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 am posting this information as a supplement or digest of the essential information. May 26, Install the new high voltage fuse. It may require redesign of the parasitic chokes.
The ticking disappeared – at least for now. Not close to L4 but far away on the PSU board.
W8JI Ameritron ALH Modification Photos & Instructions
This is for stability while testing. TWO from each filament lead to ground. One did not even light. That sounds simple enough, I thought. 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.
You can put the rest of the cabinet screws in.
While we are on the subject of arcs in Chinese glass tubes such as the and B, there was discussion of not manufacturing any more of these economy amplifiers using them. The top cover and enclosure are part of the duct work that directs the air flow to cool the tubes and other components.
We should be grateful that a reputable Chinese manufacturer responded to the problem by correcting his manufacturing process. You must avoid drilling a mounting hole that damages the neutralizing transformer.
,eter inductance of the long supply wires can not be ignored. Do not get rough with the leads, or there may be internal damage. SSB output as measured on a good peak power reading meetr is higher due to the higher plate voltage in intermittent modes.
I have to agree his approach to the single point grid ground is probably not the amritron to go. If you dispute this, join the local chapter of “Meter Benders Anonymous”, to learn to accept those things you cannot change. 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. W8JI does not include these steps, but the tubes are expensive.
See how close they are to the metal standoff at the left?
This is caused by the grid being off-center vertically, or not having enough winding length. Even if you could correct those problems, the A was designed as an audio tube, and internal lead lengths are excessive for full performance above 20 MHz. The only purpose I could see it serving was to terminate the input circuit by resistive loading, to reduce a tendency to break into a burst of RF oscillation due to the tubes not being properly biased OFF.
First, I removed the junk box resistor kludge the seller had installed. I did not try any of this, so I have no comment. The Svetlanas were better quality tubes than the current crop of Chinese tubes. 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.
The gas tubes fire at VDC, which accompanies the clicking noise. Do them ALL while you are in there. To install the Ohm 20 Watt resistor, you have to drill a hole. Support them with your business.
Irregularities in the schematic. Note some colored nail polishes use metallic or conductive ingredients. Hello all, I recently purchased an ALH.
Ameritron Als-600 10 Meter Mod Kit HF
I fixed it using Q Dope, a low Amefitron loss polystyrene cement, which is no longer available. The shield of the cable also serves as a supply line to the central ground point in the tubes. Apparently they select tubes for proper operation in their amps, since eham reviews does not note this problem.
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Ameritron ALH 10m Mod | QRZ Forums
Or doesn’t it matter? There are certain design measures in the W8JI updates that protect the amplifier from damage if arcs occur. This gives the fuse time to act. The bigger glass tubes are a little harder to install, working them past the Parasitic Choke PC board.