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Author Topic: Ameritron 811H CW question  (Read 3961 times)
W9KDX
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Posts: 771




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« on: February 28, 2013, 03:15:42 PM »

The owner's manual is not helpful here; do I need to do anything differently when I run this amp sending CW.  I already send a tone when I tune for SSB, but amps list different max. output with CW and RTTY and AM and I am unclear if there is something I need to dial back or if the amp just puts out less as a result of the signal in.

Much thanks
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Sam
W9KDX
N3QE
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Posts: 2422




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« Reply #1 on: February 28, 2013, 03:28:05 PM »

Assuming a good match... on CW you are good up to 750mA plate current, 200mA grid current.

I typically use mine with the exciter at 40-50 watts and amp plate/grid currents just a bit below the above limits (e.g. plate current at 650mA key-down.)
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W8JX
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« Reply #2 on: February 28, 2013, 03:55:22 PM »

Assuming a good match... on CW you are good up to 750mA plate current, 200mA grid current.

Last time I checked, the ICAS rating for a 811 is 175ma max for plate so 175 x 4 equals 700 not 750.
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You can embrace new computer/tablet technology and change with it or cling to old fall far behind....
AD4U
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« Reply #3 on: February 28, 2013, 03:59:53 PM »

Assuming a good match... on CW you are good up to 750mA plate current, 200mA grid current.

Last time I checked, the ICAS rating for a 811 is 175ma max for plate so 175 x 4 equals 700 not 750.

Ahhhh once again................The manufacturer's maximum rating VS the Ameritron rating.
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W8JX
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« Reply #4 on: February 28, 2013, 04:14:07 PM »

Assuming a good match... on CW you are good up to 750mA plate current, 200mA grid current.

Last time I checked, the ICAS rating for a 811 is 175ma max for plate so 175 x 4 equals 700 not 750.

Ahhhh once again................The manufacturer's maximum rating VS the Ameritron rating.

No wonder they eat tubes sometimes huh.
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--------------------------------------
You can embrace new computer/tablet technology and change with it or cling to old fall far behind....
W9KDX
Member

Posts: 771




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« Reply #5 on: February 28, 2013, 06:20:25 PM »

Assuming a good match... on CW you are good up to 750mA plate current, 200mA grid current.

Last time I checked, the ICAS rating for a 811 is 175ma max for plate so 175 x 4 equals 700 not 750.

Ahhhh once again................The manufacturer's maximum rating VS the Ameritron rating.

Actually, the guys at Ameritron suggested to me to keep it closer to 650mA. But back to my question,

Are you guys saying I just tune up exactly as I do for SSb and then hammer away?
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Sam
W9KDX
KE3WD
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Posts: 5689




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« Reply #6 on: March 01, 2013, 08:04:04 AM »

Well, I customarily used to tune up using CW, then switch to sideband if that was the mode to be used, without changing the amp settings...

Don't know if that was "right" according to the purists or not, but it always worked, and with quite the assortment of different amps over the years. 


73
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N6AJR
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« Reply #7 on: March 01, 2013, 09:21:22 AM »

I always just tune the amp for maximum power out ( that where the dip and peak  points are, ) keeping it under 700 mills, and then turn the power down on the radio a tad so you are not pushing it for every stinkin watt you can get.  they cannot hear the difference between 400 and 6oo watts on the other end.  so input 35 or 40 watts for 400 -600 out, depending on band an antenna and enjoy.
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AA4HA
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Posts: 1640




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« Reply #8 on: March 01, 2013, 12:41:28 PM »

Assuming a good match... on CW you are good up to 750mA plate current, 200mA grid current.

Last time I checked, the ICAS rating for a 811 is 175ma max for plate so 175 x 4 equals 700 not 750.

Ahhhh once again................The manufacturer's maximum rating VS the Ameritron rating.

You dare question Ameritron? They know more about what those tubes can do than any tube manufacturer.   Cheesy
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
K4RVN
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Posts: 812




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« Reply #9 on: March 09, 2013, 08:31:26 AM »

I would suggest that you read the manual. It reads 600 watts for CW. It also reads full load is 700 Ma.for the power supply. Forget the 700 ma and load the amp with a watt meter, then make sure you are not exceeding 700 Ma. I for one have used Ameritron amps for over 20 years with no complaints. Even the three tube 811 is a jewell if used as the manual dictates.
To summarize, load the 811H up in the CW mode for a max of 600 watts using a watt meter according to the manual. Bang away on CW, just not too fast.

Frank
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N3QE
Member

Posts: 2422




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« Reply #10 on: March 09, 2013, 01:34:57 PM »

Assuming a good match... on CW you are good up to 750mA plate current, 200mA grid current.

Last time I checked, the ICAS rating for a 811 is 175ma max for plate so 175 x 4 equals 700 not 750.

Ahhhh once again................The manufacturer's maximum rating VS the Ameritron rating.

You dare question Ameritron? They know more about what those tubes can do than any tube manufacturer.   Cheesy

In fact Ameritron says tubes are 650mA at full output and PS rated to 700mA out.

But the amps' designer says 750 mA :-).

I have a long habit of CHOOSING the spec I want to quote at the time. That's the wonderful thing about standards. There are so many to choose from!

Tim.
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W9KDX
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Posts: 771




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« Reply #11 on: March 09, 2013, 03:52:27 PM »

Thanks guys, I got it.  Took me a while to realize I was actually tuning it for CW all along and then going to SSB.  So, of course, The tuning procedure is already what I wanted.
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Sam
W9KDX
K4RVN
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Posts: 812




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« Reply #12 on: March 11, 2013, 07:31:09 AM »

Tim,
If you read W8JI's supplement notes to tuning the 811H, it reads to the effect that the 750 Ma carrier should be of short duration.  I perceive that to be tuning up quickly, and not actual operating current as that exceeds the supply rating and tube rating. Trying to tune without a watt meter is a venture for disaster. So many newbies I have read are simply trying to tune with the amp's meters, not for watt meter power out within the max current ratings for grid and plate currents. Just my opinion, certainly not a known fact or endorsed by W8JI to my knowledge.

Frank
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W8JX
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Posts: 6666




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« Reply #13 on: March 11, 2013, 08:48:39 AM »

Tim,
If you read W8JI's supplement notes to tuning the 811H, it reads to the effect that the 750 Ma carrier should be of short duration.  I perceive that to be tuning up quickly, and not actual operating current as that exceeds the supply rating and tube rating. Trying to tune without a watt meter is a venture for disaster. So many newbies I have read are simply trying to tune with the amp's meters, not for watt meter power out within the max current ratings for grid and plate currents. Just my opinion, certainly not a known fact or endorsed by W8JI to my knowledge.

Frank

The problem is not the power supply but rather the tubes as they can go into melt down quickly at 750ma as 811 can only dissipate 45 watts per tube continuous and 65 watts intermittently safely. A 750ma tun well exceeds these rating is is kinda like playing Russian roulette with most of the chambers loaded. 
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--------------------------------------
You can embrace new computer/tablet technology and change with it or cling to old fall far behind....
K4RVN
Member

Posts: 812




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« Reply #14 on: March 11, 2013, 02:33:14 PM »

Mfgs like Heath, Gonset, Collins and Ameritron have pushed 811A tubes beyond their specs for many years. That is beyond my scope of understanding so I rely on the wisdom of those whom I think are in the know. Some good reading on the Ameritron 811 and 811h amps is here: The key is actual plate dissipation is a time intergrated product of anode current times voltage and includes power extracted by the load to determine the heating effect so I have read.
Those who own the amps and are concerned might learn something from the designer if they read carefully and try to comprehend. May take a few times through, it did for me.
http://www.w8ji.com/al811h_schematic.htm.   As for me, when I need to replace my original tubes, I will go with the 572B tubes and crank my 811 up to 600 watts out on SSB.That way the tubes can take it and my power supply will be adequate for the 600 watts better than the 4 tube H model with 572 tubes and 800 watts out.

Frank
« Last Edit: March 11, 2013, 02:39:47 PM by K4RVN » Logged
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