View Full Version : Current drops off during modulation

Alabama Buckeye
05-03-2022, 01:06 AM
Have 2 pill drawing ~ 10 amps driving 8 pill drawing combined 75 amps and dead key 525W. On modulation amperage draw drops to about 50 amps. Modulation ~ 1050W PEP observed while the amps drop off.

What is the explanation for this; is this indicative of an issue?

Have long want to have the means to know recently hooked up 200A amperage and voltage meters; exactly how much current draw the several radios and amps were drawing. Now I know.

On the other hand driving the Fatboy with a dialed back 4 pill driver I see nearly 1300W PEP and draw upwards to 150A.

I prefer the 2 pill driver over throttling back the 4 pill.

05-03-2022, 06:37 PM
525w DK is allot of DK...

Try dropping your DK by half and see what it does...Your swing-watts shouldn't drop much (if at all) dialing back the DK...Plus, most likely your modulation will sound better. (less muffled)

Or, you could add a extra battery close to the 8 pill and that would probably fix your drop off on key-up.

Alabama Buckeye
05-09-2022, 12:46 AM
Perhaps I'm not cognizant of what the 2 pill driver [DM M80] should DK at? Radio 1.5W DK into 2 pill, DK is 35-45W with PEP ~ 200W which I understood to be quite acceptable for the 8 pill which takes the 45W in and then itself DK at 525 swinging to PEP 1050W.
Power supply is DaveMade (DM) 200A, there should be no wanting for more current with this 2 driving 8.

Tried DM M200 but the FB 8-pill DK 1050W with 1050W PEP. No modulation with M200 as low as she goes. M200 is 1x 2290 x 2x2879. Combined draw ~ 150A.

Bottom line is, I'm getting the swing to 1050W meanwhile the current drops off. Why is this?

05-12-2022, 09:06 PM
Oh so this is a base set-up? Thought we were talking about a mobile set-up...

My guess is that DM power supply isn't enough to make a 3 pill into a 8 happy...

might try separate power supply's for the two amps...

Alabama Buckeye
05-15-2022, 01:40 PM
Thanks JJ for feedback. It isn't insufficient Power Supply. I'm reading amperage drop off from accessory meter on the DM 200A P/S.
I've yet to realize exactly what make the FatBoy 8X happy. There are those who say it should perform well above 1500W. I've yet to get the right input to drive it to 1200W. I try to keep the DK input as near to 200W as possible, whether 2 or 3 pill driver. The 3 pill at 200 MOL DKs the 8X goes straight to PEP level (1200 MOL) with no increase with audio input (modulation). The 2 pill however inputs 200 MOL and the 8X DK is 400-500 MOL with 1200W PEP during audio modulation.

All the while the current meter shows amperage dropping off considerably under DK or modulation. As though during modulation the gates are opened to free flow of current. The question: Is this normal?