[Hallicrafters] Voltage Chart for the SX-115

[Richard Knoppow]

     This is actually an important question. In some instruction books 
there is a note about the meter used but not always and sometimes it 
takes some detective work. For instance, the Hammarlund SP-600 has 
voltage charts that used a 1000 ohm/volt meter for DC and a VTVM for 
bias/avc measurements. The VTVM is not specified but was probably about 
10 megohm. The readings made with the 1000 ohm/volt meter are 
significantly different from those you will get with a 20K ohm/volt 
meter or a VTVM. Because the source resistance of these circuits vary 
one to the other there is no constant correction factor. However, if you 
use a 20K ohm/volt meter you may be misled into thinking some of the 
voltages are too high. I have an old military meter that has both 1K and 
20K ohm/volt divider strings, which is sometimes helpful with older 
equipment. If there is no note about the meter type or specs you may 
have to measure with both kinds to see if one is consistently right and 
the other wrong. In some cases, like the AVC and bias lines, one MUST 
use a VTVM or electronic voltmeter with very high input resistance in 
order to get any sort of reading that makes sense and not disturb the 
line.  In the case of some sets I use a Hewlett-Packard 410-B with its 
122 megohm input in order not to disturb the voltages.
     Rider's and Sam's are partly reprinted from manufacturer's data and 
partly made up by the publisher so they can be more confusing than helpful.

On 3/29/2017 12:43 PM, Jammer via Hallicrafters wrote:
>   Just wondering about those charts; the voltages listed were taken
> with, f'rinstance, Simpson 1000 ohm/volt meters? IIRC.  What is the
> difference between those voltages and what you see with 'moderne'
> analog or digital meters?

-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL