[GreenKeys] Testing My Model 15 KSR

[WA5CAB at cs.com]

AFAIK, if this is the only machine you have it doesn't matter.  Except that 
you will need to change the current limit resistor to 6K ohms.  However, if 
you already have a 60 mA loop supply and if you are just getting into this 
and have asperations of acquiring other machines, converters and 
accessories, I would probably stick with 60.  But don't make the mistake of dropping 
the loop supply voltage to around 40 and running 20 mA.  Your range will 
suffer.

In a message dated 4/12/2010 11:49:19 PM Central Daylight Time, 
john at johnmcclung.com writes: 
> Thanks for the info.
> 
> Looks like I have the holding magnets with the toggle switch.
> 
> Which is the better way to run it, 20mA or 60mA?
> 
> John
> 
>     -----Original Message-----
>     From: WA5CAB at cs.com [mailto:WA5CAB at cs.com] 
>     Sent: Monday, April 12, 2010 10:58 PM
>     To: John McClung; greenkeys at mailman.qth.net
>     Subject: Re: [GreenKeys] Testing My Model 15 KSR
>     
>     
>     John,
>     
>     To add to or comment on what's already been posted, relatively
> few Model 14/15/19 will run on 20 mA.  That requires different magnets
> in what's called a "Holding Magnet" selector.  The majority come with a
> "Pulling Magnet" selector.  You can tell the difference by the fact that
> the pulling magnets are cylindrical and the holding magnets are
> rectangular in cross section.  I've had in my lifetime maybe 30 14's or
> 15's and only about two had holding magnets.  However, the first M15 I
> ever had (in 1962) had holding magnets.  So they do turn up.  But both
> of the ones I recall having had a selector toggle switch, too.  I can't
> certify that all did.
>     
>     You can't rewire a pulling magnet selector for 20 mA.
>     
>     If you do not disconnect the wires actually going to either
> coil, you will not accidentally get them wired so that they buck
> (oppose) each other.
>     
>     Hooking the local keyboard and selector magnets in series with
> the local loop supply (with dropping resistor adjusted to set the
> resting current to 60 mA) creates what's commonly called a local loop.
> Typically used for testing and generating local hard copy.  You can jack
> a TD or keying generator into the loop and run a FOX tape and check and
> adjust range.
>     
>     
> 
> 

Robert & Susan Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480