Dx979 + 667v issues on SSB

[Mrialsm4]

Hello guys, I'm new to the forum but not so new to the hobby. I'm not a expert of course, although I know there are some here, hence my question. As the title states, I have a dx979 connected to a 667v. On AM I'm modulating to roughly 450W from a 100W dead key. Input to the am from the radio is about 2W swinging to round about 8W. I have talked DX to several folks and locally with some and get good reports. However when the radio is placed in USB/LSB, I expect to get roughly the same output on my meter. What happens is the radio when keyed, swings to 6W and then slowly ramps up to about 20W, it's almost as if the modulation is being limited internally for the first couple of seconds when keyed. If I turn off the amp, the radio keys up and modulates properly up to about 20W with no delay.
Another issue, when running on AM, my voltage drops only 0.5VDC. On SSB, with the amp on, my voltage drops about 1.5VDC.
Any ideas as to what could be causing this?
For reference, I am reading through a Diamond sx100 meter, and running a 2500W LPF. I'm powerig this up with a 130A dell jd200 server power supply. The power is routed through 6' of #6 cable distributed on a 200A terminal block. I'm running with my voltage set at 13.5VDC. I'm transmitting through a dipole set at 32' up, placed horizontally. My SWR is about 1.2 to 1.3.

I appreciate the help guys!

 

[Mrialsm4]

Just a small update. The voltage drop is the #6 cable. I see only 0.1vdc drop at the power supply terminals when keying and modulating SSB. I also notice that the problem is apparent only when the amp's SSB delay and/or the pre-amp is on. With the SSB delay is off the radio modulates properly. It's still like the radio output hits a brick wall at 6W when the delay is on, and after a second or two, it modulates fully.

I'm going to work on the voltage drop issue and will update tonight.

 

[Mrialsm4]

I doubled up on my supply cable last night with a run of #4. With the added #4 conductors and the existing #6, the voltage drop has been reduced to less than a quarter volt. I am still hitting the brick wall on the key up, however. I did gain a few watts when at full modulation.

 

[vkrules]

sounds like the sideband delay is to long, you might have to change the elect cap to a lower value. Glad you found the voltage drop,saw your post and was about to comment when you posted the solution.