Magnetic loop antenna for 160-40 meters 1KW

Pair of 45,000 volt vacuum caps tuning a 12 foot diameter loop, showing construction of capacitor tuning cabinet.

[@knightsofnee8626]

An antenna with caps so powerful, they have to be ordered from RUSSIA!!! Very cool video and build Woody! :)

[@conradsenior5843]

Woody, you are the only guy I've seen who actually seems to know what he is doing. I am stunned only a few people are using vacuum capacitors.

[@stevecongrave1684]

Variable air capacitor - $30 Vacuum variable capacitor - $150 Woody's vacuum capacitor $500 :)

[@marcusmckenzie9528]

OMG, next christmas, all i want is a Vacuum capacitor so i can stare at the copper

[@randyterrell2261]

Woody, very impressive work and I am excited about your impending trials. I might point out however that putting the two capacitors in parallel will not help your voltage arcing problem as in a parallel circuit, voltage is everywhere the same. You might consider putting the capacitors in series which would double the voltage capability (30KV) but it would unfortunately half the total capacitance value (200pf) and probably preclude use on 160M; perhaps even low end of 80M. The really only practical solution for KW and 160M is to find even higher rated capacitors, probably unlikely, or increase the size of your loop. If you're able to currently run 300watts on this at 160M, suggest you just enjoy it or be prepared for buying a lot more copper. Good Luck, looking forward to next video.

[@samuelsmith6573]

Looks like you've got it figured out! Well done sir!

[@ehababdulburalfakhory801]

Nice presentation. I wish I have similar to your workshop.

[@GreyGhost-r4z]

That variable is HUGE

[@Garganzuul]

What a beast! I'd definitely go with pneumatic actuation for that breaker. :)

[@woodyw6933]

Pneumatic would be hard to do and where do you make the pressure? It located 100 ft away from house. Enjoy WW

[@k5wxp22]

Hi Woody, great project there! I've looked into mag loops before, and none of them take much power. Yours is going to be a HOSS! I'm subscribing and looking forward to more videos on this antenna. 73, Brett KF5WXP

[@woodyw6933]

THanks for the fine words. Did a qso this am on 3705 with about 400 watts on ssb and got a 20 over report from Philadelpia Pa this am. Its been lots for fun so far and a hoot to explore results. Seems to be mostly omnidirectional though. More to follow. Woody

[@ronangsr]

I bought the stealth loop, cant wait to test it

[@woodyw6933]

Thanks for the kind comments. loops work. woody

[@GreyGhost-r4z]

Your workbench looks like mine all the time 😊

[@nicoschadjidemetriou4373]

BRAVO for your efforts and experimentation Woody! I made several experiments after university. That time (1971-1974) the calculator did not exist. I was thinking, what if you use a cheap (RX) capacitor and put between plates sheets of mica to stop arcing. 73s from 5B4ER (Cyprus)

[@woodyw6933]

Russian vac variables are reliable and humidity does not effect them, 72. Woody

[@samuelsmith6573]

Sell em Woody?! Lotta folks are probably interested!

[@freesaxon6835]

Well that's a inventive design .... Looks good to!

[@hokepoke3540]

Nice Woody, thanks for the video and ideas. Tom N5UEB

[@conradsenior5843]

Love the T shirt BTW

[@woodyw6933]

Loop is 12 high and 100' from house on a hill, Woody

[@woodyw6933]

The coil -loop and capacitor for the resonant loop and are in parallel or series, two components form that sort of connection. The current is on the capacitor and the voltage is on the loop inductor as they are connected together. The max current is not at the same time as the voltage max, they are out of phase. Please understand the cap is max voltage when the current falls to zero and begins to rise GOING into the loop.Max current occurs as the cap discharges into the inductive loop. Nothing happens independently when the current sloshes back and forth between the two components, they share the energy at different times. I used a switch that had the largest spacing and also had three contacts in parallel to handle the current, running about 70 amps and the cap has about 35-40 kv at full power AT The contamination still had tracking marks from surface-moisture from the atmosphere, 40kv is a bitch. Enjoy Woody

[@davidharmer9398]

These vacume caps give very good performance due to low losses and high breakdown voltage ratings. Have you considered the leakage paths of damp wood in the construction and what that would do to losses... Power = v^2 / R.. if R is 1 megohm and V is 10000,, power (lost) is 100,000,000/1000,000 = 100W!

[@w1qg]

I love that switch !

[@gregboggs4721]

Dr. Frankenstein, man that’s what that throw switch reminded me of.

[@alphasxsignal]

The Alpha of LOOPS looks like:)

[@jeromekaidor7254]

I just ordered one of these Russian 45kV variable monsters. Coming via slow boat from Bulgaria. I'm hoping to build a loop good for a kilowatt on 40 & 20. OK, I'll take 15 if I can get it. Wondering about that switch...surely the capacitors are at the high voltage end - and the high current is at the other end of the loop?

[@hokepoke3540]

Nice build, wish we could get American caps like that. I doubt anyone could afford an American one even if they were available.

[@Hungry_Hunter]

With a few modifications you could mount a Hemi V8 engine on that thing and maybe get 10,000w . God bless America.

[@stevesus3295]

I've never seen any of these home made magnetic loop antennas actually working. I wonder why? Could it be because it's not as easy to do? I am building one for myself because I live in an HOA. I'm disguising it as a sculpture. Mine will also be a two stage (double capacitor) except it will have one vacuum variable and one air variable. I am switching the AV in and out using two vacuum relays.

[@k1gmmgreenmountainmaniac251]

What a MONSTER! Fantastic build! Keep'em comin'....:-O

[@anonhollmuller4032]

hi, has the feed loop on the top any disadvantages over the top capcitor? i ask because i wonder about the propagation pattetn (the elevation of radiation especially). your work is verry impessive and inspitrating! Sorry for my poor english ! best 73 , dg2r?

[@happyhome41]

Love to hear - six years later - how this worked out, your thoughts, any improvements or did you move on and why. 73 M4MQ

[@woodyw6933]

Its in pieces waiting for 65+ temps. I took it apart to change out 400pf for 250pf cap. I want to get it back on 40 meters, was there before i upped caps to 45kv for 1kw operation. Hope for 1kw again with shorter leads to cover 160 thru 40 meters. 73. Ww

[@happyhome41]

@@woodyw6933 Thank you, and 73 Please keep us posted.

[@conradsenior5843]

They say that wine drinkers start with White wine, migrate to Rose, the Reds, the Ports. I thinnk Hams migrate towards loops. First you get on the air, then you make improvements, then only loops can satisfy you.

[@KF8OD1]

Nice job! I have a 500pf at 35kv for my 160m loop, hopefully that will be enough.

[@woodyw6933]

Thank you, your probably safe, the voltage depends on the freq also, Woody

[@YTGreyFoxx]

Love that T-shirt :)

[@nininiha6233]

Hi is there no electro magnetic effect to body (like up the body temperature or muscle moving) infront of antenna?

[@nicoschadjidemetriou4373]

@Ninini Ha. Very bad effect on microwaves . They cause cancers, changes on DNA..... and sterility.

[@woodyw6933]

It was a test to see how it could be done, and 1kw is for cw/ssb. Was a challenge, why not.

[@PY2RKC-QRA-MIRO]

Saudações !!! 👏👏👏 73 !!!

[@veloyozh]

You don't need 3x switch because there is high voltage and low current at the capacitor. It would be better to make 1 switch and increase gap between switch's contacts.

[@thedeadnigerianprincehaunt5096]

Time to rip the Flux Capacitor out of the DeLorean and talk to Marconi directly with 1.21 Gigawatts of time busting RF! Remember, time is not an issue anymore with such ventures into the ether... God's speed and good luck, Doc! (I assume it will only have negative consequences on birds, household appliances, planes or automobiles if they are traveling over 88mph)

[@speedbuggy16v]

wow, just wow... going to uplink to the voyager spacecraft? lol

[@dennisjoiner3717]

I normally work 160 with 50 watts. I'm curious as to why the need for so much power?

[@GreyGhost-r4z]

Russian Collusion. Lol. I bought mine there too. 4-100 pf. I am planning on building something portable. Thanks for the video 73 KB2QQM

[@alexramos2568]

nice but where is the antenna you talk about in the video title

[@noncounterproductive4596]

So, that's a 12-foot-diameter inductor with only one turn?

[@norman-justerieyazon4819]

Hi woody, how much did you get for the capacitor?

[@sighpocket5]

Wow..... Nice!!!!

[@rickhan7394]

Woody, did you do a quick cw “TEST” on 3705khz at 9:40am, 1/30/20? Heard 50mi North, had QRM. Apologies if not you.

[@woodyw6933]

Yes. I was testing 2 watt hartley running 2 type 27 tubes getting ready for my 3705 net group. Its for awa events. Woody

[@woodyw6933]

My vacuum caps are rated at 45,000 volts c/o russia via ebay. The video showed them. N4MQ

[@woodyw6933]

Bfg

[@gideonbanez763]

How many watts output from the radio to the small loop ? to get kilowatt .

[@woodyw6933]

1000 watts input to rig per FCC

[@Centar1964]

Great job.....but I just can't understand why 11 thumbs down...they must be idiots...

[@eugenepohjola258]

Howdy. The mother of all mothers ... In regards.

[@woodyw6933]

Mine works and 40 m it caused quite a stir, people piling on to check it out on receive. Ww

[@adriancressy8363]

It's worth all the work and expense to have vacuum vairables. The only way to get control of the Volts and Currents for a mag loop on 160M. And 1 kw??? Yeeeooowww!!

[@woodyw6933]

Band width at 3DB is 5000 cycles at 1.885 Mc. Really high Q and lots of noise rejection on the band follow the utube clips to see more, oody

[@greenthizzle4]

Adrian Cressy seems like you could make your own vacuum variable capacitor using plexiglass and a butterfly capacitor and a vacuum pump..

[@hank1519]

Good job, Woody! How did it turn out?

[@mariepi]

It is expensive and hard to find that capacitor. Why do not makes one with sheets of copper and teflon?

[@woodyw6933]

Thought about that, but $129 will be functional now and retain its value without fiddling around, thanks Woody

[@kipsus]

Any solid dielectric will have losses and lower Q of the system. The loss will only matter in a very high Q and/or high power loop, like this one. So going with fixed value vacuum is very wise. Speaking of losses, I remember reading somewhere that braided connectors actually have higher RF impedance than a solid copper strip. Which again only becomes relevant in extremely high Q/power applications. Just something to keep in mind.

[@woodyw6933]

Tested antenna, was about 5kc bandwidth at 3DB points, ran 915 watt carrier at 1885 without arcing, mission accomplished and all is well.N4MQ

[@kf4dcy501]

Woody Woodworth the Cap voltage should allow you near a legal limit wattage rating. should it not? I've been thinking on building one like your's. and one for 40 to 10. but I query a phased and spaced array to make for more directional and produce gain. but before that, I want to use the extra antennas in a criss-cross setup for an omni antenna. if it's at all possible.

[@porkyfedwell]

It's beautiful, but I hope that thing is going to be out of reach of anyone when operating, or someone could be zapped very badly.

[@woodyw6933]

Caps came from EBAY...

[@GTIXAUUSD]

so you are trying to transfer the power wirelessly for longer distances

[@woodyw6933]

30kv cap arced over Hi Q is responsible.

[@gregmodder5439]

10 Kv is more than adequate for 1 kW if you do the math...

[@woodyw6933]

All try, they are attractive. Woody

[@woodyw6933]

Like $100 or so 2 years ago. Be sure they gurantee shippment security. Breakage...

[@stevejones8665]

I am confused going by your T shirt you said in the order of 20Kv 100 amps so that would make power into antenna E x I =20 Mwatts....What are you trying to do fry the Birdlife LOL....Either that or its a very very inefficient Antenna and will cost you a fortune in Electricity...Why you even need to use 1Kw let alone 20Mw is beyond me 1 S point less signal strength when using just 100W and a lot cheaper on Electricity bills...

[@stevejones8665]

House power supply would need to be 18,181Amps at 110V and that is assuming your Transmitter is 100% Efficient LORL

[@woodyw6933]

Your are missing the reactive nature, the current and voltage are out of phase. Life is short, I run 300 w am . The mag loop is less efficient than a dipole so it evens out. Woody

[@UCs6ktlulE5BEeb3vBBOu6DQ]

And then you've got scientists search left and right why birds are falling from the sky stiff as a board... Now, where's my foil?

[@agustiana1247]

Ok...