Antenna Tuner Recommendations

[W6FO]

So, I haven't had a nice base station on the air in a number of years and I'm slowly assembling a new station.  So, I've been out of the loop for awhile.

I need an antenna tuner that can handle high power and a variety of wire antennae.  My first antenna will be a 120' inverted vee fed with ladder line to the shack.  Only currently running 100W carrier but will eventually be adding a 500W to 800W amplifier.
 
Any recommendations?  Is MFJ still Mostly F**ing Junk?
 
73

JT - W6FO

[Jack-KA3ZLR-]

John,

 Hi, Yea,, MFJ is still mostly Mo Fo junk.. I edited your description for obvious reasons,Hi Hi..i hope you don't mind we try to keep and even Keel here even though we agree on MFJ..LOL ,  They do have a trail behind them.. Um, most of us here build alot of our stuff, a good balanced Tuner is easy to assemble and Tom K1JJ has a real Neat circuit he has brought on board for the group here send him a Private Message or just ask in the tech section alot of the guys would jump in to help you assemble one...

[WV Hoopie]

W6FO

I built a universal Transmatch shown in the 1976 ARRL handbook. It will handle coax, openwire, or end-fed single wire all at 2KW (PEP). Still using it today, not bad.

The design uses a dual-section 200pF per section air variable, 28uH roller inductor, a 350pF air variable, and three Amidon T-200-2 cores. I still see these parts from time to time on the e-place. By now there might be more efficient designs, I haven't seen this one develop any heat build-up with an old DX-100B or a Johnson Viking 500.

Could scan the pages if needed and e-mail.

wd8kdg,
Craig

[K1JJ]

JT,

This 50 ohm unbalanced to balanced open wire  feedline
matcher is so EZ to make and will handle mucho
power.

http://www.amfone.net/ECSound/K1JJ13.htm

I've built about five over the years-  others guys have
too.

No need for a complex split dual capacitor, balun, etc. This
matcher uses one main coil, a single floating variable cap and
an input link coil. That's all ya need.  Pre-mark the taps for
various bands and you can switch bands in seconds.

73,
T

[kc2ifr]

JT,
For whats its worth.....I use the Johnson KW Matchbox. My antenna is a 130ft. dipole fed with window line and the tuner will tune it on all bands, 80 thru 10.
Since the matchbox does not cover 160, I use a home made link coupled tuner for that band. On 160, the window line gets warm when I use my 4-1000 mono band linear but thats expected although not a good thing!! Avoid any tuner with a balun on the output if you want to use one antenna for all bands. As for MFJ.........junk.
Bill

[Jack-KA3ZLR-]

Good Day,

 I have tried alot of them, and I built Tom's and I have built a mock up of Ten-Tecs "L" network, and I have to say with out a doubt with JK's Phased array and Toms Network...I'm Sold... Deep Six the Baluns...

[WA1GFZ]

Johnson kW match box works great if the antenna and feed line are a
lenght in range of the box. I've been using a balanced/ balanced tuner
since '83 before Measures designed the name. 2 22 UH 5 KW variable inductors and 2 300 pf 10 KV cardwells with a 6 core BB transformer on
the 50 ohm side.  It is in a 5 foot rack and handles power nicely.
Both tuners make the same RF current on the feed line but the homebrew one works on 160 M. Antenna is a 250 foot dipole with 130 feet of feedline
#10 spaced 4 inches.

[k4kyv]

I still think the classic balanced tuner with link coupling and split stator tuning condenser is the best bet.  You can, of course, also use two separate variable caps.

Series tuning with the split stator is accomplished by splitting the coil, and feeding the low-Z load at the split.  Hi-Z  loads are fed off the ends of the coil.

It is best to adjust feedline and antenna lengths so that either series or  parallel tuning works on all bands used.  Complex loads, requiring tapping down on the coil, work less efficiently, in my experience.  I also had a problem with excessive rf voltages across the tuning condenser.  Complex loads occur whenever the feed point is between a voltage and current node.  Parallel or series tuning can be used when the feedpoint is on or near a voltage or current node.

In the past, I used a set of plug-in coils for the tuner, simiar to the HDL series of plug-in tank coils.  I had a jack bar with 6 banana jacks, and used the jack/plug assembly to automatically switch over from series to parallel tuning when I changed bands.  I used series tuning on 75 but parallel tuning on all other bands.

Now, I use a separate tuner for each band, and switch tuners when changing bands.  That way, the individual tuners can remain pre-tuned to the part of each band that I usually operate.  At present, the tuners are located in a "dog-house" at the base of the tower.

[W2VW]

Johnson kW match box works great if the antenna and feed line are a
lenght in range of the box. I've been using a balanced/ balanced tuner
since '83 before Measures designed the name. 2 22 UH 5 KW variable inductors and 2 300 pf 10 KV cardwells with a 6 core BB transformer on
the 50 ohm side.  It is in a 5 foot rack and handles power nicely.
Both tuners make the same RF current on the feed line but the homebrew one works on 160 M. Antenna is a 250 foot dipole with 130 feet of feedline
#10 spaced 4 inches.

This setup will deliver power to just about anything.

[K1JJ]

Bottom line is, regardless of the type of matcher used, as
long as the load is matched to 50 ohms and the individual
open lines are balanced for currents, you're golden.

To check match, just use an swr meter. But for balance,
what I usually have done is take a pair of little 6V flashlight
bulbs and solder  3" wires to each. Then solder one on each
feeder, sampling about 2" of wire. [not across the open wire
pair, but on each leg). Each bulb has to look like the other for
balance sampling too.

The eye, for measuring intensity, responds best to low level light, so
adjust the spacing of the two bulbs leads so that they BARELY
light at full RF power. You can then adjust the taps or whatever
on the matcher to achieve a perfect balance by throwing a
carrier and watching the bulbs.

I've found most antennas are NOT perfectly balanced, even
with precautions of running the feedline in textbook fashion. It
usually took an extra coil turn of tuner bias to balance the
lights. Some ant systems were right on, however.  The effects
of unbalanced openwire is feedline radiation, thus pattern distortion
and maybe even RF in the shack, etc..

Real RF sampling meters are even better, but few have them.

For the last ten years, I've gone to all surplus Heliax and use
openwire only for interconnecting larger arrays together and
then transforming to hardline for the run to the shack.

T

[W2VW]

Bottom line is, regardless of the type of matcher used, as
long as the load is matched to 50 ohms and the individual
open lines are balanced for currents, you're golden.


T

Maybe it would be a good idea to add one more thing. Model the antenna feedpoint impedance, convert the impedance to what you would have at the antenna coupler using feedline converter software then carefully measure what you have. This can help determine if the antenna coupler is a dummy load like some cheapie types. In the case of low radiation resistance stiuations like a very short dipole, the feedline current wil be many times the input to the coupler. You can get an accurate measurement with an R.F Ammeter in series with one leg even though there may be a complex impedance because the coupler provides the conjugate match. A Voltage feed situation might get a little problematic for this type of measurement though.

[Bill, KD0HG]

I've found most antennas are NOT perfectly balanced, even
with precautions of running the feedline in textbook fashion. It
usually took an extra coil turn of tuner bias to balance the
lights. Some ant systems were right on, however.  The effects
of unbalanced openwire is feedline radiation, thus pattern distortion
and maybe even RF in the shack, etc..

Real RF sampling meters are even better, but few have them.

For the last ten years, I've gone to all surplus Heliax and use
openwire only for interconnecting larger arrays together and
then transforming to hardline for the run to the shack.

Tom and all,

Measuring line and antenna system unbalance takes nohing more than a pair of surplus RF ammeters, one in each wire. If the measured currents aren't the same, then by definition the line is unbalanced and it's going to radiate.

Beyond that, I've also gotten away from balanced feeders and gone to used  (surplus) Heliax buried on the 40' run between the tower and house.
I feel that's *much* safer for lightning than any overhead run of balanced line.

I match the antennas at the tower, even running balanced line  (if I need to) down the side of the tower on standoffs, then to W2FMU-style baluns or matching networks bolted a few feet up the tower. The rest of the way is all buried Heliax.

..