In article ,
wa7kgx wrote:

My initial testing on an FT-991 I bought Tuesday indictaes AM
transmission is severely distorted. I tried everything in the manual
that seemed relevant to AM transmission without any improvement.

Transmitting into a Cobra Senior perfectly matched with a Nye Viking MBII
on 3885 showed pronounced downward modulation even on a peak reading
MFJ 870 meter. Normally a peak reading watt meter will show strong upward
movement as the peak power is 4 times carrier power.

I called Yaesu tech support. The tech was not aware of any prolbems with
AM on the 991. He suggested I reset the processor.

After the processor reset returned the 991 to its factory defaults, the
3885 morning crowd confirmed the transmitted signal was still terrible.

I have been able to get good results transmitting AM with many oher
radios including IC706mkiiG, 756Pro, and FlexRadio 5000a.

A quick check on 2 meters showed the same profound downward modulation
on the FT-991.

Anyone having better luck with AM on the FT-991?

WA7KGX-

I have the same problem with my FT-991, with the Po Meter kicking
downward with modulation. The manual’s procedure for setting AM
Microphone gain does not work. They instruct you to adjust so ALC does
not deflect when speaking. If you do that, there is no modulation. The
ALC meter has a static level that kicks upward with modulation.

It might help if we compared notes on other problems. From what I can
tell, both the hardware and firmware have bugs. Here are some other
problems I've found:

1. On several occasions the radio has locked-up, stopped receiving or
refused to transmit. Recycling power cleared up the problem.

2. On 14, 50 and 430 MHz SSB, the ALC Meter reading is missing,
depending on antenna SWR. On 14 and 50 it only works if SWR is high, on
430 if it is low.

3. If you look at the left side of the display, you may see IPO, AMP1
or AMP2 listed. It depends on the IPO setting on HF. AMP1 and AMP2 do
not apply to VHF or UHF. They may appear there as well, and can only be
changed by re-programming the frequency. If you select an HF frequency
in VFO mode, you can turn the AMPs on and off. Whatever state they are
in, remains if you then select BAND - ENT and enter a VHF or UHF
frequency.

4. The 5/10 Hz setting is stuck on 5 Hz for AM, FM, C4FM and DATA-FM
modes. Main-dial frequency step is 100Hz, but CLARifier is 5 Hz.

5. In order to use a program like CHIRP to program the radio, it is
necessary to start up the radio in Clone mode The manual is missing
information on CAT and Cloning. FT-817/857/897 Clone setup does not
work with the FT-991, which is missing the two Mode buttons.

I would be interested in knowing if you have observed any of these
problems in your FT-991.

Fred
K4DII