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TOF Tuning Aid

AL811 Changes

AL811 Tuning

811A Tube History and Construction


Power line voltage jumpers in AL80B mainframe. This includes the AL572 and AL800 series.

Power line voltage in the USA is 120 or 240 nominal.  It has not been 110V and 220V since before WWII. It has not been 115/230 since the 1960's.

If you operate SSB and have a reasonably good power line, you will see no improvement going to 240V on any amplifier shipped as 120V. Changing wiring from 120 to 240 does not lower the house electric bill. Changing to 240 does not make the amplifier run cooler and does not make it more efficient.

Changing to 240 does reduce power line voltage drop by increasing line voltage and reducing line current. If you have a marginal power line or are at the breaker limits, 240 is a good idea.

The best way to tell if the line voltage is off, or if you need to change to 240, would be to read the amplifier manual. If your amplifier is out of range on HV reading, or if the amplifier HV sags excessively (beyond manual specifications) when transmitting normally, you should seriously consider 240V wiring.


E  to F and 1,2,3 affect the buck-boost winding. The buck or boost winding either adds to or subtracts from the power line voltage. The power line is in series with E and F. The buck and boost is on 1,2,and 3. The wiring of these pads is used to fine-adjust for various line voltages.

The actual photograph below shows the buck boost not being used. This wiring setting would be for a nominal 115/230 volts. These pictures ONLY are for examples of jumper wire use. The board used for photo was not in an amplifier. The board has no transformer wires connected up from the bottom so the transformer pads are empty.  

The following rules apply:

1.)  NEVER SHORT 1, 2, or 3 TOGETHER..  Only one number pad can connect to one letter pad.

2.) IT IS OK TO SHORT E to F, as long as a number pad is not connected to E and F. This will give you 115/230. 


line voltage settings AL80B AL572 Ameritron

Note in the chart above how E and F will move between either a short or to 1, 2 and  3!!












Trouble Locating Hints


TROUBLE SHOOTING guide below generally applies to many types of amplifiers with suitable part number changes.

(In order of most common occurrence)

Warning! Never test or operate a tube type amplifier with the cover off and HV active! Always replace cover before powering up! Virtually any issue can be located without activation of high voltage on an open amplifier.

1.) Test on SSB using MOX or push-to-talk with no mic gain. With no RF drive power, but the amplifier keyed, the amplifier’s grid current meter deflects about the same as the plate current meter. This is a common problem

2.) Grid meter moves backward, and Ip meter reads forward, with no drive and amplifier in standby

3.) Amplifier blows fuses when power switch is turned on (always use proper 250V fast-blow fuses), blows step-start in other amplifiers

4.) HV/Plate Current meter reads flakey, tapping or rocking switch while in Ip position makes meter jump around (AL811 series only)

5.) Low Power Output

6.) Noise in receiver and/or erratic amplifier meter readings on standby


7.) Audible popping noise and/or clicking noise

8.) No receive or weak receive


9.) No or very little transmit power with amplifier on, OK on bypass

10.) VSWR goes intermittently high on the RF power output meter(s) when tuning

Plate or grid meters jump around with a steady carrier while VSWR changes

o     Try tuning the amplifier into a dummy load with any antenna tuner in bypass or direct

§      If the amplifier tunes up ok with the dummy load connected, you have a tuner, feed line or antenna problem

o     Change tuner output to a dummy load, and tune into the dummy load with amplifier in standby.  Now try the amplifier 

§      If the VSWR reads ok with the amplifier, you have an antenna system problem

§      Wiggle cables behind amplifier to see if connector or cable loose or bad

o     Check center pins of connectors to be sure poor soldering or bent pins have not ruined connectors

§      Too much solder on male pin will ruin female connector

§      Unsoldered male or improperly assembled male will cause poor connection

§      Some import cables and connectors are manufactured wrong size. Try different cable for better fit


11.) Transmitter or transceiver SWR too high through amplifier, should be under 1.5:1

12.) Grid meter pins with low drive power

13.) Amplifier does not appear to key, or does not release

14.) Bias system and meter problems





2011 Oct 07