Re: Astron VS-35M Powwer Supply V-

Posted by Joe Subich, W4TV-4 on Apr 12, 2018; 4:55pm
URL: http://elecraft.85.s1.nabble.com/Astron-VS-35M-Powwer-Supply-V-tp7640089p7640111.html


 > Running a heavy power supply line with a lighter gauge wire at
 > the radio end OR a lighter wire at the power supply end, the
 > overall net supply resistance (and voltage drop) will be the same.
 > For example, 100 Ohms in series with 1 Ohm equals 101 Ohms net total
 > resistance.

Use *realistic* resistance values.  For example, a 10 foot piece of
of #8 wire (0.63 milli-Ohms per foot) with a six inch "pigtail" of
#12 wire (1.5 milli-Ohms per foot) is equivalent to 11' 3" of #8
wire or less than one foot of #12 wire.

The *contact resistance* in a 15A Power Pole (0.88 milli-Ohms) is,
*by itself,* is equivalent to more than six inches of #12 wire.

Ohm's Law is *exactly* why we would all be better off if the power
jack on the K3/K3S was doubled up and the power cable replaced with
#6 or #8 wire even if it were necessary to splice in some 4" pieces
of #10 or #12 wire to mate with the 15A Power Pole connectors.

#10 or 1/4" bolts for the power terminal with #8 wire and ring
terminals on both ends would reduce the voltage drop in the power
cable by 75%, if the bolted connections were torqued properly,
compared to #12 wire and 15A Power Pole connectors.

73,

    ... Joe, W4TV


On 2018-04-12 11:19 AM, James Wilson wrote:

> Buck,
>
> Running a heavy power supply line with a lighter gauge wire at
> the radio end OR a lighter wire at the power supply end, the
> overall net supply resistance (and voltage drop) will be the same.
> For example, 100 Ohms in series with 1 Ohm equals 101 Ohms net total
> resistance.
>
> Likewise 1 Ohm in series with 100 Ohms is still 101 Ohms.
>
> It doesn't matter if you take the voltage drop at the input or
> at the output end of the power run if the total load is at the
> end of the run.
>
> I checked with Dr. Ohm to verify this.  :-)
>
> Jim - W4RKS
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