FT-7900R_SM.pdf

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1、FT-7900R/E Technical Supplement Dual Band FM Transceiver FT-7900R/E Technical Supplement Introduction This manual provides technical information necessary for servicing the FT-7900R/E Transceiver. Servicing this equipment requires expertise in handling surface-mount chip components. Attempts by non-

2、qualified persons to service this equipment may result in permanent damage not covered by the warranty, and may be illegal in some countries. Two PCB layout diagrams are provided for each double-sided circuit board in the transceiver. Each side of thr board is referred to by the type of the majority

3、 of components installed on that side (“leaded” or “chip-only”). In most cases one side has only chip components, and the other has either a mixture of both chip and leaded components (trimmers, coils, electrolytic capacitors, ICs, etc.), or leaded components only. While we believe the technical inf

4、ormation in this manual to be correct, Vertex Standard assumes no liability for dam- age that may occur as a result of typographical or other errors that may be present. Your cooperation in pointing out any inconsistencies in the technical information would be appreciated. Specifications . A-1 Explo

5、ded View check with your dealer. B-1FT-7900R/E Technical Supplement Exploded View realignment should not be done until after the faulty component has been replaced. We recommend that servicing be performed only by au- thorized Vertex Standard service technicians who are ex- perienced with the circui

6、try and fully equipped for re- pair and alignment. Therefore, if a fault is suspected, con- tact the dealer from whom the transceiver was purchased for instructions regarding repair. Authorized Vertex Stan- dard service technicians realign all circuits and make com- plete performance checks to ensur

7、e compliance with fac- tory specifications after replacing any faulty components. Those who do undertake any of the following alignments are cautioned to proceed at their own risk. Problems caused by unauthorized attempts at realignment are not covered by the warranty policy. Also, Vertex Standard m

8、ust reserve the right to change circuits and alignment procedures in the interest of improved performance, with- out notifying owners. Under no circumstances should any alignment be attempt- ed unless the normal function and operation of the trans- ceiver are clearly understood, the cause of the mal

9、func- tion has been clearly pinpointed and any faulty compo- nents replaced, and the need for realignment determined to be absolutely necessary. Required Test Equipment The following test equipment (and thorough familiarity with its correct use) is necessary for complete realignment. Correction of p

10、roblems caused by misalignment result- ing from use of improper test equipment is not covered under the warranty policy. While most steps do not re- quire all of the equipment listed, the interactions of some adjustments may require that more complex adjustments be performed afterwards. Do not attem

11、pt to perform only a single step unless it is clearly isolated electrically from all other steps. Have all test equipment ready before be- ginning, and follow all of the steps in a section in the or- der presented. ?Regulated DC Power Supply: adjustable from 11.5 to 16 VDC, 10 A ?RF Signal Generator

12、 with calibrated output level at 500 MHz ?Frequency Counter: 0.1 ppm accuracy at 500 MHz ?AF Signal Generator ?SINAD Meter ?Oscilloscope ?Spectrum Analyzer ?Deviation Meter (linear detector) ?AF Millivoltmeter ?AF Dummy Load: 8-Ohm, 5 W ?DC Voltmeter: high impedance ?Inline Wattmeter with 5% accurac

13、y at 500 MHz ?50-Ohm non-reactive Dummy Load: 50 watts at 500 MHz ?VHF/UHF Sampling Coupler Set up the test equipment as shown below, and apply 13.8 VDC power to the transceiver. E-1 Power Supply 13.8 VDC Pin 5 EXT SP Frequency Counter Deviation Meter Inline Wattmeter 50-ohm Dummy Load RF Sampling C

14、oupler RF Signal Generator 8-ohm Dummy Load SINAD Meter AF Signal Generator FT-7900R/E Technical Supplement Alignment Alignment Preparation & Precautions A dummy load and inline wattmeter must be connected to the main antenna jack in all procedures that call for transmission, except where specified

15、otherwise. Correct alignment is not possible with an antenna. After complet- ing one step, read the following step to determine wheth- er the same test equipment will be required. If not, re- move the test equipment (except dummy load and watt- meter, if connected) before proceeding. Correct alignme

16、nt requires that the ambient temperature in the repair shop be the same as that of the transceiver and test equipment, and that this temperature be held constant between 20 C and 30 C. When the transceiver is brought into the shop from hot or cold air it should be allowed some time for thermal equal

17、ization with the en- vironment before alignment. If possible, alignments should be made with oscillator shields and circuit boards firmly affixed in place. Also, the test equipment must be thoroughly warmed up before beginning. Notes: Signal levels in dB referred to in alignment are based on 0 dB =

18、0.5 V (closed circuit). Entering the Alignment mode Alignment of the FT-7900R/E is performed using a front- panel software-based procedure. To perform alignment of the transceiver, it must first be placed in the “Align- ment Mode,” in which the adjustments will be made and then stored into memory. T

19、o enter the Alignment mode: 1.Press and hold in the MHz(PRI) key while turning the radio on. 2.Rotate the DIAL konb so select menu “F-8 NOR/CH.” 3.Press and hold in the BAND(SET) key for 1/2 sec- ond. The radio is turned off automatically, and then switched on again afterwards. 4.Press and hold in t

20、he PWR( ) switch for 1/2 sec- ond to turn the radio off. 5.Press and hold in the V/M(MW) key while turning the radio on. The display will be show in the illus- tration at the right. 6.Press and hold in the PWR( ) switch for 1/2 sec- ond to turn the radio off. 7.Press and hold in the MHz(PRI) key and

21、 the Hyper Memory 5 key while turning the radio on. 8.Press the front panel keys in the following sequence. MHz(PRI) ? TONE(HM/RV) ?LOW(ACC) ? BAND(SET) ? V/M(MW) ? SCAN(SEL) ? S.SCH(ARTS) 9.Press and hold in the (L) key to cause “A-0 REF.xxH” to appear on the display, this signifies that the trans-

22、 ceiver is now in the “Alignment mode.” PLL Reference Frequency 1.Rotate the DIAL knob to set the display to “B4006”, then set the Transmit Power Level to “LOW” by press- ing the LOW(ACC) key repeatedly. 2.Press the BAND(SET) key while pressing and hold- ing in the (L) key, if needed, to set the Ali

23、gnment parameter to “A-0 REF.xxH”. 3.Press the PTT switch to activate the transmitter, and adjust the DIAL knob while pressing and holding the (L) key, if needed, so that the counter frequency reading is 435.050 MHz (100 Hz). RF Front-end Tuning 1.Connect the DC voltmeter to TP1010 on the MAIN Unit,

24、 then inject a 439.050 MHz signal at a level of +10 dB (with 1 kHz modulation 3.5 kHz deviation) from the RF Signal Generator. 2.Rotate the DIAL knob to set the display to “B4906”. 3.Press the BAND(SET) key while pressing and hold- ing the (L) key to set the Alignment parameter to “A-1 TUN.xxH”. 4.A

25、djust the DIAL knob while pressing and holding in the (L) key, if needed, so that the DC voltmeter reaches maximum deflection. The FT-7900R/Es RF Front-end has a broad bandwidth. 5.Press the BAND(SET) key, then rotate the DIAL knob to set the display to “B0106”. 6.Inject a 145.050 MHz signal at a le

26、vel of +10 dB (with 1 kHz modulation 3.5 kHz deviation) from the RF Signal Generator. 7.Adjust the DIAL knob while pressing and holding in the (L) key, if needed, so that the DC voltmeter reaches maximum deflection. As in the previous sec- tion, be sure to set the DIAL knob for the center of the ban

27、d prior to making this adjustment. MAIN UNIT TEST POINTS E-2 TP1010 FT-7900R/E Technical Supplement Alignment TX Power Output 1.Press the BAND(SET) key, then rotate the DIAL knob to set the display to “B5006”. Set the Transmit Power Level to “LOW” by pressing the LOW(ACC) key repeatedly. 2.Press the

28、 BAND(SET) key while pressing and hold- ing in the (L) key to set the Alignment parameter to “A-2 PWR.xxH.” 3.Press the PTT switch to activate the transmitter, and adjust the DIAL knob while pressing and holding in the (L) key, if needed, so that the wattmeter read- ing is 5 Watts (0.5 Watt). 4.Pres

29、s the LOW(ACC) key to increase the Transmit Power Level to “MID2”. 5.Press the PTT switch to activate the transmitter, and adjust the DIAL knob while pressing and holding in the (L) key, if needed, so that the wattmeter read- ing is 10 Watts (0.5 Watt). 6.Press the LOW(ACC) key to increase the Trans

30、mit Power Level to “MID1.” 7.Press the PTT switch to activate the transmitter, and adjust the DIAL knob while pressing and holding in the (L) key, if needed, so that the wattmeter read- ing is 20 Watts (0.5 Watt). 8.Press the LOW(ACC) key to increase the Transmit Power Level to “HIGH.” 9.Press the P

31、TT switch to activate the transmitter, and adjust the DIAL knob while pressing and holding in the (L) key, if needed, so that the wattmeter read- ing is 45 Watts (0.5 Watt). 10. Press the BAND(SET) key, then rotate the DIAL knob to set the display to “B0206”. Set the Transmit Power Level to “LOW” by

32、 pressing the LOW(ACC) key repeatedly. 11. Press the PTT switch to activate the transmitter, and adjust the DIAL knob while press and holding the (L) key, as needed, so that the wattmeter reading is 5 Watts (0.5 Watt). 12. Press the LOW(ACC) key to increase the Transmit Power Level to “MID2.” 13. Pr

33、ess the PTT switch to activate the transmitter, and adjust the DIAL knob while pressing and holding in the (L) key, if needed, so that the wattmeter read- ing is 10 Watts (0.5 Watt). 14. Press the LOW(ACC) key to increase the Transmit Power Level to “MID1.” 15. Press the PTT switch to activate the t

34、ransmitter, and adjust the DIAL knob while pressing and holding in the (L) key, if needed, so that the wattmeter read- ing is 20 Watts (0.5 Watt). 16. Press the LOW(ACC) key to increase the Transmit Power Level to “HIGH.” 17. Press the PTT switch to activate the transmitter, and adjust the DIAL knob

35、 while pressing and holding in the (L) key, if needed, so that the wattmeter read- ing is 50 Watts (0.5 Watt). TX Deviation 1.Press the BAND(SET) key, then rotate the DIAL knob to set the display to “B5006”. Set the Transmit Power Level to “LOW” by pressing the LOW(ACC) key repeatedly. 2.Press the B

36、AND(SET) key while pressing and hold- ing in the (L) key to set the Alignment parameter to “A-3 DEV.xxH.” 3.Inject a 1 kHz audio tone at a level of 80 mV (20 dBm) from the Audio Generator. 4.Press the PTT switch to activate the transmitter, and adjust the DIAL knob while pressing and holding in the

37、(L) key, if needed, so that the deviation meter reading is 4.5 kHz (0.2 kHz). 5.Press the BAND(SET) key, then rotate the DIAL knob to set the display to “B0206”. Set the Transmit Power Level to “LOW” by pressing the LOW(ACC) key repeatedly. 6.Press the PTT switch to activate the transmitter, and adj

38、ust the DIAL knob while pressing and holding in the (L) key, if needed, so that the deviation meter reading is 4.5 kHz (0.2 kHz). E-3 FT-7900R/E Technical Supplement DCS TX Deviation 1.Press the BAND(SET) key, then rotate the DIAL knob to set the display to “B5006”. Set the Transmit Power Level to “

39、LOW” by pressing the LOW(ACC) key repeatedly. 2.Activate the DCS with a “023” DCS code. 1)Press the TONE(REV) key until “DCS” appears on the display. 2)Press and hold in the BAND(SET) key for 1/2 second to enter the Set mode. 3)Rotate the DIAL knob to select Menu #9 (DCS.COD). 4)Press the BAND(SET)

40、key to enable adjustment of the selected Menu Item. 5)Rotate the DIAL knob to select “DCS.023”. 6)Press and hold in the BAND(SET) key for 1/2 second to save the DCS code. 3.Press the BAND(SET) key while pressing and hold- ing in the (L) key to set the Alignment parameter to “A-4 DSC.xxH.” 4.Press th

41、e PTT switch to activate the transmitter (with no microphone input), and adjust the DIAL knob while pressing and holding in the (L) key, if needed, so that the deviation meter reading is between 0.50 kHz and 0.60 kHz. 5.Press the BAND(SET) key, then rotate the DIAL knob to set the display to “B0206”

42、. Set the Transmit Power Level to “LOW” by pressing the LOW(ACC) key repeatedly. 6.Activate the DCS with a “023” DCS code. 1)Press the TONE(REV) key until “DCS” appears on the display. 2)Press and hold in the BAND(SET) key for 1/2 second to enter the Set mode. 3)Rotate the DIAL knob to select Menu #

43、9 (DCS.COD). 4)Press the BAND(SET) key to enable adjustment of the selected Menu Item. 5)Rotate the DIAL knob to select “DCS.023”. 6)Press and hold in the BAND(SET) key for 1/2 second to save the DCS code. 7.Press the PTT switch to activate the transmitter (with no microphone input), and adjust the

44、DIAL knob while pressing and holding in the (L) key, if needed, so that the deviation meter reading is between 0.50 kHz and 0.60 kHz. CTCSS TX Deviation 1.Press the BAND(SET) key, then rotate the DIAL knob to set the display to “B5006”. Set the Transmit Power Level to “LOW” by pressing the LOW(ACC)

45、key repeatedly. 2.Activate the CTCSS Encoder with a “100 Hz” tone. 1)Press the TONE(REV) key until “ENC DEC” ap- pears on the display. 2)Press and hold in the BAND(SET) key for 1/2 second to enter the Set mode. 3)Rotate the DIAL knob to select Menu #44 (TN FRQ). 4)Press the BAND(SET) key to enable a

46、djustment of the selected Menu Item. 5)Rotate the DIAL knob to select “100.0HZ”. 6)Press and hold in the BAND(SET) key for 1/2 second to save the CTCSS tone. 3.Press the BAND(SET) key while press and holding the (L) key to set the Alignment parameter to “A- 5 CTC.xxH.” 4.Press the PTT switch to acti

47、vate the transmitter (with no microphone input), and adjust the DIAL knob while pressing and holding in the (L) key, if needed, so that the deviation meter reading is between 0.65 kHz and 0.75 kHz. 5.Press the BAND(SET) key, then rotate the DIAL knob to set the display to “B0206”. Set the Transmit P

48、ower Level to “LOW” by pressing the LOW(ACC) key repeatedly. 6.Activate the CTCSS Encoder with a “100 Hz” tone. 1)Press the TONE(REV) key until “ENC DEC” ap- pears on the display. 2)Press and hold in the BAND(SET) key for 1/2 second to enter the Set mode. 3)Rotate the DIAL knob to select Menu #44 (T

49、N FRQ). 4)Press the BAND(SET) key to enable adjustment of the selected Menu Item. 5)Rotate the DIAL knob to select “100.0HZ”. 6)Press and hold in the BAND(SET) key for 1/2 second to save the CTCSS tone. 7.Press the PTT switch to activate the transmitter (with no microphone input), and adjust the DIAL knob while pressing and holding in the (L) key, if needed, so that the deviation meter reading is between 0.65 kHz and 0.75 kHz. Alignment E-4 FT-7900R/E Technical Supplement Center Meter Sensitivity 1.Press the BAND(SET) ke