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

donate to eham
   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Maximizing tube life  (Read 2900 times)
AE5JU
Member

Posts: 244




Ignore
« on: November 27, 2009, 10:19:25 PM »

OK, I'll admit, though long time involved in electronics, mostly audio gear, my only experience with tubes was pulling tubes out of my parents GE TV and peddling down to the 7-11 to use the tube tester, so show a little mercy.

I've just bought my first amp, an Ameritron AL-811H.  I've got it hooked up and running well, so far, and used it on some net checkins.  So far, so good.  No flashes, pops, or smoke roiling out of the vents, though I was hoping to see lightning arcing across my dipole like a Jacob's Ladder when I keyed up.  Or perhaps at least some faint "St. Elmo's Fire" around the ends of the antenna.

I'd like to lay in some spare tube sets, but at the same time want to maximize tube life.  From the reading I've done, I know I need warm the amp up a bit first and not overdrive the amp.  And in fact, there is no use running it right on the edge.  Backing it off some, or better, using no more power than needed (isn't that what we're supposed to do?) will extend tube life.  

I've looked up and read Charles W8JI's informative eHam posts and his article about loading amplifiers:

http://www.w8ji.com/loading_amplifier.htm

and

http://www.w8ji.com/vacuum_tubes_and_vaccum_tube_failures.htm

And I found this article by Matt Erickson KK5DR, "Vacuum Tube Facts".  

http://www.kk5dr.com/Tubes.html

He suggests rotating stored sets of tubes.

These articles seem to be pretty definitive, make sense.  

Any other suggestions or suggested reading?

Paul
AE5JU
Logged
HFRF
Member

Posts: 1




Ignore
« Reply #1 on: November 28, 2009, 05:39:05 AM »

The most important understanding of an Ameritron amp is that it is essentially an amp using a non innovative design stolen from handbooks and tech mags over the last 50 years.  Ameritron amps look like a typical amp out of an ARRL handbook.  But unlike some of the ham designed amps, Ameritron uses the most marginal components a "designer" could ever pick in its Bill of Materials.

That's why Ameritrons, break easily, fart, hiss, belch, and crap out.  But the most expensive result of a crappy design is poor tube cooling which will cost any Ameritron owner lots of money over the course of ownership of an Ameritron amp. You are going to pay more for tube replacement than if you owned virtually any other amp.

The best  thing you can do is add some extra air going in and out of the amp across the tubes.

Ameritron is putting a tiny little blower in their most expensive amps (AL1200.82,1500).  It is totally inadequate to cool very expensive tubes.  Look up the specs on the blower in those amps and compare the air flow with the required air flow of the tubes.

Its just pathetic.
Logged
KB9CRY
Member

Posts: 4283


WWW

Ignore
« Reply #2 on: November 28, 2009, 06:47:33 AM »

Tune it up correctly and don't overdrive it.
Logged
W8JI
Member

Posts: 9748


WWW

Ignore
« Reply #3 on: November 28, 2009, 11:14:33 AM »

The most important understanding of an Ameritron amp is that it is essentially an amp using a non innovative design stolen from handbooks and tech mags over the last 50 years.  Ameritron amps look like a typical amp out of an ARRL handbook.  But unlike some of the ham designed amps, Ameritron uses the most marginal components a "designer" could ever pick in its Bill of Materials.

That's why Ameritrons, break easily, fart, hiss, belch, and crap out.  But the most expensive result of a crappy design is poor tube cooling which will cost any Ameritron owner lots of money over the course of ownership of an Ameritron amp. You are going to pay more for tube replacement than if you owned virtually any other amp.

The best  thing you can do is add some extra air going in and out of the amp across the tubes.

Ameritron is putting a tiny little blower in their most expensive amps (AL1200.82,1500).  It is totally inadequate to cool very expensive tubes.  Look up the specs on the blower in those amps and compare the air flow with the required air flow of the tubes.

Its just pathetic.

Dick K4XU,

You really should settle down. There is no reason for you to constantly attack everyone and everybody.

There is no reason to constantly libel other people with false accusations.

Tom
« Last Edit: November 28, 2009, 11:21:01 AM by W8JI » Logged
AE5JU
Member

Posts: 244




Ignore
« Reply #4 on: November 28, 2009, 11:34:21 AM »

HFRF or K4XU,

"Presently a RF power MOSFET development and applications engineer with 30 years previous RF design experience at Ten-Tec, ETO and Harris Broadcast."

I'm sorry, I couldn't afford an expensive solid state amp, so I had to go the poor boy route and buy an old fashioned tube amp.  I know it's got to be difficult to be innovative when designing an affordable amp around tubes, but it is what it is, one of the more widely owned amps.  Perhaps I should have saved up another $3k or $4k and bought an impressive amp, but I was impatient.

Meanwhile, I don't notice a heat problem with this amp, it is barely warm when operating.  But I thank you for your comments and will take them into consideration.

73
Paul
AE5JU

PS  Decaf, Dick, decaf.
Logged
WB2WIK
Member

Posts: 21837




Ignore
« Reply #5 on: November 28, 2009, 01:34:52 PM »

Paul AE5JU, I don't think "warm up" is required with an AL-811H.  811As are good to go almost before you can get your finger off the power switch.

Avoiding overdrive and keeping the amp properly LOADED will go a long way towards keeping the amp, and the tubes, running.

Also praying for "good" 811As might help.  I think Ameritron gets what is available on the market today, but they're not as good as the old RCA 811As Collins used to use, which haven't been manufactured in a very long time.
Logged
KH6AQ
Member

Posts: 7982




Ignore
« Reply #6 on: November 28, 2009, 02:33:28 PM »

I have an Ameritron AL811 and consider it a great value. 500W CW for $650 is something and it has a tuned input.

It is a simple, elegant design with no weak points that I can find. Looking at the BOM and the schematic and running the numbers it looks like the stress on each part is balanced against the other components. That is good engineering.

At $20 for a Chinese 811 tube why worry about maximizing tube life? Run it at the rated power and don't cook the grids.
Logged
AD6KA
Member

Posts: 2243




Ignore
« Reply #7 on: December 08, 2009, 05:25:14 PM »

HFRF says

"That's why Ameritrons, break easily, fart, hiss, belch, and crap out. But the most expensive result of a crappy design is poor tube cooling which will cost any Ameritron owner lots of money over the course of ownership of an Ameritron amp. You are going to pay more for tube replacement than if you owned virtually any other amp."

I've had a stock AL-80A running almost daily for
20 years. I run balls out full power RTTY in 36 to 48 hour contests and have never had a cooling problem, arc over, or tube failure. I transported it to Madagascar and back, where I used it to win SOAB High Power Africa in the 2000 CQ WW RTTY Contest. Can you imagine how many times that Pelican 1620 case & amp were dropped, thrown, mishandled during the 10,000 mile trip and back? This is a super, rugged, reliable amp. Have never had to service it, ever.

You seem to have an agenda (at the very least) re Ameritron and W8JI. Release your rage in a healthy fashion.
Logged
KD8GEH
Member

Posts: 620




Ignore
« Reply #8 on: December 08, 2009, 08:04:34 PM »

Hi Paul,

You have the right resources. Toms info is accurate and informative.
I have had an 811H for years.  I did repleace a set of tubes out of sheer learning curve when I started out on 160 Smiley   My 2 cents:
1)Do not over dive it, about 50-65 watts is fine. 2) Assure your antenna is matched to an acceptable SWR before loading up the amp. 3) Follow the loading instructions and Toms suggestions, the last knob is always the plate.
My experience is they are well built, operate great for the service they were designed for. If you run the duty cycle up (Rtty or PSK), there are some cautions to observe.
I've been very fortunate and had help from Tom and the good ops along the way learning the basics of amps as well as good operating practice.  Easy to work on, and as far as I'm concerned well built.
Enjoy the amp and hope to hear you down the log. If there's anything further I can do to help, feel free to email me.
73, Dave  KD8GEH Near Dayton Ohio
Logged
AE5JU
Member

Posts: 244




Ignore
« Reply #9 on: December 09, 2009, 04:46:15 AM »

Well, so far, so good.  I've been able to tune the amp, using some Svetlana 572B's from Frank K5SVC without damaging anything.  With 65 watts in producing 850 watts.  I increased the load to just drop the output a bit, and then repeaked the plate.  I don't key it more than 3-4 seconds while tuning.  Then backed off the drive to 50 watts.  So far so good, and getting good reports on some net checkins.

I put the 811A's back in Monday and was able to tune it much faster now that I'm more familiar with this.  No sign of red on the plates, but not keying up more than 3-4 seconds at a time, followed by 10 seconds or more to cool off.  I was surprised to see the load setting ended up being somewhat higher.  

At 65 w drive, 850 watts out, I'm showing 600 ma plate, 100 ma grid.  Does this sound about right?

Paul - AE5JU
Logged
KH6AQ
Member

Posts: 7982




Ignore
« Reply #10 on: December 09, 2009, 05:48:23 AM »

That sounds good and a bit of red on the plates is not so bad. The 811 can run red in ICAS (Intermittent Commerical and Amateur Service).

I tune up with a keyer (I work CW) and that runs things at 50% duty.

Make a log of the amp settings for each band. When you change bands dial in the settings are ready. No 'tune up' required.
Logged
AE5JU
Member

Posts: 244




Ignore
« Reply #11 on: December 09, 2009, 06:41:21 AM »

Thanks.  Then I shouldn't see any red operating SSB.

I have printed some of the "Amplifier Tuning Chart Log" sheets, printed from the pdf version of the manual (page Cool, and am making notes there, and keeping in a 3-ring binder I keep in my station.  I notice the settings are a bit different from the 572B's and the 811A's, so I'm doing a separate sheet for each.

Thanks for the assist guys.  So far, no magic smoke released.  Still disappointed there are no arcs of current across the dipole.  That would have made a nice Christmas display. ;-)

Paul - AE5JU
Logged
KD8GEH
Member

Posts: 620




Ignore
« Reply #12 on: December 09, 2009, 07:51:43 AM »

Great idea on the chart.  I did a chart for my tuner and amp for each antenna on all the bands I operate in Excel and laminated it. Its right next to the band plan chart.
As far as fireworks on the antenna, I usually just grease least favorite child (teen boy) and install him as close as possible to the wire. If he is inductive that day he will glow a bit, if not, he makes an interesting popping noise Smiley Hi hi.

Enjoy,  Dave KD8GEH
Logged
AE5JU
Member

Posts: 244




Ignore
« Reply #13 on: December 12, 2009, 09:31:08 AM »

Well, the same old friend who gave me the Dentron GLA-1000 mentioned in another thread just gave me another big box of ham stuff.

In it were a Vibroplex bug (in beautiful condition) in the original leatherette covered box and five new/old 811A's. Four are RCA's and one GE.

Well, make that 3 RCA's. One has a loose filament spring like one of the Ameritron supplied no-name tubes that came in my AL-811H. OK, Ameritron did promptly replace it at no charge.

So, that makes four nice vintage 811A's.

So, the question is, should I even try to power them up? Just put in one at a time, power up and see if they flash?

Suggestions?

Paul
AE5JU
Logged
Pages: [1]   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!