Alpha 87A Entries

Here is the list of upgrades possible

Here is the list of possible 87A upgrades.

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87A UPGRADE

Note: all directions, i.e. front, rear, left, right - assume
positioning amp with front panel facing reader

Fault 1 revisited plus some other maintenance.

Hi All,

Thought I would share my recent troubleshooting of an Alpha 87A amp.

Got my friend's 1991 ETO 87A for repair for fault 1 error (soft fault).
The amp has had the pin diode upgrade and resistor/diode string mods done at the factory several years ago. Also the choke and spark gap on the T/R board.

I was following the fault 1 troubleshooting procedure and found it is not 100% correct.
After following step 3 the amp was not faulting with F2 on the output T/R board removed. THis shows it is probably D2 and D8. This was not the case. D2 and D8 tested fine with the Fluke 77 (1.5 M Ohms). I replaced them as a precaution anyway. Still fault 1 with F2 in and no fault with F2 out.

Further troubleshooting found R5 on the output T/R board open (10 M Ohm, 1/4 watt). I also tested D6 and D11 (which had 3.3 M Ohm resistors paralled to them) and found the diodes a little leaky. I replaced R5 , D6 and D11. No more fault 1 and back on the air!

Alpha 87a Manual

You can download the .pdf of the Alpha 87a manual: HERE

Alphamax Documentation

Alphamax documentation can be downloaded: HERE

What is the best way to use the 87A AlphaMax functions?

What is the best way to use the 87A AlphaMax functions?

When the new (since 1999) AlphaMax (Autotune) firmware is installed in the 87A, the TUNE and LOAD LEDs will blink to indicate what the AlphaMax program would do if it was enabled.

An addendum to the 87A manual was included with AlphaMax kits thatwere installed in the field, or you can download a copy of the new version of the 87A manual (with instructions for using AlphaMax) from our web site: here

Alpha 87A Checking PIN Diodes

To check the PIN diodes one end must be lifted from the circuit. The multimeter must be in the NORMAL resistance measuring range, NOT the "diode check" function.

The forward resistance will vary a bit depending on the voltage that the meter puts across the leads in the resistance measuring function. We usually use Fluke 77 meters, and they use 0.750vdc when measuring resistance, and 2.5vdc in the diode check range. I have another meter

Alpha 87A/89 Amplifiers and AM

To run AM with an amplifier, you should tune it up first at the full power level of the AM signal that is 100% modulated. If this is going to be 1500w, the carrier power with NO modulation would then be set to 375w without retuning the amp (set it with the drive control on the transceiver in AM mode).

The ALPHA 87A uses a pair of Eimac 3CX800A7 tubes, grid driven in Class AB2.

Carrier-only output is limited by the facts that

(1) the amplifier must remain linear on 100% modulation peaks, which are 4x the carrier power,

Alpha 87A Wattmeter Scaling

1) Connect PC to serial port with a modem program communicating with the amplifier.

2) With the 87A in STANDBY, transmit through the amplifier with 100 w steady carrier (use CW or RTTY) from the radio to a dummy load or antenna with low SWR.

3) On the PC, type EXT ON.

Alpha 87A noise on receive

When this occurs move the tune cap out of resonance in RX and the amp in operate and no drive. If the noise changes it is the TX diodes. If it does not it is the RX diodes.

Alpha 87A HI/LO switch

You should always use the HI setting of the HV switch. The low HV is for some overseas customers that only have an 800-1000w output limit (Japan and some Europeans). The lower plate voltage forces the plate current to be higher, which limits their maximum output. In some
countries they are required to show this in operation to the licensing authorities, etc. Control the output power by lowering the drive to the amplifier.

Alpha 87A Frequency Detect Adjustment

Alpha 87A Frequency Detect Adjustment:

The pot in the bottom of the 87A is to be adjusted as follows.

1. Place the 87A on it's right side.
2. Remove the bottom cover under the tubes.
3. Place the transceiver on 28mhz and adjust the power output to 5 watts.
4. Place the amplifier in the 160 meters position.
5. Put the pot in the full clockwise position to start.
6. Key the radio and adjust the pot counter clockwise until the amplifier changes bands then stop there.

Alpha 87A Intermittent Frequency Detect

Intermittent Frequency Detect in Alpha 87A

1) Unplug amplifier from the 220vac and take apart the plug. Make sure the screws holding the wires are tight, they sometimes get loose. When you unplug the amplifier from the power, you are also resetting the microprocessor. It has 5v whenever the amp is plugged in, even when it
is turned off. Resetting the microprocessor might fix it. Plug in the amp and turn it on. Test to see if it now works OK.

2) If it is still not working correctly, you will need to unplug it

Alpha 87A Fault 99

Please unplug the 87A for 2 minutes and then plug it back in to the 240v. This will reset the microprocessor and can sometimes correct erratic operation (possibly caused by stray RF), although it will NOT clear hard faults or remove them from the fault log.

The 87A should 'talk' to the PC anytime it is plugged into mains power, even when it is turned off. This is the best troubleshooting tool that we have.

Below are some notes about the 87A fault protection and instructions for clearing the fault log.

IMPORTANT !!!!!

Alpha 87A Fault 8

THIS IS VERY, VERY DANGEROUS. IF YOU DON'T HAVE EXPERIENCE WORKING AROUND HIGH VOLTAGE, DO NOT - WE REPEAT, DO NOT DO THIS. CALL THE COMPANY FOR AN RMA NUMBER, PACK THE AMPLIFIER IN A BOX, AND RETURN IT TO US FOR SERVICE. THERE IS A 3,000 VOLT POWER SUPPLY IN THE AMPLIFIER THAT CAN EASILY KILL YOU. THERE ARE MULTIPLE POINTS IN THIS AMPLIFIER THAT GENERATE LETHAL VOLTAGES. WE REPEAT - UNLESS YOU KNOW EXACTLY WHAT YOU ARE DOING WITH THIS, AND YOU'VE WORKED AROUND HIGH VOLTAGES BEFORE, DO NOT OPEN THE CASE AND DEFEAT ANY INTERLOCK EVER. (EVER)

Fault 8 is a problem with the -109vdc PIN diode bias voltage, usually caused by the PIN diodes or sometimes the power supply.

Alpha 87A Fault 37

Fault 37 means that either the bandswitch is just momentarily stuck, or there has been a failure on the motor-driver board.

You can try manually moving the bandswitch to loosen it up. Unplug the amp, remove the cover, and turn the white gear on the left side a half inch or so. Put cover back on and turn on amp to see if that has worked (or defeat BOTH interlocks and turn on with cover off).

If it stays on, cycle the bandswitch 5 or 6 times by manually selecting first 10m, then 160m.

Alpha 87A Fault 24

1) Do you notice that the amp is always on the same band when this happens?

2) Check the AC mains voltage and what you have the 87A set for. You must measure the AC voltage with a digital multimeter, the actual voltage must be within +/- 10 vac of what the amp is set for. Your line voltage may vary quite a bit from one season to another.

Alpha 87A Fault 22

If the 87A reports a Fault 22, it is usually caused by a blown
step-start fuse (at the center of the amp next to the AC Voltage terminal strip), or can indicate that the 36v power supply fuse is blown.

The 36v fuse is on the Low Voltage Power Supply (LVPS). The fuse is marked 125v/2A, it is called the 36v fuse because it is in the 36v circuit. The LVPS is under the HV Power Supply, its circuit board is vertically mounted.

Alpha 87A Fault 20 or 18

We have found that reseating the connectors on circuit boards may stop the erroneous filament current readings.

Stand the 87A on the right-hand side and remove the plate under the tube-deck. Unplug and carefully reconnect the plugs inside the tube deck. Also reseat the orange connector on the LVPS (Low Voltage Power Supply) directly in front of the power transformer, and just above the
bottom orange connector that is on one of the transformer cables. Use Caig DeOxit contact cleaner (available at Radio Shack) on those connectors to ensure a better contact.

Reseat the two large red connectors on the top edge of the control board. They are accessable through the slot in the top-right side of the front sub-chassis (behind the LED bargraph displays).

Alpha 87A Fault 17 and GPIO test

The Fault 17 is a TUNE, or GAIN, fault. If it is happening on all bands, it is possibly because of a failed diode (1N5711) in one of the wattmeters. There are Input and Output wattmeters.

Here are some tests.

1) Connect PC to serial port with a modem program communicating with the amplifier.

2) With the 87A in STANDBY, transmit through the amplifier with 100 w from the radio to a dummy load (or antenna with low SWR).

3) On the PC, type EXT ON.

Alpha 87A Fault 11

Fault 11 usually means that one of the variable capacitors (TUNE or LOAD) is shorted, or the PIN diode T-bias voltage is low.

If it faults on all bands, check the 1/4 amp fuse in the Output T/R Module. It is a small clear and white fuse that plugs into a white socket on the circuit board. Also look for any other burned parts in the T/R module whle checking
the fuse. Look for the leads of PIN diodes recently changed that may be touching the chassis?

Alpha 87A Fault 1 Troubleshooting

THIS IS VERY, VERY DANGEROUS. IF YOU DON'T HAVE EXPERIENCE WORKING AROUND HIGH VOLTAGE, DO NOT - WE REPEAT, DO NOT DO THIS. CALL THE COMPANY FOR AN RMA NUMBER, PACK THE AMPLIFIER IN A BOX, AND RETURN IT TO US FOR SERVICE. THERE IS A 3,000 VOLT POWER SUPPLY IN THE AMPLIFIER THAT CAN EASILY KILL YOU. THERE ARE MULTIPLE POINTS IN THIS AMPLIFIER THAT GENERATE LETHAL VOLTAGES. WE REPEAT - UNLESS YOU KNOW EXACTLY WHAT YOU ARE DOING WITH THIS, AND YOU'VE WORKED AROUND HIGH VOLTAGES BEFORE, DO NOT OPEN THE CASE AND DEFEAT ANY INTERLOCK EVER. (EVER)

Alpha 87A Fault 1 Troubleshooting Instructions

Here are troubleshooting instructions for a Fault 1. Be sure to defeat both interlocks when turning on the amplifier with the cover off, the microswitch and the HV shorting crowbar at the center of the amp! Slip the cap from a Bic-type pen over the crowbar screw to insulate it, the shorting spring
will hold it in place.

Alpha 87A Communications

Please unplug the 87A for 1 minute and then plug it back in to the 240v. This will reset the microprocessor and can sometimes correct erratic operation (possibly caused by stray RF), although it will NOT clear hard faults or remove them from the fault log.

The 87A should 'talk' to the PC anytime it is plugged into mains power, even when it is turned off. This is the best troubleshooting tool that we have. Note that the 20A fuses must be good.

Below are some notes about the 87A fault protection.

Alpha 87A Autotune Function

The 87A Autotune (AlphaMax) function is not that of an antenna tuner. It constantly monitors the input power, output power, and grid current and tunes the motorized TUNE and LOAD capacitors for best efficiency. The optimum settings will change as you move across the
band and if the drive power is changed.

Alpha 87A and FT-1000D Power Spike

Use of ALC is OK, but first the radio output must be set to the correct level for the output that you want from the amplifier. It is not a good idea to use ALC to force the radio output from 100w to the needed 50w, for example.

The ALC control on the amplifier should be adjusted so that it limits the exciter from going ABOVE the desired level. It is to keep the amp from being overdriven and should not be needed if the radio is operated correctly.

Alpha 87A AC Tap Settings

The AC voltage tap may still be set for 200v, which we have here. Measure your line voltage where the amp plugs in, then set the tap wire to the appropriate setting. The terminal strip is near the step-start fuse at the center of the amp.

The first heavy white wire at the front end of the terminal does not move (if you have the optional fan there is also a black wire on the same screw). The second white wire moves to the other terminal to determine the tap. The second black wire should stay on the lug that is 2 positions from the first one (220vac). The 240 screw is 3 positions

Alpha 87A AC Module fuse

On the Simplified Schematic (87A Manual Fig 9) fuse F3 in the AC Module is shown as a 500ma fuse. It is really a 100ma fuse and the AC module must be removed to check it. If this is blown it will keep the 87A from running and it will NOT communicate with the PC via the serial port.

To check the fuse, remove the nut at the front of the AC Module and the two screws on the rear of the chassis above and below the 20A fuse holders. When putting it back in, be sure to tighten the rear screws FIRST, then tighten the nut at the front. Doing this in reverse order

Alpha 87A 40m Clapper Fix

87A 40m (Segment 1) Clapper Fix

1) Establish computer communications with amplifier per 87A Operating
Manual (pages 19-21).

2) Amplifier plugged in, power OFF.

3) Type: EXT ON (turns on FACTORY mode)

4) Type: DM B782[enter] (dump memory at location specified)

a) If first pair of numbers is ØØ then proceed to step 7.

b) If first pair of numbers is BØ type W B782 ØØ[enter]

5) Unplug 87A AC power, plug back in.

6) Repeat steps 3) and 4) to verify data written to memory.

Alpha 87A 17m Testing Bandswitch

A problem with the tuning on 17m can be caused by the bandswitch being a little bit out of alignment on that band. To test this, first manually select a lower band, then go to 17m. Try transmitting and tuning the amp. If you are able to tune it up, save the setting (press ENTER and then press the segment that you are on). Then manually
select a higher band, then go to 17m, and try transmitting again. If the tuning changes, or if the 87A gets a Fault 17, it is the bandswitch alignment.

Alpha 87A 17m Bandswitch Alignment

The memory address for the 17m bandswitch position is B7C0 .

>From the terminal program type:

EXT ON (turns on 'factory mode')
DM B7C0 (write down first two digits)
W B7C0 xx (xx = original hex number up or down 2)

If it works when you come from a lower band, increment the number. If it works coming from higher band, decrement the number.

When done type:
EXT OFF

memory locations for the bandswitch positions:

  • 160m b7bb
  • 80m b7bc
  • 40m b7bd
  • 30m b7be
  • 20m b7bf

Alpha 87A 10m Unlock

1. Turn on the amplifier; wait until time delay completes.

2. Select - BAND 1.8 MHz, SEGMENT 1 (far left). Note the green LEDS in
the
push-button will illuminate.

3. When time delay completes switch amplifier to STBY.

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