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Re: [Amps] Advice please Ameritron amp

To: "Gerold Sklott" <gsklott@yahoo.com>, <amps@contesting.com>
Subject: Re: [Amps] Advice please Ameritron amp
From: "Tom W8JI" <w8ji@w8ji.com>
Date: Sat, 26 May 2007 19:45:57 -0400
List-post: <mailto:amps@contesting.com>
I think the other fellows gave good advice, but let me 
add...

> I can key and load the AL82(driver is 1000MP about 100
> watts).  I cannot get the load anywhere near the
> recommended value. Power out peaks at very low load
> values( the opposite of what I need). For example the
> it should be in the 3 area for 40 and I get 0 or less
> than zero. Grid current is not excessive.

Remember:

The loading control turns 360 degrees, so there is an 
"image" anywhere from zero to 360 degrees from any loading 
position.

The loading control can be set to point anywhere, but the 
factory setting should be perfectly full meshed at zero and 
wide open at 10. If it is set properly at the factory your 
'below zero" setting would be matched by another setting an 
equal distance above zero.

The loading control moves towards zero as:

Drive is reduced

Tubes go soft

Frequency is lowered

So you see.... if you aren't making full power you can 
expect the loading to move towards zero. Below zero does not 
exist, there is always an image that will be between 0 and 
10 if the capacitor and pointer are aligned.


The load
> also becomes unreactive sooner than expected, that is
> I can't push it to the higher current levels they
> suggest. I can get to 550 mils or so. So I can't do
> higher power if I wanted. I think my drive is
> sufficient.

What does a power meter on the input say? Did you connect 
the ALC? If so, disconnect it. You certainly don't need to 
use it with only 100W drive.

What is the grid current at full drive? What is your power 
meter on the input?

550mA is indeed too low, but the question is what is 
stopping it at that point. It has to be the tubes, the drive 
power, or something like that. It can't possibly be in the 
tank circuit. The others steered you in the right direction, 
although it could be any of several problems.


73 Tom 


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