Triplett Volt Meter Battery Modification

Overview

Old Triplett high-voltage meters show up from time-to-time at various ham radio and electronics swap fests.  These meters are very well constructed and are perfect for the amateur high-voltage enthusiast.

Provided that the actual analog meter movement is still intact and operational, the only real thing that will be wrong with these old meters are the internal batteries.  Triplett meters used two internal batteries, one a common 1.5 volt "D" size and the other, a hard-to-find 30 volt battery.

Thankfully, there is a really easy solution for that 30 volt battery.  It works by using three standard 9 volt batteries wired in series.  This will give you around 27 volts, close enough to the required 30 volts.

The following pictures and descriptions will help to explain everything in a little more detail.

Pictures & Construction

Triplett Model 630 AC/DC high-voltage meter in perfect shape.  They go for around $30 (used) at various ham fests.

Internal view.  Remove the four screws along the back panel and pull the two halves apart.  This particular meter didn't have any batteries inside it.

On the right are the new batteries.  You'll need one "D" size battery and three 9 volt batteries.  You'll also need a 9 volt battery snap connector.

Arrange the three 9 volt batteries in series as shown in the above picture (you'll figure it out) and tape them together.  Then cut the 9 volt battery snap connector in half.

Solder wires to the new snap connector tabs and place them onto the "new" battery terminals.  Check the voltage on a meter to verify it is all working.  It should measure around 27 volts and the batteries should not get hot.  If they do, something is wrong.

The meter's original 30 volt battery was mounted underneath the 1.5 volt battery.  You'll need to place a piece of foam under the new "D" battery so it can reach the top two battery tabs.  The "D" battery's POSITIVE end will be on the left, when facing the rear of the meter.

Install the new 27 volt battery pack as shown.  The NEGATIVE end should go to the solder tab below the "D" battery's POSITIVE connection and the POSITIVE end should go to the solder tab below the "D" battery's NEGATIVE connection.  They are labeled, but it's a bit confusing.