| Author |
Message |
    
Cobra0020
| | Posted on Monday, July 29, 2002 - 9:21 pm: | 
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Just bought A Golden Falcon Base Amp 2 driving 4 tubes 6lf6's... My Problem Is That it Will not put out what its supposed to it gives me about 200 on the low side warmed up and then after about 2 keys it does less Then less then less it goes down and down Every time i tune and plate and drive the tubes right but this is happing. Are the tubes Out.. And I Get High SWR On My radio it Lights Up The SWR Warning Every Time... Can you help me...
Thanks,
Cobra |
2600
| | Posted on Wednesday, July 31, 2002 - 12:44 am: |
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Second question first:
When the amplifier is keyed, the radio is no longer feeding into the antenna, it is feeding into a DRIVE CIRCUIT that leads into the two driver tubes. In theory, it should be designed to fool the radio into thinking the amplifier is just another antenna, soaking up the radio drive as if it were a 50-ohm load. That drive circuit on your amplifier may have an adjustable coil to get this 'input match' below 2 to 1, located on the circuit board between or to the left (your left) of the driver sockets.
First question:
The Driver Tune and Final Tune controls on this amplifier have no 'end stop' the best I can remember. If someone has changed the tubes, and HAS NOT trimmed the driver output coil and final output coil to match the tubes, you may UNINTENTIONALLY be running the tubes UNPEAKED. The way to tell is to key the amp and turn the knob ALL THE WAY AROUND 360 degrees once while watching the wattmeter. If the meter shows TWO PEAKS in that one full circle, that control is okay. The Driver Tune AND the Final Tune should each pass this test, assuming the Load was already peaked for BEST MODULATED SWING.
If either Tune control shows you ONLY ONE PEAK, then it is really NOT a peak, it just looks like one on the wattmeter. A Tune control that shows only ONE peak will reveal one of two things if you peek under the cabinet: the plates EITHER full meshed together OR all the way separated. If you see this, the Tune control simply would not turn far enough. Since there is no mechanical END STOP to go 'clang' against, what happened is that you got NEAR a peak, and turning the knob more just moved you back farther from it. Makes the wattmeter needle rise, stop, then fall BUT THAT'S NOT REALLY A PEAK, only the control running out of range. The two peaks may both be very close at one end of the knob, or 180 degrees apart. What really matters is that you have TWO of them. The manufacturing tolerances on these tubes were not very tight, from one factory to the next. The two Tune controls can be thrown out of range simply by changing tubes. The coil attached to that tune control is the COARSE adjustment. The knob on the front panel is really just a FINE adjustment.
The really bad news is that if someone was running it UNPEAKED, whether intentionally or not may have abused the tubes and damaged them permanently. If you put them into a tester, and the reading on the tester's meter falls back, the tubes have been hammered, and have to go.
If you do replace them, the TWO PEAK test will tell you if the driver coil and final coil are already adjusted close enough to match the tubes you use. If it fails the TWO PEAK test, get the coils adjusted before you hammer another set of tubes.
73 |
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