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  1. B

    Alpha 8410 shut off

    Take the plate off the bottom under the tube area and check the filament supply wires connected to the terminal strip.
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    ALC Use

    If the ALC is not adjusted correctly that is worse than not using it at all. If your radio has an adjustable output then you don't need ALC. The 811H is not a solid state amp and a leading edge spike does not bother it. If the radio's ALC does not catch the leading edge spike on its own it's...
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    Dentron DTR-2000L average used pricing

    The new tube is probably with more than the amp itself.
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    Siltronix SLM-100 Bi Linear Amplifier

    Most of Luke's viewers, and he has many, do not know when what he says is right or wrong. WIth having comments shut off no one can write in and correct his mistakes. The problem is the viewers who do not know any better then spew out what he says is wrong as being truth. That makes for lots of...
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    Ameritron 811 problem

    Very very unusual that a set of tubes will work perfectly on all other bands except one. I'd like an explanation for that for educational purposes. Tom W8JI is a busy guy and sometimes does not read full explanations and jumps to conclusions with partial reading. Your initial statement sure...
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    Ameritron 811 problem

    There are padding caps that get switched in on the lower bands. If the padder caps are missing, open, or if the contacts that switch them in parallel with the variable load cap are bad, you will never have enough capacitance to get the variable from going less than full mesh. When the amp is...
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    SB220

    How often do you ship 50-100 lb amplifiers with UPS?
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    SB220

    Fed Ex delivery men in some areas of the US are self employed. They do NOT work directly for Fed Ex as employees, they are sub contractors. If a delivery is damaged in shipping and Fed Ex gets a claim on it and it is discovered that the delivery guy was at fault, Fed Ex deducts the amount of...
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    SB220\221 Bias mod

    The best capacitor to use to completely null the SWR is 33pf. It nulls any rectance and drops swr flat. Also note that on the SB-220 vs the SB-221, the input switch pin numbers were also reverse. That means that comparing the SB-220 to the 221 the common pins of the input switch were...
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    Extra

    Many years ago, before the Beetles, I was a young novice in a radio club of around 45 members. ONLY ONE HAM IN THE WHOLE MEMBERSHIP WAS AN EXTRA CLASS. How many Extra class operators are in a club of 45 members these days?
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    Amp Supply lk500 10 meter parts,

    You’ll need the 10 meter input coil and input compression caps. You may have to tap the tank coil and may have to remove stop on band switch.
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    Old Amp

    Unless someone has a lifetime supply of TV sweep tubes it makes no sense spending 200-300 dollars to re tube a sweep tube amp. There are lots of amps running 811 or 572b or 3-500z tubes that can be re purposed at a lower maintenance cost over time, If drive power is an issue there are many...
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    Kenrich Eagle 500-Next Patient

    Why is the tank coil tapped?
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    Ameritron 811h

    How did you flatten out 572b tubes in an 811h? Something wrong there.
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    Ameritron 811h

    The SB-220 has an antenna keying voltage of about 120 vdc give or take a few volts, but it is nowhere near 235v. The best "interface" to use to lower that keying voltage is a solid state circuit using a MOSFET to key the high voltage and the keying voltage then becomes just that required by a...
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    Ameritron 811 help

    Plate current and grid current specs are only guidelines for tubes. In the case of an 811 tube, they do not have a fragile grid or plate. What ruins these tubes is heat over time. Sure you need to be quick in tuning because an out of tune tank circuit creates high circulating currents which...
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    Keying relay for amps using opto-isolator

    Is that the PE unit that Pete Gagny designed?
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    maco 75 problems

    First and foremost check the parasitic suppressor and make sure its good before you look elsewhere.
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    Amp supply LK550 have 10M?

    GOOD CATCH!! Indeed, if that is his amp it does not have 10/11 meters.
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    Amp supply LK550 have 10M?

    Nope, you can't "talk thru it" and tell. The easiest way to tell if it works on 10 meters is to see if #1 Does the band switch click one more time after 15 meters? #2 open the lid and see if the 10 meter input circuit is present on the input board. Often times the 10 meter input circuit is...