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Ameritron AL-811H Amplifier

nolyn78

New Member
Mar 25, 2022
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Does anyone knows what happened to my amplifier? When I transmit, I heard a loud noise and notice my Plate HV/IC Meter was burnt, the meter needle was gone, current resistor was burnt, R10, R9 resistor open (.6 Ohm) and both fuses open. What I noticed that diode D16 was not there and missing. I have been using the amplifier for almost a year with out the diode. I contacted Ameritron and inquired why the diode was missing and no help, he said it should be on the board. A year ago when it is still warranty, I sent it back to replace one fo the tube and the technician mentioned to me that he did something else. I did not bothered to ask him. Did anyone experienced this issue and maybe guide me on what to look for after I replace the bad components?
 

I owned an 811H for about 10 years & I had some upgrades done because it was an older model.If I still owned an Ameritron I'd call & speak with Rob Hood or Mike Enis who are two of the technicians & they are very helpful.Two good guys who go out of their way to Help.

SIX-SHOOTER
 
Inspect the 811's (or 572 whatever yours is tubed with), and inspect the plates. See pics below.... Outside of the missing glass (removed to improve images), if they are not a solid blackish color, and have those shiny, deformed areas on them as seen in these two pics, the plate is likely shorted to the grid. This example is severe, but ANY shiny metal is not good! This is caused by over-driving the amp, running it out of tune, long key-downs, or any other issue that would cause the plates to turn orange, deform then literally melt.
My Ameritron 811 loved to eat tubes until I went to 572's, and then it 'just liked them pretty good'.... But then, I'm known to key-down and speak my mind over long periods of time.

When this happened, it took out one or more components in the HV chain.... Those components you mentioned are in the HV circuit, and you'll need a new meter and other components in addition to the new tubes.
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Thank you for your reply. I removed all the tube and checked the filament and plate and all okay. Removed the HV electrolytic capacitors and checked, all okay. It seems like the section on the HV plus the meter were the only components affected. Rob from the Ameritron mentioned to me that that diode D16 In4007 should be installed for protection. I was thinking that someone have the same experience . I ordered all the components and should be arriving next week. Thank you.
 

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