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Author Topic: AL-811 Amplifiers Suck  (Read 80392 times)
K1BUX
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Posts: 8




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« Reply #15 on: September 23, 2016, 07:09:31 AM »

Oh my, I am guilty of buying an MLA-2500, those 8875 tubes are crazy expensive. Oh yea, I only paid 200 and it was still in the original box. Works wonderfully.
As for an AL-811, never had the privilege.
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N4UM
Member

Posts: 624




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« Reply #16 on: September 23, 2016, 07:46:29 AM »

VK3BL... loved it!!! 

BTW do you still go to those AL 811 Anonymous meetings every week?

I myself had an overpowering urge to buy an AL-811 once but called a friend who was a member of AL-811 Anonymous .  He immediately came over and stayed up all night convincing me not to.

I must confess I still do get a slight urge to return to my folly whenever I thumb thru an Ameritron catalog, but with the help my membership in A811A  and the guidance of my very own  personal savior and personal banker, I keep my unnatural urges in check.

Thanks for sharing.   Roll Eyes
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KD8MJR
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Posts: 5557




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« Reply #17 on: September 23, 2016, 07:48:18 AM »

This thread has Zero value!
We all get the sarcastic posts but it's kind of stupid to come into an amplifier section. With the lowest price amplifier and expect to somehow win over people or shut them up with sarcasm.
I really don't even understand why you care what people think!  If it's working for you then you should be happy, why do you feel a need to change other people's opinions?
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“A lie can travel half way around the world while the truth is putting on its shoes.”  (Mark Twain)
KD0REQ
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Posts: 2389




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« Reply #18 on: September 23, 2016, 09:48:46 AM »

if you guys would just homebrew an amp with 10,000 12AX7As and quit crabbing.............
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WY7CHY
Member

Posts: 970




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« Reply #19 on: September 23, 2016, 10:27:42 AM »

I don't think anyone is trying to change someone else's opinion. I think their simply trying to make the point that;

"If a person starts a thread or makes a comment concerning using an AL-811(H) amplifier, that if the person reading the thread/post doesn't have a constructive contribution to the thread, they shouldn't reply. Basically; replying with:
1. Buy a new amp
2. Buy a real amp
3. The AL-811(H) is over-rated
4. The AL-811(H) is junk
5. Your problem is; you have an AL-811(H)
etc.
ARE NOT CONSTRUCTIVE posts.

There's a lot of arrogance in the Ham world of users. There's the uber OLD-Timers, who think anything solid state is basically junk; that if you don't know "Code", then you're not a "REAL" Ham; etc. There's the Techno-Hams who THINK they know everything about everything because they have an Extra license and they took an electronics course at ITT Technical. Everything for them is proven with formulas, math, propagation and power charts, etc. Little do they know or accept that the world of HF/Ham is not Black and White. What SHOULD work, doesn't always work for everyone. And what SHOULD SUCK may actually work quite well for some people. Mainly because of the countless variables involved in radio.

This of course is not a blanket statement. There's a lot of old, young, new, experienced, rag chewers, techno-geeks, etc. from all categories that understand that there can be a place for everything and everyone. Especially in a hobby such as amateur radio. In this particular thread, no one is trying to convince anyone else that they need to buy and use an AL-811(H) amplifier. Simply saying, that it's not totally the junk that SOME OTHERS want to promote it as. "If it were, it wouldn't still be in production after 25 years".

It may not be the right amp for EVERYONE; but that doesn't mean it's not the right amp for ANYONE.
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Born Wild - Raised Proud: 73
Cheyenne, Wyoming
N4UM
Member

Posts: 624




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« Reply #20 on: September 23, 2016, 10:51:34 AM »

Lighten up!
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WY7CHY
Member

Posts: 970




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« Reply #21 on: September 23, 2016, 11:57:53 AM »

https://youtu.be/B65mtE2TN1w
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Born Wild - Raised Proud: 73
Cheyenne, Wyoming
M0HDX
Member

Posts: 56




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« Reply #22 on: September 23, 2016, 12:24:59 PM »

Not so much the Amp but the junk 811A/572B out of china that it uses.
« Last Edit: September 23, 2016, 01:03:04 PM by M0HDX » Logged
K9AXN
Member

Posts: 442


WWW

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« Reply #23 on: September 23, 2016, 12:33:44 PM »

As long as the AL-811H is the star of the show, I have a few questions.  Have to say I don't have a horse in the race, never used one, and have no opinion or experience with the amp.  What is of interest, are the design variations in cathode driven amplifiers that use 811A or 572B tubes.

First, What is the common adjusted capacity of the neutralizing capacitor?

Second, what is the procedure used to adjust it?

Have the frequencies of common parasitics been recorded and under what conditions.

Has instability gone through sea trials i.e. has the output, or input, or both been disconnected while tune and load caps are varied.

I haven't seen any of these specifics published.

What interests me is what logic designers used to enable a tube that was designed for audio use to work at HF frequencies.  Sweep tubes went through the same censure after some creative engineers integrated them into Ham radio equipment.  Most designers don't like sweep tubes simply because they require more careful design thinking; they can't just be dropped into common circuit designs.

Probably the wrong thread but the AL-811H has more interested parties than other cathode driven amps using the 811A or 572B tubes.

Regards Jim

  



  
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VK3BL
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Posts: 1789


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« Reply #24 on: September 23, 2016, 01:39:56 PM »

First, What is the common adjusted capacity of the neutralizing capacitor?

Second, what is the procedure used to adjust it?

Have the frequencies of common parasitics been recorded and under what conditions.

Has instability gone through sea trials i.e. has the output, or input, or both been disconnected while tune and load caps are varied.

I haven't seen any of these specifics published.
 

1) Not sure, haven't seen that published either, nor felt the need to measure it.

2) In W8JI designs, a 'sense plate' / capacitor is moved closer to or further away from the tubes.

3) Neutralisation is adjusted for somewhere between 15MHz and 10MHz in a 4 tube model, either 811A or 572B IIRC.

4) Depends on the amp.  The Collins 30L1 is not unconditionally stable on 10M, nor is the Yaesu FL-2100B  The AL-811 3 tuber isn't either in rare situations.  Both the AL-811H and AL-572 cannot be made to break into oscillation.
« Last Edit: September 23, 2016, 01:43:07 PM by VK3BL » Logged

J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio - Honesty & Integrity
VK3BL
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Posts: 1789


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« Reply #25 on: September 23, 2016, 01:41:37 PM »

This thread has Zero value!
We all get the sarcastic posts but it's kind of stupid to come into an amplifier section. With the lowest price amplifier and expect to somehow win over people or shut them up with sarcasm.
I really don't even understand why you care what people think!  If it's working for you then you should be happy, why do you feel a need to change other people's opinions?

Just a bit of fun Rob.  But it is a reaction to the fact that when a lot of people come on forums asking for help with their AL-811 amps, rather than get help they receive condemnation.
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J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio - Honesty & Integrity
KD8MJR
Member

Posts: 5557




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« Reply #26 on: September 23, 2016, 03:36:50 PM »

Jarrad I understand, I guess I have gotten so use to the negative threads on eHam that I sometimes no longer recognize the jokes Cheesy
Anyway the amp section is not that bad when compared to the HOA section.  Sometimes in that section it feels like Hams enjoy watching other Hams suffer.


73
Rob
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“A lie can travel half way around the world while the truth is putting on its shoes.”  (Mark Twain)
N7WR
Member

Posts: 117


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« Reply #27 on: September 23, 2016, 04:14:30 PM »

Hate to spoil the idea that 811's and 811H's suck but I've used a lot of them and never had a problem of any kind.  The key is to properly tune them and to understand what their "real", reasonable output is which is NOT as high as advertised.  I have never tried to get more than 450 watts out of an 811 amp nor more than 650 out of the H model.  I have an 811 here that I have had for over 10 years and the original tubes are still putting out what they should.  Driving these amps too hard and/or not tuning them properly I suspect accounts for 95% or more of the problems experienced.
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W8JX
Member

Posts: 13268




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« Reply #28 on: September 23, 2016, 05:15:11 PM »

Hate to spoil the idea that 811's and 811H's suck but I've used a lot of them and never had a problem of any kind.  The key is to properly tune them and to understand what their "real", reasonable output is which is NOT as high as advertised. 

I do agree that if you run them 25 to 30% below rated output they will last some time but problem is many do not know how to use power control on rig an drive 811 amps with 100 watts an quickly kill them. I think if Ameritron had de-rated them some and put a pad on input so 100 watts drive would not overdrive it to beyond safe levels for tube they would have done much better.
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--------------------------------------
Ham since 1969....  Old School 20wpm REAL Extra Class..
K9AXN
Member

Posts: 442


WWW

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« Reply #29 on: September 23, 2016, 06:00:57 PM »

First, What is the common adjusted capacity of the neutralizing capacitor?

Second, what is the procedure used to adjust it?

Have the frequencies of common parasitics been recorded and under what conditions.

Has instability gone through sea trials i.e. has the output, or input, or both been disconnected while tune and load caps are varied.

I haven't seen any of these specifics published.
 

1) Not sure, haven't seen that published either, nor felt the need to measure it.

2) In W8JI designs, a 'sense plate' / capacitor is moved closer to or further away from the tubes.

3) Neutralisation is adjusted for somewhere between 15MHz and 10MHz in a 4 tube model, either 811A or 572B IIRC.

4) Depends on the amp.  The Collins 30L1 is not unconditionally stable on 10M, nor is the Yaesu FL-2100B  The AL-811 3 tuber isn't either in rare situations.  Both the AL-811H and AL-572 cannot be made to break into oscillation.


Jarrad,

Thanks for the response --- couple more questions.

1)  Is the neutralization adjustment the common plate dip and max out alignment and are the other bands equally neutral after the
     10/15 Metre adjustment, and have you done this adjustment?  Don't remembering seeing the adjustment process written for
     any of the neutralized amps just fixed adjust the spacing of the neutralizing cap.

2)  Is the AL-811H unconditionally stable on 15 and 10?  That's to say if both the input and output are disconnected and left
     un-terminated will it become unstable using the common operations to provoke instability?

3)  I believe you or maybe someone else wrote that there was a recommendation to directly ground the grids rather than use
     the .01uf cap and 51 ohm resistor.  If so, what was the rational.

Thanks for taking the time to respond.

These are questions that peak my curiosity regarding any and all amps that use the 811A or 572B.

Regards Jim     


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