Triplett VOMs

[jr_tech]

After reading the wonderful thread about the Simpson 260, I thought that it might be reasonable to give a little "equal time" to another brand that has been around for over 100 years...Triplett.

Three popular models of Triplett VOMs that are still available are shown in Pix 1&2...The three meters shown, Left to right in Pix 1 are 630-NA, 666-HH, and a 310. All three have the early "meter movement" Triplett logo on the scale (used into the 60s), the 666 also displays the "red dot", which I believe was dropped in the 50s. The 630 and 310 models still look much like the older models pictured, but the "modern" 666 model now has a recessed range switch, much like that on the 630. Pix 2 shows a side view, revealing the high degree of miniaturization involved in the design of the tiny 310 (4 1/4 x 2 3/4 x 1 5/16" and about 8 oz.). The 310 is my personal favorite VOM, and I have collected many variations.

Pix 3 shows 50+ years of model 310s. The 1955 310 (type 1, although not labeled as such) on the left displays the "meter movement" logo and the "red dot", the type 7 on the right, purchased in 2006, has the stylized "T triangle" logo. The later model also features an enclosed range switch, similar to that which was incorporated earlier in only the "premium" model, the 310C.

Pix 4 shows three different models that I have collected (although there are others). The model on the left is a 310C (type 3), which has a polarity switch on the left side, better AC sensitivity (15K ohms/volt rather than 5K) and an enclosed range switch. The center meter is a fairly rare 310 FET model also with a polarity switch as well as 10 meg ohm input resistance, DC voltage range down to 0.3 volts full scale, a "center zero" scale, ohm reading to 5000 meg-ohms and ma readings down to 0.12 ma...much like a solid state VTVM! On the right is a standard 310 (type 2) for comparison. All three display the red "Triple T" logo, used in the 70s and 80s.

Pix 5 shows packaging and labels used on the late (2006 or so) type 7 310 and 310C. Volt Ohm Meters in a "bubble pack"! The 310 type 7 on the left proudly displays a "made in USA" logo.

In Jan. 2007 Triplett was purchased by Jewell instruments in Manchester NH, and apparently the factory in Bluffton Ohio was closed. The latest models of 310 and 310C are type 8.

jr