The Yaesu FT-901DM & FT902DM
Yaesu FT-901DM Transceiver
FT-901 Specifications
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Yaesu FT-902DM Transceiver with Gold display
All band coverage 160~10 meters, Including WARC bands
FT-902 specifications
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Type: |
Amateur HF transceiver |
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Frequency range: |
10-160 m + WARC |
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Mode: |
AM/FM/SSB/CW/FSK |
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RF Power output: |
SSB/CW: 100 W |
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Sensitivity: |
0.25 uV (10 dB S/N) |
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Selectivity: |
SSB: 2.4 KHz (-6 dB), 4 KHz (-60 dB) FM: 12 KHz (-6 dB), 24 KHz (-60 dB) |
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Image rejection: |
15-160 m: better than 60 dB |
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Voltage: |
13.8 VDC or mains |
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Current drain: |
RX: 1.1 A with heater off, 5 A with heater on |
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Impedance: |
50-75 ohms, SO-239 |
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Dimensions (W*H*D): |
342*154*324 mm |
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Weight: |
18 Kg |
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Manufactured: |
19xx-19xx |
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Other: |
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Related documents: |
For a detailed summary of most of the information on this page
Down Load the complete Fox Tango FT-901 Survival Guide here
**Our sincere thanks to Wim Penders PA0PGA for his contribution to the club
FT-901/902 Internal boards & components
FT-901/902 Audio
Unit PB1705 
FT-901A-Rectifier Unit
FT-901 C-Rectifier PB-1717
FT-901 Noise Blanker PB-1994
FT-901 Filter Unit PB-1716
FT-901 IFUnitPB-1704
FT-901 RF Unit PB-1702
FT-901 PLL PB-1709
FT-901 Keyer PB1728A
FT-901_Xtal-Unit
Tube socket PB-1715
FT-901 Diode board PB-1726
Switch Assy PB-1718c
LED Bank PBN-1721b
FT-901 VCO PB-1710
FT-901 Module cover
FT-901 Panel meter
FT-901 VFO Unit
VOX-marker PB-1846
FT-901 Pre-selector
FT-901 Relays
Mains, Power Transformer
PA Plate & Load
DC-DC converter
What lurks beneath an Ebay purchase
An FT-901 night mare!
Just wanted to show you what I was doing
while trying to pump some life back into this FT-901
Bought this one off Ebay, it looks innocent enough.
Was told up front it wasn't working, so I didn't expect much in the way of performance.
It lived up to my expatiations!
At first glance the rig doesn't look all that bad except for the obvious! Except where we can see it has bad capacitors on the rectifier "A" unit. The photos above came from the original Ebay auction. Deep down inside this rig was hiding a lot of sins yet to be revealed. I can only imagine the seller knew something about this or threw all his bad parts at the problematic rig! The rig has bad capacitors all over the place and a VFO that had been tampered with and wasn't working!
After replacing the capacitors on the Rect "A" unit, the rig started coming back to life, we had a red flashing digital display, no audio or signals of any kind were heard giving reason to believe possible PLL problems or more! The transceiver ran for approximately 45 minutes while I was looking around inside and checking things out before it finally cut loose and bellowed smoke into the shack and revealed another hidden secret that was not visible in the photos above at the time of purchase.
The High Voltage Filter caps shot smoke and capacitor cheese all over the place! It's not exactly an easy job getting the filter caps out of this rig!
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The H.V. filter caps reside just forward of the power transformer, under the rig you need to pull just about everything clear as the capacitors and rectifier board are under PB-1726 diode switching board. In the two pictures above (Original Auction Pictures) I didn't catch it, but a keen eye might notice from the top photo of the rig that something bleed out of the capacitors onto the chassis just forward of the blue wire on the transformer. |
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Once the memory unit was removed and the crystal unit was removed, we were ready to go to work digging out our filter capacitors. The counter unit, PLL unit and RF unit were all removed to get more access to the capacitors from the top. |
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PB-1712A the HV rectifier unit resides under the diode switching board and is directly attached to the bottom of the HV filter capacitors. |
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Now the truth is told once the capacitors were removed, this was not the first time the filter caps have blown their tops! All of this will have to be cleaned up before the new replacement capacitors are installed. |
Before I put any more time into this rig,
I wanted to see if I could at least get it to receive something.
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Having gotten lucky by chance I plugged in my spare FV-101Z VFO. This is the same VFO used with the FT-101ZD series and works fine with the FT-901/902. Ta'da we have signals. We also have a dead VFO ~ Great ! The VFO unit pulls directly out from the front of the FT-901/902. Removing the VFO unit and the counter unit also made it easier when it came to replacing the H.V. filter capacitors. Someone had already beaten me into the VFO first, they knew it did not work! Otherwise why would someone have gone into it, the lights were missing from the VFO behind the blue dial and a couple of screws were missing off the VFO shield. Repairs were made to the VFO unit and it was reinstalled. The counter no longer runs randomly and we basically have a working receiver. |
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Luckily for me at this point the receiver is working, the display unit is working and counting properly. All of the high voltage AC wiring has been cut loose and secured for safety reasons. Thus the transceiver will actually function as a receiver alone at this point. Even after getting into this mess, I believe we have really had a great deal of success to get the rig up and running to this point. |
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Along with the VFO lamps that were missing, the meter lamps were dead. Wanting to get a quick look at these, I was afraid I'd be dealing with more peanut bulbs as was the case with the meter lamps in the FR-101 / FL-101 Yaesu twins, that's a story in itself. Yaesu made an improvement here some 10 years after the 101 series and installed two axial lead lamps in front of the meter, so there is no need to remove the meter movement to replace these lamps. Lamp, Meter S8100017 Suitable sub
- Try PN 620701 LAMP, T3.8 AXIAL W/E 8V 0.6W; Lamp fitting type: Axial wire ended, T3.8; Power rating:0.6W; Current rating:0.1A; Length / Height, external:20mm; Length, lead:15mm; Light output, total:1.9lm; Time, operating life:5000h; Vo |
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It may not look like much right now. Now with a working VFO and repairs well underway, I was able to hear signals on 75 meters weak! Good enough for now, it was time to go to bed! Another 4AM night! |
Exploding Rectifier "C" unit
PB-1717A
PB-1717A resides in the very back of the transceiver
One problem to watch out for in the FT-901 is the Rectifier "C" unit with the exploding capacitor syndrome!
The FT-901 series starting with production lot No. 8 had the following modifications, the changes were made in order to provide against the loss of R1803 caused by unbalance in C1802 and C1803. The failure of R1803 could cause the destruction of the filter capacitors as seen in the photos above.
Attempting to rebuild the blown apart circuit board, PB-1717A
Members Emails regarding PB-1717A problem.
I've rebuilt several rectifier c boards over the years
for myself and
friends. I've used both methods listed on page 3-17 of the service manual.
Both seemed to work just fine. The last few I used the second method, adding
the extra diode, exclusively and they have all held up under stress. Yaesu
still has the odd value caps for this board in stock as well. So, if the
caps blew, simply add the extra diode and replace the caps with originals.
Which are very inexpensive by the way. The last time I called they sent them
to me free because the postage was more than the caps! LOL! :)
Tom KB6SSN
April 16, 2005
Subject: The FT-901
Replaced the diode and a resistor in the 190 volt side of the 'C' rectifier
board. I had to replace the resistor R-1809, 470 ohm, it had fried. Also the
diode D-1802, the input, was open. I replaced it with a 1N5408, 1000 PIV at 3
amps Mouser part number 5121N5408. Also did the mods to the board, replacing five resistors and adding a
resistor and a diode in series with existing diodes. The mods were shown in the
service manual, Yaesu suggests in the mod section of the service manual on
page 3-1. I followed the mod and replaced the four 470K ohm resistors with
180K ohm resistors, replaced the R-1803 470 Ohm with a 390 ohm, and added the 39
ohm 1 watt resistor in series with diode D-1801. And last I checked the mod on
the PB-1715A board located below the final tubes, to make sure mine had the
diode added as per the mod on page 3-16 of the manual. his may have kept
the caps from disappearing in a cloud of smoke. I think that this is the most
important mod to do. I got the parts from Mouser Electronics. Phone is
1-800-346-6873. No minimum order and quick service. They had the 2 and 3 watt
resistors and the diode was a replacement for the 10D10. The number of the
diodes I used was 1N5408, 1000 PIV at 3 amps Mouser part number 5121N5408.
By the way, the manual I used, I down loaded from Fox Tango site, and it sure
made a difference.
Larry, WB3EUS
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FEATURE |
FT-901D |
FT-901SD |
FT-901DE |
FT-901DM |
FT-902D |
FT-902SD |
FT-902DE |
FT-902DM |
|---|---|---|---|---|---|---|---|---|
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BAND CRYSTAL 160m |
O |
O |
O |
O |
O |
O |
O |
O |
|
BAND CRYSTAL 80m |
O |
O |
O |
O |
O |
O |
O |
O |
|
BAND CRYSTAL 40m |
O |
O |
O |
O |
O |
O |
O |
O |
|
BAND CRYSTAL 30m |
- |
- |
- |
- |
O |
O |
O |
O |
|
BAND CRYSTAL 20m |
O |
O |
O |
O |
O |
O |
O |
O |
|
BAND CRYSTAL 17m |
- |
- |
- |
- |
O |
O |
O |
O |
|
BAND CRYSTAL 15m |
O |
O |
O |
O |
O |
O |
O |
O |
|
BAND CRYSTAL 12m |
- |
- |
- |
- |
O |
O |
O |
O |
|
BAND CRYSTAL 10mA |
O |
O |
O |
O |
O |
O |
O |
O |
|
BAND CRYSTAL 10mB |
O |
O |
O |
O |
O |
O |
O |
O |
|
BAND CRYSTAL 10mC |
O |
O |
O |
O |
O |
O |
O |
O |
|
BAND CRYSTAL 10mD |
O |
O |
O |
O |
O |
O |
O |
O |
|
VOX/MARKER UNIT |
O |
O |
O |
O |
O |
O |
O |
O |
|
FM UNIT |
O |
X |
X |
O |
O |
X |
X |
O |
|
RF SPEECH PROCESSOR |
O |
O |
O |
O |
O |
O |
O |
O |
|
AM FILTER |
X |
X |
X |
X |
X |
X |
X |
X |
|
CW FILTER |
X |
X |
X |
X |
X |
X |
X |
X |
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FM FILTER |
- |
- |
- |
- |
X |
X |
X |
X |
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KEYER UNIT |
X |
X |
O |
O |
X |
X |
O |
O |
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MEMORY UNIT |
X |
X |
X |
O |
X |
X |
X |
O |
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DC-DC CONVERTER |
X |
X |
X |
O |
X |
X |
X |
O |
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COOLING FAN |
X |
X |
O |
O |
X |
X |
O |
O |
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POWER OUTPUT |
100 W |
10 W |
100 W |
100 W |
100 W |
10 W |
100 W |
100 W |
Source: Yaesu FT-901DM and FT-902DM Instruction Manual, page 3.
* Except in very late production FT-901DM units.
FT-901 / FT-902
(Update June 1, 2007)24 Mhz to 28 Mhz Conversion
(FT-901DM 12 Meter conversion, 11 Meter removal)
It was not totally unexpected that an occasional error might be found in some of the documentation on our web site, we strive to bring to you the most current and accurate information available for every Yaesu product. However some times errors do show up from time to time, so we often depend on those who are actively working on a specific piece of equipment to help find those errors on the web pages and we depend on you the user to help us by forwarding those corrections on to us. That having been said we have found some minor errors in the 11m / 12m conversion, but not so much that it warrants removing this information. The intention of providing you this information was for the REMOVAL of the 11 meter modifications which so often can botch up a perfectly good working amateur band transceiver. On occasion however we do find some folks around the world wishing to put the 11m band into their equipment. While we do not condone this our goal is to be a source of information and to help those of you who own these wonderful old amateur transceivers. One such correction that should be noted in the downloadable PDF file below is the 11m band Xtals; they should be 41.9875, 41.4875, 40.9875, 40.4875 MHz. Fox Tango member Jean Pierre ON4AEF has been actively working on his FT-902 in recent weeks and has kindly sent us the follow file for the master oscillator crystals required for each new WARC band. Thank you for your time on this Jean. The green portion of the chart represents the eleven meter band and is NOT LEGAL for use in the United States, however this information is being provided to you should you have those crystals in your FT-901 / FT-902 crystal unit you will not be totally surprised by what they are. Simply reorder new crystals for 10A/B/C/D bands and you rig should be once again original with a slight retuning of the master oscillator coil for those particular bands. Keep in mind too, simply changing the master oscillator crystal will not show the correct display frequency, as the display may require further modification to reflect any new band installations.
Note the following chart:
| BAND | CRYSTAL FREQ | MID - FREQUENCY | VFO | HAM FREQ BAND | FREQ DISPLAY | LOCAL VCO | ||||
| M | MHZ | IF(Mhz) | RANGE 5,0 - 5,5 Mhz | RANGE(Mhz) | READOUT(Mhz) | RANGE(Mhz) | ||||
| 10A | 42.4875 | 8.9875 | 5.000 | 5.500 | 28.000 | 28.500 | 28.000 | 28.500 | 36.9875 | 37.4875 |
| 10B | 42.9875 | 8.9875 | 5.000 | 5.500 | 28.500 | 29.000 | 28.500 | 29.000 | 37.4875 | 37.9875 |
| 10C | 43.4875 | 8.9875 | 5.000 | 5.500 | 29.000 | 29.500 | 29.000 | 29.500 | 37.9875 | 38.4875 |
| 10D | 43.9875 | 8.9875 | 5.000 | 5.500 | 29.500 | 30.000 | 29.500 | 30.000 | 38.4875 | 38.9875 |
| 11A | 40.4875 | 8.9875 | 5.000 | 5.500 | 26.000 | 26.500 | 26.000 | 26.500 | 34.9875 | 35.4875 |
| 11B | 40.9875 | 8.9875 | 5.000 | 5.500 | 26.500 | 27.000 | 26.500 | 27.000 | 35.4875 | 35.9875 |
| 11C | 41.4875 | 8.9875 | 5.000 | 5.500 | 27.000 | 27.500 | 27.000 | 27.500 | 35.9875 | 36.4875 |
| 11D | 41.9875 | 8.9875 | 5.000 | 5.500 | 27.500 | 28.000 | 27.500 | 28.000 | 36.4875 | 36.9875 |
| 12M | 38.4875 | |||||||||
