Hickok 6000A Tube Tester Restoration

The Hickok 6000A is an update of the model 600 and added a removeable tube socket plate or "island" to make it easier to replace worn out sockets. It also tests transistors and it's one of the last models Hickok released.

​A simple Internet search for a Hickok 6000 turns up a lot of good info, especially from the site tubesound.com, so no need for me to repeat the calibration instructions here. The operators manual, calibration instructions, schematic, and tube data are all freely available.
This tester is missing its top cover, but is otherwise complete. I plan to make a replacement top when time allows.

The front panel is in good condition, although it needs cleaning, and there are no missing parts or knobs.
A closeup of the meter. The tester can measure mutual conductance (Gm) or provide a quality measurement on the English reading scale. The tester does not have a Gm range selector switch like more expensive Hickoks. The range is selected by setting the Shunt control to predetermined values marked on the dial for the desired range.
The tube socket island on this tester dispenses with the older large 4-pin through 7-pin sockets to make room for newer bases. This plate has Octal, Loctal, 7-pin minature and 9-pin Noval/10-pin Noval+1 minatures, 9-pin Novar, 12-pin Compactron (Duodecar), and 5 and 7-pin Nuvistor sockets. Plus in the center of the Novar socket is a lamp test socket.

I had a question from a reader about using the tube socket island from the model 6000, which has the older 4, 5, 6 and 7-pin antique tube sockets, on the 6000A. The problem is the 6000 uses an 11-pin socket and plug for the island, and the 6000A uses a 12-pin socket and plug. So they are not interchangeable. I wasn't able to reply to the reader's email, but it was a good question so I put the answer here.
The underside of the socket island. The island is just sockets, wiring and ferrite beads. It plugs into a 12-pin socket inside the tester.
The inside is in good shape, just a little surface oxidation on a few metal parts. The dual 150Ω Shunt pots, the 3KΩ Bias pot, and the meter movement all checked OK in preliminary tests.
This little piece of the history of this tester is glued to the bottom of the case. It's a shipping label returning the tester to Hickok, presumably to be serviced.
The tester was in pretty good condition overall. Only two electronic components were replaced, plus the power cord and a few screws.

I did spend an hour or two cleaning all the switches, pots and sockets, as well as cleaning and polishing the front panel, knobs, hardware, and the oxidized surfaces. I accidentally found an easy way to clean the metal that had "white rust": Meguiers Cleaner and Wax easily removed the oxidation.

​I also noticed while checking the 10MΩ resistors on the neon shorts lamp assembly, and getting some low readings, that at least some of the exposed leads from the NE-2 lamps were touching the front panel and shorting. I pulled the lamp assembly back and placed a piece of electrical tape on the panel to fix the issue.
It's all cleaned up, both rectifier tubes tested high and with reasonably good balance, and the big yellow Astron 0.5uF capacitor tested good (it must be a film capacitor). Only the meter's electrolytic capacitor and a 220Ω resistor were replaced.

​Calibration was a breeze. I had to adjust the line setting, but every other calibration was still in spec. I tested a 6L6 and the Gm was very close to the reading on my TV-3.

​I'm surprised a tester I bought online would actually be in this good of an operating condition. Usually there are undisclosed issues with items I find in online auctions.
The front panel has a scratch in the lower right corner and the anodizing has suffered a bit along the top panel edge, but otherwise it cleaned up well.

All that's left is to make a new top for the case, but it will have to wait on warmer weather so I can get my tools and work areas better organized after our move.
Page created 11/15/2021
Last edited 3/30/2022