Bugger me, the dam think blew again, I was in the WPX contect with my FTdx3000 with the amp and the FT-991A was on 40m. I noticed that in IPO mode on the 991A nothing heard. Lucky I had bought 50 of those little 150 ohm surface mount resistors.
Pulled the bottom off the 991A and found R1005 just next to RL1001. The resistor had broken in two and the cct board was burnt where is sits. Its not worth trying to solder the bloody thing in there as its too small. I tacked a small piece of wire onto the relay pad where one side of the 150 ohm resistor connects and a small piece of wire onto the terminal of J1001. The ends of these two wires sat above the board a little and I soldered one side of the new 150 ohm resistor to one wire, bent the other wire over to touch the other side of the resistor and soldered it.
I seem to have a big drop in sensitivity on all HF bands. It has been a superb receiver for the past year. Transmit is normal.
On a strong signal with ATT off and IPO the S- meter is at 0. The spectrum display is near the bottom line. The same signal with ATT off and AMP1 is S9+5dB and the spectrum display is above the first bar. With ATT off and AMP2 the S-meter reads about S9+15dB and the spectrum display is on the second (middle) line. The difference between IPO and AMP1 is an almost inaudible signal to S9+.
A signal that is S-9 on my FT-897D (with that rigs ATT and IPO both off) is barely S9 on the FT-991 with ATT off and AMP2 on and at S0 with no amps (IPO). With the amps off it is S zero. VHF/UHF is normal. Looks like I have a receiver problem.
Glenn/WA3LAB found the fix below on the net to resolve the issue with the Yaesu FT-991 in AM mode. The techs at Yaesu they said they’re aware of it, but Yaesu has not put out a bulletin on it.
Both Glenn & I have followed this procedure and it appears to work. I wouldn’t want it put out there without letting people know that they should proceed with care, and not to change anything else unless they really know what they’re doing. Since there’s not many people running AM anymore most people have no idea there’s a problem.
(Warning: once you put the radio into the service mode you can really screw things up, so do this at your own risk.)
Information can be found about the bad transmitted AM audio quality on the internet. To be sure that’s true, I verified this with my FT-991. And the AM audio quality is indeed quite bad. The FET’s from the HF power amplifier of my FT-991 are already replaced (at the Yaesu service centre) and therefore there isn’t a relation between the bad finals and bad AM audio quality. Based on my “research” I can conclude that the solution is quite simple and can be done yourself.
verification of the facts As a start I wanted to be sure that the AM audio quality is indeed bad. The FT-2000 was set in receive mode and a dummy load is connected to the HF antenna port of the FT-991. Both radios are set to the same frequency. On all the HF bands, the AM audio quality was bad. Transmission power and other settings didn’t contribute to better audio.
Since updating to the 8/24/16 firmware, I've now had several instances
where pushing the radio front power button will not turn on the radio.
Disconnecting then reconnecting the DC supply corrects things, then the
radio will turn on with power button as normal. This problem would probably
not happen if my radio were not connected to constant DC power, since
cycling the DC power resets whatever is getting stuck/confused.
I've now performed a reset, repeated the Main, DSP, and TFT updates,
including by another reset, then restoring my settings with the RT
systems software. I will see whether the problem continues.
Has anyone else experienced this non-responsive power button problem?
I've had the radio for almost two years now, with no prior issues.