cm is the FT-790R. If I'm correct, the PLL-system was exactly the same (exept for the X-tal for mixing up).
It could well be that the mark II versions still use the same processor type.

The information was printed in the VERON DX-press/VHF-bulletin abt 11 yaers ago. I don't know the author or the exact year. The primary intention of the publication was using an FT-290 as transverter for 70 cm.

The information concerns the microprocessor chip 'HMCS45C' probably noted as Q01. On the pins 38, 39, 40 and 41 jumpers to ground specify the freqency-range, preset and step. With 4 pins there should be 16 different combinations. The factory set position determins the version for European or US-market.

In the table below you find the known combinations for the FT-290R. 'X' means jumper to ground.
My guess is that removing the jumper at pin 39, the PLL is transformed to a wider frequency range used in the FT-790R. Once you are able to reach the print-board, you could try to (de)solder the jumpers and determin the results.
These modifications are best made with power and battery backup switched off.

--------------------------------------------------------------------
band  | 144-146  |144-148  |143.5-148.5| 144-148 |145-146 |144-148
preset| 145      |145      |146        | 147     |145     |145
step  | 12.5/25  |12.5/25  |5/10       | 5/10    |10/20   |5/10
41    | X        |         |X          |         |        |
40    |          |         |X          | X       |        |X
39    |          |         |           | X       |X       |
38    | X        | X       |X          | X       |X       |X
--------------------------------------------------------------------

I hope this information is of some use.


FT-290 Bulb-Replacement


FT 290 MK1. Bulb replacement instructions.


  1. Remove speaker wires (white + & black -)
  2. Remove aerial to tag.
  3. Remove yellow wire to meter, left hand side (viewed from rear)
  4. Remove black wire to meter, right hand side (viewed from rear)
  5. Remove earth connection to pc board on front end of unit (thin braid approximately 1/2 inch, 12MM in length)
  6. Remove 2 screws from pc board.
  7. Remove both support pillars.
  8. Take off front.
  9. Remove screw (second front panel)
  10. Remove meter.
  11. Remove led display screws.
  12. Remove post.
  13. Remove black and red wires.
  14. Now test new bulb.
  15. Remove unit & fit new bulb, solder bulb wires.
  16. Replace items in reverse order.
  17. Grab a bottle of your favourite tipple and poor a glass or two from it. You have just saved over 30.00 pounds sterling. Mine has today gone for the second time, that's why i made these notes first time round.


Following a few hints about problems which I had during the work and which might save somebodies time.
(Because of that I had to disassemble my rig three times!)

There might be minor changes during the series of which I am not aware !



FT-290R (first version) Extensions


I hve nothing about the second version. Perhaps later...
73's of Ludovic.
------------------------------------------------------------------------

The pins no 38,39,40,41 near HMCS45C are used for extensions.
     PIN No          BAND         STEP FM/SSB              SHIFT
38   39   40   41     MHz         KHz     Hz
----------------------------------------------------------------------
*    *             140-150        25      1000           7.6MHz
                                 100       100
-----------------------------------------------------------------------
*    *    *        140-144        10      1000            1MHz
                                  20       100
-----------------------------------------------------------------------
*    *    *    *   140-150         5      1000     no shift possible
                                  10       100
-----------------------------------------------------------------------
*              *   144-146       12.5     1000           600KHz
                                  25       100  (European version)
-------------------------------------------------------------------------
*    *         *   144-149        10      1000          600KHz
                                  20       100
------------------------------------------------------------------------
*         *        140-150        25      1000           5MHz
                                 100       100
------------------------------------------------------------------------
     *    *        140-150        25      1000           5MHz
                                 100       100
------------------------------------------------------------------------
     *    *    *   144-148         5      1000        600KHz
                                  10       100
-------------------------------------------------------------------------
     *         *   144-148         5      1000         600KHz
                                  10       100
-------------------------------------------------------------------------
          *        140-150        25      1000         1.6MHz
                                 100       100  (FB for 70 cm transverter)
--------------------------------------------------------------------------
          *    *   144-146        10      1000          600KHz
                                  20       100
---------------------------------------------------------------------------
               *   144-148       12.5     1000           600KHz
                                  25       100
---------------------------------------------------------------------------
*         *    * 143.5-148.5       5      1000            600KHz
                                  10       100
---------------------------------------------------------------------------
Problem width packet


There is a very "hard" de-emphasis in FT-290R. This can cause serious problems copying packet signals with some demodulator chips, eg. like the XR2211. By a common request, here is a modification of this popular TCVR for packet radio. It was made after a RADIO-REF article in several copies, by HA5OB, HA5DI, HA3MA and others. Increasing the intelligibility in noisy environment, this modification is also useful in FM voice communications.

You'll have to add only a serial RC unit, the R being 4.7 kOhm, and C being a 1uF tantalum capacitor. Put them between the pin 9 of IC Q1019 and the collector of transistor Q1021, with the positive leg of the tantalum capacitor to the collector of the transistor. These points can be found as test points, near to IC Q1019. Solder the components together, wrap some insulation around them, then solder to the test points mentioned. That's all you have to do! With this modification, FM reception will sound somewhat noisy, but much louder.
How to prevent the touch-tone pad from automatically keying up your rig


Rigs involved: This mic. comes with the Yaesu FT 290 MK II (2 Meter rig), the FT 690 MK II (6 Meter rig), or the FT 490 MK II (UHF rig), and possibly others.
  1. Take the three (3) back screws off.
  2. Take the two (2) screws off the circuit board to free it from the case.
  3. Find the red wire going to the micro-switch, ie, the ptt line.
  4. Follow that red wire to the circuit board. At that place on the circuit board another red wire will join the first one.
  5. Un-solder both red wires from the circuit board and clean up the solder mess, otherwise hum will occur.
  6. Solder the two red wires together and cover with tape or shrink tubing.
  7. Put the circuit board in place and screw it down.
  8. Put the "lock" slide switch back in place.
  9. Put the rest of the case on.
  10. Put the outside screws in.
  11. You are now ready to try it out, so go ahead and re-attach it to your rig!
  12. All should work:

Some small mods for FT-290 MK I


AUDIO DECOUPLING

It seems important to fit a 0.1uF cap into the receive audio line to the TNC. Fit it inside the five pin plug. The FT290R has no decoupling capacitor in the audio output (See wiring Diag. IC No.Q1027 (uPC575C2) off pin 7.

CAP CRUNCH

Many people have problems getting the Mk1 working on packet. This is due to the receiver filtering attenuating frequencies above 2kHz, thus the 2.2kHz tone is attenuated by 10-15dB. The standard capacitor crunch mod, originally designed to give more +ACI-sparkle+ACI- to the audio cures this. To do the mod, remove the case and turn the rig so the control knobs face away and the SO239 antenna socket is nearest you. At the back of the PCB is a relay (a box shaped component made of semi-clear plastic). Just above the relay are two green capacitors.
Using small pliers, grip the capacitor nearest the relay (C110) and crush it, removing all the debris.

DE-EMPHASIS - 1

There is a very +ACI-hard+ACI- de-emphasis in FT290R. This can cause serious problems copying packet signals with some demodulator chips, e.g. like the XR2211. This modification increases the intelligibility in noisy environments, and is also useful in FM voice communications.
Add a serial RC unit, R +AD0- 4.7k, C +AD0- 1uF tantalum capacitor between pin 9 of IC Q1019 and the collector of transistor Q1021. The positive leg of the capacitor goes to the transistor collector. These can be found as test points near to IC Q1019. Solder the components together, insulate them, then solder to the test points mentioned.
With this modification, FM reception will sound somewhat noisy, but louder.

DE-EMPHASIS - 2

Yaesu seem to have goofed on both the FM de-emphasis and the audio filter. A computer analysis of the audio circuit suggests:
  1. Reduce C125 from 10n to 4.7n in filter
  2. Reduce C124 from 2.2n to 1.5n (near Q1026)
This isn't perfect but it a lot better - the tones now seem nearly equal. There appears to be plain FM (cf phase) with no pre-emphasis on Tx+ACE-

RESET TO 145MHz

This mod resets the CPU to 145MHz and sounds a bleep to tell you it's been done. Remove top and bottom covers, locate the hole in the case near the SO239 socket covered by a stick-on aluminium label. Make a hole in the label and install a push to make, non-latching switch. Connect one side of the switch to ground and the other to pin 4 of J5003 which connects the keyboard and control units. A 1nF capacitor should also be connected from pin 4 to ground for decoupling. Replace the covers, dial up any frequency, press the button and the set should reset to 145MHz and bleep.

LISTEN ON INPUT

Place the set with controls towards you, remove the bottom cover and locate the black/white wire on SK1. It's the tenth one from the left.
Cut this wire at the socket and insulate the free end. Locate the green/white wire on SK1 and solder the anode of a 1N4148 diode to it.
Connect the cathode of the diode to the red/white wire on the PCB adjacent to the mic. socket. Insulate the diode leads to prevent shorts. When the call button is pressed, it allows listen on input on both +-shift and -shift. When you want the rig to transmit a tone burst you must close the PTT at the same time as pressing the call button.

CURING SYNTHESISER WHINE

Early 290s suffered from a high level of whine. Try moving the wiring harnesses around inside the rig whilst monitoring the whine on another rig. The real cure, if you have a delicate hand for soldering, is locate LO6 in the synthesiser and solder a 15pF capacitor in parallel with it. This can usually be soldered between the hot ends of C24 +ACY- C25 which are at the rear of the IC in the synthesiser unit.

MODIFIED SQUELCH

This mod reduces the difference in level between the opening and closing points and speeds up the operation of the squelch enabling the scanner to work better. Reduce C94 from 4.7uF to 1uF, increase R79 from 270K to 330K and add a 10uF tantalum or subminiature electrolytic between the leg of R78 (4.7K) and the body of the transistor T1007.

OPENING UP TO 148MHz

Remove the battery compartment and slide out the power board to allow access to the microprocessor board. Two tinned copper wire jumpers are visible on this board, next to the microprocessor. One is easy to see and the other is not because it is next to the main board.
Cut the jumper which is difficult to see. If the wrong jumper is cut then the frequency display will not be correct when the unit is powered up.
FT-290R Mk1 - mod for 1kc and 100hz steps on FM for satellite working


I asked around for details of this Mod but no-one had attempted it.
I decided to take the bit between my teeth and sort it out. Here goes.
  1. Remove the covers of the rig and locate the mode select switch on the front panel. (you only need remove the covers...nothing else)

  2. Locate the wafer of the switch nearest to the front of the rig and identify the green and yellow wires. Arrange a suitable method of switching the wires around. With the wires transposed the rig will now step 1kc and 100hz on FM. Note though that SSB will be 25/12kc, simply flick the switch to tune SSB normally. (I used an external switch, but I am sure that the noise blanker switch could be used or replaced with a suitable DPDT switch). You will find that the rig will tune on TX making it much more suitable for satellite working.
If you want any more info please give me a call.

Joe. G4XRZ +AEA- GB7WRC.+ACM-16.GBR.EU
Common faults found on the FT-290R


NO RF O/P : PA OFF FREQUENCY RX +- TX OFF FREQUENCY FM TX ERRATIC FREQUENCY JUMPS DRIFTING POOR SQUELCH OPERATION POOR QUALITY FM RX ERRATIC TUNING TUNING JUMPS INTERMITTENT TX+-RX NO AUDIO O/P CONTINUOUS CW OR NO CW TX LOW SENSITIVITY RX LOW SENSITIVITY ON A UNIT WITH A MUTEK BOARD FADING LCD DISPLAY CRACKLING NOISE ON TX AUDIO (FM ONLY) CRACKLING NOISE ON TX+-RX MELTED NICADS POOR SSB TX (NON-LINEAR)


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