The AM Forum

Looks like I will be obtaining a Johnson Matchbox 250-23.  I presently use a G5RV with a gutted out MFJ-962D but I want to try out a Doublet.  I will be able use maybe 180 feet (90 feet each leg) inverted with the center up around 45 feet and the ends down to about 12 feet.  My question is should I use the longest doublet I can erect (180 feet) or would I be better off cutting it at a different length for any reason.  If I can get 160 meters great.  My DX-60 and SB-200 won't play on 160m but I am still working on the Johnson Viking I which will.  My plastic radio will too but that would be barefoot. 

My other question is.... I understand this model of Johnson Matchbox is rated for 275 watts carrier.  Is this conservative?  Will it handle a little more okay?  Not that I have that capability... yet.

73 and MERRY CHRISTMAS

John KX5JT

No 160 in that Matchbox.  I suggest you cut the wires for your area of the 75 meter band.  No point to go longer. The unit is bandswitched and you might not get it to tune. 

I have run a valiant at 150 watts AM through it without trouble.  1000 watts SSB.  Thats probably about it.  The key here is to tune on low power and get it flat before putting the power to it. If you fire off the heat into the little matchbox untuned, Its going to arc over. 

They are neat little tuners.  I own three of them.  Look for a KW matchbox if you want to run more power.

C

Hey Clark I appreciate the words.  BTW, I had heard you calling cq last week and tried to answer but just wasn't quite getting through... you asked for my call a few times but it wasn't quite happening.... maybe soon.

John KX5JT

Cool..  That was you!   I had the same thing happen tonight..  Band is real rough for me.  All the homes around me running modern heat pumps really makes the bands rough!

Hope to hear you soon!

Clark

John,
You might be able to get the match box to work on 160. make sure the primary tap is connected to the whole winding. Then you will need additional C across the output. The best thing to do is get 50 feet of 1/4 inch copper tubing and wind it on some 3 or 4 inch PVC pipe and build a good HD tuner for 160. Run the open wire directly to the tuner.
KB3AHE antenna configuration may be better because the ends will be higher. 160 meter inverted vee with the ends at 12 feet doesn't work all that well but it will get you on. Under 200 feet total length can be tricky to tune.

Hi John,

the 275 w. MB should handle 200 w. carrier out no problem; I think some guys run as much as 250 w. (1 kw pep).  Get rid of the G5RV by extending the balanced part all the way to the tuner.   I agree, shorten the dipole to 1/2 w. on 75 (around 130 feet) and make the feedline around 90 feet long and it should work FB.  The reason for making the dipole shorter (one reason) is that it will tune on 40 m. and give you a decent pattern on that band.   Also, the ends will be higher up.  In my opinion there is no point in trying to get it to work on 160 because it is too low.   Here's the thing with antennas:  as you know, they are not a digital binary type thing--they don't clearly either work or completely shut off.   They usually work well or work ..sort of.   That "sort of" situation traps many many hams (Gap Voyager, 43 foot "all band" verticals, Isotrons...).  If you have nothing good to compare a "sort of" antenna to, you may think it's working FB, and years may pass before you experience a truly good antenna and have that wow moment when scales fall away from your eyes etc.  :D   With the current G5RV your height on average is around 30 feet.  You have to think of height in terms of wavelength on the band of interest.   30 feet high on 160 is like having a dipole 7 feet high on 40 m.   You would never have a dipole on 40 m. only 7 feet high would you?    Huge ground loss.  So, basically on 160 you are going to have to have a separate antenna, and if you cannot achieve height (at least 100 feet for a dipole) you are going to have to work against ground.  That means something like an inverted L with a lot of radials.  You can use the L for transmitting and by pass the Matchbox and use the dipole as a receive antenna on 160.   On 160 transmit antennas are usually not the best rx antennas, another thing about 160 that's different from the higher bands. 

73

Rob
K5UJ

Very good summary, Rob. I see your new antennas worked out FB and you learned the lessons they taught well.... ;D


On the 160M dipole - here in the Northeast, (and upper east coast) there is a concentration of AM stations not found anywhere else in the USA.  In this area we can get away with "low" dipoles for 160M having TO angles of 70-85 degrees cuz the paths are usually under 200 miles or so to work many stations.  It's a great local-work antenna. But as you inferred, out where John is in TX or any western US area, the stations are very far apart and a low dipole won't cut it. It IS better to work out a vertical system with radials out there if the dipole will be close to the ground.. However, there will still be certain cornditions that greatly favor high angles during the wintertime.

Another thing to be aware of is for 160M DX work, a vertically polarized antenna usually has about a 10db advantage over a horizontal due to Earth geo-magnetic attenuation. (I forgot the proper term)   I experienced this here when I had a dipole at 190' stretched between two towers (flat) and compared it to a vertical system with 360 radials. The vertical was ALWAYS much louder into Europe. On 75M and above, it was the opposite with the high horizontals aways 10db or more louder than a vertical - at least at my QTH.

But a good vertical needs lots of clear room to work (no nearby houses, etc) and a great radial system. I think for the average ham, the best antenna system for 160M would be a full-size dipole as high as possible WITH the option to feed it as a "T" against ground. (radial system)  Just tie the feedline inner and shield together and feed it against ground. Have a quick A-B switch to be able to see which is best on the fly. Being able to switch quickly low angle/ high angle during QSOs is what gives the advantage.


T

Great comments guys.  Actually, my goal is to optimiz 80/75 while achieving the higher bands through 10 as well.  160 is more of an afterthought here but the matchbox as previously noted doesn't tune 160 anyway without some modification. 

So with 3885 Khz as the main goal, should I cut the length for that frequency or will going a bit longer be more wise.... I do operated below 3.800 quite a bit as well.

Maybe I'll just throw up 135 feet and be done with it?  Then I can worry about 160 meter for a future project, maybe the inverted L at some point.

John, KX5JT

I used 130Ft with 450 ohm line with mine. Tuned every band flat.   You will like the little matchbox. Its a neat little tuner. Download and read the manual for it on BAMA.  Search yahoo for BAMA manuals and you will find it. 

C

Oh well... I got sniped on eBay in the last 10 seconds... I was the only bidder for that matchbox... until 10 seconds and they sniped it away...

Any one have one for sale?

Shucks..  I am not selling mine but I will ask around.. Post in the wanted section here on AMfone.


C

John,

I may have missed it somewhere.....

But, why not just build a tuner?

A couple variable caps, and some wire and/or tubing, and you have it made.

(and of course a box or plywood to mount it on)

You can build a very strap-escent tuner FAR cheaper than buying one, unless you are really lucky to find a reasonably priced unit.

I'm beginning to think this way too.  Other than hamfests, where does one find the proper variable caps for a balanced tuner?  Well hamfest season is about to start here in the south.  I will be making the Orange, TX fest last weekend of Jan and then our local club has one two weeks after that in March at Rayne, LA.  I was just wanting to put up the doublet before new years.... ah well.

Thats the real problem.. People suggest you build your own tuner all the time. Great.. Send me the caps for a balanced tuner that will handle high power and I will sit down and build one. I dont have the caps and at ham fests dont ever come across large split stator caps.

C

I find them all the time on ebay...

Probably even have some here still, though I sold a couple off earlier this fall.

There are those here that say you don't NEED a split stator cap, and can use a regular single section cap, or a vacuum variable ..... which does seem to work fine.


But, if you just have to have a split-stator... let me know what value & voltage rating you want....I'll see what I have.

I have also taken single section caps, and cut the stator supports, and made them into dandy split-stator units....  a little lexan, a drill, and a hacksaw is about all you need!


And if you want an input cap, "broadcast" type, multi-gang caps are really easy to come by.

http://cgi.ebay.com/VARIABLE-TUNING-CAPACITOR-CARDWELL_W0QQitemZ170421579354QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item27adeaee5a


http://cgi.ebay.com/Variable-Capacitor-High-Voltage_W0QQitemZ290382891654QQcmdZViewItemQQptZVintage_Electronics_R2?hash=item439c2b4a86

HB tuner info:

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


John,

There's nothing like building and using your own tuner. Real easy to make and will handle 10KW - no baluns.

Simple - just a single section cap, main coil, input coil and clips for the feedline. Add a BC input cap if desired.  Check eBay for vacuum variables - they will do the job best.  Billions and billions of AMers have built their own version of this antenna tuner. Do a search on AMfone for "K1JJ tuner" for more pics and info.

73,

T


LOOK how simple this 160-10M version is:  (Cleanly built by KA2J)

Listen to Master Vu - he speaketh the truth.  Nothing at all wrong with the Junkston Flashbox, but the K1JJ tooner is extra simple and super low loss.  One coil, an input winding, and a variable cap and yer done.

I built one using an old BC xmitter tank coil and a vac variable, and it handles full scrote from the GPT-750 with ease.  Tuning the 75M dipole on 160 maketh a LOT of circulating current (enough to get a touch of talkback from the vac variable) but the coil barely gets warm.

Yes Tom I was looking at that a bit earlier and at you Super Tuner schematics.  So no split stator caps needed with that setup and it's balanced.  Very nice!  I think I'll work on the coil first.  Once I get a good coil built out of tubing I'll worry about the caps.  Thanks OM!

John

John,

You can get the copper tubing at most big box hardware type stores.  Before you wind and form the coil practice with wire.  You can also purchase a fixed value edge wound silver plated inductor and add a link around it with a few turns of copper tubing.   So there are lots of ways of doing this.   Vacuum variable caps have pros and cons.   They have a wide range and high voltage breakdown but moving through the whole range can take time and mounting them can take some doing.  And of course if you drop one it's all over  :-[ 
Sorry you got sniped on eBay.  That stinks.  I confess I did that once in an auction and felt like pond scum afterwards.  Never again.  Assuming you elect to buy a tuner (I am in no way endorsing buying over homebrewing) the KW Matchbox is the best commercially made balanced feedline tuner out there.  If you are going to buy one you may as well look for one of those.  The 275 w. model is okay but if you have the KW model you'll never worry about arcing anything at typical ham power.   You are better off getting a tuner like that at a hamfest.  Don't know about your area but around here they turn up so you just have to be patient and have some cash with you.  Unfortunately we're out of the hamfest season now.  The 275 w. mb usually goes for $100 to $150; the KW model $300 to $350.   Given the components inside one that's not too bad a deal.   If you took what they listed for in 1959 and inflated that to 2009 a new one would be around $1000.  

Okay, about eBay--you have to employ a little strategy for anything on there.  Let's first assume you found a widget that looks okay and the seller has good approval and all that i.e. it looks like a square deal.   You don't do anything.  You want the widget to just sit there and sleep and hope no idiots show up and bid it up.  If that happens forget it.   About an hour before the end of the auction check it again.  Hopefully there will be only one or two bids or none.  About a minute before the auction ends put your bid on there, the maximum you want to pay.   That isn't sniping it out from under others but it isn't going to bid up the widget like an early bid would.  If you get it you can feel like you got it fair and square.   The amazing thing about eBay is that I have seem two identical items for auction at the same time, and one will get bid way up there and the other will go for a great deal.   Go figure.   So you can snag some good stuff on there but I guess it is all about timing.

73

Rob

ebay can be a great source for tubes and parts, just look for things that the audiophiles dont wanna mess with that will still serve your purposes.

Hey Tom tnx; say, 2 or 3 weeks ago I worked a guy in the pac. northwest on the dipole on 75 m. & sig. rpt. was S9 so I quickly switched to the 65 foot vertical and went up 10 to 20 dB depending on QSB.  So the sweat and money last summer suddenly seemed worth it hi hi.  73
r.

I need to put my Vert up.  I got a Vertical off a Battleship.  Its 65 to 70 ft tall in round sections with a 200 lb Ceramic insulator and mounting bracket.  Maybe next year. 

C

Well... I am pretty stoked now to build a K1JJ suppah tuna.  

For you ARRL members, this is a great link for ideas on rolling your own inductors...

http://www.arrl.org/tis/info/pdf/9708033.pdf (http://www.arrl.org/tis/info/pdf/9708033.pdf)

As I said, going to work on getting an inductor rolled then move on to the rest.   Any information on tubing size, number of turns and spacing for a 160-10 m range would rock!  Oh heck nevermind, I see the values in Tom's schematics.  Breadslicer caps too... I think I'll forego the vacuum variable caps at least for the initial version.

John KX5JT

Good decision, John.

It pays to shed the chains of any commercial gear you can and build your own.  For some stuff, like ssb riceboxes, it's close to impossible to duplicate yourself. But an antenna tuner you build will be far superior to any of the commercial stuff out there. You will also learn a lot about antenna matching and multiband openwire use very quickly.   I've seen many guys go through the same process you are about to and they couldn't understand how they put up with all that MFJ tuner stuff in the past.

Just make the main coil large enuff to cover 160M and then some. Not critical at all. You tap it where you want, so even if it's twice the size it needs to be, it won't matter. But you don't want it too small or you can't reach the lower freqs.

I would start looking on e-Bay for a turns counter and vac variable cap. Once set up, you can tune it quickly with exact pre-set accuracy. Also, be sure to mark the taps for each band so you can change bands with a 1:1 swr without even thinking about it.  Ease of use is what makes this tuner worthwhile.

Take some pics when you're building and finished... ;D


Rob: Hope to hear ya on 75 soon. I'm about finished with some major rig mods here and starting to get on again.... both AM and DX ssb.

T

I prefer bread slicers in tuners. They never go bad and if you flash it over all you need to do is file the blasted metal. I use a pair of 300pf 10 KV Cardwells in the fugly 50 to 60 uh total l on 160 is a nice coil value. I use a pair of 22 uh rollers but my Q is a bit high on 160.

If you can do 180 feet, maybe think about adding some loading coils 3/4 the way out on each leg, some B+W coil stock over an insulator works, or whatever you can come up with, and get the antenna on 160.
It wont be great on 160, but better than lousy, and RX will be good.
I had an alpha delta dx lb plus (160 to 10 with coils (not traps)), and I could finaly hear something on 160 besides noise.
It was only 100 feet long or so, but it worked on RX.
On tx, the plastic pvc the wimpy coils were wound on melted at 200 watts carrier....

But I used to have an 80 meter dipole over the house that was only 90 feet long with coils in it, it was resonant and worked fine for many years.

I think some loading coils work much better than trying to do it all in a tuner.

Brett

Yep, loading coils work FB.

I take a lesson from the 75M rotary Yagis that use 90' elements. They are reasonably efficient within their narrow bandwidth and the best ones use loading coils about 1/2 way out on each leg to make them resonant.

However, with a simple dipole that can be fed with openwire and a simple antenna tuner, 90' for 75M and 180' for 160M is still OK without loading coils. These lengths are about the cut-off point, however.  Modeling shows them to be reasonable and the input impedances OK in the real whirl too.  But get down to 65' for a 75M dipole (1/4 wavelength overall) and the input impedance starts to deteriorate - thus needing loading coils or extraordinary meaures to keep the openwire and tuner losses low. (like heavy wire, big tuner coil and/or  flat top loading coils)

T

If you can make the dipole 180 feet long, no loading coils will be needed.

Don't go too skinny on doublet and feeder conductor size and expect the ant coupler to do some heavier lifting.

A tuner like this is great for high power.  Its also a fun project and if you have the parts, Its alot cheaper.

However, There are some major Drawbacks in my opinion:

1. Its real ugly and some just dont want a Board with coils and open caps on the table or wall.

2. Most hams never built a Screen cover or box. They install it on wood.  Not on option for alot of households.  Open RF, Pets, Kids, ect..  I the cat walks across as you are keyed down its by by Kitty.

3. Its a real pain to tune.  Clipping both leads of the coil.  Cranking on a Turns counter up to 200 times.  Not great for a band switcher ham like myself.  I use alot of bands in one day or evening looking for the fun.  Do yourself a favor and also build some RF Amp meters.  You will need them with this tuner. You have the option of accidently tuning it way off because you have two clip leads.

Build the tuner. Its a great project.  You will learn and have a sense of accomplishment.  They do work well.  But you might still want to get the matchbox.  Especialy at your power level. Make a chart and hang on wall. Switch the band with one knob, Turn the big knobs to the number you need.  No need to retune or even check it.  I have operated like this for a couple years now with my KW matchbox. I can quickly go from band to band.  This works as my 160 meter antenn is seperate and does not need a tuner at all.

Consider building a metal cage for the tuner or at least some form of RF protection and voltage protection. 

On the homebrew link tuner:

A big, well built coil and variable cap looks beautiful to me. It's all in the eyes of the beholder. Though, a cover can be as simple as buying an 18" X 18" plastic storage box at Walmart to cover it for safety.

I just checked one of my vac variables connected to a turns counter. It's 40 cranking-turns end to end and takes 10 seconds to cover the full range. Sometimes band matches fall within a few crank-turns of each other, especially on 160- 40M, depending on the match.. I once had a 75M dipole where I could change just the main coil taps and the capacitor stayed the same setting for both 75 and 40M to give 1:1.   A breadslicer could be used and be just as fast as the commercial stuff when using calibrated knobs.

If someone didn't like clips, they could do as some have - use a rotary bandswitch to select the preset taps for each band.  Personally, I thought clips with pre-band marks were just as fast once you get the hang of it.

A Johnson Matchbox does have a limited tuning range, though it can be increased to an acceptable level by adding in a switchable input link. (Add a bandswitch to the input link to X2 X3, etc, the overall range)

Once someone builds and uses the HB link tuner, they never go back to toroidal baluns and MFJ-type  tuner products.

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

T

I absolutely agree that some type of link coupled balanced tuner beats the pants off of anything being manufactured commercially today. 

The Jan. issue of QST has an article on making your own copper tubing inductors.  Incredibly the issue is devoted not to homebrewing, but "DIY" as if, modern hams don't know what HB means.   (side note:  there is also a K1ZZ editorial instructing hams on how to look at their transceiver frequency display and figure out if they are out of band or not.   I thought there was an FCC exam question on this but I guess not.)

Anyway, there are all sorts of tricks for tapping the coil -- if you don't like aligator clips you can get some of those little clamps that tighten with a thumbscrew that are designed for tapping a coil.

Even better in my opinion is to use gator clips for awhile until everything becomes routine, then note where the taps are for all the frequencies used, and solder little solid copper stiff wires there (coming out maybe only an inch) to banana jacks, one on each wire of course, then put banana plugs on your tap leads going from the coil to the capacitors.  After that, QSY means unplugging and plugging banana plugs on the coil and you avoid sourcing an expensive RF bandswitch and dealing with aligator clips.

All kinds of tricks, probably you will come up with some yourself which is part of the fun.

One of those photos Tom showed had the tuner upside down which helps solve the problem of kitty walking on it.

K5UJ said:
The Jan. issue of QST has an article on making your own copper tubing inductors.

Partially true Rob, it's about making coils out of solid # 10 to 14 awg household wiring, but it seems easily adaptable to tubing, just upscale the homebrew ribs.  I'm not sure the stretching part applies to tubing.  It does seem a bit daunting to someone without a drill press or table saw, but doable.  Actually, it had me checking out Habor Freights website for a cheap drill press.  Surely that would be a great addition to the workbench.  

KE7TRP said:
Its also a fun project and if you have the parts, Its alot cheaper.

I have no parts but the plywood.  ;D   But I figure it would be a great idea to build the coil, and if it comes out half as decent as the example shown on the K1JJ tuner thread, I'll be all set for bidding and begging for some appropriate breadslicers.... I may have a couple nice ceramic standoffs but hey, hamfest season is coming up real soon.   I still have the G5RV and it does get me on the air until I can get this puppy going.  

K1JJ said:
A big, well built coil and variable cap looks beautiful to me. It's all in the eyes of the beholder.  

This beholder thinks they look very buzzardly!  (Buzzardly is Beautiful!)  I have no pets except the occasional field mouse (I live among rice and other crops 10 miles outside of town).  I live alone but I do get my youngest son from time to time.  He's 13 and knows not to touch my radio stuff, as I have told him it could be deadly.  I've always offered to teach him whatever he wants to know about this stuff if he ever becomes interested.  He's more into XB0X360 and dreaming about the girls at this point.

I have hand tools and an electric drill at this point.  I think a drill press could come in very handy for such projects.  I wonder if it's too late to ask Santa for one?  ;D

BTW, B&W has these coil clips cheap enough... they should do right?  Or maybe they aren't big enough....
http://www.bwantennas.com/coils/coilclip.htm (http://www.bwantennas.com/coils/coilclip.htm)

John,

Your question about the coil clips....  The ones pictured in the ad are for #10 wire max.  You want to wind the coil out of at LEAST 1/4" copper tubing or prefereably 5/16".  This is for the likely event some of your multiband matches are low impedance and generate some serious current. If the coil size is rugged enuff, it will not generate meaningful heat losses.

What works well is to buy some of those copper battery alligator clips, maybe about 2" long.  Then file the teeth so that they are smooth and the grip hold is rounded - to make perfect contact with the rounded copper coil stock.

Otherwise, do a Googie search for battery clips and find some smooth ones.

Another method is to use temporary alligator clips until you find the permanant taps for each band. Then solder on small 3/4" wide copper flashing strips to the various coil points to use with heavy flat alligator clips. Use a propane torch, of course.  

There's lots of ways to do it.

T

How about Automobile Jumper Cables??  ;D

Sure, why not?...  ;D

The problem is unless you are using soldered on copper tabs on the coil to clip to, large alligator clips will short out the adjacent turns due to size. You need smaller clips.  Just try to duplicate the contact surface area that the wire diameter of the feedline makes as a minimum.  Try to simulate a soldered-on connection in contact area or the clips will develop "hot spots" and burn when matched to low imp/high current situations.  With poor contact area, I've had some clips get so hot the springs lost their annealing and failed.... :o

T

Clips like this are almost perfect.
If you need to, you can file, or bend with pliers too make them perfect.

You can make your own clips by folding over a piece of copper flashing (maybe two pieces depending on thickness). Solder a tabs onto the coil at the proper locations and all you need to do is slip your clip over the tab. This arrangement will provide much more surface area f or contact than most alligator clips.

Color code the tabs for each band, mark the cap settings on a cheat sheet and you'll be able to change bands in well less than 30 seconds.

Don't waste you time putting a metal box around your tuner. It's not needed. If you want a box for safety, make it out of plexiglass or masonite.

If your cat is stupid enough to hang around a tuner it isn't long for the world anyway.

Bruce, I just gave my cousin a pair of those clips yesterday. Great for gripping 1/4 inch tubing.
Once you figure out the right tap you can change bands quickly. I use a receiver with a 6 or 10 dB pad in line . Then i tune for maximum noise. It gets you quite close. The pad forces the rX input to 50 ohms so when you attach the transmitter it will see the right load.

Indeed. Darwin in action.

Does Darwin apply to cats?

The only good cat is a stir fried one.

Okay so WOW!  I looked up 1/4" copper tubing and that stuff is QUITE expensive!!  Most places want from about 60 to 120 bucks for 50 foot roll.  Apparently the main use is for icemakers and cold water lines in refridgerators.  I did find one placed selling "50 ft roll generic 1/4" copper tubing" for under 30 bucks but more like 45 once shipped.  That's not TOO bad. 

http://salestores.com/gen72refcopt.html (http://salestores.com/gen72refcopt.html)

I hope this is the stuff!  How many feet does the 40 turns actually take?  I suppose it's better to get more than enough rather than not enough.  ;D

Just over 50 feet for 5" inside diameter...
But it's not like you can't drop a couple turns.

OR wind it on 4"   Sched 40 PVC ...
That gives you 4 1/2" to 4 3/4"  inside diameter on your finished coil..
CLOSE ENOUGH!

I believe I use all but 6" off a 50 foot coil ..

Question is, are you sourcing  1/4" ID or 1/4" OD

I used the standard 1/4" ID tubing... it isn't "special".
Home Depot 2 years ago, when copper prices were high, it was under $50.

You can use #4 solid wire if you find it cheaper (doubt it, but you never know..)

Solid #4 was about $1.85 a foot the last time I bought it. Standard ground wire for 200 amp service.

Again, about 2 years ago I found a spool of #4 at a "rural" hardware store for $0.79 / ft.

They said they aren't like the chain stores, and are still making money on the wire,  based on the price they pay for it.... they don't raise the price based on speculation like Home Cheapo and others do.

I went this summer, picked up some more from them, and it was $0.99 / foot.

They don't use solid wire around here for grounding... always  stranded.
Well, the power Co. uses #8 or #6 solid on their poles, but a lot of that has dissappeared over the past few years .

1/4" copper refridgeration tubing  50 foot roll.  on EBAY

$28.  plus $8 shipping.


http://cgi.ebay.com/NEW-724-18000300-Copper-Refrigeration-Tubing-1-4_W0QQitemZ380167544905QQcmdZViewItemQQptZSmall_Kitchen_Appliances_US?hash=item5883c06049

 " The only good cat is a stir fried one. "

Not true.....  They are delightfull when baked, rapped up in a little bacon....

klc

HUZ, I was at our lightning Contractor test house and saw a cool coil made from 1/4 inch. They used large chrimp lugs as taps. The small hole size was just right for a banana plug and the bolt side of the lug was wrapped around the coil and soldered.
W1GUC (SK) told me once that a real QRO tank tap is never soldered, it is bolted. He turned me on to my first model 85 band switch. He told me solder will melt and you would lose the connection.

Banana plug. That would be FB!

Yup, I thought it was a cool idea. Just plug the banana plug in to make the tap connection. The lugs were bent so a banana plug would go all the way into the back of the lug. A tuner would require 2 of them and maybe a couple more to switch between shunt and series mode.