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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I cannot imagine users of new ALH amplifiers not complaining about the clicking, so Ameritron must select the tubes for cut off characteristics as well as burning them in to reduce the arcing problem with new Chinese tubes.

It is a cheapsimple and proven effective method. You will need to remove those components and replace them with a ground lug that attaches to the mounting screw nearest the grid pin of the tube. I am not ripping the information off; I have ameriitron credit where it is due, and linked back to the original authors. The shielding of the cable is meer grounded at the side of C This cutoff bias mod appears to me to be logical at least, since it directly addresses the problem.

If your meter is not good at peak power, do not push the amp harder to make it look good on your meter. It makes it easier to troubleshoot. Do them ALL while you are in there. In the process of upgrading and repairing this ALH, I spend a lot of time reading these informative pages to distill the information I needed to complete the work.


Sending your damaged transceiver back for repair because the front end is nuked by a tube arc is a lot more annoying than dealing with the clicking noise by setting the AGC to fast. The ohm resistor does not have a DC path to the cathode circuit, so I did not understand how it would improve the cut off bias situation.

The top cover and enclosure are part of the duct work that directs the air flow to cool the tubes and other components. Some authors had questionable suggestions.

Copper Talk: Ameritron AL

This prevents metal chips falling into the amplifier. The new tubes used in the rebuild worked fine otherwise, but they were not from RF Parts or Ameritron.

Also, my friend bought new tubes at a small savings from a supplier other than Ameritron or RF parts. The 10 meter output will never achieve the 40 meter level, regardless of mods.

ALH 10/12 meter mod

It should not be necessary, if you are using the tubes the amplifier was intended to qmeritron. T he least IMD is produced with that power. Be careful of the fine wire. My inspection yielded a burned grid resistor and a partially conductive varistor on. There are others out there like the Amp Lady or even Ameritron who will do great work on amplifiers and other gear.


W8JI had numerous exchanges over the parasitic choke design, and did extensive analysis with equipment I cannot afford.

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Ameritron Als-600 10 Meter Mod Kit HF

When I finished with this amp, Amerotron got a good solid watts CW on 80, 40, and 20 meters. This is for stability while testing. If you apply RF drive by transmitting, the grids will see that, with NO plate current. W8JI also has a number of individual pages discussing the various design and modification and repair techniques for this line of amplifiers.

The bread always falls jelly side down. TWO mete each filament lead to ground. On the other bandthe SWR will be high and is an internal tuner required for full ouput.

He has some mods to increase amsritron meter output. With the new high voltage fuse OUT, test the power supply first. The suppression of the third- order harmonic is the difference between marker 3D and 4D. I fixed it using Q Dope, a low RF loss polystyrene cement, which is ,eter longer available. Not close to L4 but far away on the PSU board. These often burned out if the tube arcs.

The reason for this is that the glass is not rated for high temperature like the slender Svetlanas of the past.