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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This shameful conduct is unfortunately all too common. 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. At this point, I do not know ametitron to fix the clicking problem other than using selected tubes. Connect the amplifier to a dummy load and adjust for maximum ouput. The ohm resistors are not present in current production, at least according to manuals posted on the Ameritron site.

Then I tested the output power on various bands, and let the plates get hot with a lengthy SSB transmission at full specified power. SSB output as measured on a good peak power reading meter is higher due to the higher plate voltage in intermittent modes.

W8JI does not include these steps, but the tubes are expensive. To install the Ohm 20 Watt resistor, you have to drill a hole. The fuse protects the amp if the tubes arc. But I am adding some of the photos I took while repairing this, and adding some comments on problems I encountered with this particular project. After modd modification the amplifier was firmly tested and plates never becames red.


This amp is not the only grounded grid tube amp that needs this protection; it moxs become a problem, due to inferior tubes of today. Please note that the output in the table is partly achieved by exceeding the maximum grid and anode current. Driving this amp harder than watts CW on 80, 40, and 20 meters or about Mos CW output on 10 meters is unreasonable, and reduces tube life without gaining any signal level noticeable at the receiving end. See how close they are to the metal standoff at the left?

Don and I were aware of the growing glass tube quality problems, and that is why we decided to go with the Ameritron ALS It is not a guaranteed protection, but in most cases it increases your chances of amplifier survival by limiting the energy stored in the capacitors, which discharges through the tube arc. 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.

Also, this procedure is simpler than the one recommended by PA0RFI, which requires that you remove and rotate all tube sockets degrees to get the grids pointing to the center, where he uses a wire to ground them at a central ground lug. W8JI first removes the side bar between the front and rear panel. I disconnected the filament wires to avoid abrasion or damage to the thin meetr coating on the wires.

Ameritron Als-600 10 Meter Mod Kit HF

That ‘s nothing compared to modd deceased tubediodes, or worse a faulty transformer. Luckily, these did not arc over and do even more damage. These often burned out if the tube arcs.


Do not use a junkbox resistor for this. I am speculating that it may be a combination of improper tube grid construction and inadequate vacuum in modern Chinese tubes.

Copper Talk: Ameritron AL

It is not standard on metwr economy amps in the AL series. This is a lot of work, and the ameritfon metal chassis is probably a better ground than a wire of any size. Which green ameritrno is it?

That is why vernier knobs are essential, and all the readings for the plate tuning are squashed together at the higher numbers above 40 meters. The ALH still is a pretty good little amplifier but with an annoying habit.

This is why I recommend people new to amateur radio just buy a new amp with a warranty. It is a cheapsimple and proven effective method. We should be grateful that a reputable Chinese manufacturer responded to the problem by correcting his manufacturing process.

Ameritron AL-811H 10m Mod

The down side is that you can only kods the tubes through the ventilation holes, with a mirror, so you can simultaneously monitor the meters. Plus, s and Bs ain’t what they used to be. Support them with your business. It is not surprising, since if meger tubes exhibit sufficient gain, and there are no resistive terminations on either the input or the output, oscillation may occur, even in a well designed amp.

Use the parts from Ameritron to guarantee you have no mechanical problems with fit. That way, you maybe can shut it down before damage occurs. April 23, Click on any photo on this page to enlarge it.