Transcript Government Surplus equipment

Government Surplus equipment
Why consider using and modification
considerations
Using Such Equipment
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Proven design
Cheap
Availability is generally good
Documentation usually available
Components are top quality
Past equipment
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BC-457
(Command Sets)
BC-458
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BC-458
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BC-348A thru Q Models
R-389
R-390 R-390A
AM-494
SCR-522
APX-6
T-368
RT-68
Popular 144-220-432 Equipment
• AM-494 AMP (2 X 4X150A)
• SCR-522 (2 meter AM 15 watts)
• AM-6154/55
Modifiable to 2 – 220- 432 MC
AM=6155
350 – 400 watts All bands
Readily available
Reasonably priced – $250-350 plus tube
AM-6155
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Conversion data easily attainable
High quality
Tetrode tube (lower drive requirements)
Cavity tank circuit design
Desk top unit
-heavyNo special tools needed to complete mod.
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A few evenings (Weekend timeframe to mod.)
In stock at Fair Radio Sales – Lima, Ohio
Numerous mod procedures on line
VE2ZAZ – W3RJW – K7XC
Plenty of assistance available
Can be made to appear as an attractive piece
of table top amplifier.
AM-6155 AMP
• Must build a new grid input circuit
• Must build a new grid negative voltage
regulation circuit.
• Modify AC input to operate on 220 VAC
• Blower may be noisy
• For tabletop usage install a god set of rubber
feet
• AC input connect may be modified
AM-6155 Improved Grid Bias Ckt.
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Uses a LM-337T Negative regulator
Uses 9 parts
Can be mounted a small PC board
Construction not critical
Plenty of space inside to mount
Advise that you test first on the bench
Modification suggestions
• Remove input coupling knob and shaft
• Close front hole with a rubber plug
• Remove black name plate from front of cavity
unit.
• Erase the unused lettering
• Painting is optional
• Use 4 good quality rubber feet
• (remember the unit weighs about 80 pounds)
Tune up and operation
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Turn unit on – power light should come on
Check meter readings
Wait at least two minutes
Turn on high voltage switch – HV light should
Come on.
Again, check meter readings
Key unit via external pnono jack in rear of amp
Operation continue
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Key unit and adjust bias pot for 70 – 80 ma.
Check voltage on screen and HV
Screen 40 = 400 volts
High voltage = 20 or 2,000 volts
Apply a small amount of drive (2 – 5 watts) and
adjust input tune for maximum Ip
• Connect a watt meter to output and again adjust
input tune, plate tuning and outputcoupling for
maximum output.
Operation Cont.
• NOTE: If another watt meter available place in
the drive input so you can monitor the input
and output power simultaneously.
• Apply NO MORE than 10 to 13 watts.
• Output, if all meter readings are with in limits
should 275 to 350 watts.
• Plate current (Ip) should not exceed 300 ma.
For an 8930 – 350 ma. For a 4CX400A tube.