10/12 Meter Modification Instructions. AL (not A or B). The AL needs a kit to modify for 10/12 Meters. Write to us for details. All other units DO NOT require. Do the Ameritron H have to have the tuning coils adjusted when you do the 10 meter mod? I have not done the mod on my H and. the al & h mod is SIMPLE. you cut 1 wire for the meter mod, you will need to adjust input coil (inside amp)for lowest swr. if you do.

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ALH 10/12 meter mod

The powerful spark induced scorching and inside a hole in the glass. If you obtain watts CW, it is in spec. If you got a capacitor in backwards while rebuilding the power supply, it will show up here, without involving modds new tubes.

The second one is at the lower right, just out of view. The burst of oscillation is very brief, and no current is indicated on the plate meter. This protects the operator, and also the tubes by temporarily reinstalling the “ductwork” for the fan to cool the tubes while testing.

Now, I would have gone with the ALS for better 10 meter output. This allows you to carefully rotate the tube socket sub chassis, laying it down on the main chassis, as shown in this photo. Yes, I have a tube tester that will do transmitting tubes; get the right tools for the job, if you are going to repair stuff, at least a tube checker for receiving and smaller power tubes.

The shield of the cable also serves as a supply line to the central ground point in the tubes. I have to agree his approach to the single meher grid ground is probably not the way to go.

Install the new high voltage fuse. Note particularly the way the spacer and RF safety choke are assembled, and where the orange ceramic plate blocking condensers connect. At this point, I do not know mete to fix the clicking problem other than using selected tubes.


The suppression of the third- order harmonic is the difference between marker 3D and 4D. You can now ameritton the resistors and capacitors from grid to ground used on the older ALH amplifiers.

May 26, W8JI states that in some cases the clicking happens on different bands with varying plate and loading settings.

Ameritron ALH 10m Mod | QRZ Forums

To put a db in perspective, it is the smallest change in power that is barely discernable, and then not by everyone. The photos may give different views showing you how to get the job done.

The adjustment procedure is explained in detail. Don and I were aware of the growing glass tube quality problems, and that is why we decided to go with the Ameritron ALS I have a small container with a lid to save all the screws removed, so they do not get lost.

Bring it up slowly on a variac with a watt incandescent light bulb in series, if you have one. I like to bring the amp up for the first time with new tubes using a variac with the cover off, so I can observe any tendency to arcing, like a blue or purple glow inside the envelope. Notice in the photos the huge size of the glass envelope.

Ameritron AL-811H 10m Mod

Rather than buying engineering lab grade test equipment and learning how to use it, you might be smarter to either buy a premium grade amp with the money, or accept that you own a good economy amp and enjoy operating it within its design specs. Neither is the W8JI cutoff bias modification. The ameitron for this is that the glass is not rated for high temperature like the slender Svetlanas of the past.

At the end of this article, there is a bibliography of the pages of others who have written about the Ameritron Xmeritron or its cousins as well. A ham without the engineering level test equipment who comes along afterwards with a speculative parasitic suppressor circuit design that works on one amplifier leaves me uneasy. For long life, we should operate them at the specs of the originalnot the A, ameriron to the shortcuts of the new plate construction. I fixed it using Q Dope, a low RF loss polystyrene cement, which is no longer available.


Amdritron ” 10 meter mod” There are color pictures all over the place showing the wire If you have an older model ALH which does not have these design updates, I urge you to install them, or send the amp back to Ameritron for rework to current specs. It is a cheapsimple and proven effective method.

So now you have your parts and the W8JI pages above printed out. Anyway, thanks to those that replied. In the standby mode, neither the input nor the output of metfr amplifier are terminated, and the plate supply voltage is ON.

Once again, if you are new to the hobby, buy a NEW amp with a warranty and known good burned in tubes. But the owner reports it has returned. The lowest priced amplifier, the three tube AL, lacks neutralization and some ametitron important design features that are included in the ALH. Therefore, a sumiere test was done with the two types. Why not solder the wire directly near the slug and save metee couple inches of wire? That sounds simple enough, I thought.

If not using the safety switch jumper, the simplest way to safely operate the amp temporarily is to put the cover back on, securing it with a single screw nearest the safety switch. I installed it differently from W8JI, because the terminal strip was mounted differently, and this resulted in the shortest lead length.