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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For instance, you may have to replace D16 and other components damaged from tube arcs. Even if you could correct those mrter, the A was designed as an audio tube, and internal lead lengths are excessive for full performance ameritton 20 MHz. To put a db in perspective, it is the smallest change in power that is barely discernable, and then not by everyone. It is a cheapsimple and proven effective method. The ohm resistors are not present in current production, at least according to manuals posted on the Ameritron site.
This results in a significant life increase if you are a bit slow on tuning or run high duty cycle modes at high power. Otherwise, the plate and load or band settings would be irrelevant.
You will never again find tubes of the quality standard of RCA or GE, but the new Chinese tubes from reputable sources are a good value. I have to agree his approach to the single point grid ground is probably not the way to go.
Ameritron Als-600 10 Meter Mod Kit HF
The first time I heard it, I assumed it was an electric fence. W8JI arrows on his photo states: Some authors had questionable suggestions. Google mteer 10 meter mod” There are color pictures all over the place showing the wire If you apply RF drive by transmitting, the grids will see that, with NO plate current.
Don and I were aware of the growing glass tube quality problems, and that is why we decided to go with the Ameritron ALS The wire-wound resistor also acts as a replacement for aeritron L7.
That ‘s nothing compared to a deceased tubediodes, or worse a faulty transformer. The ratings I’ve suggested are approximately 1 db down from claims for cw output and only about 1.
Ameritron Als 10 Meter Mod Kit HF | eBay
Luckily, these did not arc over and do even more damage. Do not rely on this page alone to do the work; go back to the referenced pages and read up on it first.
This divider can be used to force the cathode high. Also avoid damage to the red HV wire to the plate RF choke. This allows mors to carefully rotate the tube socket sub chassis, laying it down on the main chassis, as shown in this photo. It happens at a rate of about once every 2 seconds. Given its damage in the depicted tubeI think it’s caused by parasitic oscillationswhich led to a high voltage. It is much easier to get VHF performance from those external anode ceramic tubes with their short internal leads, instead of taller glass tubes.
Mmods will need to remove those components and replace them with a ground lug ameritfon attaches to the mounting screw nearest the grid pin of the tube.
W8JI Ameritron ALH Modification Photos & Instructions
If you remove the four ‘s and replace then with three B’s, there will be virtually no change in SWR or neutralization. The schematics in the most recent releases on the Ameritron web site do not show either this mster, or the other W8JI mod which I did not try which uses a DC bias derived from the High Voltage supply to drive the tubes into cutoff no plate current.
SSB output as measured on a good peak power reading meter is higher due to the higher plate voltage in intermittent modes. If you got a capacitor in backwards while rebuilding the power supply, it will show up here, without involving the new tubes.
If you are an expert, maybe Volt, longer life, degree capacitors could be substituted, but you will have to check for proper fit. Please note ,ods the output in the table is partly achieved by exceeding the maximum grid and anode current. This measure is standard in Ameritron higher priced amplifiers, and a common mod to update older amps like the Heathkit SB Bring it up ameditron on a variac with a watt incandescent light bulb in series, if you have one.
This keeps the front and rear switch wafers on the same band, in sync. In ameritorn case the simplest modification is to add a That way, you maybe can shut it down before damage occurs. I fabricated a small support from some bare G PC board for the fuse and resistors.
So I took this project on to get him out of a jam.