Hewlett Packard 4800a Vector Impedance Meter - Overhauled And Calibrated

US $500.00

Calgary, Alberta, Canada
Jan 29th

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Hewlett Packard 4800A Vector Impedance Meter - Overhauled and Calibrated http://www.pearl-hifi.com/22_eBay_Sales_Current/4800A/Front_Back.jpg Hewlett Packard 4800A Vector Impedance Meter - Overhauled and Calibrated This 4800A is ex-U of Calgary is complete. It is supplied with an original copy of the manual that contains all the manual changes and as seen below, an original HP Vector Impedance Calculator slide rule is provided. The rarely seen input terminal shield is supplied, as are two spare parts essential to certain repairs that might be needed years hence. And there is of course a power cord On the AGC board, and seen in the pic below, located in the oscillator enclosure is a light-dependent resistor assy in a light-tight enclosure where the photocell is illuminated by a small, incandescent grain-of-wheat bulb -- which fails. The LDR assy, a Clairex part, is simply unavailable so we determined that the g-o-w bulb was a 6V part and scouring eBay turned up a replacement that works perfectly; a spare is included. Also included, although not presently needed, is an HP-specific thermocouple assy that also uses g-o-w bulbs. By pure luck there happened to be some these, NOS, for sale on eBay so we bought one and it is included as well, see below . . . While spending three full days re-doing this piece we also cleaned all the rotary switches, with Q-tips wetted with a good grade of contact cleaner; a proper cleaning. As seen in the pane of measurement pics below, the unit meets spec and although not shown does so across its entire 5Hz to 550kHz frequency range and its 10 ohm to 10 megohm FSD impedance range. Available for download here is HP Application Note 86, "Using the Vector Impedance Meters," which covers both the 4800A and the 4815A RF Vector Impedance Meter which measures thru the 500kHz to 108MHz frequency range. In all then, a perfectly functioning, fully kitted out example of the marque that meets cal' and is in immaculate condition from end to end. The unit will be superbly packed, thereby ensuring intact survival of UPS' penchant for throwing goods off at least one shipping dock between origin and destination. Above is the AGC board fitted with the required new LDR assembly. The original photocell is toward the bottom while the grain-of-wheat light bulb is seen fitted onto the board by its white leads. The new light-tight enclosure was carefully fabricated from several, built-up layers of heatshrink The tan colored cylinder seen above right is the original, incandescently heated thermocouple assembly while to the lower left is seen the NOS, original HP replacement part supplied. For anyone concerned with replacement semiconductor availability, 90% of the transistors are garden-variety, unselected 2N23904s and '06s while the part nos. of the remaining devices are clearly indicated The "L/C" line on the frequency dial is the 1.592 frequency multiplier used when it is desired to read unknown values of 'L' and 'C' directly from the 'Z Magnitude' meter, see below. ======================================= ANY SHIPPING COST SHOWN BY eBAY IS A BEST ESTIMATE ONLY AND IS SUBJECT TO UPDATE ONCE WE KNOW YOUR ADDRESS, SHIPPING, TRACKING AND INSURANCE REQUIREMENTS. Shipping is at cost plus $US10.00 for packing materials International bidders welcome. Payment by PayPal only please. ====================== .