[Hallicrafters] My First Boat Anchor Restoration: SX101 MkIII

[lrlayton at cox.net]

Something to be aware of.  Many of the older manuals have tables with  DC voltage readings taken with a 20,000 ohms per volt meter like the Simpson 260 or even older 1000 ohms per volt  meters . Readings taken with a VTVM can read significantly higher and indicate a problem that's not really there. For instance,  I am looking at a Riders manual for a Hammarlund HQ-129 and the table for tube socket voltages is for a 1000 ohm per volt meter.

Les Layton

---- Paul <w2ec at bmjsports.com> wrote: 
> 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.
> 
> 
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