Shaun Merrigan's Information Pages



Hickok 209A VTVM Restoration Part 6

Posted by Shaun Merrigan in Electronics, Restoration, Tech, Test Equipment. Comments Off on Hickok 209A VTVM Restoration Part 6

13th January

This is the sixth part of an “N” part series documenting my restoration of the Hickok 209A VTVM, SN 1333254.

Hickok 209A VTVM Restoration Part 6: Component replacement decisions

In this Part 6 of the series I will document the condition of the passive circuit components in the Hickok 209A VTVM, and justify why I decided to replace (or not replace) them.

Initial resistor and capacitor measurements Hickok 209A

Starting with the resistors, I measured 8 initially, and of those 5 were out of marked specification on the high side. One more was right at the high side specification and two were within specification. These were all 5% and 10% tolerance carbon composition resistors. Based on these data, I made the decision to replace all the 5% and 10% carbon composition resistors. I used 1% metal oxide resistors with … Read More »


Hickok 209A VTVM Restoration Part 5

Posted by Shaun Merrigan in Electronics, Restoration, Test Equipment. Comments Off on Hickok 209A VTVM Restoration Part 5

1st January

This the fifth part of an “N” part series documenting my restoration of the Hickok 209A VTVM, SN 1333254. Hickok 209A VTVM Restoration Part 5: Checking the meter movement.

This piece of test gear is all about the large, beautiful meter movement, so I need to determine if this one works properly. What I intend to do is connect the meter to a precision power supply and good ammeter through a current limiting resistor and then determine how the meter responds. The meter is supposed to be a 500uA full scale movement.

Here is the test setup:

Analog Meter Test Instrumentation Setup

A 10kohm limiting resistor is connected in series with the power supply. The power supply is a Tektronix PS5004 and the meter is a Tektronix DM5120.

Full Scale Deflection on the meter was about 497 uA:

Analog … Read More »


Hickok 209A VTVM Restoration Part 4

Posted by Shaun Merrigan in Electronics, Restoration, Test Equipment. Comments Off on Hickok 209A VTVM Restoration Part 4

1st January

This the fourth part of an “N” part series documenting my restoration of the Hickok 209A VTVM, SN 1333254. Hickok 209A VTVM Restoration Part 4: Restoring the battery holder.

In Part 3 of this series I documented the condition of the D Cell battery holder and outlined the restoration plan for the unit. The first step is to remove and restore the corroded battery holder.

Hickok 209A SN 133254 Corroded Battery Holder

Besides the obvious corrosion, the white connecting wire to the negative terminal was corroded under the insulation from the battery spring clip to the switch solder lug. I replaced the entire length of this wire. The other short wire and ring terminal were cleaned as described below.

Hickok 209A SN 133254 Corroded Terminal Wire

The process I used to restore the battery holder:

Desolder the two … Read More »


Hickok 209A VTVM Restoration Part 3

Posted by Shaun Merrigan in Electronics, Test Equipment. 1 Comment

1st January

This the third part of an “N” part series documenting my restoration of the Hickok 209A VTVM, SN 1333254. Hickok 209A VTVM Restoration Part 3, corrosion issues and restoration plan.

As mentioned in Part 2 of this series, a visual inspection of the chassis of the 209A revealed a serious corrosion problem with the battery holder. The corrosion had migrated to the bottom of the case but not to the remaineder of the chassis. There were no batteries in the unit when I received it.

Hickok 209A SN 1333254 Battery Holder Corrosion

Hickok 209A SN 1333254 Battery Holder Corrosion

Hickok 209A SN 1333254 Battery Holder Corrosion

Hickok 209A SN 1333254 Battery Holder Corrosion

From the above images, it is clear that the battery holder will require some corrosion mitigation and restoration. Fortunately, it is restorable as the parts are … Read More »


Hickok 209A VTVM Restoration Part 2

Posted by Shaun Merrigan in Electronics, Test Equipment. 1 Comment

1st January

This the second part of an “N” part series documenting my restoration of the Hickok 209A VTVM, SN 1333254. Hickok 209A VTVM Restoration Part 2, visual inspection.

Outside visual inspection results:

Overall good visual condition outsideMeter appears to move freely and does not stickMeter face is excellent and there are no scratches on the glassMeter bezel is dirty, but does not appear to be corrodedArea of corrosion noted at bottom of caseThe case has some minor paint scuffs and nicks accumulated over the past 60 yearsLine cord appears to be original and looks to be in good conditionHas an original rubber grommet where the line cord enters the caseNo obviously broken parts: lamp, pin sockets, dials are in good conditionHas DC Probe (reads 3.36 Mohms)No AC probe but does have the 4 wire AC probe connectorNo pin tip test … Read More »