Acom 600S Operating Manual

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Acom 600S Operating Manual Manual pdf 17 page image

Page 16 of 33the size, consider the frequency range in which the offered ferrites are effective – normally they areoptimized for suppression of interferences on HF (with larger permeability), with medium permeability forHF-VHF or with low permeability - only the VHF range. The latter are ineffective for HF;- whenever possible use shielded cables and ground their shields at both ends;- screen (at least partly) the disturbed apparatus, for example, put under the keyboard, the mouse, thedesk microphone or the Morse keyer a large metal sheet, connected to the grounding system of theshack;- the addition of even quite simple low pass L/C or R/C filters directly to the disturbed inputs or outputs ofthe apparatus is very effective, provided it is practically applicable.Last but not least, have in mind that the benefit of the above measures is two-fold. Firstly - they reduce theinterferences from your transmissions to the ambient environment and secondly - they reduce the backgroundnoise floor for your reception. Practically, with no great efforts, implementing the above measures, you can reducethe background noise floor with one or more S-units across the different bands. This will allow you not to missweaker stations, which will hear you because of your increased transmission power.4. OPERATION WITH THE AMPLIFIER4-1. Change of modes RX / TX and Operate / Stand-by; option AUTO OPERATEa) In Stand-by mode, as well as with un-powered amplifier, receiving and transmitting with thetransceiver is implemented via RF by-pass between RF INPUT and RF OUTPUT of the amplifier. Attransmission in Stand-by, RF power of the transceiver is not amplified by the amplifier, the controlKEY-IN input does not influence over its operation, and the KEY-OUT output (S. 2-3(c)) follows thestate of the KEY-IN input unconditionally.b) In Operate mode the final stage of the amplifier is powered and it is fully functioning; the receive-transmit (RX / TX) direction is controlled by the KEY-IN input:- at open KEY-IN (Operate/RX mode), the transceiver receives the signals from the antenna through thesame RF by-pass path between RF INPUT and RF OUTPUT through which receiving is done withamplifier turned off or in Stand-by mode;- at grounded KEY-IN (Operate/TX mode) the amplifier input relay connects the RF INPUT connector(drive from the transceiver) toward the final stage input and the output relay feeds the amplified signalfrom the final stage output to the antenna through the RF OUTPUT connector.C A U T I O NIn order to provide time for the relays and the final stage in the amplifier toswitch safely from receive to transmit, the transceiver should provide adead time i.e. must “notify” the amplifier in due time grounding its controlKEY-IN input not later than 10ms before feeding drive power toward theamplifier RF input. Otherwise, the “HOT SWITCHING ATTEMPT”protection will trip.In Operate mode the KEY-OUT output (S. 2-3(c)) follows the state of the KEY-IN input only after all conditions forsafe transmission have been satisfied and found OK by the amplifier control unit. The KEY-OUT output dulydisables transmission, if this is inadmissible or there is a potential risk for the amplifier or the transceiver.The two modes - Operate and Stand-by - may alternatively be changed in three different, independent ways asdescribed below:- manually (locally) – by successive pressing the OPR/STB button – Fig. 3-2;- remote control – through the respective command “OPR” or “STB”, received through the serial RS232Interface;- automatic control – if the AUTO OPERATE option is activated – see next item and S. 5-4(b).