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KL-7505 warble/crunch

Jun 28, 2021
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I have a KL-7505 that, I have some questions on.

I set this amp up with a 2950dx with a md-1. I set the radio using my scope and it sounds fine and I normally run about 200% modulation. When I paired this combo up to the 7505. I found the amp really only likes to run to about 20 watts dead key and150-160 watts PEP, the amp will do more, but it really sounds bad. I did a lot of searching on here I read a thread where someone said the same basic thing that I said.

I used my o-scope and I can see that when I speak in a normal voice that about 80% of the time I am hitting about 200% which I think the math works about right that is an 8X increase in power, so a 20 watt dead key works out to 160 watts, that about agrees.

Is this all I can expect out of this amp? it seems if I try to push the amp any harder I can hear a what I would call a warble on my audio, some people call it "crackle", some call it "crunch". I can definitely hear it on recordings of myself.

I had read a similar thread on here describing the exact same thing on a KL503 and people were saying the amp needed to I believe have the bias modded. I had hoped to be able to run more of dead key, but even at the inflated specs of a 350 PEP, that's still around the 40 watt mark. I've tried running the amp there all kinds of happy swing and nifty things, but it sounds like poo.

I just want to make sure I am not missing something.
 

Jun 28, 2021
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How many volts are you running the amp on? I have been told on my KL203 that it warbles when running off just the battery(12v) on SSB. When my truck is running, 14.3v, no warble.
This is with the motor running, so around 14.7 volts. That's why I wonder if something in the amp is failing and the voltage isn't keeping up with modulation at higher wattages.
 

Greg T

945 (Jazz Singer) Upper Peninsula of Michigan
Sep 18, 2014
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715
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Escanaba, Michigan
This is with the motor running, so around 14.7 volts. That's why I wonder if something in the amp is failing and the voltage isn't keeping up with modulation at higher wattages.

My buddy had the same issues running a 503 with a 2980. Sounds like crap even at very low output. We connected a Stryker to it and it's fine. BUT, he's now using an older 2 pill with the Stryker because it sounds much better and actually puts out more. Basically, I think RM Italy is not really compatible with Ranger products.
 
Jun 28, 2021
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My buddy had the same issues running a 503 with a 2980. Sounds like crap even at very low output. We connected a Stryker to it and it's fine. BUT, he's now using an older 2 pill with the Stryker because it sounds much better and actually puts out more. Basically, I think RM Italy is not really compatible with Ranger products.
Yes Greg T, I recognize the avatar and you were the thread I was reading about that had the similar issue.

Voltage is only half the equation, are your cables heavy enough to provide adequate amperage?

Just a thought.
Yes I agree, voltage and current not keeping up. I can't remember I am bad with remember gauges but it was pretty heavy stuff and I'm pretty confident its up to the task.
 

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