Donkey stomper 2x4

[Rob Berger]

So my question is I'm running 2 xs extreme battery ( 950cca each and a 136amp alternator ) on a 6 pill amplifier ( Donkey Stomper 2x4 2290 driving 2879). Dead key is about 500 watts on the bird meter. No forward swing though. My radio is a Stryker 655 keying 2 watts and swinging 70. Swr and coax are all good ( predator 10k antenna) . I checked everything and set antenna with my mfj analyzer. I feel like this box should at least get swing wattage close to 1000. I'm running 0 awg wire to the amp with extra body and frame grounds. Does anyone have any idea? The amp is new and so I'd everything else. I checked voltage at the amp its 13.96 constant.

 

[Rob Berger]

I forgot to mention these are amg type batteries designed for car stereos systems. I use them on my boat and they will play the stereo all day without charging. Running 3 stereo amplifiers.

 

[Crusher]

The box should not dead key 500 with only a 2w DK into. Variable or something is not right. If your bird meter does not have a peak kit installed, you won't see 1000w pep out.

 

[Rob Berger]

The box should not dead key 500 with only a 2w DK into. Variable or something is not right. If your bird meter does not have a peak kit installed, you won't see 1000w pep out.

It does have the peak kit in it. Ive even backed the radio down to where it won't key the amp and start turning it up until it does and 500 watt dead key.

 

[9C1Driver]

500 watts is way too much carrier for that amp, something like 100-150 at the most would be more realistic. Next thing that concerns me is that radio is way too strong for an amplifier with a driver stage. Did you just get this amp or has it always worked this way? You would be better off with a straight 4 pill comp style box with 2879's.

 

[Rob Berger]

Just got the amp. And yes I probably should have went with a straight 4 pill but I did try a older radio and still have the same issues. Thought it was coax or antenna. Running new 213 coax and predator 10k. Bought the mfj analyzer to make sure everything was right. Now my only thoughts are the amp or batteries.. But I know I have plenty of power to supply this amp.

 

[nomadradio]

Wait a minute!

You're feeding 70 Watt peaks into two 2SC2290?

Should blow the caps off of them. That's almost four times the drive power they should be able to tolerate.

73

 

[Sonar]

Just got the amp. And yes I probably should have went with a straight 4 pill but I did try a older radio and still have the same issues. Thought it was coax or antenna. Running new 213 coax and predator 10k. Bought the mfj analyzer to make sure everything was right. Now my only thoughts are the amp or batteries.. But I know I have plenty of power to supply this amp.

From what it sound like to me you tried the low dead Key lo pep rig after running 70 pep watts into it first. I wouldn't be surprised if the 70 watts fried something. I'm not sure but don't think one need see smoke or smell burning components to actually fry an amps components. Very possible parts are cooked. I Knew less than anyone but driving amps that contain a driver pill/tube with more than 1/12 DK and (at least for me) 15 pep is a no no.

 

[Rob Berger]

Swing watts.. 2 watt dead key.. But the amp is keying 500. On a 2 watt dead key it should be somewhere around 200.

 

[Rob Berger]

Trust me I'm not new at this.. I've been around a while.. I've ran several different mobile rigs and base stations. My last mobile was a sweet 16. I've never run one of these xforce style boxes but I know better than to dead key 70 watts in it.

 

[Robb]

Sounds like oscillation.

 

[543_Dallas]

2x4 is a bad choice of amplifier and always has been. A 1x4 is fine with a single final radio. With your export you should have went with a straight 4.

Oscillation sounds like the issue to me also. It's not uncommon for amps like a 1x2 and 2x4 if they aren't perfect they are unstable. With an export rig going into it you're more likely to have problems like this. What kind of older radio did you try? Id take a stock cobra and turn the deadkey down and use it for troubleshooting. No exports or hack job tunes.

Try different jumper lengths between the radio and amplifier to see if it will settle down. Try 6 or 12 ft of rg8. Sometimes just backing down the variable power knob on the amp will stop it but if you're beating 70 watts into it expect the potentiometer to fail soon.

 

[Rob Berger]

Thanks. I have a galaxy 88 I'm going to try and I'll definitely try different length jumpers. I have the stryker set to dead key 1 watt with the variable down and 10 watts all the way up.

 

[Sonar]

2x4 is a bad choice of amplifier and always has been. A 1x4 is fine with a single final radio. With your export you should have went with a straight 4.

Oscillation sounds like the issue to me also. It's not uncommon for amps like a 1x2 and 2x4 if they aren't perfect they are unstable. With an export rig going into it you're more likely to have problems like this. What kind of older radio did you try? Id take a stock cobra and turn the deadkey down and use it for troubleshooting. No exports or hack job tunes.

Try different jumper lengths between the radio and amplifier to see if it will settle down. Try 6 or 12 ft of rg8. Sometimes just backing down the variable power knob on the amp will stop it but if you're beating 70 watts into it expect the potentiometer to fail soon.

I don't want to get off the op subject. But Is it a fact that different lengths of jumper from a transceiver to an amplifier or any Appliance for this matter make a difference? I've read so many posts about jumper lengths and the fact that those posts/replies are all over the place Leeds me to believe the truth to whether this will change anything or not is totally up to the person who is posting or replying. Is there any real scientific testing to back the jumper lengths theroy to where it either makes or doesn't make a difference? And why would a particular length make a difference if indeed it does? 73

 

[wavrider]

Hi sonar,

I will take a crack at answering your ??

The different lengths of coax is a "band aid" at best for an amplifier that may be having issues with input impedance thus causing oscillations.

VF of the coax will change the input impedance thus trying different lengths to make the radio work with the amplifier.

I prefer to put an antenna coupler ( tuner) between the radio and the SS amp and adjust for minimum VSWR.

If memory serves me correctly( I may be wrong) I think Chad Jolly builds the donkey stomper type amps,,basically copies of X force,, try contacting the builder to see if he has any suggestions.