The tune knob i am talking about is the one on the front right corner of the amp marked tune. The other plate tune is inside the amp. The one i am turning is the one on the front. All the way to the right is low at about 10 or 15 watts it has no hum. But as you turn it up the hum starts. I never run it over 15 or 20 watts. At 15 watts it will swing 250 or so with 5 watts out of a Sonar 2340. That is on a Swan meter on AVG.
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Maco/ Brute 75
- Thread starter 238
- Start date
The control on the front is really the Load control. Never mind how they labeled it. The Plate Tune control is the one on the inside, sticking up out of the chassis deck.
The Load control is normally set for max modulated power, not for carrier. The Tune control gets peaked with carrier, no modulation.
And if it does erratic things when it's turned, that tells you the amplifier is unstable and is oscillating.
73
The Load control is normally set for max modulated power, not for carrier. The Tune control gets peaked with carrier, no modulation.
And if it does erratic things when it's turned, that tells you the amplifier is unstable and is oscillating.
73
Yes. I moved the tune control to the front. Changed the coax inside to 316 grounded on both ends. I have 4 or 5 of these little Maco's/ Brutes. Some of them have the plate coil tapped at 4 coils. The Brutes tune across all 12 coils. Do i need to change this or dose it matter? 238
This is determined by the behavior of the Plate Tune control.
If it shows two separate peaks in one full turn of the knob, you're good to go.
If you see only one peak in that full 360-degree turn this means that your "peak" is just the control reaching the end of its travel, not really finding a proper peak.
A look at the plates on the control will reveal if they are all the way apart, or fully meshed together. This will determine which direction you need to adjust the coil, for more or for less inductance.
And yeah, it matters. A control that has no end stop and simply spins free will have two positions where the plates are positioned for a proper tuned peak. The two peaks might be close together, or 180 degrees apart. That doesn't matter so much as making sure that you really have TWO separate peak positions on that knob.
73
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