My yaesu ft 902dm sometimes can not transmit in ssb mode but running well in am and cw,why?

Dbl check your swr in am mode.. Ch your ssb power and mic gain default is 50 on both on hf .. If you use the mh-59 you will need to reduce the mic gain to 35 and it needs to be set for remote mic in the menu. Also the ssb needs to be set 2.5k wide with the ssb carrier zeroed both tx and rx

If your receiver was operating previously but now the SSB option is not working, very likely the sideband detector has failed. I'm not directly familiar with your Yaesu unit but, in most Yaesu transceivers, the SSB chip and control circuit (including diodes) is identified in print on the main board.

Lynn, SSB (Single SideBand) only applies to AM (Amplitude Modulation) transmission. There is no way to broadcast SSB in FM (Frequency Modulation) mode.

I would flash it back to the older version. Double check you have the correct firmware. This almost sounds like the incorrect version for your radio.

It appears that there is one transistor difference in the two models.

Connect the transmit antenna output to a "dummy load" (such as a 50 ohm resistor network in a gallon can of mineral oil), turn the output power to max, operating mode to CW, and hold the key down with a weight. The output stages should get hot enough to turn on the fan in a minute or two. You might need a flashlight to see whether or not the fan is turning, since it's supposed to be quiet and may not turn as fast (and noisy) as a computer fan. You'll want to make sure that the dummy load can handle the power, and that the SWR is low to begin with. If the oil gets warm before the fan turns on, the fan probably isn't going to turn on. Stop.

Hi,

May I suggest you join yahoo group specific to your radio Make/Model,

There you will get all the info you need, plus you can download manual, schematics and other goodies.

I hope I have been of help.

Cheers,
Peter

Hi John,

To get the info you require, may I suggest: yahoo group specific to your radio Make/Model, there you will get all the info plus you can download manuals, schematics and other goodies.

I hope I have helped.

Regards,
Peter

The Yaesu FT-8900 is a quad band FM transceiver only. It can not be modified to receive or transmit AM, SSB, RTTY or CW. It works on all or portions of 70 centimeter, 2 meter, 6 meter and 10 meter bands. The 26.805 Mhz frequency is 11 meters, so it is out of range of the 10 meter band in the radio, it is close. Even if able expand the transceiver, the AM / SSB mode commonly found in this band makes it impossible to use. Further, the radio is not FCC Type Accepted for use in this band.