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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Under normal conditions with the relay closed, the tubes are connected to a transceiver on the input and an antenna on the output, and it is stable.

A ameirtron 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. There are regular discussions on forums about whether the A tubes can be better mpds by the more robust type B. 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. This amplifier was sold used to my newly licensed friend.

With a solid state amplifier, you do not put your transceiver at risk if a tube arcs; there are no tubes and therefore no need for all these modifications. There is discussion about how many turns of wire are proper for the parasitic coils. This divider can be used to force the cathode high. Please note that the output in the table is partly achieved by exceeding the maximum grid and anode current.

If it meets spec on CW, use those settings for SSB and don’t look at your power meter if that bothers you. You should now see normal power supply voltage on the panel meter. If you obtain watts CW, it is in spec. I took out the other support brace after I marked the location for the mounting hole to drill it.


That sounds simple enough, I thought.

My friend made a reasonable attempt, but knew when to quit. The directions say to snip a green wire off the 10 meter slug coil. I installed it differently from W8JI, because the terminal strip was mounted differently, and this resulted in the shortest lead length.

After each modification the amplifier was firmly tested and plates never becames red. This is designed differently mdter a standard resistor, and will handle a surge current properly, without exploding.

The three tube AL seems to be fading away; no neutralization and a number of other lacking features may make it worth while to spend more on the 4 tube model, which has the essentials.

It passes through a hole on the pc board near the slug, up and around the back side of the board and back to the foil side of the board and soldered to ground, appearing to look like two green wires. In the standby mode, neither the input nor the output of the amplifier are terminated, and the plate supply voltage is ON. Given its damage in the depicted tubeAmerktron think it’s caused by parasitic oscillationswhich led to a high voltage.

Otherwise, the plate and load or band settings would be irrelevant. Ameriyron you got a capacitor in backwards while rebuilding the power supply, meted will show up here, without involving the new tubes. The suppression of the third- order harmonic is the difference between marker 3D and 4D.

Other bands are proportionate in drive demands. It happens at a rate of about once every 2 seconds. That is why vernier knobs are essential, and all the readings for the plate tuning are mefer together at the higher numbers above 40 meters.

Google ” 10 meter mod” There are color pictures all ameditron the place showing the wire The purpose of the wire is to short the input to the 10M input matching circuit to ground.

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Ameritron ALH 10m Mod | QRZ Forums

The fuse protects the amp if the tubes arc. Which green wire is it? The replacement choke is Ameritron Log these exciter power settings and amplifier knob settings for each band, so that you can quickly tune up the next time. This will exert enough pressure on the switch to close it, without having to deal with a zillion case screws. Even if you could correct those problems, the A was designed as an audio tube, and internal lead lengths are excessive for mofs performance above 20 MHz.

Copper Talk: Ameritron AL

In this case the simplest modification is to add a To install the Ameditron 20 Watt resistor, you have amefitron drill a hole. If you already own an ALH, it is worth the cost of parts to rebuild it and bring it up to current factory specs, if the amp suits your needs.

Don’t look for more than about watts cw or watts pep out of a three 3 tube model. The extra clearance from the hot plate avoids the glass melting.

Ameritron AL-811H 10m Mod

It is not standard on the economy amps in the AL series. He amertron made a good effort to extend the design life of the ALH amplifier in the face of parts procurement problems. Use the parts from Ameritron to guarantee you have no mechanical problems with fit. The reason for this is that the glass is not rated for high temperature like the slender Svetlanas of the past.

Also amerotron damage to the red HV wire to the plate RF choke. The seller KNEW its condition, and that is why he dumped it. This gives the fuse time to act.