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Author Topic: instructions to build the k1jj tuner  (Read 41889 times)
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N7ZDR
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« Reply #25 on: March 07, 2016, 10:58:40 AM »

Looks like we posted at the same time Fred-----Don't get me wrong-- I love any big Vacuum cap as there all but bullet proof. I just found myself spending too much time looking at the turns counter and wondering when the dip was coming.

Cheers,

Larry
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kk6noh
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« Reply #26 on: March 07, 2016, 04:40:10 PM »

lol talking about 100-200 dollars like its nothing. That will likely take me months to save up for.


not to mention the copper wire... that will cost a good 30 dollars.


and now people are telling me I need an antenna analyzer? Well the cheapest I could find was over 50 dollars. I can safely say this project will not happen for at least 6 months, when hopefully I am finished paying off this years auto insurance.
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KA2DZT
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« Reply #27 on: March 07, 2016, 07:53:47 PM »

lol talking about 100-200 dollars like its nothing. That will likely take me months to save up for.


not to mention the copper wire... that will cost a good 30 dollars.


and now people are telling me I need an antenna analyzer? Well the cheapest I could find was over 50 dollars. I can safely say this project will not happen for at least 6 months, when hopefully I am finished paying off this years auto insurance.

Take your time with the antenna tuner.  No rush, I've been licensed for 55 years and I haven't used an antenna tuner yet and I have all the parts to make one.

Fred
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KD6VXI
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« Reply #28 on: March 07, 2016, 07:59:25 PM »

You don't need an antenna analyzer.   It just makes it a LOT easier.

An antenna noise bridge can often be found for ten to fifteen dollars.   Work just as good,  and you'll learn how to use it very quickly.

A bread slicer cap will work just fine.   Yes,  a vac variable from the commies looks nicer  handles more V (and usually I),  but if you can't make more than a couple hundred watts pep,  you don't have a need for a kw level tuner.

Yes,  power makes it easy to have long distance QSOs a lot more easily.   But,  if you don't have the capabilities today,  throw a ten dollar bread slicer in your project tuner,  and when you can afford a vac cap,  replace the bread slicer.

Or,  use coax cable and resonant dipoles.  No need for a tuna.

--Shane
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Steve - K4HX
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« Reply #29 on: March 07, 2016, 08:54:31 PM »

You may want to consider no tuner.

http://www.w5dxp.com/notuner/notuner.HTM
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kk6noh
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« Reply #30 on: March 09, 2016, 09:50:49 PM »

I am afraid that the antenna design I have decided on requires a tuner. I have no desire to get a 100+ foot tower and pay thousands of dollars to get onto 160 meters. This is the antenna I am going to use this tuner on. http://home.4x4wire.com/deddleman/photos/WireLoop.pdf
EDIT
Noise bridge huh? I like it! Thanks for pointing that out!
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Steve - K4HX
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« Reply #31 on: March 09, 2016, 09:55:23 PM »

Where did you get the idea that a 100 foot tower is required? The subject antenna at the link I provided was only 37 feet in the air. It requires only 137 feet of wire and two supports. The antenna at the link you posted requires over 500 feet of wire and 4 supports. The loop is a more expensive antenna.
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kk6noh
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« Reply #32 on: March 09, 2016, 09:57:54 PM »

Where did you get the idea that a 100 foot tower is required? The subject antenna at the link I provided was only 37 feet in the air. It requires only 137 feet of wire and two supports. The antenna at the link you posted requires over 500 feet of wire and 4 supports. The loop is a more expensive antenna.

1000 feet of wire and 3 supports actually. However from what I can tell using a dipole too close to the ground results in all kinds of problems. I am using the one resource I have plenty of....... acreage.
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Steve - K4HX
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« Reply #33 on: March 09, 2016, 09:59:14 PM »

All kinds of problems? Such as?

You claim you don't have money to spend. Why waste it needlessly wire and a tuner?
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kk6noh
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« Reply #34 on: March 09, 2016, 10:07:15 PM »

All kinds of problems? Such as?

You claim you don't have money to spend. Why waste it needlessly wire and a tuner?

problems with feedpoint impedance, radiation pattern and elevation, and ground losses. I learned that from several ARRl publications including their antenna book and this--> https://www.arrl.org/files/file/antplnr.pdf
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Steve - K4HX
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« Reply #35 on: March 09, 2016, 10:26:36 PM »

Those are so general statements as to be nearly useless. For example, let's take radiation pattern. This cannot be called a problem unless some specifics are known. Frequency and desired radiation pattern would be two very important ones. Type of operating or coverage area (local or DX) would be another very important one.

You really cannot pick an antenna or make judgements on any given antenna without some specifics. Example: too low (whatever that means) on one band is high enough on a higher frequency band. Saying an antenna is too low without any other info is  just about meaningless.

Is this your first home-brew antenna?
How high will your loop (or any other antenna) be?
What bands will you use? In priority order?
What sort of coverage is desired, local versus DX.

Yes, the antenna at the link I posted was at 37 feet above ground. However, the concept will work with the dipole at greater heights. It is simpler and less costly than the loop and a tuner.
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KD6VXI
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« Reply #36 on: March 09, 2016, 11:27:46 PM »

I'll play Devils advocate here.

You might want to listen to what Steve says.   

You're going to find a wealth of knowledge here.   There are government spooks (three letter agencies with way better radios than we have),  commercial shortwave engineers,  antenna engineers,  etc.   Then,  you have guys with money that can throw up multiple hundred plus foot towers and can listen to gnats fart in Brussels.   When the band's are closed.

But you have to want to learn.   

Don't settle on any antenna you read about.   Ask around.   Post something here about what you want to accomplish,  and how much you have to spend.   Someone here,  somewhere on the face of the earth,  on this forum,  probably has the answer.

Don't approach it with the 'I stayed in a holiday in express and read three ARRL books,  so I already know what I want'  attitude,  or you really will miss out....   Simply because no matter what,  someone has a different take on it.

Or,  as Carl,  KM1H,  told me when he saw me opening my yap here a few years ago...   "Shane,  shut up.   The people on amfone are the real deal.   Ham for them is a hobby.   Real life was spent doing it for a living,  and there are real experts there'.

He was right.   I've learned more here in a few years here than I did devouring every book I could find.   Because the guys here will help,  within whatever constraints you have (practically of course).

Before you poo poo Steves idea.   Scrapped 75 ohm cable TV coax for feedline.   Dipole will resonate around this value at heights you and I have available (I have a 37 foot tower and a 32 foot pole.   And a pair of 80 foot towers laying in my back yard I can't use).   So your swr will be 1.5 at resonance (or thereabouts).   Use your radios internal tuna.

Since your coass feeding it,  a 40 dipole will work for 15 as well.   Has limits,  but hey,  you just saved a feedline and another 50 feet of wire on the dipole. Add a 20 meter dipole to the feed point,  and you have three bands covered by two dipole and coass you can get for free.  (Make friends with cable or satellite TV installers.   They usually have extra coax on 'roll ends'  that get tossed.   Ymmv.

--Shane
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K1JJ
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« Reply #37 on: March 09, 2016, 11:28:10 PM »

1000 feet of wire and 3 supports actually. However from what I can tell using a dipole too close to the ground results in all kinds of problems. I am using the one resource I have plenty of....... acreage.


There is a misconception that the more wire in the air, the better the antenna.

For local work, for 160 or 75M, a simple flat 1/2 wave dipole  as high a practical (60'-100' high)  is the most efficient antenna you can use.  Use open wire for multi-band - coax for single band. It does not really matter.

The problem with bigger wire antennas, like full wave loops or larger, 2-half waves-in phase, double extended Zepps, etc., is that the take off angle starts to get higher and the ground losses start to build. More wire coupling to the Earth becomes a problem.  

For example, on 75M, you need to put the double extended Zepp up 20' higher than a standard 1/2 wave dipole to get the same take off angle. So with limited support height, use a standard 1/2 wave dipole for lowest take off angle and efficiency.  If you have the height available, then use whatever length you desire.  I have a 190' self supporter tower and have full wave loops .. works great only because I have the height to work with. If lower, I would opt for 1/2 wave dipoles.

An extreme example would be putting up a 2 mile long wire, either end or center fed for 160M and the higher bands -  fed with OWL. Some would think that is the ultimate antenna. But it would have lobes like an octopus, exhibit sharp long wire directivity, with deep nulls due to random phasing - heavy ground losses -  and perform more poorly than a standard 1/2 wave dipole at the same height.


Stick with a 1/2 wave dipole for the lowest frequency (1.8 MHz) and the pattern will be a nice broadside figure-eight for both 160 and 75M when using OWL.

For lower DX angles, Steve's suggestion to use an end fed inverted L is excellent.


Hope this helps.

Tom, K1JJ


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« Reply #38 on: March 10, 2016, 12:18:45 AM »

this isn't my first antenna project. I have spent literally years in planning this station. I have experimented with several different antenna designs trying to find one I like.

my goals are
80m, 40 and 20, 160m, and 10m in that order of desire.
it needs to cover all those bands, be cheap, be low to the ground, Omni directional, be quiet(low noise level), and not be some sort of compromise. I have a half mile square of acreage to deal with. Despite all the room I want to avoid anything resembling a tower because of high winds and hostile neighbors with high power optics. I found that dipoles work, but are not truly omni-directional and have to be mounted very high to be at the right takeoff angle. Inverted L's work ok on the longer bands but are very noisy. Yagis are completely out of the question. Vertical antennas are also out.

so that is what lead me to the long loop skywire. I plotted the antenna in software and it seems to check out.

It covers all ham bands with a tuner to match the impedence. It has a low noise floor. It is omni-directional. It is practically invisible. It has a nice low dx takeoff angle with an overhead null. I can get the wire for rather cheap, the mast poles for practically nothing, and the twin lead for a lot cheaper than coax. The only thing holding the project back was a lack of a tuner... which has been solved.

I guess my main issue with dipoles is pretty much every single ham on the planet either uses them or recommends them. I hate being mainstream. Cheesy
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K1JJ
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« Reply #39 on: March 10, 2016, 10:58:29 AM »

my goals are
80m, 40 and 20, 160m, and 10m in that order of desire.
it needs to cover all those bands, be cheap, be low to the ground, Omni directional, be quiet(low noise level), and not be some sort of compromise.

It's hard to beat a 1/2 wave dipole for pattern and efficiency.

To satisfy your objectives:

1) I would put up a 1/2 wave dipole for 75M fed with open wire and use it on both 40M and 75M.  This will give a nice figure 8 pattern, but because it will not be that high, it will exhibit a quasi-omni-directional horizontal pattern on 75M, which you desire.

2) For 10M - 20 M put up another 1/2 wave dipole fed with OWL -  this time for 20M and it will have reasonable patterns on 10M and 15M.

3) Put up an inverted L for 160M.  A 160M horizontal dipole, if not very high, is inefficient on 160M -   thus use an inv L vertical which does very well for 160M.

In contrast, if you put up a big 160M / 75M loop or dipole and use it on 10M - 40M, it exhibits  a cloverleaf or octopus pattern with yuge nulls.

The next step up would be a Yagi, which you said you do not want.

T

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« Reply #40 on: March 10, 2016, 06:49:26 PM »

Nothing wrong with being out of the main steam. Smiley That's pretty much what AM is all about.

Just a couple of thoughts.

1. A low loop will work no better than a low dipole (maybe worse) in most scenarios.
2. A horizontal loop will NOT produce any more low angle radiation than a dipole at a similar height.
3. A loop is not necessarily any "quieter" on receiver than a dipole. If you have a bunch of acreage, you may already be in a quiet receive location.
4. A low dipole is omni-directional for all but the lowest takeoff angles.
5. There is no "right" takeoff angle. It depends on what coverage or distance you need.
6. Low is relative. A dipole at 30 feet above the ground could be considered low on 80 meters. But, for example, on 15 meters, it is more than a half-wave above ground and will produce plenty of low-angle radiation (assuming that's what you want).
7. If you really want to hear well on the lower HF bands (160, 80 and 40 meters), put up a specialized receive antenna like a Beverage, K9AY, etc. These are easy and cheap.

Good luck with the loop. I have nothing against them. I've had as many as four up at the current station and still have two.
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kc1gtk
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« Reply #41 on: April 11, 2021, 09:24:41 PM »

Greetings--- I know this is an old thread, but relevant to my project, maybe I should have started a new one, I'm a newby here.
Anyhow attached is my working but not mounted up version of K1jj's tuner.
50-1000pF vac cap, and 2000pF Air var/cap. and an 8 turn link.

 Tuners fascinate me in my short ham career so I wanted to make one for my open fed doublet. Thanks to info here and some emails to a few members, I ended up with this. Fired it up morning after tuning it with a nanoVNA smith chart and it's almost flat on 80 thru 20m.

My doublet is only 125' long, I know it should be longer for 160m. This tuner won't tune 160, ( nor will my palstar BT1500A).

I wonder if I put the vac cap in series with the big coil's center like I've seen in some info here, it would tune a short antenna???

My wife thought I was building a still when she saw the coil!

It was a blast making this beast, I'll neaten it up and make it presentable.

And thanks to all who posted about this cool tuner
73
 Paul KC1GKT


* 80m junpers.jpg (1244.41 KB, 2560x1440 - viewed 497 times.)
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kc1gtk
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« Reply #42 on: April 18, 2021, 11:29:52 PM »

Okjust to report, I did split the coil and put the feed line on the split, so now it's series connected. It tunes up fine now and I can run the amp with it, low swr at the amp and the radio. putting out 500w I got over nine reports into VA. not real effecient on a 1/4wave double but am happy with it
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K1JJ
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« Reply #43 on: April 19, 2021, 12:15:16 PM »

Ok just to report, I did split the coil and put the feed line on the split, so now it's series connected. It tunes up fine now and I can run the amp with it, low swr at the amp and the radio. putting out 500w I got over nine reports into VA. not real efficient on a 1/4wave double but am happy with it

Glad you got it running well, Paul.

Yes, usually a 1/4 wavelength dipole like a 75M dipole tuned up on 160M (low impedance feed) may require series tuning, whereas the same 75M dipole tuned up on 75M or 40M (higher impedance feed) may require parallel tuning. So having a way to quickly jumper back and forth from series to parallel tuning is desirable.  You will find you can match any reasonable, balanced antenna on the planet to a perfect 1:1 with enuff playing around.  Mark the taps and tuning positions for later and you're all set.

There was a time when I had five separate dedicated tuners using OWL dipoles, each serving one band. Quick band selections. But it was more practical to run separate coaxial feedlines in the end, so that these days I have a total of  5,000' of 75 ohm hardline run underground in 4" PVC pipes. Each antenna is a click of a switch.

Just to make one last point... if you listen long enough on 75M AM, you will find that the biggest signals on the air, the big guns, are mostly running coaxial feedlines. This includes the biggest contest stations.  My point is that there is really little difference between open wire feed and coax when it comes to losses and signal strength of a properly tuned antenna. Remember that the tuner has losses too... and we lose control of our clean bi-directional dipole radiation pattern on the higher bands. Open wire is more for convenience and more bandwidth when separate antennas are impractical, (or feeding balanced arrays) despite its increased physical complexity for installation.

But I must admit, saying you are running open wire feeders is MUCH cooler than coax...  Wink

T

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« Reply #44 on: April 19, 2021, 09:13:06 PM »

Thanks for the reply Tom.

In the process of neatening the lay out now that I know it works.  I put 2 banana sockets on the split which is at 12Oclock. I can grab them with the clips on the feedline for series, and shunt them out with the banana plugs when going to parallel.
input cap is needed on 160m, not needed on 80-20. so I'll make up a quick shunting switch for the cap on 80 up.

 Waiting for a turns counter  to arrive for the vac cap.
 here is how it looks at the moment, with taps for 160m

My new homebrew Elmer, W1IA who lives nearby, pointed me in this direction and your version.
 The 8 turn link gets to about body temp when running 700w on 160, but not on 80 - 20

 I'll post another pic when it is mounted and pretty

Thanks again, I found many of your variants online, which helped me understand and make this
73 kc1gtk


* on 160.jpg (1226.56 KB, 2560x1440 - viewed 367 times.)
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K1JJ
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« Reply #45 on: April 19, 2021, 11:57:49 PM »

Looks like yours will work very FB, Paul.  The turns counter makes a huge difference in ease of use.  That 50 ohm input tuning cap with the link gives you good control of the input  --  and with combined output control, there are virtually infinite combinations of taps and adjustments. Not to mention your new series/parallel modification. That's the objective - wide range impedance control.  I have used this design up to 10M when feeding a large wire array in the field. It was a custom made tuner with 10M optimized coils, etc.

Just to set the record straight:  This tuner is not my original design, but a circuit that has been used for many purposes going back to the 1920s. Back in 1987 I needed a cheap antenna tuner design that could use a simple single section tuning cap (like a vacuum variable) and a minimum of parts and be able to run 2KW+, etc. Everything out there was either too expensive, needed multi-ganged caps, dual rotary inductors or whatever. One day looking thru the 1930s handbook I came across a similar circuit that was being used as a 500 watt plate tank matching circuit. I adapted it for antenna tuner use and built five as I mentioned. The copper tubing was real cheap then as well as vacuum caps and input 365 pF X4 receiver tuning caps.

I have talked about this design since the late 80s and the name "K1JJ Tuner" eventually stuck and became a convenient way to quickly identify the simple design. Some call it a "link coupled tuner with a one section [vacuum] capacitor and coil,"... but it's all the same thing.  

BTW, the 2nd harmonic suppression (additional attenuation) of this tuner design is less than a more complex split stator of grounded capacitor design.  If your transmitter is already of good design (pi-network) with a reasonable Q with standard harmonic suppression numbers, all will be fine.  I know of only one guy over the years who had an RFI problem (when using this tuner and OWL) possibly due to harmonics. It was later fixed by replacing some (rectifying) oxidized CATV connectors at his neighbor's house.

FB on Brentina being your Elmer. You can't find a better one.  Tell him I said hi and I listen in quite often. I need to get back on the air with youse guys soon.  I have finished all my rig building for the time being.

T
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« Reply #46 on: April 20, 2021, 03:03:25 PM »

BC-610 coils are FB for this application.

Run a 2.5 mH choke in series with a 3K 1 watt carbon from the neutral point of the BC-610 coil to chassis ground. Mod this a bit if you use a split stator, as the rotor must float in such a cap.

Put a 500 to 1500 pF variable in series with the link and chassis ground.
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Chuck...K1KW
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« Reply #47 on: April 22, 2021, 03:22:41 AM »

Just saw this thread after building another balanced tuner for a new open wire line fed antenna going up this year here.

These balanced tuners need a RF center tapped return to ground on the "secondary" side driving the open wire line to ensure a true balanced drive.  Otherwise any small imbalance will create a significant common current which will cause the open wire line to radiate.  This means that 1) the tuning cap on the secondary needs to be a balanced split one with the rotor grounded or 2) with a single isolated cap tuning on the secondary the coil center needs to be grounded directly.  Think of this like driving a pair of modulator tubes in push pull using a driver transformer with no center tap return as an analogy. What would happen?

You should not do both (split stator, rotor grounded, and ground the CT of the secondary coil) since this will now give you two separate resonant circuits forcing an imbalance unless they are exactly identical and there are no antenna induced imbalances.

I have always opted for grounding the secondary coil center since this provides a "DC" ground return for any static build up on the antenna.  It makes a quiet antenna especially during "rain" static.  It also protects the receiver front end from static build up which will cause arcing and could jump to the the primary turns  blowing up the receiver front end!  Experience speaks here!!!!

In the case of a low impedance current feed driving from the split center of the coil, you should use a balanced tuning cap with the rotor grounded to ensure a decent balance.  No short cuts on this one since current feed is more susceptible to common mode currents.  However, on these low bands feed line radiation may not be an issue unless it gets into your audio or your neighbors!  


Chuck K1KW

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73, Chuck...K1KW
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« Reply #48 on: April 22, 2021, 11:59:21 AM »

Yep, for parallel feed a center tap to ground off the main coil is a great idea for the reasons described.   I notice adding one usually has no effect on the general matching operation of the tuner when it is centered perfectly which is a good thing.   Those CT points and features have been asked from time to time and should be edited / added into past postings for future builders to implement with any of these tuners.

Another point to ponder:  Since most OWL antennas, or any large wire antenna in the real world, are usually physically unbalanced due to one dipole leg being higher than the other or the feedline coming closer to metal objects on one side or another...   is it beneficial to tap one side of the feedline connections either out or in farther on the main coil than the other leg to achieve a better feedline current balance?  A current balance could be indicated by the relative brightness of two light bulbs, one on each feeder or an RF current meter indication on each leg, looking for balance...

T

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« Reply #49 on: April 24, 2021, 12:34:43 PM »

I would not recommend using transmitter plug in coils for a tuner, especially in a high power application. The conductor size of these coils is often too small for the amount of current involved because of the higher Qs involved. Remember, these coils were designed for use in an output tank with a Q lower than 10 or so.
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