This article will discuss repair and calibration of the Heathkit TC-2 tube checker. High voltages are present, repairs should only be attempted by a qualified technician. Copyrighted, all rights reserved.

A new SS9 socket saver has also been installed, and new Top Cap assembly has been installed.

(Heathkit TC-2 testing Arcturus Blue #127 detector tube)

Introduction

The Heathkit TC-2 was a self-assembled tube tester kit offered by the Heath Company. It was popular among servicemen because they could buy a “name-brand” tester and save money by building the kit themselves. Since the TC-2 is fundamentally the same as the Eico 625, Triplett 3413, and Knight 600/600A, which was the subject of my last repair-and-calibration article here on my website, I will not reiterate what was discussed in that article, and instead will focus on the minor differences between the TC-2 and the Knight 600. (Click HERE to read the previous article.)

Differences

The following minor differences exist between these models, and they need to be addressed when rebuilding and calibrating the TC-2:

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This article will discuss repair and calibration of the Knight 600 tube tester. High voltages are present, repairs should only be attempted by a qualified technician. Copyrighted, all rights reserved.

(Knight 600 testing Sovtek 5881/6L6 audio tube)

Introduction

The Knight 600 series (600, 600A, 600B) was a self-assembled tube tester kit offered by Allied Radio Corporation. The copyright date of the Knight 600 manual is 1955. This tester, along with its brothers Eico 625, Triplett 3413, and Heathkit TC1/TC2, was popular among servicemen because they could buy a “name-brand” tester and save money by building the kit themselves.

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I have updated my article entitled “Rebuild & Calibration of Jackson 648A” to discuss how to eliminate the 1S5 tube from models 648 and 648A and upgrade to solid-state circuitry.

Newer versions of the “648″ (648R, 648S, etc…) use a solid-state circuit instead of a 1S5 tube. The benefit of the solid-state circuit is that the tester calibration should remain accurate much longer. If you do not mind checking your calibration on a regular basis, there is no need to perform this upgrade. It is more appropriate for power users.

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This article will discuss repair and calibration of the Jackson 561 tube tester. High voltages are present, repairs should only be attempted by a qualified technician. Copyrighted, all rights reserved.

Also, the exact Jackson 561 that is the subject of this article is for sale [SOLD], rebuilt and calibrated as discussed below.

Introduction

The Jackson 561 appears to be a rare model. Very little documentation exists. In my 19 years in the hobby, I have only seen one other example. When I had the opportunity to buy this one, I jumped at the chance.

The model 561 is a combination of the Jackson 634 and the 648. Photo below shows Jackson 561 (left); Jackson 648A (right).

If the 634 and 648 mated, the 561 would be its offspring. It shares the following characteristics from the 648: (a) the same meter, (b) variable leakage control, (c) color scheme, and (d) case design. From the 634, it shares (a) the same test method (which Jackson calls “Dynamic Output”), (b) Shorts Test control, (c) lack of a Noise test, and (d) function control layout. In fact, the 634 tube setup chart can be used (with slight modification) with the 561, as explained later.

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This article explains a more professional method to “free-play” a Rockola Princess Jukebox (model 1493). This theory can be adapted to many other jukeboxes, including other brands such as 1950s Seeburgs.

This method will: (1) not require any freeplay button, (2) prevent the Lock Bar Solenoid from energizing until the person begins selecting a song, and (3) keep the Select Light illuminated. Benefits: eliminates Solenoid noise during machine operation and standby, eliminates unnecessary solenoid wear, and increases usability and enjoyment of the jukebox.

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If you appreciate vintage tube test gear, you will enjoy this 1940 vintage Jackson 634 Tube Tester. It is an excellent choice for anyone looking for a quality, well-built, tester that can test the VERY OLD tubes, such as #50, 01A, 1V, #10, 2A3, #15, #19, HY113, HY115, HY125, #26, #45, 71-A, #83, etc. [SOLD]

This article is also relevant to Jackson 637 tester, which is same as model 634 tester with additional integrated multimeter functionality (volts and ohms testing).

(Jackson 634 testing Cunningham CX-350 Globe #50 Triode tube)

What is really “cool” about this tester is its very small size. Measuring only 8.5 x 8.5 x 6 inches and weighing 9 lbs, this unit packs a big punch in a small size!

This tester has been in my personal collection since 1990, and it is the oldest tester in my collection (except for a Supreme 550 Radio Tester from 1936, which also has some basic tube testing capability).

Jackson 634 - 637 modernization bulletin. Click to enlarge.

This tester is so old that it did NOT come with a 9-pin-miniature socket installed — that was too modern!

(Article UPDATE, Nov 3, 2008): I found an original Jackson modernization bulletin, and the Jackson 634 and 637 testers were released in 1939. All 1939 models were sold without the 9-pin-miniature socket installed. The 1940 models were already modernized at the factory.

I have installed a new 9-pin-miniature socket, and will teach you how to “modernize” your 1939 vintage Jackson 634 also. (Jackson sockets are wired unique, and do not correspond to the 1-to-1, 2-to-2, wiring that many testers employ).

Service information and many additional photos are as follows…

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This article will discuss my method of professionally installing a socket saver into the socket panel of a Hickok 6000 / 6000A / 6005 tube tester, and is designed so that (1) you cannot even see that a socket saver is installed, (2) the case lid will close normally, and (3) the socket saver is easily replaceable when it wears out.

The Hickok 6000-series of tube testers use a plug-in socket panel instead of individual sockets affixed to the chassis. The socket panel protrudes upward, and there is no extra room between the socket panel and the case lid. Therefore, traditional installation of a socket saver (plugging it into an existing socket) is unacceptable for these testers because the case lid will not close.

Fortunately, if you are willing put forth effort, you can have your cake and eat it too! This project will demonstrate a 9-pin miniature socket saver installation, but the process can be adapted for other sockets.

When you are finished, here is what you will accomplish:

Photo above shows Hickok 6000 after my method of professionally installing the socket saver. It is impossible to see that a socket saver is even installed!

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This article discusses the B&K 707 Dyna-Jet Dynamic Mutual Conductance tube tester, including repair and calibration. Much of this discussion is also relevant to the B&K 700 (the 700 is almost identical) and the B&K 650.

The B&K 707 tube tester dates from the late 1960s into the 1970s. My manual is stamped August 1969, and a modern tube data setup chart dates 1978.

First of all, a brief explanation of the circuitry of this tester is necessary. Is this a Mutual Conductance tube tester? Well, yes and no.

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For Sale: $2,400. Shopped out and works fabulous.

Kenwood KT-917 Pulse Count Detector FM tuner

Some people believe that the Kenwood KT-917 is the finest FM tuner that was ever manufactured. This is truly the cream of the crop. Pulse Count Detector, high build quality, Made in Japan.

A fellow in my community decided to trade-in this KT-917 for some quality tube audio gear. He had his eye on some nice tube gear in my collection, and his KT-917 needed repaired for quite a long time. Since he was currently more enthused with rediscovering his music tastes (vinyl and CD), he decided to forego repair and trade for tube gear.

Repairing the KT-917 was straightforward. The tuner was not decoding, and some quick troubleshooting revealed a defective MC1496 IC, which is a Balanced Modulator-Demodulator designed for FM detection.

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Here is a rare tube — a Marathon MX-280 Globe #80 rectifier tube featuring MESH PLATES construction!  Not only that, but each section tests very strong Emission, comparable to an NOS #80!

In 18 years of collecting, I do not remember ever seeing another Mesh Plates #80 tube.  Look at that Glow!  You can see right through the Mesh Plates into the filament!  This would be a beautiful tube for any serious collector.  You could really impress your friends with this one.

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