[Amps] LCR meter/review

Thu Apr 1 03:14:38 PDT 2010

Hi 

Jack K8ZOA has recently reviewed the AADE meter. His review makes for some interesting reading.

http://www.cliftonlaboratories.com/aade_l_c_iib_meter_review.htm

73
Craig
VK3HE

--- On Thu, 4/1/10, Alex Eban <alexeban at gmail.com> wrote:

From: Alex Eban <alexeban at gmail.com>
Subject: Re: [Amps] LCR meter.
To: "'Jeff Blaine AC0C'" <keepwalking188 at yahoo.com>, "'Jim Thomson'" <Jim.thom at telus.net>, amps at contesting.com
Date: Thursday, April 1, 2010, 2:32 AM

 The AADE instrument is more than adequate for all practical purposes. It's
nice to have variable frequency option, but in any case, at the higher
frequencies, the influence of unpredictable strays in the circuit becomes so
strong, that frequency dependent variables in the component cease to be
relevant. These unpredictables strays make any accuracy over a few percents
superfluous.
BTW, another very adequate instrument is the Autek RFxx series at half the
price of an MFJ, with variable frequency AND reactance sign.
Alex        4Z5KS

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Jeff Blaine AC0C
Sent: Wednesday, March 31, 2010 6:24 PM
To: Jim Thomson; amps at contesting.com
Subject: Re: [Amps] LCR meter.

Jim,

My question is to the fundamental accuracy of the MFJ vs. the effects on
calibration variation.  Is the MFJ really this inaccurate, or is the
accuracy in your case atypical.  It would be interesting if someone else
could do a controlled test with the MFJ vs. a lab type unit (well, a unit of
known capability).

I only have the AADE meter here in are the Fo there is variable; as well as
the MFJ.

73/jeff/ac0c

--------------------------------------------------
From: "Jim Thomson" <Jim.thom at telus.net>
Sent: Wednesday, March 31, 2010 6:06 AM
To: <amps at contesting.com>
Subject: [Amps] LCR meter.

> Date: Tue, 30 Mar 2010 19:21:27 -0700
> From: "Jack/W6NF" <vhfplus at gmail.com>
> Subject: Re: [Amps] LCR meter
>
>>
>> > Here are some real numbers I just measured on a network analyzer 
>> > calibrated at the plane of the core being measured.
>> >
>> > Core = T94-2 powdered iron u=10, 22 turns #18 occupying about 80% 
>> > of core
>> >
>> > Msmt. freq.     L(measured)
>> >
>> > 50KHz           3.06uH
>> > 100KHz          3.86uH
>> > 200KHz          4.53uH
>> > 500KHz          4.51uH
>> > 1MHz            4.50uH
>> > 5MHz            4.50uH
>> > 10MHz           4.58uH
>> > 20MHz           4.89uH
>> > 30MHz           5.52uH
>> > 40MHz           6.80uH
>> > 68.1MHz         parallel resonant freq.
>
> ###  I tried using the inductance measuring capability of the MFJ-259B.. 
> with dismal
> results.   A  10 uh commercially made roller inductor,  wound   with 1/4" 
> tubing... measures
> exactly 10 uh  on my B+K 875-B  lcr meter. Same deal on my 50 uh roller. 
> When the mfj
> was used, the same coil measures a LOT less than 10 uh.... as low as 5 
> uh.....depending on what freq the mfj is on. Even with the mfj set  to 
> 1.8 mhz.... the  same coil is way  <  10 uh !!!
>
> ##  If I design  a simple PI net  for a tube amp using GM3SEK's 
> software.. and it  spits out various values  for  C1... L... C2.... 
> and then build it, using the B+k 875B.... everything  comes out
> dead on.    And that's using a resistor  between  anode and chassis, to 
> simulate plate load  Z....
> [and mfj on output of C2].    Tune and load tweaked till mfj reads 1:1 
> SWR.
>
> ##  If instead, the MFJ 259 is used  in it's inductance measuring 
> mode, to tap the coil  for the various
> bands... the inductance, comes out on the HIGH side  vs the 875B.   What 
> happens, is the C1  and C2
> caps both have to be DECREASED  in value to compensate for the too 
> high uh used on each band.
> This of course, results in decreased  loaded Q.
>
> ## The mfj inductance measurements  are just the opposite of the  
> results in the above tabulated chart, which used a network analyzer.  
> The mfj-259  shows lower uh values.. as freq goes UP.
>
> ##  the B+k  875A/B  uses  1 khz  for the measuring freq.   I measured 
> some other commercially made
> coils  with it.. and the 875 is dead on with the stamped value of the 
> commercial coil.
>
> ## OK, now maybe the commercially made coil maker used a similar lcr 
> meter to wind his coils  with.
> Now if the coils are actually out to lunch in value... and a 10 uh  
> coil is actually 6 uh on the  mfj-259...
> OR  is actually way higher than 10 uh  per the  network analyzer above....

> then  the  give away/ proof
> would be that the tune  + load caps would be WAY off value  from the 
> spread sheet.
>
> ##  well, the tune /load / coil  measurements  are dead on.. when the 
> 875A/B  is used.. and compared to the PI  spread sheet.  All other  
> test gear  throws the pi net way off.
>
> ## I checked a LOT  of vac caps with the 875.. and also  stuff like  
> HEC
> ht-50-58-59  TX  doorknobs,  cardwell
> air variable  tune and load caps, broadcast variables,  HV lytics , etc. 
> Even tried plane jane coax , and measured
> pf  between  center conductor and braid... and it's all dead on.    If I 
> want a screw up.. either the mfj-259  or the network analyzer used in 
> the above example  will  do the job of messing things up.
>
> ##  we also used the 875  to  build all the  various tuned inputs over 
> the years, both the  type that have 5-9 x individual  tuned inputs.. 
> and also the tapped  coil  +  2 x broadcast
> variable types.   The  LC networks  were also
> built using the 875 [ used to stack either  2 x identical yagis.... or  3 
> x identical yagis]   Ie:  50 ohms in... and  either
> 25 ohms out.. or  16.66 ohms out.  We  used Bing's  Rf software  to 
> design the various LC networks, and then used
> the 875 to build em.   They came out dead on the 1st time round.
>
> ##Until  I find something that works  better, which is unlikely, I'm 
> going to stick  with what I know  currently works.
> This is  for  160-6m  stuff.......  nothing higher   than 6m.
>
> later....... Jim  VE7RF
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