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Ameritron al800
- Thread starter ss396
- Start date
B
BOOTY MONSTER
Guest
The quick-n-dirty answer is that the AL-800 will do AM. It will not stand much 'pushing' at all (the tube), and if you see about half of the SSB power output on AM, you had better be satisfied with it. Believe the max numbers for grid/plate, etc! It isn't the amplifier's design that's a limiting factor, it's the tube. If you don't 'push' it, it ought'a last you a good while. How good does it sound on AM? Just depends on what you feed it, and who is defining 'good'. Mistakes are very expensive...
- 'Doc
- 'Doc
Doc;
For AM it's 1/4 of cw PEP for max AM carrier isn't it?
So for a 1kW you are looking at 250W carrier max.
Also AM/FM/RTTY/digi modes are higher duty cycle in general than SSB or CW so even if rated for 250W carrier, you better keep in mind that it's really hard on the amp. Don't expect to do super long key downs at 250W and have that thing last optimally.
For AM it's 1/4 of cw PEP for max AM carrier isn't it?
So for a 1kW you are looking at 250W carrier max.
Also AM/FM/RTTY/digi modes are higher duty cycle in general than SSB or CW so even if rated for 250W carrier, you better keep in mind that it's really hard on the amp. Don't expect to do super long key downs at 250W and have that thing last optimally.
There really isn't a 'max' for AM carrier, but about 1/4 of CW is about right. Figuring that the tube's max plate dissipation is about 800 watts, that's a pretty good 'goal' for output power. It'll probably do more than that, but just consider that 'extra' as a sort of bonus. It won't make that much difference in how the signal is heard anyway.
The power output meter is a terrible way to 'judge' any amplifier's state of 'health'. Keeping a careful eye on those meters in the amplifier, not exceeding the stated values in the manual, are -the- way to do it. Theres a very good reason those recommended max readings are there, mainly having to do with $$$ out of your pocket, and a less than optimal signal. Not to mention the bangs/pops/'tinks' that can be a result of not following the recommendations. Just treat it like you have to pay for it, that ought'a work...
- 'Doc
The power output meter is a terrible way to 'judge' any amplifier's state of 'health'. Keeping a careful eye on those meters in the amplifier, not exceeding the stated values in the manual, are -the- way to do it. Theres a very good reason those recommended max readings are there, mainly having to do with $$$ out of your pocket, and a less than optimal signal. Not to mention the bangs/pops/'tinks' that can be a result of not following the recommendations. Just treat it like you have to pay for it, that ought'a work...
- 'Doc
B
BOOTY MONSTER
Guest
page 20 of the pdf manual i posted above tells how to drive the amp on am and what max power to expect .
The AL800 manual is quite clear.
150 watt carrier, which means 800 watts PEP at 100% modulation.
However if your AM transmitter can do asymmetrical modulation, where the positive modulation is more than the negative modulation, you can do up to 1200 watts PEP.
As far as the 811H amplifier:
The 811A tube is rated at 65 watts plate dissipation, and that amp has four of them.
the 811A datasheet claims a single tube can output 310 watts (ICAS) at 1250 plate volts and grounded grid.
A single 3cx800a7 is quite a bit beefier, since 800watts > 65watts x4.
150 watt carrier, which means 800 watts PEP at 100% modulation.
However if your AM transmitter can do asymmetrical modulation, where the positive modulation is more than the negative modulation, you can do up to 1200 watts PEP.
As far as the 811H amplifier:
The 811A tube is rated at 65 watts plate dissipation, and that amp has four of them.
the 811A datasheet claims a single tube can output 310 watts (ICAS) at 1250 plate volts and grounded grid.
A single 3cx800a7 is quite a bit beefier, since 800watts > 65watts x4.
Mole',
An 811 probably can be 'pushed' a bit more than a 3CX800, sort of. Most ceramic tubes are very picky about what they are fed. Fairly low grid capacities. The only exception I'm aware of is the 3CX1200. I certainly am not familiar with many ceramic tubes, so that's not a very good comparison really.
- 'Doc
Don't misunderstand, there is absolutely no comparison between an 811 and a 3CX800 as to ability. That 'push' is a percentage.
An 811 probably can be 'pushed' a bit more than a 3CX800, sort of. Most ceramic tubes are very picky about what they are fed. Fairly low grid capacities. The only exception I'm aware of is the 3CX1200. I certainly am not familiar with many ceramic tubes, so that's not a very good comparison really.
- 'Doc
Don't misunderstand, there is absolutely no comparison between an 811 and a 3CX800 as to ability. That 'push' is a percentage.
http://www.eham.net/reviews/detail/227
This is what I use for AM.... 8-10 watts drive/375 watt carrier... 45-50 watts PEP yield 1500 out, with 1,000 watts of headroom
..... Can't go wrong here...
This is what I use for AM.... 8-10 watts drive/375 watt carrier... 45-50 watts PEP yield 1500 out, with 1,000 watts of headroom
..... Can't go wrong here...
BJ radionut
Supporting Member and 6m addict
AL800
The Al800 contains a single 3cx800a7 rated at 1250w/PEP...700 watts output continous duty max output...this would be the MAX modulated Peak output rating for this amp configuration.
So going a little further depending on the exciter and using a good peak reading wattmeter...
I would say 500-600 watts Peak would be where I would operate this amp...reason being $500-$700 for a Eimac replacement tube...yes they can be found cheaper at times but when suppliers like Eimac/RF Parts/Qro tubes say CALL where the catalog pricing should be...hold on to your heart my friend when you hear the price.
And that also is if nothing else failed when the tube crashed.
There is one more thing to consider, has this amp had the 10/12 meter mod done to it?
Unless this was an export model or unless this mod been already completed on the stateside model...it will not work on 10 meter AM
Be Careful...my 2 cents worth
All the best
BJ
The Al800 contains a single 3cx800a7 rated at 1250w/PEP...700 watts output continous duty max output...this would be the MAX modulated Peak output rating for this amp configuration.
So going a little further depending on the exciter and using a good peak reading wattmeter...
I would say 500-600 watts Peak would be where I would operate this amp...reason being $500-$700 for a Eimac replacement tube...yes they can be found cheaper at times but when suppliers like Eimac/RF Parts/Qro tubes say CALL where the catalog pricing should be...hold on to your heart my friend when you hear the price.
And that also is if nothing else failed when the tube crashed.
There is one more thing to consider, has this amp had the 10/12 meter mod done to it?
Unless this was an export model or unless this mod been already completed on the stateside model...it will not work on 10 meter AM
Be Careful...my 2 cents worth
All the best
BJ
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