|An impressive piece of HP hardware when it came out in 1980 (or thereabout) and sold for about $11,000 per unit (in 2014 dollars, that would be $31,250), and even more impressive at about $275 today for a good working unit on Ebay.|
There are actually three versions: A, B, and C and several options for each. The best version for ham radio is the 3586A with Option 001. (The crystal oven option is also nice, but somewhat rare.) The A model with option 001 model gives you the greatest number of functions that are applicable to ham radio and provides a 75 ohm BNC input on the front panel. The 75 ohm input (on the 3586A with option 001) is no problem because you just use a T-connector to attach a 50 ohm dummy load, along with the 50 ohm coax from the device that you want to measure, and set the instrument input impedance to 10,000 ohms using the front panel switch. In this way, the input impedance ends up being about 49.75 ohms, which is fine for nearly any use. You'll also need to set an offset from the front panel to cause the dbm readings to be correct for 50 ohms.
The C model gives you a 50 ohm BNC (instead of 75 ohms) on the front panel, but has less function overall that the A or the B models.
These units have a NiCad battery on the power supply board that maintains the settings when the unit is powered off. The battery will surely have leaked by now if it hasn't been replaced by a previous owner. In some cases, the leakage may have damaged the power supply board. When you are looking at buying one of these units, ask the seller if the battery has been removed. If it hasn't been removed, ask him to pull out the power supply board and check for leakage and damage to the power supply board. If there is leakage and the unit is working, it can be saved from further damage by removing the battery, cleaning the leaked material from the board, and then installing a new NiCad battery. Or better yet, it's easy to route a pair of wires to the back of the unit and mount a battery pack there instead. A 2.5V, 500 mA cordless phone NiCad pack will work fine.
This is an old piece of equipment but it is built to quality standards that are virtually unmatched by any other electronic gear. (Disregarding the NiCad leakage problem, of course.) Agilent has the user manual and the service manuals on their web site. Other web sites, which can be located by using Google, have additional documents. The manuals are very clear (as long as you have some background in electronics) and go into great detail about how to calibrate the unit and service the entire unit down the component level. The unit has a number of built-in diagnostic functions, all of which are described in the service manuals. It is possible to do a good (although not exhaustive) evaluation by running through the tests described in the service manuals (mainly Volume 1) without using any external test equipment.
Some of the uses of this unit are:
1. Calibrate your frequency counter to within 1 Hz. -- even if you get a 3586 without the oven feature, since it can use WWV as the frequency reference, or a local radio station as the frequency reference if the local radio station is locked to the GPS timing system or some other NIST reference. (Nowadays, modern AM radio stations are on frequency within 5 Hz, and often better.)
2. Measure amplitude of signals to very precise levels at various bandwidths.
3. Act as a signal generator from 50 Hz to 32.5 Mhz.
An excellent reference that is targeted to ham radio use of the unit was written by Bill Feldmann, N6PY (SK). It can be downloaded from:
If you have any questions about this product or want to share information, please feel free to contact me directly.