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HAMTRONICS COR-3 Instruction Manual
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©1990 Hamtronics, Inc.; Hilton NY; USA. All rights reserved. Hamtronics is a registered trademark. Manual revised:10/2/07 - Page 1-FUNCTIONAL DESCRIPTION.The COR-3 module is designed foroperation with Hamtronics fm excitersand receivers and CWID board to pro-vide repeater operation. The unitmay also be used with other makes oftransmitters and receivers if the re-quired interface signals are available.The COR-3 module features acourtesy beep tone, which helps toprevent talk over by encouraging us-ers to wait a short time before pickingup the repeater. After the waiting pe-riod, a beep sounds on the repeaterand the time-out timer is reset. Wait-ing this short period allows any newparty to break in and identify himself.The unit comprises four main circuits.1. An electronic carrier-operatedrelay provides operating power to theexciter in the transmitter enclosurewhenever the receiver squelch is open.U1-B senses the presence of a COSsignal from the receiver and keys thefirst timer, U1-A, which provides thecourtesy wait period. That trips timerU1-D, which provides the silent re-peater tail. That timer, in turn, keysQ1/Q2, which switches the B+ to theexciter. If the receiver should be heldon for longer than the legal transmitperiod, (e.g., 5 minutes), time-outtimer U1-C automatically shuts downthe transmitter until the receiver is re-leased.2. An audio oscillator and pulsegenerator circuit provides the beepsignal. The output of timer U1-A trig-gers one-shot multivibrator U2-C/Dwhen the waiting period elapses. Theone-shot keys square-wave oscillatorU2-B. The audio output is integratedby an R/C network to create a sign-wave tone, which is applied to themixer for output to the exciter audiocircuits.3. Audio mixer stage U2-A mixesthree audio inputs from the receiver,the CWID, and the beep generator toprovide the audio for the transmitter.The receiver audio level is set at thereceiver to a predetermined level. Potson the COR-3 board adjust the levelsof the CWID signal and the beep toneto the desired levels relative to the re-ceiver audio.4. A speaker amplifier which pro-vides adjustable drive for a localspeaker separate from the repeateraudio, U3, avoids having to use "L"pads, etc. and compromising localaudio for benefit of repeater. Thisallows the receiver audio to be run ata low level to avoid distortion.Refer to catalog for completeCOR-3 module specifications.CONSTRUCTION.There is no special constructionsequence; but following are somenotes regarding various parts.a. Resistor bodies are designatedas circles on the assembly diagram forthose which are mounted vertically.b. Note the polarity of ic's, transis-tors, diodes, and electrolytic capaci-tors.c. Trim pots may be marked withsignificant figures and multipliers,such as "105" for 1 megohm.d. Terminal pins for E1-E15should be cut from the metal carrierstrip, then snapped in place from topof board using care not to crush them.Firm pressure with a pair of fine nosepliers grasping one wall of the pin willcause it to snap and lock into hole.e. Use ic sockets for U1 and U2but not for U3, which must be sol-dered to the board for heatsinking.f. Be careful not to interchange re-sistors which have similar appearingcolor bands, eg., 150K and 510K or 1meg and 10 meg.INSTALLATION.The COR-3 module can bemounted with standoffs in the fourcorners of the board. No specialshielding is required. Connections aremade to the terminal pins either bysoldering hookup wires into hollow topof pin or wrapping around pin andsoldering. Following are descriptionsof required interface connections.When used with Hamtronics exciter,receiver, and CWID boards, requiredinterface levels are assured. Whenused with other equipment, some caremust be taken to be sure compatibleinterface connections are arranged.Referring to the Repeater System dia-gram, it can be seen that the ex-citer/pa and the receiver are mountedin rf tight boxes with feedthru capaci-tors used at control and audio signalentrances.a. COS OUTPUT FROMCOS OUTPUT FROMCOS OUTPUT FROMCOS OUTPUT FROMRECEIVER.RECEIVER.RECEIVER.RECEIVER. This control signal at E7,taken from the squelch stage in thereceiver must be about +3 to +10 Vdcwhen the squelch is open and nearground when squelch is closed.b. AUDIO FROM RECEIVER.. AUDIO FROM RECEIVER.. AUDIO FROM RECEIVER.. AUDIO FROM RECEIVER. Thehigh level audio output from the ic inthe receiver, which normally feeds thespeaker, is connected to E6 on theCOR-3 board instead. The COR-3board applies it to the audio mixerstage for application to the exciter.The receiver audio is also connectedthrough a (user supplied) 100K SPKRVOL control to E14. A speaker am-plifier on the COR-3 board amplifiesthe signal from the SPKR VOL controlto provide an isolated signal for a localspeaker on the repeater panel. Thenominal audio level at E6 should be1.5V p-p at full 5 kHz deviation on thereceiver.c.... LOCAL SPEAKERLOCAL SPEAKERLOCAL SPEAKERLOCAL SPEAKER connected toE15 on COR-3 board should be an8-ohm speaker. Up to 2W of audiocan be obtained from the COR-3speaker amplifier. Note that thespeaker must return to ground.d. B+ FOR CORB+ FOR CORB+ FOR CORB+ FOR COR----3 BOARD3 BOARD3 BOARD3 BOARD shouldbe +13.6Vdc connected to E3.Ground should be tied to E10 unlessa good ground is picked up throughthe mounting hardware from thechassis. Current drain depends onspeaker level and amount of currentsupplied to exciter keyed B+ line, butnormally should be about 600-700mA.e. KEKEKEKEYED B+ TO EXCITERYED B+ TO EXCITERYED B+ TO EXCITERYED B+ TO EXCITER at E1is +13.4Vdc (slight drop in Q2) at upto 600 mA. Because the pa is class C,it is unnecessary to switch the B+ tothe pa.f. REPEATER AUDIOREPEATER AUDIOREPEATER AUDIOREPEATER AUDIO from E5 isconnected to the microphone input ofthe exciter. A 500 ohm dynamic mi-crophone can also be connected to thesame exciter input. Resistor R47 pre-vents the microphone from beingloaded down.g. LOCAL KEYLOCAL KEYLOCAL KEYLOCAL KEY input E12 may begrounded by the local microphone PTTswitch to key the transmitter locally.h. Connections to CWID are asshown on the Repeater System dia-gram. ID TRIP normally is high andgoes low when the receiver squelchcloses and the beep timer elapses toprovide a pulse to trip the id. The IDKEY signal normally is low and goeshigh to key the COR circuit while theCWID runs. The CWID audio outputshould be tied to E4, the input to theaudio mixer on the COR-3 board. TheCWID input level at E4 normally isabout 4kV p-p.i. Outputs at E2, E8, and E11drive front panel led's to indicate re-peater status. Led's are not suppliedwith this kit, but they are supplied inthe hardware package if you bought acomplete Hamtronics Repeater Kit.HAMTRONICS® COR-3 MODULE: INSTRUCTION MANUAL |
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