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> Hp 1725A 275MHZ 2-channel analog oscilloscope working
Hp 1725A 275MHZ 2-channel analog oscilloscope working
This is an HP Model 1725A 275MHz Oscilloscope, S/N 1915A 02792. The HP 1725A is an all-analog, moderate weight (30lbs.), dual-trace, portable oscilloscope. Because of the all-analog signal processing circuitry, it is useful for examining complex signal waveforms without concern of signal contamination caused by sampling artifacts; as sometimes experienced when using digital oscilloscopes. The HP 1725A originally cost over $4,500.
Because there are no buried menus to navigate through, the scope is much easier to use than newer, digital scopes. If you haven’t used this scope in a few months, it will be an easy relearning curve because of the user-friendly, intuitive controls. Everything you need to adjust is simply available at your finger tips; a feature often sought after and found in older test equipment manufactured in the 1970-80’s.
The HP 1725A’s dual trace scope’s primary features include 275MHz bandwidth, 10mV/division vertical sensitivity, 10nS/division sweep rate (1ns/division with x10 magnifier switch), delayed sweep measurement, autofocus circuitry, 1 Meg Ohm and 50 Ohm input impedance. Included is a probe bag on the case top. No cable or probe accessories included.
This HP 1725A scope has been tested for basic signal measurement functions. The delayed sweep portion appears to be operating properly and the scope passed a burn-in period for twenty hours. The Time/Division switch contacts were cleaned with DeoxIT. The rear, plastic feet for standing up the oscilloscope are broken, as typically occurs to all HP 1700 series scopes. These feet become very brittle over the years and will shatter into small pieces. Four, 3/4" diameter by 1-1/2" lengths of wooden dowel could be used to replace the plastic feet.
Because of the multitude combination of switch position settings and functions, I can not guarantee everything is perfect with this scope.
Overall physical condition is good. Reason I’m selling this HP 1725A is because I’m reducing my test equipment inventory used for personal use.
Prior to delivery, a personal check must have cleared.
The backside, lower left connections are Interval Out (Volts) and Ground. The backside, lower right connections are Probe Power. Option 3 label is on the backside.
To compare the HP 1725A to the Tek 485, my personal preference is the HP 1725A. Recently, I've repaired both the 1725A and the 485 scopes and the 1725A is clearly a much easier scope to repair. The 1725A has a much more "open" chassis interior while the 485 is surrounded by circuit boards, making the internal sweep board very difficult to access. Every 485 I've worked on has had loose hardware inside; falling out after a lot of jiggling. The 485 uses a switching power supply which adds complexity versus the 1725A's typical power transformer / bridge rectifier topology common to most equipment. The 485's scope controls are better layed out and the CRT screen is larger for easier viewing. Because the 485 scope is a smaller, higher density design, it probably has less reliability because of thermal issues. It does have a fan, but doesn't provide adequate cooling, in my opinion.
