L 4b manual

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Transmitting AGe threshold adjustment and push-pull switch that allows the L to remain on while operating with the exciter only. A transmitting AGe circuit controls the exciter gain to allow the highest average power without peak clipping. An internal changeover relay feeds the antenna through when the L-4B is turned off.

A pair of relay contacts bias the output tubes to cutoff, eliminating unwanted heat and diode noise when receiving. The output tubes are forced-air cooled by a. Two taut-band suspension meters indicate plate current, grid current, plate voltage, and relative RF output power. The separate solid state power supply requires no warm up period and provides excellent dynamic and static voltage regulation. Do not turn on the L This Is a potentially dangerous situation and should never be attempted for any reason.

Carefully remove your L-4B Amplifier, tubes and chimneys, and power supply from their packing cartons and examine them closely for signs of shipping damage. Should any damage be apparent, notify the delivering carrier immediately, stating the full extent of the damage. Inspect the packing material closely before putting it away to be sure you have not overlooked the cables or other hardware shipped with the.

The tubes are installed first o Notice that base Pin 3, the pin with no immediately adjacent pins, face In either SOCket, the ends of the amplifier case.

The chimneys should be installed by. The parasitic chokes are installed after the tubes and chimneys. Do not overtighten this screw when connecting the parasitic chokes: a snug fit is adequate. After replacing the top cover, the amplifier can be connected for operation. In general, the location of the L-4B is not critical, however, there are certain considerations which must be given to insure optimum performance.

Care should be taken to insure that space is allowed around the amplifier and power supply cases to allow adequate air circulation. Extremely hot locations, such as near radiators or heating units should be avoided.

The L-4B is shipped from the factory with jumpers connected to operate on VAC 0 It 1s highly recommended that the L-4B be operated from its own If a V circuit Is all that is available, it should be fused for 30 amps and the circuit conductors should not be less than il0 and no other equipment should be operated from this circuit.

Below are pictorials of jumper connections for both V and V operation. The jumpers in both the amplifier and power supply must be connected as shown or serious damage to the L-4B components may result.

The L has been designed in accordance with good engineering practices and second harmonic content Is attenuated from the fundamental by at least 35 dB. Because of the posSibiUty that you may be using a multiband antenna or have a feed line that is resonant at a harmonic frequency, it is highly recommended that.

The nominal output impedance of the L-4B is 50 ohms and the SWR of this load should never exceed For a detailed discussion on antennas, we suggest referring to an appropriate antenna book.

Most practical. For this reason we recommend using an antenna matching network such as our MN which will allow the L to work into a 50 ohm load for maximum power transfer into the antenna. The L-4B should be attached to a good earth ground through as short and as large a ground strap as possible for best results. A binding post is provided on the. We recommend that. The TR-3, TR The exciter should be placed as close to the L amplifier as practical so that the coax and ground strap will be short.

The L is supplied with a cable to connect this jack to a similar jack on our Model AC-4 Power Supply which terminates in the particular transmitter the AC-4 is powering.

A two pin Jack on the rear of the L amplifier Is prOVided for connection to a pair of nonnally open relay contacts in the exciter which close on transmit and thus tum on the L-4B at the same time.

Some exciters except TR-3, TR For these exciters it will be necessary to plug the two pin connector tnto the L vox socket in the correct. With the exciter 1n standby, if plugging in the vox connector causes the L plate current to read up scale, reverse the vox connector 1n its socket so that the" plate current Is zero.

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