[Hallicrafters] My First Boat Anchor Restoration: SX101 MkIII

[Paul]

Oh man.......... Here I've been using Simpson or other VOM's for nearly 60 years to measure both AC and DC voltages using the meters appropriate function switch settings and never realized I had to use a VTVM for my DC measurements. Even some of the meters I used in the military were VOM's. How could they have been so wrong? 
 
OK, enough tongue-in-cheek. VOM's can be used to measure both AC and DC with the switches set in the proper position. However for more accurate DC voltage measurements, the VTVM is the preferred instrument. That is due to the higher voltage drop that occurs when a VOM is used vs when a VTVM is used. For general B+ readings etc, a VOM will work just fine as you're probably looking at several hundred volts and a voltage drop of several volts will be negligable to your overall reading. When performing alignment where your are only measuring a volt or even less, then use a VTVM to reduce the voltage drop to the minimum so you get a more accurate voltage reading. 

 
> AC is read with a 1000 Ohm/Volt meter!  DC is read with a VTVM!
> 
> There is a BIG difference.