Author Archive

Posted on April 7, 2018 - by DLandon

Weston 981 Type 3 Tube Tester

This is a Weston 981 Mutual Conductance tube tester that was not functional when I received it for calibration.  One of the electrolytic capacitors was shorted and blew a fuse when the line adjust was turned up.  This tube tester uses selenium rectifiers instead of vacuum tube rectifiers.  The selenium rectifiers should not be replaced with solid state diodes because this affects the calibration of the tube tester.  The tester was designed for the voltage drop across the selenium rectifier and is difficult to replicate with solid state diodes.  Luckily the selenium rectifier was not affected by the shorted capacitor.  The line adjust was pot was also bad and had to be replaced.  The line adjust pots in the old tube testers are wire wound pots with around 25 watt handling capability.  They are still available in NOS or as new units.

This tube tester is a mutual conductance tube tester and provides good quality testing of vacuum tubes.

Posted on April 7, 2018 - by DLandon

Hickok 752A Tube Tester

This is a Hickok 752A that I restored electronically and calibrated.  This is a very nice tester and is very clean.  The 752A has the ability to test a multi section tube without having to re-do the settings for the second section.  You just make the settings according to the tube chart, test the first section, then select the second section and make the tests in the second section.

The tester came to me with a blown Bias fuse so tubes could not be tested.  The Bias fuse is used to protect the Bias potentiometer if incorrect settings are made for the tube being tested.  When it is blown, the Bias voltage is not applied to the tube.

The 752A has the ability to test the older and newer tubes, including compactrons.

Posted on April 1, 2017 - by DLandon

Hickok 539C with Digital Meters

This 539C was not working because all three meters were bad.  The meters were replaced with digital meter replacements and the tube tester was calibrated.  Analog meters in tube testers that are 50 plus years old will have problems.  If they are working, they are most likely no longer calibrated and readings will be off.  The digital meters are very accurate and not prone to the mechanical issues with the older analog meters.  The micromho reading is read from the Gm meter as a percent of the selected scale.

Posted on February 6, 2017 - by DLandon

Hallicrafters SX-96

The Hallicrafters SX-96 is very similar to the SX-100 without a few of the features like notch filter and crystal calibrator. This radio was quite a mess and required some repairs after the restoration was complete. The 2nd converter sub-chassis had to be replaced. A parts SX-100 provided the replacement sub-chassis. The sub-chassis is very difficult to work on because it has to be unwired and removed from the chassis. The radio is not a looker, but works well and has strong reception. As is comon on the Hallicrafters with bakelite knobs, the bandspread knob is chipped. It could use a new paint job on the chassis lid.

Posted on January 15, 2017 - by DLandon

Magnavox AM/FM Table Radio

This Magnavox AC-DC radio needed five new tubes, a re-capping, and troubleshooting to find a broken connection in the FM tuner. I added an inrush current limiter and some additional power supply filtering to reduce the hum. The radio is is great shape and the finish was restored and not refinished. The radio has two speakers – a mid-range and a tweeter for great sound. I picked up this radio to use as a shop radio because of its AM/FM capability.

Posted on November 27, 2016 - by DLandon

Heathkit IO-102 Oscilloscope

The Heathkit IO-102 is a transistor based oscilloscope. I replaced the electrolytic capacitors and some transistors that were very temperature sensitive and caused the unit to drift badly. This unit is used regularly on my test bench. I built one of these from a kit many years ago, but not this one.

Posted on November 27, 2016 - by DLandon

Precision EV-10A Vacuum Tube Multitester

This Precision EV-10A was brought to me by a Customer wanting to get it fixed and working again. When this tester was made, they installed .01 uf RF filter capacitors across the AC line and ground. The paper capacitors used then were not made to withstand the 110 Volt 60Hz power line voltage and the capacitors were known to destroy themselves. This unit had one capacitor that had blown apart. I re-capped the power supply and found a loose connection on the back of the main PC connection board. The unit would not zero on ohms testing. The meter in this unit had some Bakelite debris floating around in it that interfered with the mechanical operation of the meter. I had to remove the meter, take off the cover and remove the debris. I am constantly amazed at the accuracy this old equipment. This unit is no exception.

Posted on February 16, 2016 - by DLandon

Zenith 5-S-119 Table Radio

This Zenith radio came to me partially working with the wrong knobs. The cabinet was left alone. The radio was electronically restored. All electrolytic and wax capacitors were replaced. Several out of spec resistors were replaced. The speaker was in excellent condition with no tears or holes in the cone. The most challenging part of the restoration was a bad tone control. The tone control was made of a thin conductive paint that had deteriorated. A conductive glue was applied to the deteriorated areas of the tone control to repair to control. Replacement reproduction knobs were installed.

Posted on April 20, 2013 - by DLandon

Philco Model 60 Cathedral

This is a Philco Model 60 that has been restored. The electronics were previously repaired. The repairs were undone to restore the electronics as much as possible to original. The capacitors inside the bakelite housings were taken out and replaced with modern capacitors. This radio had a common issue with the Model 60 – the antenna and oscillator coil primaries were open and had to be rewound. The case was restored and not refinished. The Model 60 receives broadcast AM and the obsolete police band. Overall the radio is in good condition and plays very well.

Posted on February 22, 2012 - by DLandon

Heathkit LG-1 Laboratory Type Signal Generator for Sale – SOLD

This is a very nice Heathkit RF Signal Generator that has been completely restored and calibrated. Included is the original manual (not a copy) in excellent condition. Original cable is included. I will only ship this unit to the lower 48 states because of the weight. Contact me by email at dlandon@vintagetubeelectronics.com if you are interested.