why is my amp clicking on and off during TX on high?

[bushwacker]

Initial reaction was stray rf getting into the circuit somewhere, but...

I don't think that power supply is enough for the amp. How many watts does that amp put out...500 or so? 500/13.8 volts / .5 (efficiency for an AB biased circuit) = 72 amps . Your power supply is a 50 amp, but probably about 40 amp constant?

I agree ... he could be getting a voltage drop on high peaks when the current draw is at its max.

 

[loosecannon]

500 watts?

not sure, but i think the 2290 is only a 90 watt device right?

in my car, i have seen 350 to 400 watts out of the amp.

that equals about 57 amps by your equation, and im sure you are right about the power supply being 40 amps constant.

good call, that is probably it.

i think i forgot that AB biased amps such as this draw more current for the same output as a class C amp would.

thanks for the advice, now i know where to start to fix it.

LC

 

[fnkycoldmedina]

you could try it in a car ,if it works good in a vehicle then you know its the power supply.good luck with it .

 

[Space Cadet]

Excessive negative modulation will also cause this... is the limiter intact?

 

[loosecannon]

limiter was not intact.

but i tried it with bone stock radio and still did it.
(deadkey turned down to 2 watts)
thanks for the interest,
LC

 

[Captain Kilowatt]

Initial reaction was stray rf getting into the circuit somewhere, but...

I don't think that power supply is enough for the amp. How many watts does that amp put out...500 or so? 500/13.8 volts / .5 (efficiency for an AB biased circuit) = 72 amps . Your power supply is a 50 amp, but probably about 40 amp constant?

His power supply is rated at 46 amps continous and 52 amps peak. It also has overload protection. My guess is that on voice peaks the amp is drawing too much current for the power supply to handle and is causing the power supply to shut down. As soon as it shuts down it resets and kicks in again and the cycle starts all over again.Check the output voltage from the supply.

 

[loosecannon]

so, if it is the supply that is the culprit; i should be able to put a voltmeter on the pos and neg leads, key the mic and talk, and see the voltage drop out and come back in?

will try that.
thanks,
LC

 

[Captain Kilowatt]

It may happen faster than the meter can respond but you should see a movement in the meter of some sort. You could also connect a small light bulb,like a brake light bulb, across the terminals and see if the brightness changes much.I'm guessing it will look like a modulation indicator only in reverse.

 

[loosecannon]

cool tip QRN!
i like it, and will try it when i actually get a day off to play with radios!
thanks,
LC