DX-100 Resistor Source

[ve3fwf]

Another trick is to use a slightly larger value resistance for the 5.4 ohm 
and then file the resistor
material away in the centre until you get precisely 5.4 ohms.  This only 
works with carbon resistors!

Place some epoxy over the exposed area that you removed. You are derating 
the wattage
of the resistor so consider that when picking a resistor. Use a 1 watt 
resistor if you
have them.

73, Bernie

----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at VERIZON.NET>
To: <HEATH at LISTSERV.TEMPE.GOV>
Sent: Tuesday, January 23, 2007 1:44 PM
Subject: Re: [HEATH-TEMPE] DX-100 Resistor Source


> On 22 Jan 2007 at 20:06, Mike wrote:
>
>> Does anyone know where to buy replacements for the 5.4 and .092 ohm
>> resistors that are used as meter shunts?
>
> When I need such, I make them.
>
> The .092 ohm shunt can be made out of a certain length of hookup wire
> of the appropriate diameter, wound on a form like a pencil or something
> similar, then tied or glued down. I usually adjust them "in place", so to
> speak, before winding them on any sort of form, with an accurately
> calibrated VOM or VTVM in series with the meter I am trying to shunt.
>
> The appropriate size of wire can be chosen from a standard wire table,
> one of which is always in the back of every ARRL Handbook. The wire
> is listed at so many ohms per foot, or per 1000 feet. The smaller the
> diameter, the more "ohms per foot".
>
> The 5.4 ohm resistor can be made in a similar way, although I normally
> use the closest common value of resistor from Radio Shack, but on the
> LOW side, and adjust it with a series wire as above.
>
> Although you could undoubtedly BUY a precision, special order, shunt
> resistor, it would be FAR more expensive than making them by hand,
> and in addition, often they aren't any more accurate when you take the
> resistance of the connections into account.
>
> In some instances, just to see how it would work, I finished adjusting my
> meter shunts with a file. Such accuracy far exceeds the read-out
> accuracy of the meter itself, and is totally unnecessary, but can be fun.
>
> Ken W7EKB
>
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