Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: Another AL-811 Question  (Read 3106 times)
KD8GKR
Member

Posts: 47




Ignore
« on: February 15, 2011, 09:08:37 AM »

Here goes. My AL-811 doesn't seem to load very well into a dummy load on 80 and 160. I have to turn the load CCW to "0" and it still hasn't peaked on my meter. On 40 i am only getting right at 475-500 with 65 watts. Assuming the tubes maybe weak could this be causing the loading problem on 80 and 160 meters? The amp has 572b's which was in it when i bought it used. Before i purchase a new set of tubes i am wondering about the loading problems. I have never put this amp inline since i purchased it. I regularly use a FL-2100B, but a buddy of mine just had to have it so i am now wanting to get the AL-811 permanently inline. Thanks for your time in advance.
73 Brent/KD8GKR
Logged
WB2WIK
Member

Posts: 20542




Ignore
« Reply #1 on: February 15, 2011, 02:31:28 PM »

Sounds to me like it's not fully loaded, due to insufficient drive.

What is the grid current when you drive it?
Logged
KD8GKR
Member

Posts: 47




Ignore
« Reply #2 on: February 15, 2011, 11:28:31 PM »

Steve,
I have switched one of the 572b's(bad?) out with a 811a. here is what i have:
60watts drive, Plate 450, Grid 110, 600 out on 40 meter.
 Still cant tune 80 into a dummy load though. It hasn't peaked by the time load gets to "0".
Padding caps?
I plan on a new set of tubes, just wanting to see if 80 and 160 tuning is/maybe tube related?
Thanks Brent
Logged
W8JX
Member

Posts: 5444




Ignore
« Reply #3 on: February 16, 2011, 05:57:11 AM »

Generally a 811 can have a bit more gain(ie need less drive) but need to be careful because if you run a 3 tube amp at more than 500 watts out you are exceeding tubes rating for plate dissipation and can have a shorter tube life. Consider this, if you are content with running no more than about 450 watts out, buy 811'a and they will last a long time. If you feel you need to push it hard buy 572's. But, remember that between 450 and 600 you will only have about 1 db of signal level increase. Another tip, I run same exciter power out barefoot or not. Meaning I normally drive my Dentron amp with 45 to 50 watts to get 800 to 850 out  and in your case when you go from say 45 watts or so to 450 you will see a 10db increase vs 7 db from 100 to 450.
Logged

--------------------------------------
Entered using a  WiFi Win 8.1 RT tablet or a Android tablet using 4G/LTE or WiFi.
WX7G
Member

Posts: 5917




Ignore
« Reply #4 on: February 16, 2011, 07:42:00 AM »

The AL-811 with 811A tubes will run fine at 600 watts SSB and even at 600 watts CW. With on-off keying (a string of DITs) the power disispation is 67 watts per tube (assuming 60% efficiency). The tubes are rated for 65 watts ICAS. I would not worry about the 2 extra watts and besides the tubes are $20 each. With SSB the power dissipation per tube will be less than the 811A ICAS rating. Don't baby the tubes, use them. Make them do your bidding and don't be a slave to your tubes.

With the 572B tubes you have plenty of margin and the power supply becomes the limiting factor.

On 160 meters my AL-811 Load control was always at 0. It worked fine. If it outputs rated power on 80 meters with the Load at 0 it seems to me there is no serious issue.
« Last Edit: February 16, 2011, 07:44:18 AM by WX7G » Logged
KD8GKR
Member

Posts: 47




Ignore
« Reply #5 on: February 16, 2011, 07:47:57 AM »

On 40 meter the knobs are: load just below 3 (2.8 ) and plate just under 8 (7.8 ). The Plate has a sharp dip at the same time the Grid peaks. Dummy load is a heath cantenna. Just trying to provide as much info. so we can possibly get the low band tune-up solved.
Brent/KD8GKR
Logged
W8JX
Member

Posts: 5444




Ignore
« Reply #6 on: February 16, 2011, 07:52:39 AM »

The AL-811 with 811A tubes will run fine at 600 watts SSB and even at 600 watts CW. With on-off keying (a string of DITs) the power disispation is 67 watts per tube (assuming 60% efficiency). The tubes are rated for 65 watts ICAS. I would not worry about the 2 extra watts and besides the tubes are $20 each. With SSB the power dissipation per tube will be less than the 811A ICAS rating. Don't baby the tubes, use them. Make them do your bidding and don't be a slave to your tubes.



If they were so sturdy they would not fail as often as they do. When you run a amp that requires its tube(s) to operate at or about if CONTINUOUS dissipation rating you can have shorter life and damage tube tuning. When you exceed ICAS rating you are really playing with fire. BTW the continuous dissipation rating for 811 is about 45 watts per tube and Ameritron is not overly generous with airflow for them either and focuses more on being quiet. One 572 can safely dissipate about the same power as three 811's
Logged

--------------------------------------
Entered using a  WiFi Win 8.1 RT tablet or a Android tablet using 4G/LTE or WiFi.
KD8GKR
Member

Posts: 47




Ignore
« Reply #7 on: February 16, 2011, 08:02:44 AM »

The previous owner of amp ran it with 100 watts drive. As for 811a and 572b tubes, i want to purchase 572b's. I also would like to solve the fully meshed loading on 80 and 160 first. I feel this is not a proper way to run a amp. I have a SB-200 and just sold a FL-2100b in which neither of these amps loaded fully meshed. Lets not make this thread into a debate between 811 and 572 tubes, please.
Logged
K8AXW
Member

Posts: 3651




Ignore
« Reply #8 on: February 16, 2011, 09:05:46 AM »

Contact the manufacturer and see what THEY say!
Logged
WB2WIK
Member

Posts: 20542




Ignore
« Reply #9 on: February 16, 2011, 10:49:19 AM »

Steve,
I have switched one of the 572b's(bad?) out with a 811a. here is what i have:
60watts drive, Plate 450, Grid 110, 600 out on 40 meter.
 Still cant tune 80 into a dummy load though. It hasn't peaked by the time load gets to "0".
Padding caps?
I plan on a new set of tubes, just wanting to see if 80 and 160 tuning is/maybe tube related?
Thanks Brent

That didn't quite answer my question.  You described how it tuned up on 40 meters, and then how the LOAD control is always at "0" on 80m and 160m.  But you didn't answer how much output power it runs, and what the grid current is, on 80m when the plate tune is peaked and the LOAD control is at zero.

If the Ig is fairly low, I'd drive it harder and see if that creates the need to increase LOADing, thus taking it up off zero.

If the Ig is very high already, then this wouldn't be a solution.  But you'd have to monitor that on 80m, not on 40m.
Logged
WX7G
Member

Posts: 5917




Ignore
« Reply #10 on: February 16, 2011, 03:40:15 PM »

We have not been told if the amp makes rated power on 160 and 80 meters.
Logged
KD8GKR
Member

Posts: 47




Ignore
« Reply #11 on: February 16, 2011, 10:04:46 PM »

Steve,
I have switched one of the 572b's(bad?) out with a 811a. here is what i have:
60watts drive, Plate 450, Grid 110, 600 out on 40 meter.
 Still cant tune 80 into a dummy load though. It hasn't peaked by the time load gets to "0".
Padding caps?
I plan on a new set of tubes, just wanting to see if 80 and 160 tuning is/maybe tube related?
Thanks Brent

That didn't quite answer my question.  You described how it tuned up on 40 meters, and then how the LOAD control is always at "0" on 80m and 160m.  But you didn't answer how much output power it runs, and what the grid current is, on 80m when the plate tune is peaked and the LOAD control is at zero.

If the Ig is fairly low, I'd drive it harder and see if that creates the need to increase LOADing, thus taking it up off zero.

If the Ig is very high already, then this wouldn't be a solution.  But you'd have to monitor that on 80m, not on 40m.

Ok, i forgot to mention what i am getting on 80. Plate is 525ma, Grid is 90ma and output is 475-500w. Load is at "0", of course if i increase loading Plate goes higher.

Contact the manufacturer and see what THEY say!

I called Ameritron today before i went to work and talked to a Technician. He said that there should be 3 padding caps, one 360pf, and one 360pf in parallel with the 500pf. Mine only has 2 caps, one 360pf and one 500pf by itself. He stated it is a updated that was added to the current production amps to increase the loading. He also said this is common with older AL-811 amps(load at zero). so i had him throw a 360pf 1kv cap in the mail. Does anyone own a newer AL-811 that has the 3 padding caps installed?
Logged
KD8GEH
Member

Posts: 464




Ignore
« Reply #12 on: February 17, 2011, 01:55:17 PM »

You should be able to look at the schematic on their site and find how its installed.  Shouldn't be too big a deal. Be sure and dischrage the caps before you poke around in there. If you talk to Mike at Ameritorn, I think he can walk you thru it. If needed I can take a look in in mine, its a 4 yr old 811H, may have the mod.

73, Dave  KD8GEH

Logged
K4RVN
Member

Posts: 758




Ignore
« Reply #13 on: February 17, 2011, 07:32:41 PM »

My AL 811 was purchased in Nov. 2009.  The schematic only shows two caps, not 3. I have not looked to see if the amp has three caps for padders. It is not unusual for Ameritron not to revise their amp schematics as my AL 80 A has a relay installed but does not show on the schematic. The relay was added on later AL80a amps for the power switch so I have beeen told.
It should not hurt anything to add another if you are on zero loading now. Maybe you will hear from the guy that really knows.
Logged
KD8GKR
Member

Posts: 47




Ignore
« Reply #14 on: February 17, 2011, 09:53:29 PM »

It should not hurt anything to add another if you are on zero loading now. Maybe you will hear from the guy that really knows.

I have been waiting for him to chime in with a response.
Logged
Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!