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SIGNAL CONNECTION SELECTOR GUIDE R F Oscillators (transmit or receive) 1. Always replace fuses with correct value. Improper fuse(s) voids warranty. 2. Refer to specifications for maximum 1 Meg input and 50 Ohm input voltage. Most electronics technicians are finding more and more need for a high accuracy digital frequency counter. Communications shops and commercial broadcast stations need both a wide frequency range and high ac- curacy in their frequency counters to meet the FCC requirements for accurate measurements of various transmitter frequencies. Service technicians find that a frequency counter is a valuable piece of test equipment for troubleshooting the digital circuits found in UHF and VHF television tuners and the modem digital FM receivers. Other applications (like video tape recorder, medical equipment, and industrial maintenance) require frequency counters for many tests and adjustments. The FC51 offers both a wide input frequency range and high accuracy for work in any of these applications where the signal is between 10 Hz and 1000 MHz. Extra features, like all pushbutton operation and automatic selection of prescalers, are normally found only on frequency counters costing much more than the FC51. A review of the following section will cover these special features and explain how they simplify the operation of the FC51 and offer versatility not usually found in a frequency counter in this price range. The FC51 1 GHz Frequency Counter allows direct readings of all frequencies from 10 Hz through 1 GHz with accuracies that exceed the FCC specifications for all communications work up to 1 GHz. The metal case of the FC51, along with internal RF shielding, provides interference-free measurements in practically any type of RF field. The large (.5") 8-diiit display allows direct readings with automatic placement of the decimal. Special indicator lights show whether the counter is measuring "Hz", or "MHz", and an overflow indicator indicates that a reading requires more than the full 8 digits of readout. The FC51 features large, comfort-sized push buttons for ease of operation. These buttons select the de- sired input jack, read rate, and frequency range. Three inputs are available. The first is a fuse-protected 50 Ohm termination for proper reading of high frequency signals. The 50 Ohm termination prevents cable ringing which could cause inaccurate readings. The second input is a high sensitivity input with 1 Meg-ohm loading to allow direct connections to lower frequency circuits. This input is controlled by a front- panel sensitivity control which allows many noisy signals to be measured which normally will produce erratic readings on a high sensitivity counter. The sensitivities of both of these inputs have been de- signed for fast signal tracing in most applications. If additional sensitivity is required for special applications, the optional WBA52 1 MHz through 1 GHz Wideband Amplifier provides an additional 30 dB of input gain. The WBA52 is powered from the accessory jack on the front of the FC51. The third input is Sencore's exclusive crystal check which allows any crystal to be tested by simply inserting it into the special front panel test socket. Two read rates give a choice of fast updates or maxi- mum resolution, depending on the type of signal you want to measure. Four different frequency range but- tons provide the best resolution for any measurement. Two built-in prescalers extend both the high and low frequency capabilities of the FC51. The first prescaler allows frequencies from 100 MHz to 1 GHz to be measured and the second "audio prescaler" pro- vides additional digits of resolution when measuring frequencies below 20 KHz. Both prescaled options provide automatic decimal placement for direct readings. The high accuracy time base oscillator is built into a proportionally-controlled oven to assure the highest accuracy possible over a wide range of ambient temperatures. The entire oven and oscillator is contained in a single plug-in module to allow the option of ex- changing the module with one that is freshly calibrated so that it is not necessary to return the entire counter for accuracy calibration. ' Finally, the FC51 offers a choice of 110-120 V AC line operation or 12 VDC operation for versatility of use in bench or portable testing. Input connections are made with the supplied counter probe, pickup loop or adjustable antenna. 50 Ohm VSWR: Lower than 2.5:1 through 1 - 20 MHz Fundamental Frequency (Overtone crystals read at approximately fundamental frequency.) ..:!:.. Time base accuracy +- 1 digit TIME BASE (replaceable module) Crystal Frequency: 10 MHz-proportional oven- controlled Stability: .2:. 0.01 ppm (.000001%) Temperature Stability: 0.5 ppm (.00005%), 0-40° C. Ambient after 10 minute warm-up Maximum aging: 2 ppm/year Time base output available through rear panel BNC jack. Recommended recalibration interval: 1 year for FCC tolerances below 800 MHz, 6 months for frequencies above 800 MHz. MAXIMUM RESOLUTION 10 - 500 Hz READ RATES (gate times) 1 second or .1 second Pushbutton selected. 25 m V average when sensitivity control is at maximum - continuously variable to cut-off (See response curve.) 5 Volts RF, fuse-protected 100 Volts DC max. DISPLAY: 8 digit, 0.5" LED, auto decimal, overflow, "Hz" and "MHz" indicators. SIZE: 5.5" x 7.83" x 9" HWD (14 cm x 19.9 x 22.9 cm) POWER: 105-130 VAC, 50/60 Hz, 45 W max. (220 V AC conversion available) 12 VDC, 2.2 Amps maximum FUSE REQUIREMENTS: 1/8 Amp RF fuse for 50 Ohm input, 2 spare fuses included on P.C. board. 3 Amp, 3AG Fast blow for 12 VDC leads. One spare fuse included. AC LINE: Transformer internally fused. ACCESSORY OUTPUT VOLTAGE: 9-12 VDC through the front panel jack to power WBA52 1 GHz Amplifier. Supplied: 39G112 Direct/isolated Counter Probe 39G111 Fused DC Supply Lead 39G138 RF Pick-up Loop and extension Optional: WBA52 1 GHz Wide band Amplifier Specifications subject to change without notice. Above Picture with a 2.097152 MHZ Crystal as input Above picture the FC-51 and SC-3100 are fed a 7 HZ square wave signal Above a 100MHZ signal is applied to the 50 OHM input Above a 1GHZ Signal is applied to both FC-51 Above the SC-3100 is fed the time base output from the FC-51 The Sencore FC-51 is used but in good condition all inputs are functional and the over all cosmetically in good condition Manual included on disk in PDF format (We do not proofread any ads submitted by members) |
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