[MFJ-Ameritron] MFJ-259B impedance reading

[Dick KF4NS]

>From 1.8mhz to 70mhz the impedence is 58 ohms (R x X), the reactance is X=zero, capacitance Xc=zero, inductance Xl=zero the last two values obviously zero since X=0.

That should cover it all. Any other questions  ?
73, Dick KF4NS
  ----- Original Message ----- 
  From: Gene Mason 
  To: kf4nsradio at verizon.net ; mfj-ameritron at mailman.qth.net 
  Sent: Friday, June 24, 2011 6:14 PM
  Subject: RE: [MFJ-Ameritron] MFJ-259B impedance reading


  On the MFJ 259B WHat does the Z read?  also, what does the reactance read?  also You might check the capacitance and inductance readings, they are all there for free and for a good reason. This may answer some of the good questions put forth by the viewers here.
  KZ5V



  > From: kf4nsradio at verizon.net
  > To: mfj-ameritron at mailman.qth.net
  > Date: Fri, 24 Jun 2011 16:38:09 -0400
  > Subject: Re: [MFJ-Ameritron] MFJ-259B impedance reading
  > 
  > Ok guys, you got me. I should have been more detailed in my post.
  > 
  > It is an RF test termination made my TEK and is enclosed in a BNC 
  > male/female adapter. There are no leads. I tested it on my bench top 
  > HP digital meter, reading 51.8 ohms, and on my Fluke DMM, reading 51.7 
  > ohms. Not exactly 50 ohms but pretty darn close.
  > 
  > Sorry for the lack of detail.
  > 
  > 73, Dick KF4NS
  > St Petersburg, FL 33714 USA
  > Keep The Glow!
  > 
  > > -----Original Message-----
  > > From: mfj-ameritron-bounces at mailman.qth.net [mailto:mfj-ameritron-
  > > bounces at mailman.qth.net] On Behalf Of Dick KF4NS
  > > Sent: Thursday, June 23, 2011 3:04 PM
  > > To: mfj-ameritron at mailman.qth.net
  > > Subject: [MFJ-Ameritron] MFJ-259B impedance reading
  > >
  > > This group seems to have been dead for some time but will give it a
  > > try anyway.
  > >
  > > I never tried this before but was messing with my antenna tuner and
  > > decided to compare my antenna impedance reading with a precision 
  > > 50ohm
  > > resistor. I noticed that the resistor reads 58 ohms (much to my
  > > surprise) when connected directly to the antenna jack on the 259B.
  > >
  > > Is my instrument in need of calibration or is this typical? I would
  > > think pure resistance should read right on.
  > >
  > > 73, Dick KF4NS
  > > St Petersburg, FL 33714 USA
  > > Keep The Glow!
  > 
  > 
  > 
  > ------------------------------
  > ------------------------------
  > 
  > Message: 4
  > Date: Fri, 24 Jun 2011 00:26:07 -0400
  > From: Andy <ingraham.ma.ultranet at rcn.com>
  > Subject: Re: [MFJ-Ameritron] MFJ-259B impedance reading
  > To: mfj-ameritron at mailman.qth.net
  > Message-ID: <BANLkTi=UN=nu7fJaw8tZ4zYviS_UX==VGA at mail.gmail.com>
  > Content-Type: text/plain; charset=ISO-8859-1
  > 
  > > I never tried this before but was messing with my antenna tuner and
  > > decided to compare my antenna impedance reading with a precision 
  > > 50ohm
  > > resistor.
  > 
  > What exactly does "precision resistor" mean?
  > 
  > Can you measure its resistance with an accurate DVM?
  > 
  > Is it supposed to be a good RF resistor too?
  > 
  > At what frequency did you measure it on the '259B?
  > 
  > Using what leads, or connectors? How is it constructed?
  > 
  > > I noticed that the resistor reads 58 ohms (much to my
  > > surprise) when connected directly to the antenna jack on the ?259B.
  > >
  > > Is my instrument in need of calibration or is this typical?
  > 
  > That depends. See previous questions.
  > 
  > > I would
  > > think pure resistance should read right on.
  > 
  > Well, "pure resistance" that is known to be exactly 50 ohms, should
  > measure 50 ohms. Why do you say it is a pure resistance, and do you
  > know that it really is 50 ohms?
  > 
  > For example, it might be a good 50.0 ohm resistor, but inductance of
  > the leads could make the Z measure higher.
  > 
  > Even dummy loads, which are supposed to be good over a wide range of
  > frequencies, can measure off from what you'd think they ought to be.
  > I've got a good dummy load that measures quite nicely; and some others
  > that surprisingly do not.
  > 
  > Andy
  > 
  > 
  > ------------------------------
  > 
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