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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10/12 meter Mod for Ameritron

A curmudgeonly old amp designer would probably observe that if you have an RF amp with more than 2 tubes, you are using the wrong tube. Few power meters on the market accurately modds PEAK power. Which green wire is it?

This will exert enough pressure on the switch to close it, without having to deal with a zillion case screws. In the meantime, avoid the cheapest priced products. It is much easier to get VHF performance from those external anode ceramic tubes with their short internal leads, instead of taller glass tubes.

This measure is standard in Ameritron higher priced amplifiers, and a common mod to update older amps like the Heathkit SB Be very careful to install them in the correct polarity. The lowest priced amplifier, the three tube AL, lacks neutralization and some other important design features that are included in the ALH. 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.


It happens at a rate of about once every 2 seconds. The shielding of the cable is only grounded at the side of C Installation of the ohm swamping resistor is “optional”, according to the W8JI instructions. The Svetlanas were better quality tubes than the current crop of Chinese tubes.

With the screw connection style capacitors, it is very easy to make a mistake. You can build a test jig from junk parts for big RF tubes. For decadesI advise to mount a resistor and fuse in series with the anode choke as flash over protection for tubesrectifiers and transformers. Do not get rough with the leads, or there may be internal damage.

The parasitic choke resistors were totally fried. The burst of oscillation is very brief, and no current is indicated on the plate meter. 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.

Powered by SMF 1. A newcomer would find that overwhelming. This cutoff bias mod appears to me to be logical at least, since it directly addresses the problem. If you dispute this, join the local chapter of “Meter Benders Anonymous”, to learn to accept those things you cannot change.

Ameritron Als-600 10 Meter Mod Kit HF

A tentative conclusion is that this AL – H does not distort the signal of the drive stage. With this methodthe distance between S1 and C26 changed to a small capacitance in parallel with the load capacitor and the total inductance of the coil 10 m is thereby reduced.

One is soldered to the pc board near the slug and the other loops over the pc board and solders on the back of the pc board. Once you have the shaft removed, the next step is to remove the tubes and set them aside for safe modx. He went through our club’s licensing classes and Don and I personally were the VE’s present when he took his tests.


If you already own an ALH, it is worth the cost of parts to rebuild it and bring it up to current factory specs, emter the amp suits your needs. Route it so that it can be reconnected to the Power Supply PC board, but do not reconnect it yet. Then try normal SSB operation. Doing this kind of work with high voltage present is not for the inexperienced.

They produce a lot of these amps. 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. meteg

ALH 10/12 meter mod

I fixed it using Q Dope, a low RF loss polystyrene cement, which is no longer available. 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 ameriron burning them in to reduce the arcing problem with new Chinese tubes. It is a cheapsimple and proven effective method. Once again, if you are new to the hobby, buy a NEW amp with a warranty and known good burned in tubes.

The W8JI ohm resistor mod increases the drive power from about 40 watts to 45 watts on 80, 40, and 20 meters.