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Discussion in 'Amplifiers' started by wild turkey, Jan 6, 2012.
Its like RF feedback.
What is happening can be changed; but you are going to need to jump thru some hoops to get there.
Improperly grounded equipment, need for ferrite on wires and coax, and even an 'ugly balun'/RF choke will be things to look into.
Most of them do not, I agree with Rob, RF is getting back into the supply somewhere and by putting the big cap inline you are filtering it out.
Any Modifications done to the 2510?
If the limiter is disabled or modified and not properly adjusted along with the Amplified Mic may be contributing to the problem.
What happens if you push in the "mic gain" button in on the radio or reduce the mic gain on the turner?
The Amp meter going back on high power I would also say could be a sign that RF is getting back into the supply.
What voltage are you running?
Anything over about 14.8 volts into a Texas Star Amp will lead to Failure, they do not tolerate over-volting at all and will increase the chance that the signal is getting dirty coming out of the amp.
After that, as you have already said, just keep going over the whole system, grounds, the Choke that Rob talks about will help if CMC`s ( common mode currents , this is RF that is flowing on the outside of the coax) are letting stuff get back into the supply.
Here is the way it works.
With the big cap in place, the power peaks are being fed out of the stored capacitor current and helping the supply to be more stable in output by not allowing the internal regulation to swing so wide trying to adjust output vs load.
If this is allowed, the transformer could react to current changes at an 'audio' rate you are able to hear.
The use of big caps in automotive audio systems is for the same purposes when a very large audio amplifier is used and especially during base notes of high power content when the power cables, alternator and battery cannot hold up to the needed current requirements.
Actually some alternator voltage regulators were never designed to control output at varying audio rates.
This is why they are available.
If you check with a voltmeter on the output with no cap in place you may see the voltage droop or swing with modulation from the current being drawn.
These are all indications of too small leads, supply defficiecies in regulation and ability to track current demands "at an audio rate" etc.
Using the big cap largely aleviates or reduces many of the problems.
It can also be some RF getting back into the supply and upsetting regulation.
3.5 F does not always shunt RF frequencies well due to the large inductance that may be inherent in it's design, so smaller values are often needed in along with the large value.
Also be awhere that with the big cap accross the power supply that on inital powerup it can/will act like a dead short accross the supply before being charged up.
Sometimes this trips the fuse, the circuit breaker or the Crow Bar circuit or whatever over current protection the supply has.
The proper way is to have a push button switch pressed to put a current limiting resistor in series with the big cap for a second or two the let the cap connect to the supply, begin to take a charge, then connect with out the resistance in series with the cap..