OHR WM-1

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OHR WM-1

N2PD
Does anyone have the alignment instructions for the Oak Hills Research
WM-1 wattmeter?  Now that I have the K2 I want to use mine again.  
Changed the battery and would like to re-calibrate it but can't find the
instructions.  And thanks to all for help with my previous questions.  
Great group!
73s
Paul
N2PD
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Paul, N2PD
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RE: OHR WM-1

Don Wilhelm-3
Paul,

The OHR WM1 was based on the QRP Directional Wattmeter by Roy LeWallen, and
although I don't know how OHR may have changed it, I would believe that the
calibration procedure is quite similar.  You may want to check the QRP
Directional Wattmeter article originally published in QST Feb 1990 and
appeared in several editions of the ARRL Handbook and Antenna book after
that time.

73,
Don W3FPR

> -----Original Message-----
>
> Does anyone have the alignment instructions for the Oak Hills Research
> WM-1 wattmeter?  Now that I have the K2 I want to use mine again.
> Changed the battery and would like to re-calibrate it but can't find the
> instructions.  And thanks to all for help with my previous questions.
> Great group!
> 73s
> Paul
> N2PD

>

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RE: OHR WM-1

Tom McCulloch
In reply to this post by N2PD
Here is the link for the 1990 QST project:

http://www.arrl.org/tis/info/pdf/9002019.pdf


Does anyone know if the WM-1 can take 13.8 volts or do I need a 9 volt voltage regulator.

Tom
WB2QDG
K2 1103

 -------------- Original message ----------------------
From: "Don Wilhelm" <[hidden email]>

> Paul,
>
> The OHR WM1 was based on the QRP Directional Wattmeter by Roy LeWallen, and
> although I don't know how OHR may have changed it, I would believe that the
> calibration procedure is quite similar.  You may want to check the QRP
> Directional Wattmeter article originally published in QST Feb 1990 and
> appeared in several editions of the ARRL Handbook and Antenna book after
> that time.
>
> 73,
> Don W3FPR
>
> > -----Original Message-----
> >
> > Does anyone have the alignment instructions for the Oak Hills Research
> > WM-1 wattmeter?  Now that I have the K2 I want to use mine again.
> > Changed the battery and would like to re-calibrate it but can't find the
> > instructions.  And thanks to all for help with my previous questions.
> > Great group!
> > 73s
> > Paul
> > N2PD
>
> >
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
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>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com


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RE: OHR WM-1

Gregg R. Lengling
It would change the calibration procedures.  It uses very low current so if
you want to use 12 volts just put a dropping resistor and a 9volt zener
after the dropping resistor.

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of [hidden email]
Sent: Wednesday, November 29, 2006 3:09 PM
To: [hidden email]; Paul Del Negro; [hidden email]
Subject: RE: [Elecraft] OHR WM-1

Here is the link for the 1990 QST project:

http://www.arrl.org/tis/info/pdf/9002019.pdf


Does anyone know if the WM-1 can take 13.8 volts or do I need a 9 volt
voltage regulator.

Tom
WB2QDG
K2 1103

 -------------- Original message ----------------------
From: "Don Wilhelm" <[hidden email]>
> Paul,
>
> The OHR WM1 was based on the QRP Directional Wattmeter by Roy LeWallen,
and
> although I don't know how OHR may have changed it, I would believe that
the

> calibration procedure is quite similar.  You may want to check the QRP
> Directional Wattmeter article originally published in QST Feb 1990 and
> appeared in several editions of the ARRL Handbook and Antenna book after
> that time.
>
> 73,
> Don W3FPR
>
> > -----Original Message-----
> >
> > Does anyone have the alignment instructions for the Oak Hills Research
> > WM-1 wattmeter?  Now that I have the K2 I want to use mine again.
> > Changed the battery and would like to re-calibrate it but can't find the
> > instructions.  And thanks to all for help with my previous questions.
> > Great group!
> > 73s
> > Paul
> > N2PD
>
> >
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft   
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com


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RE: OHR WM-1

Don Wilhelm-3
In reply to this post by Tom McCulloch
Tom,

As long as the op amps behave like proper op amps, there should be no
difference.  I observe that the only place the power goes is to power the op
amps - the calibration is used to set the op amp gains, so there should be
no calibration dependency on the power supply voltage (unless the voltage
gets very low).

One caution that I should mention - using a separate battery makes the meter
independent of the grounding system for other powered equipment, so if you
get 'funny' readings it may be due to ground loop currents coupling into the
op amp inputs - of course you would have the same ground loop potential if
you used a regulator to bring the 13.8 volts down to 9 volts.

73,
Don w3FPR

> -----Original Message-----
> Does anyone know if the WM-1 can take 13.8 volts or do I need a 9
> volt voltage regulator.
>
> Tom
> WB2QDG
> K2 1103
>

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