20 or so years ago I ran an almost identical MFJ-945E mobile on 11 meters, I used an RCI 2950 into an Elite Line TX2250 (about 200 watts) into the 945E Tuner and the antenna was a 102 inch whip on a pickup. Tuned fine from 26 to 28 Mhz and never any arcing inside.
My guess for the blue wire might be that it is a point to attach a scope probe through the hole in the back to be able to monitor your signal on an oscilloscope. However the blue wire is attached to ground, isn't it? I think for 20$ you did get a nice little tuner or atleast some nice variable capacitors and connectors.
741 always comes through ! Bought a 945E first video that came up ! Thanks Rob for the quick video ! That mystery hole port may have been for an off board RF sampler ? Seems to be a hole for BNC... 73 WA2KGG
That’s a common place for arc over from running to Much power. I’d say probably had a 10:1 on 80 with mismatched coax length and it arced over. Adding that long screw would not help though ? Might want to remove that screw.
$20 is a decent deal considering the tuner seems to function as it should. Too bad it had been butchered up. Sometimes these tuners can arc if the wrong inductor setting is selected and they throw high power to it. Some say that you are supposed to set the transmitter and antenna to zero and adjust the inductance for lowest SWR first, then fine tune the antenna and transmitter controls for lowest SWR. I have the MFJ-945E and have never had an arcing problem at 100 watts using this system of tuning. These little tuners are great to have around!
One word of caution. This is a T network and there is more than one setting that will give a 1:1 or low SWR. I think you want to tune for the minimum SWR corresponding to the highest value of the output capacitor. The previous owner may not have known that. I prefer L networks as there is only one combination of two controls that give you a 1:1 SWR. The coil is in series and if working into an impedance greater than 50 the capacitor is at the antenna end of the coil, but when working into less than 50 ohms the capacitor is on the transmitter side. Simply swapping the input and output cables is used on some L network tuners without an extra switch.
@@SevenFortyOne I asked the vendor, DX Engineering. They said sometimes there are problems, but also true of any company. A radio friend don't buy unless you can test it as soon as you get it. It may be that MFJ had a bad period. I know that is true about power supply fans, because I asked them. They said they changed fan vendors. If there were too many ongoing problems their dealers would probably drop them.
If you have a high impedance feed point the antenna the tuner will act as a voltage transformer to a *higher* voltage. Now crank up the TX power and you can end up creating an arc in the tuner!
And some idiot at the factory decides that a TRS connector is good for DC. That would the first thing removed and replaced with a proper DC input connector. Otherwise, with a bit of a clean up, it is quite a good little unit.
I remember you showing it to me when you bought it. I'll speculate that the mod was done to tune for 60 meters? I say that because 60 meters wasn't around yet when it was made.
Hi Rob, Looks like you have a winner. Did you locate an interior view of a stock tuner to see what might have caused those scorch marks? You and the family stay safe. 73 WJ3U
People like to hard knock MFJ. But they are one of the few companies still innovating. They produce products that customers ask for. And personally, I've never seen the inside of any MFJ product that wasn't pristine. YMMV.
You stole it, it is worth 20$ in parts. Rob, I'm having issues with sdr2, I hooked up to a new computer, and whatever software I load I receive an error {out dated} and it shuts down. Hmm. What are you running?
The word "budget" and ham radio don't go well together. Ham radio is a crazy expensive hobby up there with horses, racing, classic cars, and model trains.
Ham radio is cheaper than most of the things on your list....by a lot. You can get started for under $100 with a cheap HT. A pretty decent HF home station can be out together for under $2,000 if you buy everything brand new; half that or less for used gear.
20 or so years ago I ran an almost identical MFJ-945E mobile on 11 meters, I used an RCI 2950 into an Elite Line TX2250 (about 200 watts) into the 945E Tuner and the antenna was a 102 inch whip on a pickup. Tuned fine from 26 to 28 Mhz and never any arcing inside.
My guess for the blue wire might be that it is a point to attach a scope probe through the hole in the back to be able to monitor your signal on an oscilloscope.
However the blue wire is attached to ground, isn't it?
I think for 20$ you did get a nice little tuner or atleast some nice variable capacitors and connectors.
741 always comes through ! Bought a 945E first video that came up ! Thanks Rob for the quick video ! That mystery hole port may have been for an off board RF sampler ? Seems to be a hole for BNC... 73 WA2KGG
possible the hole held a micro toggle switch to put the tuner in by pass...i did this with my tuner
I was thinking exactly the same thing. But I wonder why anyone would un-do the mod. Maybe they were stranded and needed the switch...lol!
!♡♡♡ it was fun looking inside this thing with you :) and at a fabulous price! Appreciate it hamFam
Previous owner was doing some Doc Brown Flux Capacitor mods !
That’s a common place for arc over from running to Much power. I’d say probably had a 10:1 on 80 with mismatched coax length and it arced over. Adding that long screw would not help though ? Might want to remove that screw.
I like MFJ products. Back when I was into SWL I had an antenna tuner and preselector.
$20 is a decent deal considering the tuner seems to function as it should. Too bad it had been butchered up. Sometimes these tuners can arc if the wrong inductor setting is selected and they throw high power to it. Some say that you are supposed to set the transmitter and antenna to zero and adjust the inductance for lowest SWR first, then fine tune the antenna and transmitter controls for lowest SWR. I have the MFJ-945E and have never had an arcing problem at 100 watts using this system of tuning. These little tuners are great to have around!
Good tip, thanks!
Very interesting tuner... Not bad for the price!
Video length 7:41. Nicely done sir!
One word of caution. This is a T network and there is more than one setting that will give a 1:1 or low SWR. I think you want to tune for the minimum SWR corresponding to the highest value of the output capacitor. The previous owner may not have known that. I prefer L networks as there is only one combination of two controls that give you a 1:1 SWR. The coil is in series and if working into an impedance greater than 50 the capacitor is at the antenna end of the coil, but when working into less than 50 ohms the capacitor is on the transmitter side. Simply swapping the input and output cables is used on some L network tuners without an extra switch.
Are you hearing anything about quality problems with MFJ tuners?
Mfj is notorious for quality issues
@@SevenFortyOne I asked the vendor, DX Engineering. They said sometimes there are problems, but also true of any company. A radio friend don't buy unless you can test it as soon as you get it. It may be that MFJ had a bad period. I know that is true about power supply fans, because I asked them. They said they changed fan vendors. If there were too many ongoing problems their dealers would probably drop them.
don't know who has poorer quality control MFJ or the HAM that "fixed" it. Some ham's could screw up a ball bearing. KC8ZUL
If you have a high impedance feed point the antenna the tuner will act as a voltage transformer to a *higher* voltage. Now crank up the TX power and you can end up creating an arc in the tuner!
And some idiot at the factory decides that a TRS connector is good for DC.
That would the first thing removed and replaced with a proper DC input connector.
Otherwise, with a bit of a clean up, it is quite a good little unit.
From 80-10m it's a fine working little compact tuner. But absolutely not usable for 160m.without giving it a modification first.
Good stuff Rob, like a detective
I remember you showing it to me when you bought it. I'll speculate that the mod was done to tune for 60 meters? I say that because 60 meters wasn't around yet when it was made.
You might be on to something! I'll have to check it out
I thought that too. But I wonder why anyone would un-do the mod. Were they desperate for the switch???
Looks like Old Doc Brown modified that to tune his flux capacitor.
Hi Rob,
Looks like you have a winner. Did you locate an interior view of a stock tuner to see what might have caused those scorch marks? You and the family stay safe. 73 WJ3U
I couldn't find one for this model, just outside shots.
thanks, Another fantastic video 73 from kb2uew
Nice find.
Look Like you got a good deal if it does what it's supposed to do and you got it at a low price then enjoy 73s from w30j.
Impressive you were able to "Steal" this Hamfest find!! What a BARGAIN!! (Still looking for "741" license plates)
is MFJ really that bad?
No, someone modified this tuner
@@SevenFortyOne I just seen a lot of folks fussin about it mfj in comments. Made me wonder
Its a MFJ, most likely its factory burns, solder blobs, and the normal hacks.
People like to hard knock MFJ. But they are one of the few companies still innovating. They produce products that customers ask for. And personally, I've never seen the inside of any MFJ product that wasn't pristine. YMMV.
Just more M. F. J
You stole it, it is worth 20$ in parts. Rob, I'm having issues with sdr2, I hooked up to a new computer, and whatever software I load I receive an error {out dated} and it shuts down. Hmm. What are you running?
I use sdruno on a 2 year old windows 10 computer. Give me a call sometime if you want to try and figure it out, maybe I can help
@@SevenFortyOne Thanks for the offer, I think I've used it 3 times in 3 years. lol. what times are good if I do call?
Tuner 🐟
👍🏻
The word "budget" and ham radio don't go well together. Ham radio is a crazy expensive hobby up there with horses, racing, classic cars, and model trains.
Ham radio is cheaper than most of the things on your list....by a lot. You can get started for under $100 with a cheap HT. A pretty decent HF home station can be out together for under $2,000 if you buy everything brand new; half that or less for used gear.
I wouldn't buy anything used, especially for 20 ,then hope for the best when I attach it to my 12k rig .....
If you can afford a 12k rig I wouldn't expect you'd be shopping for gear at a hamfest or looking for a budget tuner in the fist place.