[ARC5] AN/URM-90...

[Kenneth G. Gordon]

On 8 May 2015 at 12:37, WA5CAB--- via ARC5 wrote:

> Actually ZM-3/U and ZM-3A/U are capacitor analyzers.  AN/URM-90 is an R-L-C
> bridge, and the nomenclature of the main component is ZM-30/U, not ZM-3/U.
> 
> On the ZM-3, I have a ZM-3A/U that replaced a Sprague TO-6 years ago and 
> that I use regularly for reforming capacitors, and also as a megger.

I guess I'll have to keep my eyes open for a ZM-3 then. I have a clone of a 
TO-6 which was made in Puerto Rico, but other than that, I have two 
Heathkit C-3s which I rebuilt years ago, and use regularly. They are quick 
and as accurate as I need. Their leakage-test function is VERY accurate.

For as simple and as small as they are, I find them to be extremely useful.

>  Once in a
> while I also use either of the other two functions.  The quick fix to the spring
> return switch problem is to simply remove the spring (and tie wrap it inside the
> unit).  Later, I removed the switch from one unit (I have three) and machined
> the cam to make it detented in all three positions instead of detented in two
> and spring return in the third.

That's neat.

Hmmmmm...maybe I need to aquire a small lathe...

> I've never had a ZM-30 and don't have any manuals except for calibration 
> procedures so am not familiar with it.

Well, it is a very interesting piece of equipment.
 
> On the analog versus digital question, digital is not inherently more 
> accurate than analog.  It is just less prone to operator error.  And can be a
> great time waster as you sit and fiddle with adjustments trying to get that last
> digit dead on zero.  :-)

Indeed!!! You're sure correct about that !.

Ken W7EKB