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Author Topic: AL-811 center tube plate glowing...  (Read 25725 times)
K6AER
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Posts: 5743




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« Reply #105 on: February 26, 2017, 08:39:14 AM »

Reading this post is like reading a book. Sort of like the TV series Dallas with amplifiers and Bill Orr as J R.

I know hams are always looking for the best in matched tubes but forget that not all tubes age the same. With time, some tubes will have lower gain and as a result the higher gain tube will be pulling more of a load. That could be the case with one tube glowing hotter.

My experience with Ham Tube Amplifier manufactures has always been with ceramic tubes. We never bother with matching 3CX800A's and 4CX800A's.  Then again, the specifications on a more expensive tube is probably a lot closer.

What is interesting is how many new hams are buying these entry level amplifiers and really don't understand what amplifier specifications mean. They just see 800 watts PEP and place the order.  With so many used high power amplifiers (SK factor) hitting the used market, it needs to be pointed out that they would be well served to buy one of the larger used amplifiers. You don't need to drive them to full output. $1800 will buy you a very nice full legal limit amplifier. When you want something else you can sell it for what you paid for the unit. Your depreciation cost is null. You are not overdriving the amplifier for the last watt out, and the output will be clean, (ZIMKE Factor).

There are over 100 amplifiers listed on QTH.com capable of over 1200 watts out. Some of these amplifiers will require some TLC but others are ready to roll. It is interesting the resistance of new hams to buy used equipment. Maybe it is the lack of Elmers in the hobby.
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W1QJ
Member

Posts: 2981




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« Reply #106 on: February 26, 2017, 10:30:52 AM »

Reading this post is like reading a book. Sort of like the TV series Dallas with amplifiers and Bill Orr as J R.

I know hams are always looking for the best in matched tubes but forget that not all tubes age the same. With time, some tubes will have lower gain and as a result the higher gain tube will be pulling more of a load. That could be the case with one tube glowing hotter.

My experience with Ham Tube Amplifier manufactures has always been with ceramic tubes. We never bother with matching 3CX800A's and 4CX800A's.  Then again, the specifications on a more expensive tube is probably a lot closer.

What is interesting is how many new hams are buying these entry level amplifiers and really don't understand what amplifier specifications mean. They just see 800 watts PEP and place the order.  With so many used high power amplifiers (SK factor) hitting the used market, it needs to be pointed out that they would be well served to buy one of the larger used amplifiers. You don't need to drive them to full output. $1800 will buy you a very nice full legal limit amplifier. When you want something else you can sell it for what you paid for the unit. Your depreciation cost is null. You are not overdriving the amplifier for the last watt out, and the output will be clean, (ZIMKE Factor).

There are over 100 amplifiers listed on QTH.com capable of over 1200 watts out. Some of these amplifiers will require some TLC but others are ready to roll. It is interesting the resistance of new hams to buy used equipment. Maybe it is the lack of Elmers in the hobby.


Very apropos posting.   I am going to be guest speaker at the Murgas radio club out of Wiles Barre,Pa. Wednesday evening.  I'll be speaking about amplifiers in general and one of my points is exactly what is mentioned here.  The talk is geared towards helping hams select the correct amplifier for their needs based on a number of criteria.  The point made here will be well stressed.
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NZ4ZN
Member

Posts: 188




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« Reply #107 on: February 26, 2017, 03:21:23 PM »

Reading this post is like reading a book. Sort of like the TV series Dallas with amplifiers and Bill Orr as J R.
<grin>
Quote
....It is interesting the resistance of new hams to buy used equipment. Maybe it is the lack of Elmers in the hobby.
That, and I'd also attribute it to that it can be very hard to find someone to work on this stuff if you don't have confidence to do it yourself. I bought new transceivers because I can't work on those intricate parts and wanted warranty, but those old amps are typically big enough to park a bus in and not at all bad to troubleshoot & repair.
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KM1H
Member

Posts: 5513




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« Reply #108 on: February 28, 2017, 04:58:54 PM »

Im disappointed I never met him or worked him on any band.

His accomplishments and place in amateur lore is cemented in place for eternity.
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