Great video. I’ve just acquired an 811H and was unsure what I needed to connect to the exciter on my ft950. After watching this I think I’ll be able to do what I wanted. Thank you very much. Paul de M6PNW
Thank you for the inside shots and the details about the re-fit. I currently run a Yaesu FL-2100Z which uses 2 572B's and it performs very well. Those tubes should last a lifetime with the drive you are giving them As you suspected, the limiting factor is the voltage and capacity of your power supply in the stock 811H. All the best! Christopher VA3NTH
I'd like to complement you on the editing of this video. Some may find it "jumpy" but quickly cutting in and out the way you do saves lots of wasted time so I feel like I'm getting lots of input in a short time rather than so much "ahhhhh" or "mumbling" time the way so many other similar videos are. I really appreciate that because your video doesn't make me feel like I've wasted any time. Thanks very much for the very informative video.
Better make sure you can trust your 572B tubes. I was going to convert mine and, as soon as I turned it on, there was a loud bang and smoke. After about 5 hours of work and the replacement of a couple of varistors, and putting back the original 811 tubes, it works great. The 572B tubes were supposedly matched. Don't upgrade to 572B tubes unless you are prepared to do some serious repair work. It is a big gamble for very little benefit. If you tune it correctly the 811 tubes will last a long time and put out as much power as the 572b's. The main power limitation is the stock transformer does not put out the high voltage the 572b's can use. Don't even think about upgrading the transformer or you will blow up your 811H amp.
The 811A tubes should last for years if you don't try to squeeze every last watt out of them. Replacement cost on AliBaba (China) for 811As is about $15.00 each. Same source...572b costs at least twice that...more like three times. It's silly to run this amp at 750ma plate current and over 170ma grid current The difference in signal strength between 600 watts out put and 800 watts is less than 1db. Run the piss out of it and plan on replacing tubes a couple of times a year. Keep it under max output...and relax. Worst case...order spare a set of tubes and if you lose one...replace it.
Hey Brendon, Buck king transformer on ht transformer pri, to up the Ht, needs about 2400v dc, even 2200 will help to lower your drive requirements, the diffs: 811a run redhot at 700, 572b loaf along, much less heat in amp, saves parts, as is now, only benefit long life. tks for vid enjoyed watching. zs2cx
Hi Johan, the power supply is only rated to 2kv, so boosting the transformer voltage would also mean upgrading the voltage rating of the power supply components. Also the filament voltage would increase with this method as they are common in the transformer. A swinging choke may help stabilize the AC Voltage as another method but I have found as you will see in another video I have put 3 Cetron 572B tubes in an AL811 and it screams, since then I have tested more of the Chinese 572B and they really are poor performers compared to the original Cetrons. I also noticed the AL811HD amp has a higher voltage power supply than the AL811H amp, so there is a difference between the two, I did look up the MFJ website to see the costs for the HD transformer and rectifier board but they changed to a new website and don't list the parts anymore. I believe using 572B in the AL811 amps is still a good investment for reliability despite not any real change to power output.
@@vk3mh i agree Brendon, 572b will endure just about forever... (dang that common transformer :) anyway 2kv psu (noted) so you just keep it the way it is , as you know 600 to 800 watt no real diffs in signal other than bragging rights :) , tks for reply, looking forward to the next video.
I didn't see the fan change / upgrade? Per designer "Users should increase airflow if extending duty cycle with 572B tubes substituting for 811A tube. For higher duty cycle operation with 572B tubes, a doubling of CFM is required. The replacement's CFM rating above .08 inches of backpressure must be compared to the AL811's rated flow at 18 CFM. Ideally any new fan would flow 35 CFM at about 0.15 inches water."
I'm not quite sure of what this rapid fire video was. I don't tune this way although I suppose you could. But it would have been nice to see the face of the radios and your meters instead of you jus saying so.
I had the AL-811H with the 811a's in it. It could tune up very carefully to around 925W on 20m, into a dummy load. I found the 572B's didn't quite have as much gain as the 811a's, but they should last longer...
How did you get 925 watts peak out of a stock AL811H? You may want to check the accuracy of your watt meter. Unless it is a Bird watt meter, I seriously doubt 925 watts out. I can't afford a Bird but I have checked mine on 20 meters using the stock meter on my A2TK Palstar and, for 20 meters, I can get 700 watts peak using CW with 70 watts exciter power and not go over the grid or plate maximum current. At high power you may want to have your amp tested using a properly attenuated spectrum analyzer for signal distortion especially on side band transmission. Most hams are not truthful when telling others the signal quality they are receiving. It's kind of like a white lie to keep from hurting someone's feelings.
@@hankhamner3671I part exchanged that amp for an Alpin 100 mkIII, back in September 2015. I've since built 4 homebrew linear amplifiers and use a spectrum analyser to test the spectral purity of them.
The hi voltage power supply in the 811 and 811h not up to supplying the extra amperage drawn by 572 tubes. I have had over the years dozens i have had to replace the high voltage transformer. If it was made for 572's thats what Ameritron would have used.
Thanks for a nice and informative video. I have the AL811 with 811A tubes and I am considering switching to the 572B tubes just to give longer life to the amp. Hope to have a QSO with your one day! 73s, Scott, N6CIC
Spot on there i noted on the wiring the white wire is on the right side on my plug , must of been changed . i blew a fuse every time i power the amp up with 811,s the 811 only lasted a few months one is crook, changed them to 572,s matched pair from eBay china just recently and all is well, i noticed the booklet setting are close the tune also.But not on 10m 3.9 load 9.1/2 on plate but varied a bit depending on antenna i wont use it on 10 m don,t trust it.great video mate .
I have the AL 572 ameritron with 4 572B tubes and on 10 meter I can get appx 1300 PEP watts into dummy load . with icom 735 radio. with the alc I like to run around 1Kw letting the tubes run cooler. remember dip the grid current when tuning. 73s .
Looks like your 811H with 572Bs is loafing along...I assume with 811A's in there, would be about the same output, 800W Key Down but driving the tubes a bit harder
It would have been nice if you would have included more footage of the tuning of the amp. Camera work is quite dizzy and confusing. Good video other than what I mentioned.
Good job. Now convert a unstable @28mhz AL-811 3 tube amplifier/oscillator. Please include specific electrical/mechanical details in particular about neutralization modifications to tame a wild parasitic pig.
My friend has my old 3 tube 811A and it is running fine with 3 x 572B on 10m. If you are having stability problems, your tubes are unmatched same as happens in a FL2100B that has parasitic problems, put a matched set in or add neutralisation.
I have the older Ameritron AL-811H with the red lighted power switch that I put four 572B’s in. Does that make it an AL811HD? Or was there other mods done to make it an AL-811HD?
The tank circuit is heavy duty in the 811HD(as compared to the 811H) Also, it has grid + overdrive protection that the 811H does not have in it's stock configuration. But you can always put it in there.
Nobody can see or hear the difference so it is a Bad choice and if used properly the 811A tubes will last a very long time.I had the 811H for about 10 years and tried the 572B tubes and I went back to the 811A’s.
No that I am aware of, you could check the part numbers in the manuals. The HD refers to Heavy Duty tubes. They consume about the same current as the plate voltage is still about 1550v.
It takes a long to time edit hours of video into 18 minutes and keep all the content, usually about 10 hours to do with multiple camera angles to get it to this stage, in order to make it less dizzy it would take another day. I have 41 videos to edit when I get a chance, the later videos I filmed with fixed focus lenses on tripods so they should present a bit more stable. I hope to add a third camera in the future above the work to make it easier to see the workflow.
Great video. I’ve just acquired an 811H and was unsure what I needed to connect to the exciter on my ft950. After watching this I think I’ll be able to do what I wanted. Thank you very much. Paul de M6PNW
Thank you for the inside shots and the details about the re-fit. I currently run a Yaesu FL-2100Z which uses 2 572B's and it performs very well. Those tubes should last a lifetime with the drive you are giving them As you suspected, the limiting factor is the voltage and capacity of your power supply in the stock 811H. All the best! Christopher VA3NTH
Nice video, I will buy one which has been converted with 4 x 572 tubes, thanks for the info!
Sounds very nice looks like you have a nice surf shack here I’ll be listening have a nice day God bless
I'd like to complement you on the editing of this video. Some may find it "jumpy" but quickly cutting in and out the way you do saves lots of wasted time so I feel like I'm getting lots of input in a short time rather than so much "ahhhhh" or "mumbling" time the way so many other similar videos are. I really appreciate that because your video doesn't make me feel like I've wasted any time. Thanks very much for the very informative video.
Better make sure you can trust your 572B tubes. I was going to convert mine and, as soon as I turned it on, there was a loud bang and smoke. After about 5 hours of work and the replacement of a couple of varistors, and putting back the original 811 tubes, it works great. The 572B tubes were supposedly matched. Don't upgrade to 572B tubes unless you are prepared to do some serious repair work. It is a big gamble for very little benefit. If you tune it correctly the 811 tubes will last a long time and put out as much power as the 572b's. The main power limitation is the stock transformer does not put out the high voltage the 572b's can use. Don't even think about upgrading the transformer or you will blow up your 811H amp.
The 811A tubes should last for years if you don't try to squeeze every last watt out of them. Replacement cost on AliBaba (China) for 811As is about $15.00 each. Same source...572b costs at least twice that...more like three times. It's silly to run this amp at 750ma plate current and over 170ma grid current
The difference in signal strength between 600 watts out put and 800 watts is less than 1db. Run the piss out of it and plan on replacing tubes a couple of times a year. Keep it under max output...and relax. Worst case...order spare a set of tubes and if you lose one...replace it.
You should start the load and plate dials at the place stated in the manual.
Ameritron are partially finished kits! 😮
Ha!
Hey Brendon, Buck king transformer on ht transformer pri, to up the Ht, needs about 2400v dc, even 2200 will help to lower your drive requirements,
the diffs: 811a run redhot at 700, 572b loaf along, much less heat in amp, saves parts, as is now, only benefit long life.
tks for vid enjoyed watching.
zs2cx
Hi Johan, the power supply is only rated to 2kv, so boosting the transformer voltage would also mean upgrading the voltage rating of the power supply components. Also the filament voltage would increase with this method as they are common in the transformer. A swinging choke may help stabilize the AC Voltage as another method but I have found as you will see in another video I have put 3 Cetron 572B tubes in an AL811 and it screams, since then I have tested more of the Chinese 572B and they really are poor performers compared to the original Cetrons. I also noticed the AL811HD amp has a higher voltage power supply than the AL811H amp, so there is a difference between the two, I did look up the MFJ website to see the costs for the HD transformer and rectifier board but they changed to a new website and don't list the parts anymore. I believe using 572B in the AL811 amps is still a good investment for reliability despite not any real change to power output.
@@vk3mh i agree Brendon, 572b will endure just about forever... (dang that common transformer :) anyway 2kv psu (noted) so you just keep it the way it is , as you know 600 to 800 watt no real diffs in signal other than bragging rights :) ,
tks for reply, looking forward to the next video.
I didn't see the fan change / upgrade? Per designer "Users should increase airflow if extending duty cycle with 572B tubes substituting for 811A tube. For higher duty cycle operation with 572B tubes, a doubling of CFM is required. The replacement's CFM rating above .08 inches of backpressure must be compared to the AL811's rated flow at 18 CFM. Ideally any new fan would flow 35 CFM at about 0.15 inches water."
I'm not quite sure of what this rapid fire video was. I don't tune this way although I suppose you could. But it would have been nice to see the face of the radios and your meters instead of you jus saying so.
Nice video, but buy a tripod for your camera!!!
On this side of the pond those are tubes, on THAT side of the pond those are valves.
I had the AL-811H with the 811a's in it. It could tune up very carefully to around 925W on 20m, into a dummy load.
I found the 572B's didn't quite have as much gain as the 811a's, but they should last longer...
How did you get 925 watts peak out of a stock AL811H? You may want to check the accuracy of your watt meter. Unless it is a Bird watt meter, I seriously doubt 925 watts out. I can't afford a Bird but I have checked mine on 20 meters using the stock meter on my A2TK Palstar and, for 20 meters, I can get 700 watts peak using CW with 70 watts exciter power and not go over the grid or plate maximum current. At high power you may want to have your amp tested using a properly attenuated spectrum analyzer for signal distortion especially on side band transmission. Most hams are not truthful when telling others the signal quality they are receiving. It's kind of like a white lie to keep from hurting someone's feelings.
@@hankhamner3671I part exchanged that amp for an Alpin 100 mkIII, back in September 2015.
I've since built 4 homebrew linear amplifiers and use a spectrum analyser to test the spectral purity of them.
Tuner?
The hi voltage power supply in the 811 and 811h not up to supplying the extra amperage drawn by 572 tubes.
I have had over the years dozens i have had to replace the high voltage transformer. If it was made for 572's thats what
Ameritron would have used.
The AL-811HD comes from the Ameritron factory packing 572b's.
Show the meters when you test. We don't need to see your face when the system is keyed down.
An Elmer told me the transformer in the 811 is different than the 811 H
nice video but you move the camara to much.
You don’t know how to spell camera
Bad idea. Higher voltage and costlier tubes for little gain. Stupid.
wtf? this is not a funny cat videeo,
Thanks for a nice and informative video. I have the AL811 with 811A tubes and I am considering switching to the 572B tubes just to give longer life to the amp. Hope to have a QSO with your one day! 73s, Scott, N6CIC
Chines 572b Tubes don,t last very long Mine lasted 3 weeks.
Spot on there i noted on the wiring the white wire is on the right side on my plug , must of been changed . i blew a fuse every time i power the amp up with 811,s the 811 only lasted a few months one is crook, changed them to 572,s matched pair from eBay china just recently and all is well, i noticed the booklet setting are close the tune also.But not on 10m 3.9 load 9.1/2 on plate but varied a bit depending on antenna i wont use it on 10 m don,t trust it.great video mate .
Nice looking shop you have there, Dave in Va. W4GSM
Nice video as I'm thinking of getting a new amp. 73's ON9CJD / EI4GO
I have the AL 572 ameritron with 4 572B tubes and on 10 meter I can get appx 1300 PEP watts into dummy load . with icom 735 radio. with the alc I like to run around 1Kw letting the tubes run cooler. remember dip the grid current when tuning. 73s .
Looks like your 811H with 572Bs is loafing along...I assume with 811A's in there, would be about the same output, 800W Key Down but driving the tubes a bit harder
It would have been nice if you would have included more footage of the tuning of the amp. Camera work is quite dizzy and confusing. Good video other than what I mentioned.
Cool 73 de ve3hip in Welland Ontario Canada 🇨🇦
Have the input coils been replaced? The green coloured enamelled wire inductors are usually red.
I did not change them, so I can't tell you the answer.
@@vk3mh you'll be glad you didn't have to change them, they're a major pain to do!
Not to my knowledge.
Good job. Now convert a unstable @28mhz AL-811 3 tube amplifier/oscillator. Please include specific electrical/mechanical details in particular about neutralization modifications to tame a wild parasitic pig.
My friend has my old 3 tube 811A and it is running fine with 3 x 572B on 10m. If you are having stability problems, your tubes are unmatched same as happens in a FL2100B that has parasitic problems, put a matched set in or add neutralisation.
ua-cam.com/video/S5191dXsuMo/v-deo.html&frags=pl%2Cwn
Hey Danish, I love it right on !
Nice video Brendon vk3mic Mikey....need to talk to you
I have the older Ameritron AL-811H with the red lighted power switch that I put four 572B’s in. Does that make it an AL811HD? Or was there other mods done to make it an AL-811HD?
Hi John, I am unsure as I only tested this one, as it was already modified. Regards Brendan
@@vk3mh Were any other mods done to this besides using 572B tubes and running 240 VAC?
I did not modify the amp however I am not aware of another other mods. My friend also installed 572b in his 3 x 811 amp and he did not do any mods.
The tank circuit is heavy duty in the 811HD(as compared to the 811H) Also, it has grid + overdrive protection that the 811H does not have in it's stock configuration. But you can always put it in there.
Nobody can see or hear the difference so it is a Bad choice and if used properly the 811A tubes will last a very long time.I had the 811H for about 10 years and tried the 572B tubes and I went back to the 811A’s.
I thought the HD had a heavier transformer?
No that I am aware of, you could check the part numbers in the manuals. The HD refers to Heavy Duty tubes. They consume about the same current as the plate voltage is still about 1550v.
I just got the amp, when I transmit into it, the grid current is 0 and the plate current is 75 ma. Does anyone know what the problem is?
That is the idle - bias current showing. When you modulate the amp it will increase and so will the grid current. It is normal for this to happen.
That helps alot! I will see if talking into the mic at full volume helps.
AHA it works!!!! thank you!
Yikes! The camera work made me dizzy.
It takes a long to time edit hours of video into 18 minutes and keep all the content, usually about 10 hours to do with multiple camera angles to get it to this stage, in order to make it less dizzy it would take another day. I have 41 videos to edit when I get a chance, the later videos I filmed with fixed focus lenses on tripods so they should present a bit more stable. I hope to add a third camera in the future above the work to make it easier to see the workflow.