Need your opinion on a tuner.

[K7NCR]

I currently have an old MFJ 969 tuner. It is the older 3KW ( ) roller tuner for 160-10m. It has the ceramic roller. I have a chance to swap it for a Johnson Matchbox, the 275 watt one. I think it would be a good move, since I run open wire feed. Any thoughts from the esteemed gallery?
Norm K7NCR

[WD8BIL]

In a heartbeat!
He who hesitates is lost!
Don't look back!
In the wink of an eye!

or as we said in Cleveland; snatch n' run!

[Jim, W5JO]

If you ever plan to run much power I would take pause.  But with  lower power the matchbox beats the hell out of any tuner with a balun to get to balanced feedline.

[WD8BIL]

Fast as your li'l feet can fly!
Damn the naysayers. Full speed ahead!
Don't let the sun go down.

[The Slab Bacon]

it depends on how much powah you plan to run, and whether or not you're using a resonant antenna or not.

The Viking matchbox is a better, more robust tuna (especially the KW model), but the rollie duck will have more "range" matching up a bad load. (nonresonant antenner)

I am currently using a homebrew tuna that is a supersized copy of the mfj tuna. It is a "T" type with the roller inductor out of a broadcast transmitter and 2 large wide spaced breadslicers. The Balun is wound on 10 t-120 cores and never even gets warm, even with a bad load and very high power levels. it fills a cabinet the size of an R-390. I had no space at the operating position for it, so i cut a hole in the wall and racked it into the wall, henceforth its name: "the hole in the wall tuner". It will load a bedspring dead flat on 160!
Chris, W2JBL, calls it "the world's largest MFJ tuner"

A tough choice, you'll have to pick the one that best fitz your situation    

                                                               The Slab Bacon

[WV Hoopie]

Since you are running open wire, it is a no brainer. A junkston KW matchbox should handle almost anything u could throw at it. It has the fast make/slow break antenna relay. Stock it doesn't do 160 very well or handle a wide tuning range.

Homebrew a big beast for 160 and QSYing up n' down the bands.

Craig,

[Pete, WA2CWA]

I currently have an old MFJ 969 tuner. It is the older 3KW ( ) roller tuner for 160-10m. It has the ceramic roller. I have a chance to swap it for a Johnson Matchbox, the 275 watt one. I think it would be a good move, since I run open wire feed. Any thoughts from the esteemed gallery?
Norm K7NCR

If you want to operate on 160, not a good move. It doesn't cover it.
If you plan to operate high power, this baby version won't do it.  I tried using this low power version with a Valiant several years ago, and on modulation peaks, I could arc this thing.  Finally gave it away to someone using a DX-40.
Although I don't have high regards for many of MFJ's antenna tuners, the one you have has the baby Matchbox beat. If you do the trade, you would be getting the lesser deal.

[K7NCR]

My antenna is the nearly folded slab bacon special, only with 120' per leg folded with 12" spacing. Some photos of the antenna are posted in my gallery, along with my tuner setup. I plan on a home brew tuner at some point, but right now with the Apache I worry about the MFJ balun.
Norm K7NCR

[ke7trp]

The others have laid it out for you.. But I agree:

Better tuner for open wire line, its balanced.

The little 250 wont take a ton of AM power. I ran a Valiant on mine with out issue. 150 watts AM.

Limited Tuning range. The matchbox is a band switched box.  Not an issue for me. If it would not tune, I hacked the feedline until it tuned all bands. 

I have three  250s and two KW versions.  I wont look back.  I have owned palstars, MFJ, Heath, and even that mega buck Bliss tuner.  I would rather have the band switched KW any day.  Simple to operate and they are balanced.

There are a few versions..  One has the built in SWR meter and requires the almost always missing  Coupler.  The other has no SWR meter.

If you get it, Open it up.  Lots of people modify these because in stock form they had an antenna Changover relay built in. They bypass this in lots of crappy ways.  The last one I opened had Electrical tape jammed into the relay.. LOL.  If you want to bypass it, Do it correctly, read the manual.

If a Guy Hotswitched it even one time, The bandswitch might be damaged. You can find new switches and used switches around.


C

[KF1Z]

Fast as your li'l feet can fly!
Damn the naysayers. Full speed ahead!
Don't let the sun go down.

You missed:  "Make hay while the sun shines"   

[K1JJ]

Hi Norm,

I would sell that MFJ tuner on e-Bay for top dollar.  Take the cash and take your girlfriend/wife out to dinner at the best joint in town.

Then wind up some copper tubing and mount a vacuum capacitor to build up a K1JJ Super Tuner...
It will take 10KW easily and can be configured quickly to tune both series or parallel feeds. 160-10M

You'll be real proud of your own homebrew tuner and learn a lot about matching antennas. I know of at least ten tuners that have been built on this BB.

Here's a few threads with descriptions and pictures:



http://amfone.net/Amforum/index.php?topic=18054.0

http://amfone.net/Amforum/index.php?topic=10989.0
http://amfone.net/ECSound/K1JJ13.htm

For additional info do a search on this BB for " K1JJ Tuner"

Good luck -

Tom, K1JJ


** Build one and get your very own  JJ/Fabio QSL card!  (good towards WAF - "Worked all Fabios" award.)

[Steve - WB3HUZ]

Strike while the iron is hot.
A stitch in time saves nine
Here today, gone tomorrow.
Order before midnight.

Fast as your li'l feet can fly!
Damn the naysayers. Full speed ahead!
Don't let the sun go down.

You missed:  "Make hay while the sun shines"   

[K7NCR]

Hi Norm,

I would sell that MFJ tuner on e-Bay for top dollar.  Take the cash and take your girlfriend/wife out to dinner at the best joint in town.

Then get on some copper tubing and a vacuum capacitor and build up a K1JJ super Tuner...
It will take 10KW easily and can be configured quickly to tune both series or parallel feeds. 160-10M

You'll be real proud of your own homebrew tuner and learn a lot about matching antennas. I know of at least ten tuners that have been built on this BB.

Here's a few threads with descriptions and pictures:



http://amfone.net/Amforum/index.php?topic=18054.0

http://amfone.net/Amforum/index.php?topic=10989.0
http://amfone.net/ECSound/K1JJ13.htm

For additional info do a search on this BB for " K1JJ Tuner"

Good luck -

Tom, K1JJ

Hows this,,,
I have an old navy tuning unit I made into my first tuner, a T with switchable output capacitance. But it never worked well on 80 due to low ind. value rollers. BUT I have 2 of the rollers and all the other assorted junk from 2 of them navy tuners,,
Maybe the 2 rollers in syc ballanced on the lines would be enough. All this in old buzzard style mil-spec parts. Mesa thinkin,,,
Norm K7NCR

[KB2WIG]

.....and they are mild.


klc

[W3RSW]

Strike while the iron is hot.

um,

"Solder whilst the hammer is cold."

      ****  Carpe diem ****

[W2JBL]

I have 275 watt matchboxes at two of my stations, and they both easily handle a 300 watt carrier and 150% positive peaks on AM with no problem. note however that this is into good antennas, miniumum 130 feet center fed on 80 meters, 50-60 feet up in the clear fed with open wire line. if you try this with a blister packed G5RV six feet from the aluminum siding of your house 20 feet off the ground you may have issues.

[N3DRB The Derb]

operators are standing by.

use these coil clips instead of JS clip leads. Clip leads R NG for tunas.

http://www.bwantennas.com/coils/coilclip.htm

[K5UJ]

I have 275 watt matchboxes at two of my stations, and they both easily handle a 300 watt carrier and 150% positive peaks on AM with no problem. note however that this is into good antennas, miniumum 130 feet center fed on 80 meters, 50-60 feet up in the clear fed with open wire line. if you try this with a blister packed G5RV six feet from the aluminum siding of your house 20 feet off the ground you may have issues.

This brings up a philosophical(?) point about tuners.   Sure you can build up the mother of all tuners that will match a coat hanger but do you want to?  Only if you want a coat hanger for an antenna.  There's a reasonable tuner range beyond which, if the tuner doesn't solve the problem, maybe something else is the problem.  It's hard to know the difference without experience but for example, someone trying to use one of those 88 foot center fed ("Cebik") dipoles on 80 meters, if the tuner can't give a match, it might be better to make the antenna longer instead of finding huge L and C values that hide the real problem.

[K7NCR]

So far its a GREAT discussion!
I'm inclined to do the swap for now.
However, I thought I had read on this site about a balun input balanced tuner design that may be something I can use my mil-spec parts on. I can use the Matchbox for now, and brew a heavier tuna to use if I increase my power or need broader matching range.
Norm K7NCR

[The Slab Bacon]

This brings up a philosophical(?) point about tuners.   Sure you can build up the mother of all tuners that will match a coat hanger but do you want to?  Only if you want a coat hanger for an antenna.  There's a reasonable tuner range beyond which, if the tuner doesn't solve the problem, maybe something else is the problem.  It's hard to know the difference without experience but for example, someone trying to use one of those 88 foot center fed ("Cebik") dipoles on 80 meters, if the tuner can't give a match, it might be better to make the antenna longer instead of finding huge L and C values that hide the real problem.

Rob,
      Sometimes ya just gotta do what ya gotta do. Its ALWAYS better to build with overkill so you dont have to worry about it later. If you are gonna run 500w, design and build everything to handle 1000w. This way you incorprate a large reliability factor, and that good "cant hurt it, its bulletproof" feeling. Not to mention minimise losses.

I am running a 60' flat top for the lower bands (160. 80. & 40) Not because I want to, but because I have no other choice. Many of the people here have been to my house and seen my dilema. I run a lot of power and a short antenna - the ticket for RF disaster!! I have melted and smoked commercial tunas, had burning and exploding baluns etc.

I finally got tired of playing around with stuff I knew would fail, and designed the whole system to be "bullet proof". Everything is designed to take the abuse of running a lot of power into a short antenna. with only a 60' antenna, I put out a signal that is right up there with many or most of the "tall ships" on 75m. I figgered out how to make it work for my specific application. NOTHING EVEN GETS SLIGHTLY WARM ! ! ! ! Nothing getting warm means minimal losses and most, if not all of the rf energy is going to the antenna instead of being dissapated heating things

Sometimes you just gotta do what you gotta do. The real deal is to pick what application works for YOUR particular situation.


                                                        the Slab Bacon

[K5UJ]

Rob,
      Sometimes ya just gotta do what ya gotta do.

Slab, I agree but if ya got the room....full sized ant. when possible.  I used to use one of those 88' dipoles on 80, what eventually came to be called a Cebik dipole, with my tuner and 600 ohm feed & thought it was great.   Didn't think I could fit a full sized 80 m. dipole.  Never thought about putting one up and letting the ends dangle down until K1JJ and HUZ recommended it.  So my point was don't use a tuner to limit yourself any more than necessary, but of course every situation is different.

73
Rob

[Steve - WB3HUZ]

Good points Rob. Every situation is different. In general you should put up the best (longest, highest) antenna you can fit (this may mean zig-zag or ends hanging down, etc) into your space, then build an appropriate tuner to suit,

[W7SOE]

I would sell that MFJ tuner on e-Bay for top dollar.  Take the cash and take your girlfriend/wife out to dinner at the best joint in town.

Then wind up some copper tubing and mount a vacuum capacitor to build up a K1JJ Super Tuner...
It will take 10KW easily and can be configured quickly to tune both series or parallel feeds. 160-10M

That is one kewl tuner!  It would look so sharp on the shack wall.  Maybe I will build one up and ditch the JV KW matchbox.

Rich

[W1RKW]

T,
How did you get such a nice even wind on the coil?  I'm reworking my tank coil on the 813 rig but cannot get what appears to be a almost factory look on the coil.  Just wondering what technique you used to get such a nice wind.
B

Hi Norm,

I would sell that MFJ tuner on e-Bay for top dollar.  Take the cash and take your girlfriend/wife out to dinner at the best joint in town.

Then wind up some copper tubing and mount a vacuum capacitor to build up a K1JJ Super Tuner...
It will take 10KW easily and can be configured quickly to tune both series or parallel feeds. 160-10M

You'll be real proud of your own homebrew tuner and learn a lot about matching antennas. I know of at least ten tuners that have been built on this BB.

Here's a few threads with descriptions and pictures:



http://amfone.net/Amforum/index.php?topic=18054.0

http://amfone.net/Amforum/index.php?topic=10989.0
http://amfone.net/ECSound/K1JJ13.htm

For additional info do a search on this BB for " K1JJ Tuner"

Good luck -

Tom, K1JJ


** Build one and get your very own  JJ/Fabio QSL card!  (good towards WAF - "Worked all Fabios" award.)

[K1JJ]

T,
How did you get such a nice even wind on the coil?  I'm reworking my tank coil on the 813 rig but cannot get what appears to be a almost factory look on the coil.  Just wondering what technique you used to get such a nice wind.
B

B,

That first tuner was made by KA2J. The second shot is one made by Fred/MOP.

Maybe KA2J will let us know how he wound that coil so perfectly.

I generally use something like a paint can as a form to wind it. Though, he obviously threaded it thru some Plexiglas to give it some good support.

 T