Power Level Measurements Using the Selective Mode

6.POWER LEVEL MEASUREMENTS USING THE SELECTIVE MODE

6.1General - The most basic function of the HP3586 is to measure the power of signals on telephone lines using its selective measuring mode. This useful feature can also be used to do on the air measuring of radio signal strength or on the bench measuring output of electronic circuits such as oscillators and amplifiers.

For maximum accuracy the HP3586 has front panel selectable measuring ranges of 10db or 100db to look at only a portion of its total measuring range of +20dbm down to –100dbm. The 10db range will have a measurement resolution of .01db or better over its complete range. The 100db range will have a lower resolution of .1db over the upper 80db of is 100db range. When tuning a signal by looking at the strength of the signal on the analog meter it’s best to be in the 100db auto range. However, you must only use the 10db range for audio tuning of signals whose strength is under –60dbm. For high precision measurements it’s best to always select the 10db auto range.

By fixing the range by pressing [ENTRY] we can fix the range’s location. I only use the [ENTRY] button mode when using audio in the 10db range to tune a signal that is rapidly changing like a SSB station or measuring rapidly varying signals, but more on that later when we tune a SSB station. For the following section stay in the low distortion, 10db auto modes.

6.2Setup for Performing Power Measurements - Now let’s go through a typical example of measuring the power output of a typical electronic circuit. Assume we have a small crystal oscillator tuned to 14.020 MHz followed by a 12db 50 ohm unterminated attenuator pad in a RF sealed enclosure. We want to know its output power since it will be used in a test circuit to measure receiver dynamic range. We first connect the circuit through a short 50 ohm coax line to the 50 or 75 ohm input on the termination sub panel. Since the circuit requires 50 ohm termination we must provide this at the HP3586. On a C version do this by pressing [50 ohm] with the shift button light off to select a 50 ohm terminated input. On an A or B versions things are more complicated. We must add a 50 ohm resistor at the output but only if the frequency is very low and the line to the instrument’s connector is very short. It would be best to have the resistor in an adapter across the 75ohm input. This will now provide a 50 ohm terminated input for the oscillator circuit. In Appendix C I show the circuit I use to provide a 50 ohm termination for my HP3586B.

6.2Setting Input Termination Impedance - Make sure the display is reading in dbm by confirming the dbm annunciator on the level display is on, if it isn’t press [dbm] under units on the measurements/entry sub panel. We still have another little problem when using an A or B versions instrument with a 50 ohm input, it does all its power calculations based on the 75 ohm resistance it was designed for. But since the HP3586 measures power in dbm, we can add a offset to the level measurement to correct the data to power across a 50 ohm load. This offset can be calculated by:

OFFSET = 10 log (R1/75) = -1.76db R1 will equal 50 for our 50 ohm load termination resistor

Enter the offset by pressing [OFFSET] on the entry panel, and then enter the value, 1.76, using the number keyboard, press [-db] for it’s sign and units, and then press [MEAS CONT] to return to the measurement mode. Last activate the offset feature by pressing [OFFSET] on the measurement/entry panel. When we first pressed [OFFSET] on the entry sub panel the value in its offset register will be displayed and then when we enter our new offset it will overwrite the old offset to confirm our entry. Now our display readings will be in dbm referenced to a 50 ohm load as long as the light on the offset button is on. Also an O annunciator behind the dbm annunciator will turn on indicating the readings are offset by the value in the offset register.

6.3Performing Power Measurements - Now tune the frequency of the HP3586 to that of the oscillator’s output by any of the earlier described methods. Once we have found the oscillator’s frequency by hearing it’s beat tone in the SSB audio speaker, or seeing an upward deflection of the analog level meter

B, 3586A, C specifications

The HP C3586A and C3586B tape drives are notable components in the realm of data storage solutions, primarily designed for enterprise-class environments. These SCSI (Small Computer System Interface) tape drives are regarded for their efficiency, reliability, and capacity to meet the growing demands of data backup and archival processes in businesses.

The C3586A model utilizes the DAT (Digital Audio Tape) technology, which allows it to deliver high performance and high data density. It features a native capacity of 2.3 GB per cartridge, which can be extended to 4.6 GB with the use of compression. This is particularly advantageous for businesses requiring significant amounts of data storage without the necessity for multiple tapes. The transfer rate is rated at up to 12 MB per minute, which ensures quick backups and restores, minimizing the operational downtime.

In terms of data integrity and security, both models incorporate advanced error correction techniques to guarantee that data remains pristine and intact throughout the storage duration. They are designed to work seamlessly with a variety of operating systems and backup applications, enhancing compatibility and user convenience.

The HP C3586B, on the other hand, offers similar foundational technologies but with enhanced features. It supports higher capacity tapes and is engineered to work seamlessly in high-performance environments. With the integration of SCSI-2 interfacing, users can expect faster data transfer rates, which is critical for organizations dealing with large volumes of data.

Another key aspect of both models is their rugged design, which provides durability and reliability needed for long-term storage solutions. The drives are built to withstand extended usage, which makes them a cost-effective choice for businesses looking to invest in dependable data storage systems.

Furthermore, these drives come with a user-friendly interface and straightforward maintenance. This allows IT personnel to handle backups with ease while keeping the workflow uninterrupted.

In summary, the HP C3586A and C3586B tape drives epitomize the union of technology, usability, and dependability. Their robust features, including high data capacity, fast transfer rates, and durable construction, make them a formidable choice for enterprises seeking efficient data backup and archival solutions in the ever-evolving digital landscape.