Ameritron AL 811 H.
To wrap up 2014 I will comment on this offering from Ameritron and its good points and some not so good points.
I had one of these units briefly for test and check out for a friend of mine a few years ago, I was asked to install the tubes and turn on this unit to see if indeed it worked. My friend was a little cautious about electronic gear and was not sure how to proceed.
This amp is the light duty model, it offers 800 watts, or at least that is what is claimed, but let’s see what really happens?
There are four 811A tubes in this model, these tubes will not break you up even if you have to replace all four of them at once. I do question as to why the 572B was not used since it is a direct replacement for the 811A. The 572 gives more plate dissipation and slightly more power output, but I imagine there was a design reason for the use of the 811A. tubes. Maybe, some one at MFJ/Ameritron had stock interest in the tube factory that made 811A tubes and not the 572B.
Enough of this speculation, this unit is light in comparison to the AL82 and AL 1500 units, you can pick this one up with getting a hernia. Now Ameritron tells you in the manual this unit will run on 120AC, or you can make the change of taps, change the plug and run it on 220AC.
Running this unit on 120AC you have a couple of problems that surface, one you will achieve about 650 watts output, you will be at the maximum plate current and the maximum grid current.
But wait, there is one thing I noticed, once you approach the maximum plate current the filament voltage starts to drop, this is evident by the brilliance of the 811A tubes, you can see them from the side of the amp. There are four of them in a circle, of course if you bought this amp new, you would know this already, but if you did not then the tubes may already be installed.
The brilliance of the tubes drops once the maximum current is achieved, low emission results, low emission causes power to drop it is that simple. The filament voltage is unregulated and subject to line drops due to heavy demand. I would suggest changing the taps, cut off the 120AC plug, make a trip to the local store and secure a 220 AC plug and install it.
You can expect some more drop of power on ten meters as well, but once you have the 220AC connected you will see about 750 to 800 watts output. This amp is quiet, I had the opportunity to run this one in the cw sweep stakes and managed to work 42 states over two days. I had some huge pile ups and callers from everywhere on 40 meters. So with that said if you are in the market for a small, yet good amp give this one a try, no it will not do 1500 watts, it will make about half that amount.
Now, it is rather pointless if you have a rig that has a 400 watt final to add this to it, you will not see that much gain, you may think about the 200 watt rigs and adding this unit. Those 100 watt rigs will see a 9 db gain, well worth the effort. The choice is yours, the AL 811 or the AL 82, or AL 1500.
