The first thing the Hickok adventurer needs to know is that most postwar Hickok tube testers were 500-series. Beyond that the model number are seemingly randomly dispersed with a 546 being an earlier model than the 533 and the 539 lasting longer than any of them while the 560 was one of the earliest and the the 580 was the last introduced and is found in the last section
As with most immediate postwar products, the first units were essentially carryovers from the was while the engineers were busy designing new and better products using lessons learned the hard way. In keeping with this, the first commecial tube testers greatly resembled the 510X and I-177 and are exemplified by the 530B.This has the same five basic knob settings as the 510 but now has sockets for minature tubes for which previous models required an adapter.
The small meter to the upper left measures the line voltage which was not nearly as stable as it is now. This ac voltage meter was to be a hallmark of "One Step Up" systems such as the 536 and 539.
Note that the 530 was incrementally followed by the 540 (1943), 550(X) (1944), and 560 (1945) which were essentially the same except for addition of subminature sockets and VOM function on the X model.Evidently Hickok planned on incrementing model numbers by 10 at this point but that thought stopped with the 560 - there was no 570 and the 580 is a completely different tester..
Probably the first new postwar design was the shortlived 532 of 1947. While somewhat flawed in execution, the basic package and design persisted for well over twenty years as a rugged, standard benchtop machine. The major complaint about the 532 (and first 533 and 539) was the windowed knob settings which were more difficult to move quicly than the later surface ledgends.
Concurrent to the 532 was the smaller 546 series which is probably a commercial version of the Navy TV-3 tester shown is the representative 547A, a slightly later model including soctes for the Minar and Inline subminature tubes. The model 548 also included VOM capability.
My favorite of the 1950's Hickocks is the 533 series. Ostensibly portable but really better suited as a benchtop tester, the spacious layout makes for easy operation. There were actually three distinct types of 533(A) produced - the portable model with case and cover, a benchtop with metal case, and the distinctive "Display Meter" with its extra large meter (also used on one of the Hickok VOMs) so that an owner could see his tube reading bad from across the counter.
The 534 is essentially the same but with the addition of VOM function (breaking with the previous use of a X to mark combination testers. The 536 is a 533 with the addition of a separate line voltage meter.The 538 is a similar companion to the 536 with VOM.
Probably the most sought after series is the 539. While its merits may be debated (it used the same basic circuit as the 532-533-534-536 and the additional meters are not necessarilt fine enough to add value - seting a .5v grid bias for a 1L6 requires a DVM. It was probably the longest lived tester made by Hickok spanning from 1948 through 1975. Billed as a "laboratory quality" tester, the 539/A/B/C series did provide for measurement of plate current using a separate DCMA meter which is difficult on most other testers.
Perhaps the most popular of the 539s is the C model which was the last in the line and the most versitile. Note also the lack of a Good-?-Bad scale or an English potentiometer, the 539 series reads only in GMhos. The two binding posts on the top right are for a plate current meter.
The other introduction in the early fifties was the replacement of the 546 series with the 600 series (600, 605 with VOM, A revisions). There were considerably smaller than the 530 series (not much larger than a portable typewriter) and designed for the serviceman to carry to the site in his truck.
Finally, the fifties saw Hickok's short-livedattempt at a true laboratory quality tube tester, the 700. Definately non-portable. Nine meters covered just about every function conceivable however a separate accessory power supply was required for meaningful testing and it lacked sufficient regulation to keep from changing the screen voltage when the plate was adjusted. The single metered RCA WT-100A had essentially the same capability and regulated power supplies.