Alpha 86 Amplifier
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                  Alpha 86 1.5 KW No Time Limit Amp

Massive 3.5 KVA Power Transformer RF Section with 2 - 3CX800A's

Front Panel is clean and has a very nice layout

RF Section L Network - Silver Plated 3CX800A Blower and Pin Diodes

Rear of AMP - Extra Fan, Fuses, Relay, RF In/Out, 

Specifications (Per manual):

Frequency Coverage: 1.8 to 30 Mhz (as modified with ham license)
Power Output: 1.5 KW continuous carrier, CCS
Driving Power required: 60 to 70 watts nominal for rated output
Spurious signal and harmonic suppression: better than 50 db.
IMD: -35 dBc at 1 kW output, typical
Maximum Load SWR: 2.5:1
SWR Trip circuit threshold: 250 W reflected power at 1.5KW output
Primary Power requirements: 220-240 V, fused at 20A
ALC: negative going, grid current derived, adjustable on rear panel (some models)
Protection Features: primary and step-start fuses; primary ac interlock, HV interlock, anode over current, hihg SWR
SIze (H x W X D): 7.5 x 17 x 15 inches
Weight: 66 lbs.

Operational Commentary:

This is one of the great amps I have owned.  In fact I liked it so much, I had two of them; each being driven by an Icom 775.  I directly keyed them with the 775 relay output with no problem as relay current requirements were small.  It took about 60 watts to drive to full output.  I used them in FSK mode with full output and 80% duty cycle (Contest CQ mode).  They do get warm but air flow is quiet and tubes never seem to have a problem.  Only operational challenge is to keep SWR below 2:1 or protection circuit will trip and you have top reset. This is sometime challenging on 40/80 and 160 when you want to QSY quickly and your antennas have small 2:1 SWR bandwidth. There is a 3 minute warm-up period with these tubes when you first turn the amp on.  Standby/operate switch put to standby when not using.  If you try and transmit into the wrong antenna or no antenna, you may blow the pin diode protection fuse in which case the amp will work but you can't receive in operate, only standby mode.  Solution is to take cover off and replace fuse - about a ten minute job if you have the fuse (1/4 amp, 125 volt axial - looks like small diode and available special order from Radio Shack or Alpha).  This amp only works on 240, there is no provision for 208, 220, 240 taps as on Alpha 89 and Alpha 91B.  I ran on 208 for a year and could only get about 1200 watts output.  Then switched to 240 and got full 1500 watts output on all bands.  I never used the ALC or the QSK keying circuit (key the amp which keys the exciter) as the QSK on the Icom 775 worked just fine.  I also never experienced any Icom 775 spike problems even with 775's with serial numbers in the 11xx range (early models).  My only reason to change amps was to go to automated band change model for quicker contest operation.  These amps also work from the WARC bands where permitted.

Note: The Alpha 86 amp was reviewed in the April 1989 QST and is available as an Adobe Acrobat(R) file from the Members Only section at the ARRL Website (www.arrl.org).  Current used prices for this amp are in the $2,000 to $2,400 range.  Some models don't have the optional fan on the back or the adjustable ALC pot on the rear panel.

Typical Settings and Power Input verses Power Output:

Control Setting And Power Reading for Alpha 86 s/n 6-88500157

BAND

FREQUENCY

TUNE

LOAD

PIN

POUT

NOTES

160

1.85

60

25

65

1400

80

3.75

39

68

75

1500

40

7.02

47

45

70

1500

30

10.12

18

68

70

1500

band "C"

20

14.20

42

79

70

1500

17

18.10

66

76

65

1400

band "15"

15

21.25

25

85

65

1400

12

24.90

45

84

65

1500

band "10"

10

28.50

14

88

50

1500

Notes:

TUNE is tune control settings

LOAD is load setting

PIN is power input as measured on Icom 775 internal wattmeter

POUT is power measured on Bird 43 wattmeter with 2500H slug

Antenna was Heathkit Dummy Load (Cantenna)

Measurements on 5/31/01 by Bob Brehm, AK6R

PIN was increased up to 1,500 watts POUT or until 70ma of Grid current

These settings are unique to this amplifier and your settings may differ