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- เผยแพร่เมื่อ 14 ต.ค. 2024
- This is a redo of a previous video that got corrupted, and has been deleted, it's not exactly the same, but it's close enough. A quick look at the MFJ945E 'mobile' ATU. Although it's called a 'mobile' ATU it can be used portable or at home, it just doesn't have the balanced or wire output connections. Being a 'mobile' tuner it should be happy with small antennas. You can re-align the Transmitter and Antenna knobs to the correct positions (10 being maximum capacitance, not 0) by rotating the knobs 180 degrees on the capacitor shafts, as suggested by Roger below.
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Maybe the MFJ assembler simply installed the capacitance knobs 180 degrees off orientation?
I just received my new 945E today and it has the capacitance knobs backwards also. Very easy to set them up correctly as I suggested, by backing off the set screws and rotating knobs 180 degrees. Do it with cover off to ensure precise alignment.
If only all electronics were that easy to correct haha.
capacitor shafts are round.. reset knows 180 degs and it matches instructions. carry on smartly N6DL
Just had one delivered today. One of the variable capacitors has played in contact for a quarter of a turn
The instructions are not wrong, the knobs are 180 degrees off.
CORRECT BAD QC MFJ
Thank you so much for clarifying max inductance is 0 not 10 , best 73 :-)
Thanks Phil. Note: it's the capacitance that's at max at 0, not the inductance. 73
VK6CS
Oops once again thank you for the correction, tbh, I've only had it two days & I'm just getting back in radio . Hope to take my foundation licence soon
Over here in the U.K. But until then I'm just gunna use 27megs & PMR 446. But once again thankyou so much , as I think I would of pulled my hair out ( if I had any ) hi, 73 de 26CT2037 :)
Cheers Phil. Good luck with your exam.
VK6CS from 26CT2037 cheers and beers my friend ,hope we can keep on having little chats do you use any VOIP's at all ,QSL ?
No, I don't use any internet radio system. I'm old school, at the moment I think it's plastic radio. However, if I get old enough to be put in an old folks home I will no doubt embrace Echolink, DMR and D Star etc.
I have two of these tuners, mobile and base station, both have same issue with knobs needing 180 degree adjustment. They handle 300W nicely though. Also, one came with a burnt out light bulb, otherwise good units.
REALLY GOOD INFORMATION,
ON MFJ- 945E
AND HOW REALLY WORKS !!!!
Thanks Fernando.
Hi once again Tony, thank's for another interesting video. Reading down through the comments I see Roger McCarty hit the nail on the head in one , so to speak. That is what I was going to say about reversing the knobs. When in the Army there were a lot of knobs I would have like to have reversed. I think I would have got court marshaled though, Hi Hi. Say no more. I think MFJ could have used a ceramic rotary switch for the inductance for not a great deal more in price wise. I did a stupid mistake myself on that by using what Maplins had on stock and ended up with a burned out switch on my own built mobile ATU. You live and learn has the saying goes. 73 de John - G0WXU.
Blimey... I can remember buying bits and pieces from Maplin. I built a few of their audio amplifier kits. I think they worked pretty well from memory, but it was a long time ago. Knobs in the workplace is not exclusive to the military as I'm sure you know, at least you were in an environment where you could put them in harms way HI. The trick with small/cheap ATUs is to never switch them with the RF power applied, and if possible cold tune them with an analyser before you apply power from the transmitter. 73 John.
hi dgreat info say not under stand after gett i get the swr correct ...i noitice the receiver i ge ts real quite not understand that what you guys think
Just curious, why not simply take the knobs off and rotate them to match the instruction booklet? My guess is there was a mistake made during assembly.
Roger McCarty Thanks for the feedback, that's a very good question... I hadn't thought of that. I have rotated my knobs so that 10 is now the maximum capacitance, now I'll have to redo my quick tuning chart. And, remember they're now correct.
give that man a cigar!!!
Well... it is amateur radio.
that it is....and boy do I feel like one most of the time...I am only a part time nerd so I have a lot of trouble with all this, I just got that Tuner yesterday in the mail so i am trying to research on how to use it, I believe you taught me enough to use it....I hope to put my antenna up tomorrow, I put the tower up today with my dual band on top at 55 feet top the bottom of that..
Thank you for those kind words. Your antenna system sounds great. I wonder what power you're planning to use?
Pretty interesting bug or feature. This is that particular case when manufacturer upgrade device without prior notice. :)
Hi, Thanks for the explanation, Mr. VK6CS, but I would like to know the part in the middle ( With green color ) about what it is and its role in the device. Have a nice day, man
It’s a circuit board that holds all the buttons and bypass switch and connects them to their respective functions as far as I can work out mate.
Regarding the cap knobs... I simply rotated those two cap knobs 180 degrees and now my 945e knobs are in synch with the real capacitance.
Same here. MFJ is notorious on wrong assembly. It seems they just attach knows without aligning them.
The best would be for one who gets this tuner to open it, set capacitors to maximum position and then align knobs to show position 10.
Very well done. I like the size of this little tuner. just picked up one at a hamfest. Planning on using it on portable and qrp use .But after I tried it . I noticed that the meter was off . and be4 anyone asked ! yes I checked it to another tuner. my q is . are there any adjustments on the board that I can correct this .??
Thanks for that. There is an adjustment but unfortunately being MFJ you have to choose which reading you want to be reasonably accurate... the high range or the low range. I chose the high range. You just have to put up with one range being wrong.
are these on the board ? I see 3 pods . thanks
I honestly can't remember. MFJ have the circuit diagram of this tuner on their website, that should show you all you need to know.
Once you get the tuning properly set, can you unplug the unit? Or is it required to be energized to work?
I apologize for not responding sooner. The tuner remains inline between your antenna and your radio, unless your antenna is sufficiently resonant on the current frequency on which you desire to work. The tuner has a bypass button to engage and disengage it from the antenna feedline, but any tuner needs to remain engaged inline when you are working a non-resonant frequency on any given antenna structure, whether homebrew or commercial.
@@craigszwed That makes perfect sense. Thanks for the update
Which is best for all around tuning and power output? More inductance? Least inductance possible? More capacitance? Less capacitance?
With a T match like this one the most series capacitance is the most efficient power throughput. I tried a few experiments and found the throughput power difference between the most series capacitance match and just tuning the usual way by initially having both caps set to mid point made negligible difference. It's also much easier to get a good match by starting with both caps set half way and then finding the best inductance, then tweaking the caps.
Thanx for the response! So, the inductance is really not a factor? You would use the conductance that requires the greatest capacitance?
With a T match like this one the most efficient power throughput will be when minimum SWR is achieved with as much as possible inductance of the coil, and as much as possible capacitance of the second capacitor marked as "antenna"! You can find more information on my web-page, which is originally written in macedonian language, but you can use google translate: www.qsl.net/z33t/antenna_tuner_mkd.html and this one: www.qsl.net/z33t/mfj-945e_antenna_tuner_eng.html
Hello Mile, could you measure the diameter of the wire but also the inner diameter of the coil? I tried to make a tuner myself. 73 de 9A6GEZ
@@TheLonesometoad If you had watched the video he already mentioned the answer to your question!
Your LC meter looks great. Where did you buy this ?
I'm VERY sorry to take this long to respond to your question!! That is the MFJ-945E model that is available from Ham Radio Outlet and many other online vendors. It is very light, handles 6M through 160M when using an appropriate length of wire. It is relatively inexpensive. I use it whenever I do portable operations, instead of using autotuners. It doesn't take long to get used to the proper and highly effective use of a manual tuner.
Thanks for the redo!
How silly of MFJ on the labeling for the tuning caps and inductor. the caps should indicate 10 to the left and 1 to the right and the inductor A B C counter clockwise. A being min inductance and K max. they have both labeled backwards.
Didn't catch the Morse code in the beginning
*SO !! THE BUTONs ARE WRONG MOUNTED (OR WHAT)*
Don't like how they put the balun in the centre of the inductor would prefare it on the back of the unit .
It's not too flash having a metal plate at each end of the coil either... but it is MFJ.
Keep up the good work!
I don't know why this comment was held for approval, I've only just seen it. Thanks Jim.
Looking at the comments and watching the video, it looks as if MFJ has a QC problem.
+Wyowanderer777 I believe they're famous for it. I've heard MFJ stands for More F*****g Junk. However, it seems to do the job for a reasonable price so personally I can take the occasional re-solder or screw-tighten.
MFJ quote RF Input to the PA and not output, hence 150W o/p not 300W. Think this is just a marketing ploy.
Sneaky.
Good video but poor choice of words in the posts " OM" Old Man!
just a quick look... 19 min...
Hi Janez... yes, I know. I regularly timeout the 2m repeaters too.
Never have I seen such an era when user manuals are so full of sloppy mistakes, typos and false statements.
A IS A NOT I
yes yes
Latest batch is pretty much junk. Used for 10M mobile, max 200W applied.
Purchased 5.2021, dead by 7.2021.