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SECTION IV
Maintenance


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SECTION IV
Maintenance

4.1 GENERAL

Adjustment of the r-f input circuits requires the following equioment :

  1. R-f wattmeter and directional coupler, such as are included in the 312B-4 or 312-5 Station Controls, or the 302C-3 Directional Wattmeter.

  2. 50-ohm, 500-watt, nondirective dummy load. (For short tests where key-down conditions do not exceed 30 seconds, the DL-1 Dummy Load can be used when applicable.)

The filamen circuit in the 30L-1 is fused with a length of number 30 wire in the center-tap ground return of filament winding on T1. The fuse is connected betwee the two outer lugs of a terminal strip located near R11 in the power supply compartment (refer to fig 6-1). Under some conditiond, the amplifier may appear to function normally even though this fuse has blown; however, this causes hum to appear on the output signal. Check for shorts in the filament circuit.

4.2 REMOVAL OF CABINET AND COVER.

  1. Lift the cabinet lid, and remove the two Phlips-head screws located at the top-front edge of the cabinet. Remove the four feet and the Philips-head screw located midway between the rear feet. Push the amplifier forward from the rear until the front panel projects from the cabinet about half inch. Grasping the front panel at edges, carefully slide the amplifier out of the cabinet, making sure the a-c power cord clears.

 
  1. To remove the r-f compartment upper cover, loosen the ten screws about thee turns, slide the cover toward the front panel, and lift off.

  2. To remove the power supply compartment upper cover, remove screws located about the edges of the cover.

  3. To remove the bottom cover, remove two round Philips-head screws from from each end of the cover and three flat-head screws near the middle of the cover, and lift off.

4.3 BLOWER LUBRICATION

Every 1000 hours of operation (or 6months, whichever comes first), lubricate the blower motor bearings with three or four drops of sewing machine oil. Do not overlubricate.

4.4 ALIGNMENT OF R_F INPUT CIRCUITS.

Remove the amplifier from its cabinet as outlined in paragraph 4.2. Do not remove any of the covers. To align for amateur band coverage, observe the following procedure :

  1. Connect the directional wattmeter between the exciter otput and the 30L-1 R-F INPUT jack. Connect the dummy load to the R-F OUTPUT jack on the 30L-1. Setup the equipmment on 28.5 megacycles. Set the exciter EMISSION switch to LOCK KEY, and 30L-1 METER switch to TUNE.

  2. With 30L-1 power off, tune and load the exciter to aproximately 30 watts output as indicated on the watt-meter (forward power)


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