See if you can spot the problem with the following

[KJ3N]

From one of the FB ham radio groups:


Your not dedicated till you drive a ground rod home thru the south texas clay. Today i set up my hf20a wire antenna. This antenna needs 2 ground rods. The good news is that i get 1:1 swr from 160-10m no tuner.

Anyone? Bueller?

[NQ6U]

1:1 SWR from 160m through 10m without a tuner? That's not an antenna he's using, it's a dummy load.

[koØm]

From one of the FB ham radio groups:



Anyone? Bueller?

You got me, maybe a picture of the installation might help. I looked the antenna up, looks like a OCF dipole terminated like a Beverage Antenna.

Him claimed "1:1" match is problematic in wording and most likely improbable in real life; maybe he misread or misspoke in his description

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This was useful (not) in my understanding.

.

[KJ3N]

1:1 SWR from 160m through 10m without a tuner? That's not an antenna he's using, it's a dummy load.

Da Pope is wise.

The only way you get those kind of results is with a lot of loss in the antenna system. Oh, you can get RF to radiate off of it, but the question is exactly how much of the total applied RF is getting radiated.

[KG4NEL]

Whenever someone confuses RF ground with AC ground, Domo kills a kitten.

Now we have to perform a sacrifice to W4RNL to right the wrongs.

[WØTKX]

I suggest a 200 watt incandescent bulb.

[PA5COR]

My homebrew OCF works from 160 - 10 but will not be 1:1 everywhere....15 meters is baaaaaad ;)
Though nowhere worse as 1:3 ( needs tuner) 160 - 80 - 40 - 20 -18 -12 -10 are moostly below 1:3 or even 1:1.2.

First thought this is not an OCF antenna but an end fed antenna with a short piece counter poise and earth connection, clearly from the provided piccie you see only the short end grounded, the longer wire has the "Special purpose part" in it.

Still a wire fed with 1:4 or 1:9 un un won't give you 1:1 on all bands.
Possibly with a ruddy large non inductive 50 Ohm resistor in it ;)
From their advertisement:

Package Contents:1× HF20A Balun(The white Box)1× Special-purpose part (The golden metal Box) Must be that 50 Ohm ruddy big resistor then ;)
http://www.aliexpress.com/item/HF20A-HF-Full-Band-0-5-30MHz-100W-non-blind-Antenna/2050744819.html
More piccies of the gold colored heatsinked "Special purpose part" LOL
Here they state SWR < 1 :2
Radiating wire 20 meters, short side 1.5 and after the "special purpose part" to ground also 1.5 meters.

So in effect a radiating dummy load.
Most power will be lost in the balun and resistor, though on some frequencies it might actually radiate a bit better as a leaky dummyload.
You know how things work, if anyone didn't had a decent antenna up and tries this as first one it is a very good antenna.....
Till he finds out what a real antenna does.

[WØTKX]

Same reason I'm not a fan of the folded dipole. Resistive loads are futile.

[NQ6U]

Da Pope is wise.

The only way you get those kind of results is with a lot of loss in the antenna system. Oh, you can get RF to radiate off of it, but the question is exactly how much of the total applied RF is getting radiated.

I made a PSK-31 contact with a friend while he was testing his rig into a dummy load so, yeah, I agree—you can get some RF to radiate off of pretty much anything. That doesn't make it a good antenna, however.

Cor, I think you're right. That “Special Purpose Part” looks suspiciously like a high-wattage resistor, doesn't it? Check out this page (http://www.grandtech.lv/shop/index.php?language=en&currency=EUR&manufacturers_id=5&sort=6a&filter_id=3541&page=90)!

[KG4NEL]

Same reason I'm not a fan of the folded dipole. Resistive loads are futile.

They make fairly good driven elements, though.

[KG4NEL]

I made a PSK-31 contact with a friend while he was testing his rig into a dummy load so, yeah, I agree—you can get some RF to radiate off of pretty much anything. That doesn't make it a good antenna, however.

Cor, I think you're right. That “Special Purpose Part” looks suspiciously like a high-wattage resistor, doesn't it? Check out this page (http://www.grandtech.lv/shop/index.php?language=en&currency=EUR&manufacturers_id=5&sort=6a&filter_id=3541&page=90)!

Sort of like the "terminated tilted folded dipole" - which of course, works great for the military because with ALE nobody ain't got no time for antenna tuners or all that, and the huge losses are just overcome with mo powa.

[KF4ZGZ]

Might make a fairly good sub-terranian antenna.

Matt

[K4PIH]

Cantenna!

[n2ize]

I get excellent results 160-10m with a lightbulb for an antenna. However I have yet to make a contact with the bulb.

[KJ3N]

I get excellent results 160-10m with a lightbulb for an antenna. However I have yet to make a contact with the bulb.

Slacker...

http://www.ok1rr.com/index.php/antennas/94-everything-works

[kb2vxa]

"Might make a fairly good sub-terranian antenna."
Yeah, raise the antenna for sky wave, bury the antenna for ground wave. Uh huh, that's how ya do it, uh huh.

I recognized that golden metal box immediately, a wire wound power resistor made to be mounted on a heat sink. I used to work with them and measured a fair amount of inductance when I got curious. Maybe on the antenna it's a loading coil? Just could be, ayup.

[PA5COR]

The resistor will dissipate ( depending on the band used) some or more R.F. and lower the SWR that way.
The grounded section makes sure the SWR will stay low but efficiency? 25 to maybe 75% through the 20 meter or 66 feet section that radiates.
As I said before, for some without a good reference antenna he /she will state it is a magic antenna, till he / she puts up a decent dipole at reasonable height.

Don't forget conditions can vary 60 - 100 dB much mor as the difference between this piece of crap and a decent dipole.
10 dB gain between 100 watt out or 10 watt efficiency output from the antenna without reference is unnoticeable for some.

[W3WN]

From one of the FB ham radio groups:

Your not dedicated till you drive a ground rod home thru the south texas clay. Today i set up my hf20a wire antenna. This antenna needs 2 ground rods. The good news is that i get 1:1 swr from 160-10m no tuner.
Anyone? Bueller?Well, let's see...

Ignoring the non-technical issues with the post (such as the OP's inability to properly use contractions)...

The HF20A is, essentially, a dipole/inverted V with a balun/matching network of some sort at the feed point. Although you can also rig it up as an OCF dipole, or even as a delta loop.

So what the heck do ground rods have to do with a it, from an RF standpoint?

(As already noted, too, having a 1:1 SWR without a tuner only means that the antenna is presenting a 50 ohm load to the transmitter. Doesn't mean it's radiating a signal. I can find cheaper dummy loads at Mendelson's tent at Dayton.)

[W3WN]

I get excellent results 160-10m with a lightbulb for an antenna. However I have yet to make a contact with the bulb.I knew I should have read this thread three months ago...

Way, way, way back when I was in school and one of the ops at K3CR for the WPA section traffic nets... one night, Walt N3WS checked into the WPAPTN net with an extremely weak signal. Usually he was booming in (6:15 PM EST on 75 meters), since he was only about 2 miles from the club shack. We could hear him, but the NCS that night couldn't. So I called him on the 2 meter repeater to see if he was having a problem.

He was.

He'd tuned up the radio and forgotten to take it off the dummy load before checking into the net.

And the dummy load he was using that night, or so he said? A 100 W light bulb.

[WØTKX]

http://hk2.image4.pushauction.com/350/350/b2f014a8-d93a-46fa-ac8e-cbc10101c805/07a85342-494f-089c-3bc9-e7846fec3f7f.jpg

Balun on the left, Gold Standard SWR device on the right.

:doh:

[W3WN]

That "gold standard SWR device" looks like a big resister with screw terminals hidden inside of a big heat sink.

There was some company, in the neighborhood of 20 years ago, who was marketing a magic antenna with a secret box that you hooked the wires to. Someone (was this in QST or 73?) who finally reviewed it took the secret box apart, cleaned out all the gunk heat sink material around the central component, and discovered... a big 50 ohm resistor bank. So of course the antenna always presented a 1:1 SWR, all the radio saw was the resistors.

After the review was published, if memory serves, the magic antenna and the company marketing it quickly disappeared.

[KJ3N]

That "gold standard SWR device" looks like a big resister with screw terminals hidden inside of a big heat sink.

Give that man a cigar.... and a kewpie doll! We have a winnah!!

[N8YX]

Sonny Irons' old company offered the Max-Comm. Was touted as manna by people who should have known better and/or didn't have access to a network analyzer.

[XE1/N5AL]

He'd tuned up the radio and forgotten to take it off the dummy load before checking into the net.

And the dummy load he was using that night, or so he said? A 100 W light bulb.
I'd swap out that 100 W bulb for a 300 W monster, to get a: 10 log (300W / 100W) = 4.8 dB SIGNAL BOOST!!!!
And to insure top station efficiency, I'd "go green" with an energy saving CFL or LED bulb! Yup! :yes:

[K4PIH]

I remember looking at thise Isotron antennas and thinking if I got anough parts and pieces and starting putting them together I would eventually come up with a design that worked, to a degree. Same principle as putting 1 000 000 chimps in a room with typwriters and sooner or later getting the constitution.

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