811 Tube History including 811A 572B
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- Опубліковано 5 вер 2024
- This video looks at the evolution and operation of the 811 tube.
There are more details on my old legacy website www.w8ji.com
My other websites are www.commandtechnologies.biz and www.ctrengineering.com
I hope to become more comfortable making educational videos as time goes on. Thank you!
The 811 types are the only tubes I own anymore. I'm glad to hear you are still pushing the Chinese to put out at least a satisfactory tube.
I really appreciate these videos Tom, I have learned so much from your channel as well as on our FB group. . I have a 811-H I bought years ago and just because I could buy 572 B tubes for $40.00 each at that time I put them in.
Thank you. I am working to get a good 572B tube. I have good 811's and 3-500, but the 572's are not good so far.
Tom,
Nothing better than the bottom line inside dirt on the topic, appreciate your experience and efforts in producing and sharing your knowledge! 73 ND7C - David
Thanks for the great insight into the 811/ 811A and 812 tubes. It would appear that your design of the AL-811 series is solid, but about 12 years ago I bought an AL-811 (3-tube) and never could get it to perform properly. Tech support in Starkville was no help and Instead of taking advantage of any warranty, I sacrificed it for parts (no big deal). I bought a second AL-811 and have been using it for about 10 years. I have never been able to get more than about 450 watts out of it however. Last week - using parts from the cannibalized amp, I added a 4th tube and now I get 550 to 600 watts from it. So I'm running 3 - 572Bs in the original sockets and an 811A in the added socket. Not the best configuration but So far, So good.
so you have 3 572b and one 811 running in the same amp?
@@swingdaddy2126 Yep - the original positions have 572Bs and the added one is an 811a that I had. So far it's working OK. They're all parallel, so there's no trouble w mismatch.
Very much enjoyed this video! I have an AL-811H and continue to document and verify settings before applying exciter power via an ICOM-7300.
My brain got duty cycled watching this. 'Thanks for posting.
Great info as always Tom! Thanks so much and 73
Thanks for a great video on the 811. Eight years ago when I changed the 811s in my AL-811 you were good enough to explain to me the limitations of AM use of the AL-811. Last month my AL-811 blew a fuse and again your "Amp Troubleshooting Tips" were a great help in determining the problem, which was a bad 811 tube (the plate showed no burning). It looks like a grid short but I'm not sure. I also made the protection mods 8 years ago when I bought the amp used and that might have saved the rig. Thanks Tom for your help. I'm hoping I can buy a replacement set from you. -Ken
Thanks for the information. Between here, and the other places we run across each other, you have educated me more than you will ever realize. I do appreciate it and please keep sharing your knowledge across the platforms.
Thank you Tom and 73’s.
Great videos !!! Nicely done Tom, thank you for sharing your knowledge and experience with all of us .. truly invaluable !!!! Thank you!!
Thanks Alex. I am overwhelmed with work. I'm also not that great on videos so even these videos take hours of time. I really appreciate the kind words. Ham radio is a great fraternity.
That was a great video. Thanks for doing it. I just bought a used AL 811, the three tube model and this is great information. Thanks again and 73 Jeff KE0KRO
Tom, never saw this vid before today. The Time vs Dissipation chart was new to me. Feel guilty for all those long tune-ups into DL Loved those comments on Ameritron design process.
P.S. That HVPS board ready for install in a few days. Came out good. Ned, NYC
Learned a lot from this video. Thank you very much. I have a 10 year old AL-811 that I use on SSB with my ICOM 7300 running anywhere from 25-50% out of the radio and it works great.
Well done Tom! Thanks for the education!
Excellent!
Many thanks & 73
de K4WRF
Thanks really appreciate this many more should be watching.
As always very educational and interesting, thank you.
73, Rune LA7THA
@ 8:00
That looks like an 8005, not 812.
811's make great audio amplifiers.
Fabtastic Tom I have a 811 and a 811H they are great and simple to use
Thanks for the invaluable info!..
That was too short! What did they do in the 572b to make it better?
Basically they made the anode heavier and threw a little oxide on the 811 filament.
Very informative! As cheap as IR sensors are these days, maybe it would be worth employing them to watch plate temp on the 811s? They could easily trip a safety mechanism, just like grid current.
I thought about that but the target goal of the 811 was to be as cheap as possible. I had a hard time convincing them to use a fourth tube. :)
Some of us still like to play with AM. What can we do?
Thank you. Nice video..
You talk down the Chinese tubes, but yet your CTR Tube looks just like this one? How are your tubes dfferent?
I don't "talk down" about Chinese tubes. Some Chinese tubes are good, some okay, and some are just bad news. It depends on which Chinese plant and what tube. All new RF 811's now come from China. There are some old surplus tubes and so called Russian tubes floating around, but they are not substantially better than the better Chinese 811 tubes. There are of course some Chinese plants that can't make a good tube.
Very interesting information thanks for taking the time to do this. I have the 811 with RF parts 572B tubes had to change the parasitic board from Aneritron to the updated board, I heard it helps to change the resistors on that board from 3 watt 100ohm to 5 watt 100 ohm resistors to keep it cooler especially on digital modes. Could you elaborate on that at all?
73's
The original improved suppressor used a metal film resistor that was intentionally inductive. That resistor was series tuned by two small mica capacitors to have a very low impedance at the frequency area of instability. The brand and type of resistor was critical. The capacitors are selected for a specific resistor style. If anything changes, the system will go out of whack and the capacitors need to be resized for the new style resistor.
The combination of series capacitors in the resistor path and shunt fixed inductor causes the current to shift out of the suppressor's coil more rapidly with frequency. This significantly reduces resistor heat for a given operating condition across all of HF, especially up on the high end. It is explained here near the page bottom:
www.w8ji.com/vhf_stability.htm
MFJ unfortunately might not quite be up to industry standards on quality assurance or assurance of consistency in critical components, and that resistor was supposed to be noted as a critical component. It is possible they changed vendors or styles of resistor and the circuit at some point became "out of tune". The original 3W resistors are far more than adequate if suppressors are tuned and manufactured correctly. I used the same scheme in the AL80B, and I've used it in commercial decks up to 50kW. The compound suppressor works quite well *if* properly and consistently manufactured. If you go swapping resistors, it needs looked at with the new resistors. The capacitors and/or inductor may need changed.
@@Jerrythenerdful thank you. I didn't think I should touch it. I just got the new one from mfj with the 5 turns on the windings and I have 5 watt metal film resistors but I didn't want to go reinventing the wheel persay. I figured 30 watts in giving 200 or so out on ft8 or ft4 wouldn't hurt it. If I try to go any higher the grid current goes way beyond the 200ma which I know is a no-no
@@Joe_HamRadioGuy If you open the load control up the grid should drop for a given drive. If not, the meter protection diode is likely shorted.
Thanks for the reply. Do you recommend anywhere to buy 572B tubes ? Gerard KH7AW
Understand that all these tubes come from the same few manufacturing plants, and they are resold under different names. DX Engineering is probably the most reputable business around. Ameritron, although sometimes slow to deal with, would be selling the same tubes they actually use. I'm just not sure how well anyone weeds through the tubes, how they test or inspect, or if they even do. I don't even know where some people are getting the tubes, if they are surplus or new or what they are.
We do a pretty extensive test on the tubes. We have a tester that runs the tubes at very high voltage and current. We check peak emission and match tubes at the upper end of curves. We have about 10% fall out, getting tubes from the better sources. But we are almost out of 572 at the moment, and only have enough for service work units.
What do you think about the Penta 572B tubes ? I was afraid to buy tubes directly from China even though they were much less expensive. I am replacing the tubes in my 811H amp that I ran for twelve years with the original tubes. One finally gave out. I noticed the originals looked like the Chinese tube you had on your video. I felt much safer buying the tubes from Ventura Ca. I live on the island of Maui. Thanks for your great video. KH7AW
All new 811A tubes come from just a couple places. Everyone puts their different names on them. One plant is better than the others and has about 10% rejection rate in testing new tubes. Some of the other plants are 40-80% fall out, but the tubes are very inexpensive.
I don't know where Penta buys their 572B tubes at any moment of time. I do know that Penta, over the years, has a very shady past with selling counterfeit or rebranded parts. They sold Ameritron thousands of dollars worth of washed and relabeled defective tubes, we never got a dime back. Years later they did the same to MFJ, and they have done that to the US government.
They were involved in selling banned equipment to Iran, too. All of this is public record in DOJ documents.
I never knew the 811 tubes weren't good for AM.
What?
Love the American made Penta Laboratories Tubes.
Where did you get the idea Penta makes tubes, or that Penta tubes are USA tubes? Penta hasn't made a tube for as long as I can remember. They relabel and resell things under their brand name, just like everyone does with Chinese tubes.
In the 1980's when 8877's were having problems, Penta approached Ameritron to buy 8877/3CX1500A7. We bought a large batch of supposedly new tubes, they were all bad, and we never got a dime back. It turned out the tubes were "washed" and relabeled Eimac duds. Some of the tubes had engraved codes the same number as Eimac tubes we had returned for warranty! They did something similar to MFJ years later.
@@Jerrythenerdful Penta Labs that make tubes for Ham radio and many for Hospitals such as xray tubes and braodcasting tubes are in Chatsworth California for many years and still a tube maker in America. They test each tube at full power for 24 hours before selling them.
@@Jerrythenerdful Well I called them and you are right they also are made in China. Bless my little heart..
@@timbacchus Nonsense. They don't make any tubes and have not sold their own tubes since the 1960'sor 1970's.
You might want to read this:
www.justice.gov/sites/default/files/criminal-ccips/legacy/2012/03/15/dojHost.pdf
@@timbacchus Or this
www.upi.com/Archives/1985/11/19/A-company-executive-who-admitted-shipping-300000-in-military/7156501224400/
PURE GOLD