Hidden Features of the MFJ-948 + Setting Up Your ATU

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We take an in-depth look at one of the world's most popular ATUs. It has some features which are not immediately obvious. Get yourself a coffee or cup of tea and watch Peter G3OJV, as he takes you through the features, and shows how to get the best out of this product. .

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Опубликовано:

10 фев 2021

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Комментарии : 82

@lorrainemilford6157 Месяц назад

Thank you Peter for that informative video; I now know why there is a tuned and bypass on my 949E.

@tonypoloney8721 3 года назад

Excellent video, as always Peter. I purchased one from your company before Xmas. It works a treat and is a great addition to my growing hobby.

@watersstanton 3 года назад

Great to hear! 73 To you Tony. de Peter

@robbsanderson3572 2 года назад

I just ordered a MFJ 948 antenna tuner. After watching your channel.?Thank you so much for the step by step instructions. I was thinking of getting the more expensive one. But went with this one. The most I run is 100 watts on HF with my Kenwood TS 180 S. 73s Rob, wa2fmh.

@runabout44 3 года назад

Nicely presented Peter, thank you. Especially appreciated your advice regarding switching in and out on either end of 80m. I read an interesting paper once that explained how in one exception, the atu could justifiably claim to tune an antenna. Where the balanced line feeder forms part of the radiating element, the unit is influencing its physical radiated length, not just its impedance. Or something like that. Still, it’s kinda fun to see people get uptight over nomenclature.

@watersstanton 3 года назад

Great to hear from you. Yes have read all kinds of views. Basically if you can interface the ladder line with a balun and then on to the ATU andt works, it kind of proves the device does not tune the antenna but matches it. 73 peter

@andy8315 3 года назад

Another great video Peter thank you

@watersstanton 3 года назад

Glad you enjoyed it 73 Peter

@andrewsturch Год назад

Thank you for another great video!

@watersstanton Год назад

Our pleasure!

@Touchatout59 6 месяцев назад

Bonjour Peter, Excellente vidéo bien détaillée. Félicitation et merci

@watersstanton 6 месяцев назад

You are very welcome.

@donbernat2483 3 года назад

Peter: As usual, an excellent video. I’m no spring chicken but a rather a relatively inexperienced ham. I have learned so much through your informal style. I realize that this is somewhat marketing related, but that’s fine. Your video always puts the needs of the viewer first and the marketing is extremely subtle. If I were in the UK, I would certainly purchase through your store. Again, thanks for the time and effort put into these videos.

@watersstanton 3 года назад

So nice of you. Great to hear from you Don. Much appreciated. Take and 73. Peter

@quintinlourens2674 3 года назад

Very nice. I dont own a tuner, my antennas are resonant where i want them to be, but after watching this video im thinking of investing in one, but i need one that can handle more power. I want it for the open feedline

@carl-gunnarhillefors7612 Год назад

THANK YOU AGAIN PETER! USE MFJ969 MFJ962D AND LDG Z11 AND LDG PRO-200II. YES MANY THINKS THEY C A N LOWER SWR OM A NONRESONANT ANTENNA F EX G5RV (ZS8BKW ETC) WHICH IS PRIMARY FOR 20M BAND. I WOULD USE A VERTICAL 9.1m OR A LOOPANTENNA FOR 80M (83,0m OR 273 feet)). FOR 40M/15M (42,25 m) WORKS FINE IN 10M LOW /HIGH AS WELL AS 6M THAT WAS MY COMMENT IN ANTENNATUNERS! I SURELY ENJOY YOUR G3OLV DIFFERENT VIDEOS. I HAVE TP LEARN MORE AND YET MORE! 73s de Gunnar sm6oer

@AdamosDad 3 года назад

I have a 300 watt MFJ-945E and a 600 watt MFJ-944B Intellituner, for some reason there are tuner snobs that are old hams, that make fun of or look down on them. As a new ham of a little over a year I think they work quite well. Thank you for this review. 🎙73's kd9oam

@watersstanton 3 года назад

Great to hear from you. 73 Peter

@needhelp2453 3 года назад

Thank you, very help.

@watersstanton 3 года назад

You're welcome!

@IZ0MTW 3 года назад

Hello Peter, I follow you with lots of interest, always nice contents. I own the 949E, pretty much the same unit but with an internal dummy load. Another hidden feature that I’ve used successfully is to use the “tuned” side of dummy load and unmatch on purpose to a resistive value like say 25 ohm to check that you get 2.0:1 swr in case you need to check an external meter or the radio’s meter. Best 73 and hope to meet on air! Diego

@watersstanton 3 года назад

Many thanks for sharing. 73 Peter

@avaughan585 2 года назад

Great idea, I might use this when I get mine

@dericksherwood3611 3 года назад

Well presented and informative Peter as usual, enjoyable video on the ATU, nice to see it in action with its features illustrated and explained clearly by yourself. Derick. G1AEG

@watersstanton 3 года назад

Glad you enjoyed it. Many thanks Derivk. 73 Peter

@TonyLing 3 года назад

Hi Peter, thanks again for another fine video. 4:22 The power button seems to me to have a little more to it than just meter illumination. It you have a flat, or absent internal battery, the ON/OFF switch appears to activate the meter, but it is actually giving a low reading on the forward meter. Some current passes from the SWR bridge through BE of the transistor, but naturally, without voltage at the collector, the current through the emitter is attenuated by the forward Voltage drop.

@watersstanton 3 года назад

There is no internal battery option in the sample I have. Peter

@adam-g7crq 3 года назад

Hi Peter thanks for another interesting video, you briefly mentioned end feed wire's and the need for a ground, I live in a block of flats and use a end fed wire and because of the distance down to ground I use an artificial ground there's a lot of confusion around artificial grounds maybe you could do a video explaining the need for some of us to use such grounding system, many thanks for the video Adam G7CRQ

@watersstanton 3 года назад

Hi Adam, OK will keep that one in mind. 73 Peter

@tonyturtle5805 3 года назад

thanks for video !!

@watersstanton 3 года назад

You are welcome!

@Raenman66 3 года назад

Thanks Peter. Never thought of using the FM for tuning. I'm still plodding along with my Heathkit SA-2040 roller inductor tuner and MFJ-870 meter. Keith KB2LDM

@watersstanton 3 года назад

Hi - I had a number of Heathkit products. They were good in their day. 73 Peter

@jeromegrzelak8236 3 года назад

fm in the usa is 28 mhz never tx fm go to am kg6mn

@Raenman66 3 года назад

@@jeromegrzelak8236 Good to know. Didn't think that one through. Thanks. kb2ldm

@Tommyr 3 года назад

Very good video! I have the MFJ 969 tuner. Didn't work at first due to cold solder joints and a dirty roller inductor but a quick touch up and it was back in shape. They need to really fix their quality control. I like MFJ otherwise.

@watersstanton 3 года назад

Thanks for sharing. 73 Tommy

@bigjoes999 3 года назад

Excelente muy bonito video

@stuart0604 3 года назад

Thanks Peter I ordered one, I currently have an Mfj rf switch so that I can split my antenna between my SDR play an d the transceiver, I'm assuming I can just put the tuner between them so my antenna will go to the tuner then the tuned feed to the RF switch ? Thanks again

@janvelter3253 8 месяцев назад

Thx for this nice video review Peter ;) I do still have a question. Is it ok to use this or another tuner on an EFHW antenna with a 49:1 transformer to get non resonant bands tuned ?

@watersstanton 8 месяцев назад

It does work, but I suspect there is a significant loss in the 49:1 - try it

@tombaffa9374 3 года назад

TNX Peter

@watersstanton 3 года назад

Thank YOU Tom

@avaughan585 2 года назад

Hi, great video. Just a question about transmitting a carrier. I know that you can use FM or AM mode, or indeed just whistle into the mic on SSB mode. However, the Yaesu FT450D has a hidden feature that you can custom program into a a button to check SWR. When you press it, it supposedly transmits a 5W carrier to show you the VSWR as measured by the radio. I use it all the time with the built in AMU. I haven't tried it with an external tuner because I don't yet own the MFJ Tuner, but could I use this programmed key to tx a carrier rather than keying the mic, and thus proceed to find a match on the MFJ Tuner? If it works, it would have the added benefit that I wouldn't have to remember to set the RF Power. I might forget one day that the power is set to 100W

@watersstanton 2 года назад

Many thanks for the additional info. I am sure others will be interested. 73 Peter.

@shartne Год назад

I made an antenna from different antennas trying to make a new Imax out of miss matched parts. The Imax is 24 foot originally. I used a bottom imax section 8 foot then attached a Atron 99 section that was shorter 5 foot 8 then I put a stainless steel whip on the top 8 foot 6 inches. Any way it turned out to be a length of 22 feet 2 inches. I know its a little short of 24 foot. Can i use the antenna tunner to match it to my 11 meter cb radio. I suppose it will work but will there be a disadvantge to using the miss matched parts. or basically a shorter antenna ? A new Imax antenna is over 200 dollars. I read someplace that it would a shorter band witdth. It would be better suited for a lower band. I guessed that if it matches it dont matter. I have heard of people using rain gutters for an attenna or even a 500 foot wire that goes around the whole property. I dont know it my mismatched antenna will work using an antenna tuner?

@roger5809 3 года назад

Very good explanation of using an ATU, thank you. I do have a question though. I understand you are tuning at low power as should be, but being on the CW portion of the band is tuning with a broad FM signal appropriate as opposed to using a key with CW tone? AE0TE

@adam-g7crq 3 года назад

Good point, I flick over to rtty on my 7300 and then press the transmit button.

@watersstanton 3 года назад

Hi Roger, with FM I am not modulating so it is simply a silent carrier wave sugnal. 73 Peter.

@roger5809 3 года назад

Apologies, I guess I should have known this but didn’t. I have never used FM or AM so have not looked into it. Again you have taught me something new!

@Testalan1212 3 года назад

@@watersstanton Apologies, just tested and FM does inded just send a carrier.

@soggytablet4852 3 года назад

Hello from Canada Peter. Is there any benefit to buying a tuner with a Roller inductor vs one with a tapped inductor. I recently built a doublet fed with 450ohm balanced line. The ATUs in my rigs struggle a bit. I only run 100w, so is the cost of a tuner with a roller inductor justifiable? Cheers (David VE3VID)

@mikeramsey9747 2 года назад

Good video, my question is do you prefer an auto tuner or a manual tuner?

@watersstanton 2 года назад

That deserves a video to answer the question .

@stevewarren4292 3 года назад

No HF station is complete without an antenna tuner. If you haven't used one get one and try it. You'll never want to be without one again.

@nr3rful 3 года назад

Great.....never used the "peek" function....thanks

@watersstanton 3 года назад

Glad it was helpful!

@thomasmaughan4798 3 года назад

If you moved the pointer any faster it might enter and leave the scene entirely between frames! That would be interesting.

@davidw3gzs55 3 года назад

Hi, I believe you may have the "jumper Wire" contingency incorrect at 7:50. You say the jumper is necessary when using the random wire. However, the manual indicates the opposite as per the following: "4. A random wire (longwire) antenna may be connected to the five-way binding post marked WIRE. See the ANTENNA HINTS section for detailed suggestions on bringing a single wire feeder into the operating position. MFJ-948 Versa Tuner II 5. A balanced feedline (twin lead, open wire, or twin-axial line) may be connected to the two binding posts marked BALANCED LINE. Connect a jumper wire from the WIRE binding post, as indicated by the dotted line on the MFJ-948, to one of the BALANCED LINE posts. This connection activates the internal 4:1 balun. " This practice matches the performance on my MFJ tuner which doesn't work properly on balanced line without the jumper. Hopefully, I have got this sorted properly but let me know if otherwise. This antenna "matching network" is very useful and effective. Didn't know about using the dummy load circuits as alternative antenna connections. One last item: Do you know of any tuner with similar features that uses a Pi network? Thanks and 73, David W3GZS

@watersstanton 3 года назад

Hi David, yes you are right. The rear panel markings show the jumber but don”t make it clear that it is for the balun. I made the assumption that two terminals together and marked balun were just that! Thanks forthe correction. 73 Peter.

@1crazynordlander 3 года назад

Is there a manual tuner out there that will handle more than 300 watts? Thanks for sharing.

@stevewarren4292 3 года назад

MFJ makes a 1.5 KW version of this tuner. I think it's model number 969. Check their catalog. There are several companies that make KW tuners with and without meters and other features.

@1crazynordlander 3 года назад

@@stevewarren4292 Thanks! I appreciate this information.

@g4jnw 3 года назад

Like the "hidden" features, i have an MFJ one and have been using for ages is the MFJ-949E and i use it with my IC-7300 too, the only difference i can see between the one your reviewing is my old 949E has a built in dummy load and thus does not have the dummy load or 3rd antenna socket.

@watersstanton 3 года назад

Hi Les, yes the load is the only difference. 73 Peter

@ianharling9569 3 года назад

Hi Les...I have the same model as you and I'm very happy with it.73 G7HFS/PA3IKH

@nr3rful 3 года назад

can you adjust a roller inductor with transmit power on ?

@watersstanton 3 года назад

Yes because the contact is in constant connection with the coil. 73 Peter

@Pioneer936 3 года назад

Just maybe, it's called a tuner because it does tune an antenna system electrically to resonance

@watersstanton 3 года назад

No it matches.

@Pioneer936 3 года назад

@@watersstanton a conjugate match electrically tunes the antenna system to resonance by adjusting the capacitive and inductive reactances to zero

@ianharling9569 3 года назад

Good video Peter.I have the MFJ -949E.I also have a MFJ-16010 L match radom wire unit but the rotary inductor switch has failed.Do you know if spare parts are available in the UK or should I contact MFJ directly? Any advice would be appreciated if possible? 73 G7HFS/PA3IKH

@watersstanton 3 года назад

Hi Ian, if you are happly to put switch in yourself MFJ will send one direct to you. 73 Peter.

@ianharling9569 3 года назад

@@watersstanton Thanks Peter yes that's fine so I will contact MFJ directly.73.

@nickaxe771 3 года назад

Thankyou for that Peter. I wonder...I have an MFJ 941E....when I tune at low power.....and get a perfect 1-1 match....I always find the SWR goes up quite a lot as I increase the power out from my radio after the initial tune up. I then end up tweaking the controls of the tuner with the radio at higher power....this worries me....should I be doing what I do....in tweaking at higher power. My email is correct in QRZ if anybody would like to comment. My antenna is a 57mt long doublet fed with 450ohm ribbon....to a 1-1 current Balun. Nick 2E0LPL

@watersstanton 3 года назад

This is usually a metering problem. Many VSWR meters give slightly better readings at low power. I tend to belive the higher power readings! 73 Perer

@thomasmaughan4798 3 года назад

Yes, and you'll find that you can get 1:1 again but it requires re-tuning. A 100 watt transmitter at 1 watt not only is inefficient, but is also not the same impedance it is when at full power. I can think of two reasons for it; for a brief moment both power transistors or MOSFETS are OFF at the crossover and this will change impedance. Also, MOSFETS in particular are capacitive and when "off" manifest some capacitance and as they go into full conduction the capacitance decreases (search on "parasitic capacitance"). "CGS is the capacitance due to the overlap of the source and the channel regions by the polysilicon gate and is independent of applied voltage. CGD consists of two parts, the first is the capacitance associated with the overlap of the polysilicon gate and the silicon underneath in the JFET region. The second part is the capacitance associated with the depletion region immediately under the gate. CGD is a nonlinear function of voltage. Finally, CDS, the capacitance associated with the body-drift diode, varies inversely with the square root of the drain-source bias." www.infineon.com/dgdl/mosfet.pdf?fileId=5546d462533600a4015357444e913f4f As you can see, MOSFET powered transmitters change capacitance during EVERY cycle! If your cycles are mostly "off" (that is to say, running at low power) then your capacitance will be relatively higher.

@Pioneer936 2 года назад

Nick because the tuner tunes out the reactance within the system not the swr, the feedpoint mismatch is still there so any increase in power the ratio of the power to the reflected power increases and so requires further adjustment of the tuner