MFJ Analyzer Xs mystery

[flintstone mop]

I finally found out some badly needed info on this famous analyzer.
No one here seemed to know what the Xs reading meant on the display. I always knew my little friend was telling me more than I could understand and how to get that perfect match.

The MFJ-259B measures reactance, and converts reactance to inductance. The MFJ-259B
can not determine if the reactance is actually inductive or capacitive. You can usually
determine the type of reactance by adjusting frequency. If frequency is increased and
reactance (X on the display or Impedance on the meter) decreases, the load is capacitive at the
measurement frequency. If frequency is reduced and reactance decreases, the load is
inductive at the measurement frequency.


In the RF world we use reverse thinking and if it's a capacitive load then we counter it with more inductance. And vice versa.
NOW I can move onto perfecting my vertical for 1880 khz

FRED

[W1UJR]

I believe "Xs" is reactance slope, (ohms/Hz) or source reactance.

See http://www2.wcoil.com/~tlee/GI7B%20Amp/Pi.pdf

Sure that Walt or one of the other fellows can explain it far better than I.

[KF1Z]

Could have sent you a copy of the manual Fred.

It explains all that in the manual.

 

[DMOD]

Hi MOP,

This why I prefer this one:

http://www.autekresearch.com/va1.htm

Phil - AC0OB

[KF1Z]

Phil,
That's true....

I use the VA-1 and the RF-1
(Also own the WM-1 wattmeter Autek has.)

The only thing "better" about the MFJ, or actually the Vectronics (same thing, different name on it) is they have the analog meters, that makes "dialing-in" a tuner or tweaking some other resonant circuit a little quicker.

[wa1knx]

Phil, I had one and it lasted a cpl years. what a nice instrument, but something
broke in it. it sits in tucson alas unused now sigh.  deano

[WA1GFZ]

Dean,
They are DC coupled so good chance the diode(s) in the bridge is blown. 1N5711 should work.

[K5UJ]

Fred,

I did not know you were having trouble understanding ur MFJ.  I have one of those and would have been happy to explain reading the reactance.  If you asked this somewhere as a question I missed it, sorry.

rob

[W3SLK]

You know, I've been quick to criticize MFJ and their 'Mighty Fine Junk'. But I will let the record show that my -258B has been a godsent. Best $224 I ever spent, (that's also including the padded jacket. Their pseudo grid dip option leaves a lot to be desired. I think at the time the only other unit out there was a Timewave/AEA unit that was about $200 more. Even though it had a nice lcd display sweep, I found that the -258B was gobs easier to use.

[W1UJR]

You know, I've been quick to criticize MFJ and their 'Mighty Fine Junk'. But I will let the record show that my -258B has been a godsent. Best $224 I ever spent, (that's also including the padded jacket. Their pseudo grid dip option leaves a lot to be desired. I think at the time the only other unit out there was a Timewave/AEA unit that was about $200 more. Even though it had a nice lcd display sweep, I found that the -258B was gobs easier to use.

I agree, they work pretty darn well.

Just keep them away from strong RF fields.
Had a 6 foot lead dangling off mine when I building my loop antenna back in the Buffalo days.
That short lead coupled enough RF into the unit to smoke it, necessitating a trip back to MFJ.

Other than that, its been trouble free, and sure a better investment than my old and mega bucks AEA graphing unit.
Agree, padded case a must, mine has been dropped and bounced multiple times without fail!

[Jim, W5JO]

I agree, they work pretty darn well.

Just keep them away from strong RF fields.
Had a 6 foot lead dangling off mine when I building my loop antenna back in the Buffalo days.
That short lead coupled enough RF into the unit to smoke it, necessitating a trip back to MFJ.

Other than that, its been trouble free, and sure a better investment than my old and mega bucks AEA graphing unit.
Agree, padded case a must, mine has been dropped and bounced multiple times without fail!

Also watch connecting them to any antenna when static can be present.  Wind blowing sand, water droplets or snow can ruin the diodes as well.   Lightning within 20 miles or so can get them in a heartbeat.

[K5UJ]

I've dropped mine, hooked the dc up backwards, plus one or two other things and it still works.  MFJ did pretty well on it and I use it to measure capacitance.  Also could not operate without their phase shifting noise nulling box. Then there's other stuff of theirs I couldn't give away.  Never saw a MFJ tuner I could use.

[DMOD]

I still use my 259b occasionly.

I did notice that it will generate 2nd and 3rd harmonics.

If you see erratic oscillator tuning problems, open it up and apply blue thread locker to the screws securing the tuning cap, since they may get loosy-goosy.

I have also found the frequency counter needs about 5 volts peak to register accurately.

Phil - AC0OB

[flintstone mop]

hey everyone,
Thanks for the info. I thought Xs was a series reactance, I can't find my manual, so I opened the PDF on line and finally saw the secret.
They will repair an analyzer for a flat $81.00, I think. I have the 1.8 to 30 mhz and the other that goes to 470mhz. The 1.8-30 got transmitterd into and I haven't gotten around to send it in for repair.
They warn to touch the connector from the antenna to ground to bleed off any charge.
Very nice box. It has saved the finals on my poor TS440 a lot of grief and interference to others tuning up a new antenna or QSY an antenna to a new freq.

Fred