25B/28B Frequency Counter

The 25B and 28B CW frequency counters are ideal for communications applications. These portable, rugged, all-die-cast-body units combine durability and small size with high-performance features typically found in larger, benchtop instruments. The 25B measures CW, FM, AM as well as complex modulated frequencies from 10 to 20 GHz, and the 28B extends the range up to 26.5 GHz.

Unsurpassed Burnout Protection

Typically found in high performance spectrum analyzers; only Phase Matrix counters feature a YIG-preselected microwave input, which provides unparralled burnout protection, FM tolerance and frequency selectivity. The YIG preselector works like a tunable bandpass filter, preventing harmonics and other out-of-band spurious signals from interfering with measurement of the desired signal. It also protects the counter from accidental application of high level signals (up to 200 watts peak), reducing downtime and the associated high cost of repairing damaged microwave circuitry.

Selective Frequency and Power Measurements

With a single connection, the 25B and 28B can simultaneously measure and display the input signals frequency and power level in the microwave band, eliminating the need for a seperate microwave power meter. Within the 25MHz bandwidth of the YIG-preselector, only the selected signals frequency and power level are measured. Signals to be analyzed are selected by keystroke entry of an individual center frequency, or search a range between a low and high frquency limit. This signal selectivity, combined with 20MHz of FM tolerance at all rates up to 10MHz, allows the 25B and the 28B to make accurate frequency and power level measurements even while the input signal is carrying traffic; there is no need to take the transmitter, or adjacent channels, off the air for routine checks.

Easy to Read and Operate

Frequency and Power measurements can be made to a resolution of 1Hz and 0.1 dB, respectively. Easy keystroke entry of frequency and power offsets allows systemunder-test frequency translation devices and cable losses to be compensated for in the displayed measurement results.

Portable, Rugged Construction

The small size of the 25B and 28B, along with their convenient carrying handle and protective front cover, makes these units perfect for portable field maintence applications. Their rugged, durable construction will provide years of reliable operation under the roughest conditions. The units even feature an optional fast warm-up ovenized time base (Option 05) that delivers a reference frquency within 5×10-9 of the final value within 10 minutes of power-up. This ensures the best possible accuracy with minimum warm-up time delay.

Proven Reliability

The design of the 25B and 28B is based on the Phase Matrix / EIP 545B CW microwave frequency counter. This counter has become the standard in reliability, achieving over 26,000 hours (12.5 years) of field-proven MTBF. The high performance, economy and compact configuration of the 25B and 28B make them the ideal choice for your communications applications in the field and on the bench.