Had to look it up , a very good long series of videos with Martin Jue at the AtlantaRadioClub here on KZfaq showing a lot of uses of the 259 / 269 . I've repaired a few of these , currently have a 269 that does 440 Mhz . MFJ gets a lot of piss-an-moaning , but they do have most of what hams need / want ---- to a price point . seems to me until all the stuff running on chips / programing coming from china , MFJ was hams 1st gear at lower prices , and sometimes we would have to call them kits - but that is a good thing - find a broken version of what you want & learn to repair ;)

I've got the 269 and it works just fine. In measuring SWR, I compared it to a Diamond SX400 and the reading was the same.so I'm happy with it. I do believe when you desoldered the SO239, it could've affected the the calibration of the cicuit that is why it says in manual to short your coax connectors before inserting it coz a simple static from your antenna may result on false readings or worst, it may damage the unit.

A friend of mine has the 269D. The 269D comes with an N connector rather than the SO-239 on top. He loaned it to someone who promptly tried to plug in a PL-259. Of course the fingers on the female N connector broke. He asked me if I could replace the connector. I wish I had found your video before saying yes. The 269D has one additional PCB that’s perpendicular to the main boards and connected with a ribbon cable. The N connector is mounted to that board. Of course there’s no additional room in the case, five pounds of crap in a one pound box. Anyway, I was able to find a replacement N connector and replace it, but not without breaking the ribbon cable that leads to the additional board. Curse words were uttered. Whoever designed the packaging had no thought of repairability. By the way, the one I worked on had really goofy readings afterwards also. I don’t think anything I did should cause that, but after taking it apart 3 or 4 times I’m not eager to open it up again to calibrate it. 😢

I've got one that I've had for over 20 years. It's an awesome tool. I built a 10m 2 element cubical quad and an 8 element 2m cubical quad in 1999. Also a bunch of HF dipoles. All made big signals and the radio was happy with the impedance. I would note that once you get above 4 elements on a 2m quad, tuning gets really quirky. I really wish I still had those two homemade antennas, but wood and bamboo just don't hold up for decades. ;) Edit: mine always seemed accurate. Gotta keep in mind that, unless your antenna is purely resistive and 50 Ohms, the feed line is part of the system being measured. One should really use half wave multiple coax feed line to do the measurements, this should eliminate the effects of the feed line length. I think this would apply to any tool used, including the fancy new VNA boards.

I❤mine and i have build a couples of antennas over the years. Im glad to be have one😊

I have one of these and yes they are a pain to take a part. I checked mine with a 50 ohm dummy load and it is right on after all of these years. I still use it to tune antennas outside because I can see it better than the new digital ones. Happy with mine. Good video. ke9le

I have one need to check it. Worked ok on the hf bands agreed with the power swr meter. Good video

I think yours is out of calibration, I bought one new 25 years or so ago, still works great. I put it on my Heathkit Dummy load and it is rock solid at 50 ohms anywhere you tune it. Have checked it against other devices and always very close. Lots of functions too, you can even get Length from random coax. Great tool but it is pricey. edit: If using alkaline cells there should be 2 dummy batteries, 10 cells are for rechargeable.

So now you another project for another video - calibrating the 259 ;) Thanks again

Thank you. I enjoyed your video. I have had my MFJ-269 for over ten years. It still works. I got it to rough tune antennas to avoid frying the RF transmitter finals. I have not fried any finals since I received it. So it did what I wanted it to do. I have also used it to measure coax length, velocity factor, and so forth. I does the job I need to do. After reading the comments, there is a thing called measurement theory and it is complex. There is also the electromagnetic theory expressed by Maxwell's quaternion equations and transformed to vector calculus by Oliver Heaviside and other Maxwellians. Also complex. I do not understand either very well and I am a retired professor and have worked with electrical wiring and electronics for years. To get really precise measurements requires expensive calibrated equipment. The nanoVNA's and V-SWR meters are inexpensive. The highly calibrated equipment ranges from thousands to tens of thousands of US dollars, or more. I checked on an oscilloscope and it was over $ 1,000,000! Only for frequency measurement do we need high precision. Most everything else we do not. The cheap nanoVNA's and the more expensive V-SWR meters get the job done. And neither is very accurate. N0QFT

I'm glad I'm not the only one that drooled over one, but I did have one. It wasn't the greatest thing as a nano VNA blows it out of the water, but it's still a useful tool. Yes, it took an army of batteries lol

The device has many advantages: 1. Preliminary setting of P-circuits 2. Antenna tuners (SWR, tuning frequency) 3. RF amplifiers (Rin and Rout, bandwidth) 4. Capacitors of capacitors (in pF) 5. Chokes and inductors 6.Frequency transmission and generation 7. Wave R of symmetrical lines, Kukor. and resonances 8. In coaxial lines - SWR, K shortening, resonances Much more, up to measurements of the length of the RK By the way, this device was used to check the antenna pattern, using it as a beacon

I still use one. Build a copper Jpole. Used it to tune. Compared it to a network analyzer I was surprised how close it was. Had mine for about 20 years paid around 300 or so.

I bought an MFJ269c about five years ago.. It's been made redundant by my NanoVNA-F V2 although it's still useful as a rough sig gen and frequency meter.

Hi great video I bought one of the first from US took a while to get to the UK . Working still many years of use and abuse. Great for checking antenna and a quick and dirty check of receive. Use other stuff on the bench . I got fed of changing batteries so converted to lipo batteries . Another mod I tried was to put a slow motion drive on the frequency control but more trouble than it was worth so took it off. Yours seems a bit off maybe needs calibration?

I am happy with mine. The manual says you could get software upgrades, but you had to send the chip in, that is why the cpu is in a socket.

I have an MFJ-269 and it seems stable everywhere with a 50-ohm load. What I don't care for is the discrepancy between the meter and the digital display. I also wonder if there is a calibration routine to zero in on more accurate values. I do find the unit useful at time and use it alongside my NanoVNA. Thank you for sharing.

A glorified resistive swr bridge, complete with signal generator (although that is also the heart of the nano VNA, but the construction is probably a bit better). It's a shame it can't tell you which sign the reactance is. It has an amplitude stabilised signal source, but I'm sure that is just so you don't need a 'cal' setting for the benefit of the analogue meters; the processor only needs voltage ratios to determine the SWR. You could do a video (if not already) about making a resistive SWR bridge that also has a way of determining if the load is capacitive or inductive (one variable and one fixed capacitor extra) - a fixed band (due to the capacitors), poor mans analyser - what the young, and poor, pirates had to use (at around the same year as the copyright on the MFJ software!)

I've had a few in to repair and a common problem is tarnished contacts on the band switch, causes intermittent or total drop out. The diodes give problems too.

IMSAI guy, interesting video as usual (thanks). Sorry for this long message but I do have numerous comments since I designed and built my own antenna analyzer using the same basic approach as what MFJ used which is similar to a design by VK5JST. In the MFJ antenna analyzer there is an oscillator that feeds a 50 ohm resistor that's connected in series between the oscillator output and the output jack. The 50 ohm series resistor connected to the output jack forms a simple voltage divider circuit with the oscillator being the source to the voltage divider. Diode detectors then allow you to measure the voltage level on the output of the oscillator, the voltage across the 50 ohm series resistor and the voltage across the output. If the load connected to the output jack was purely resistive then the voltage across the series resistor added to the voltage across the output jack should equal the oscillator output voltage. When you connect a load that has some reactance then the voltage across the series resistor and the voltage across the output jack when added together actually measure greater than the output of the oscillator (their voltages are out of phase due to the reactance of the load) and you can then use math to determine what the load resistance as well as load reactance must be to have generated the simple additive voltage measured which is greater than the source (oscillator), but you can't determine if the reactance is inductive or capacitive. The diode detectors are not perfect and that's what causes inaccuracy using this technique. The microcontroller just measures the DC voltages produced from the 3 diode detectors mentioned above and then the microcontroller does the math to determine the R, X, SWR, etc. The resolution of the analog to digital converters within the microcontroller is another limiting factor in regards to accuracy. The detectors can get damaged which would then cause the unit to produce bogus values. You measured a 50 ohm load up on 144.8 MHz and you measured R= 46 X = 7 which actually is not too bad using the above mentioned circuit topology (and it takes very little lead length to generate 7 ohms of inductive reactance on 144.8 MHz as an example). I would also suggest measuring a resistive load of 100 and 200 ohms to see how far off they measure. I would not go much more than 200 ohms as the accuracy will quickly plunge using this measurement technique. I also suggest you do the checks on resistive loads down on some HF frequencies to see how their measurements compare (again remembering that any lead length introduces inductive reactance that can't be calibrated out on the MFJ analyzer). What kind of surprised me in your video is how flat the SWR looked when measuring your J pole using your two different VNA's, and that made me just as suspicious as the measurements being made by your MFJ analyzer. Your SWR is so flat on your J pole when measured with your VNA's that I suspect you have a lot of feedline loss which makes your SWR look much better than it really is compared with if you measure the SWR at the antenna feed point. This is a totally different topic but thought I should mention it. I no longer use my homebuilt antenna analyzer as I switched to the NanoVNA a few years ago, but the circuit topology used in the MFJ antenna analyzer can produce reasonable results as long as it's calibrated properly at the factory and not damaged but it certainly has limitations. Also the MFJ antenna analyzer can produce bogus results if used close to a nearby transmitter and sometimes this is an issue for guys trying to measure antennas down on 160 meters that live in close proximity to a commercial AM broadcast transmitter. Just FYI, Don

I have a 259C myself. it is actually a very handy tool around the bench. Yes, the battery requirements are the biggest complaint I hear about these analyzers. You can install rechargeable batteries. I usually use it inside so I just plug it into 12vdc most of the time. The assembly us a bit strange, tganjs for showibg that. At least it wasnt assembled by lil old lady in china...lol

I have offen wondered if when a outside power supply is connected...if the wire on the ground side will effect the opperation?

I just got the mfj -259D got the wall charger and the batteries I put batteries in and turned it on and nothing happened plug the wall charger in to the unit and it turned on do I need to change the batteries first ? Or maybe I got a bad set of batteries 😮 and will the unit charge the batteries it self ?

Great stuff!!! Ive got a feeling.....And i'm sure it's already started.....when everybody sees how great these nano vna's work, and how much more they can do..........these antenna analyzers will come down in their outrageous prices or become obsolete!!!

I got mine from a friend was given to me, same model 259 was not working, replace the LM324(mounted on it's socket) wish turn out that was bad, it's work back again, greetings you all

Once I got my NanoVNA, I knew I'd ever use this thing again -- I'm glad you're having fun with it. I'd love to see what you think about using this head-to-head with the NanoVNA to see what is better -- I have a feeling it will perform better on HF than VHF. I think the 2-meter band was an afterthought for it. (And you're the person who turned me on to the NanoVNA! I bought one after seeing your video.)

You need to press gate and mode at the same time to get to the advance feature just a little more information on calibration

Just watched & this video IS so Informative. Thx So much for making This video !!...Don't own the MFJ but do have 2 NanoVNAs that Do measure Identical & seem Reliable that I can Trust...Your 259B measurment is "Kinda sorta" usable Accurate (better than Nothing) & I wonder how Reliable the Other 259C & D and 269 models (as Received out of Box) are at typical Ham Vhf & Uhf antenna measurements ?? Having to send it back for a "Factory Calibration" Dosen't cut it !! USA made Budget grade meters have always been given a "Pass" expectation at the Upper Frequency range but the Really Low Cost NanoVNAs seem Extremely Consistent & Reliable in comparison....Plz keep doing your Style of Helpful videos your calm,casual & Just Enough Math Theory Level is Best for me I've Ever seen !!! Thx...

Hey! One question. These test leads for the PSU looks cool! Where did you bough them?

interesting. I got one of these things used, after buying my Nano, and I do see differences. I have an earlier all analog version (208?) with no freq counter, and just one SWR meter. I'll have to compare all three. Whatever I find, I won't be taking this apart! BTW I ALWAYS use an antenna tuner!

Maybe the frequency is off. How does the VNA look if you zoom out a bit? You could also verify the frequency counter at 140 MHz if you have a waveform generator.

Hi, I was having a high regard for the analyser for a long time until recently. I was shocked to see the extremely wide bandwidth of any single frequency you are tuning in. Yes, suppose you tune in on 7100 kHz; the oscillator outputs not only 7100 kHz but also 10-15 kHz +/- . I have been wondering how people have been tuning their antennas and proudly declaring that their antennas are 1:1 spot on 7100 kHz. And apart from this they're able to say that the 1.5:1 SWR of their antennas happen to be 80 or 100 kHz on either side of the centre frequency of say, 7100 kHz. You may want to zero beat a single frequency (7100 kHz) on your radio receiver. It's wide, too wide like 20-30 kHz on either side. It has never been the "holy grail" test instrument in the amateur radio world; people have just believed so much that they have not inclined to test the authenticity of its performance. So, please try to check the single frequency out put on this pathetic machine.. 🙄😀 De VU2RZA

I wanted one of these when I was a kid too 😂

So? No answer?

Criminal mechanical assembly, all to common.

I have one, I'll have to dust it off and see how it compares to my tinyvna

not the first piece of MFJ equipment that I used that was faulty ....

It,s MFJ what would you expect.

Removing board with standoff wont work but removing standoff first than take board out.

I'm a bit suspicious of these measurements. Measuring return loss and rolloff versus SWR and resistance do not seem to be measuring the same thing. A J-pole is *very* frequency dependent, basically a half wave antenna on top of a quarter wave transforming section that is in turn very sensitive to nearby metal. At resonance the coax cable is unlikely to participate in the antenna system, but off resonance the coax starts to participate in the antenna system and that's probably why the MFJ is showing two dips. Naturally, the MFJ analyzer (as also the NanoVNA and HP) is also part of the "system". This can be discovered by inserting a short stub into the feed line and see if it makes a difference. In resonance, it won't change things inserting a few feet of feedline; but if you have some standing waves on the coax, adding a few feet can change things significantly. Where that's the case the coax is definitely part of the antenna system and that's generally unwanted. Since the coax becoming part of the antenna system is particularly true for half-wave antennas, and a J-pole is a halfwave antenna, it follows that the coax *could* easily become part of the antenna system. Consequently I *expect* analyzers to show a complex frequency to swr and reactance plot; it is the simple rolloff that seems suspicious in this case.

Mr. IMSAI Guy, After viewing your video on the MFJ-259B I write to inform you that by desoldering the antenna connector accuracy of the instrument can no longer be guarantied and that regrettably you must now consider the warranty on the product as null and void. Should you wish to attempt self recalibration of your instrument unsupported instructions are available on our website but unfortunately only in the Kyrgyz language (as opposed to Fuyu Kyrqyz language). Be advised that tens of thousands of dollars worth of test equipment is required and that the procedure must be performed exactly as written lest you let the magic smoke escape. Should that occur, well then, consider the warranty as null and void (Oh, I already said that) and send lots of money to us for a deprecated replacement unit. Sincerely, your antenna analyzer team.

LOL. Oh look ! lots of "stuff" in there... there is a 2nd menu. hold diwn both buttons for 3 seconds..

I’ll bet 90% of the price was based on the lack of manufacturability. What a manufacturing nightmare!

I owned one and also two nanoVNAs. The MFJ readings were consistently different on all frequencies compared to the VNAs and the VNAs were very consistent to each other after calibration. I called MFJ and they told me I need to send it back for calibration which was too costly and time consuming. I returned the MFJ and received a refund but was still out the return shipping. A generation of Hams has falsely placed faith in these analyzers that are essentially worthless.

They don't call it "Made From Junk" for no reason... 😅

The MFJ's ae known for poor freq calibration .....

MFJ was a big delusion for me. Since my friend had one of those I had the chance to use and compare to a real instrument. It doesn't look professional and it doesn't measure professional. It does look professional in the price though..😄

$310.00

Mighty Fine Junk falls through again!!! I will NEVER EVER buy anything from them ever again!

Made From Junk

NO NO Don't open it! You will let the magic out!