Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: Prev 1 [2] 3 4 Next   Go Down
  Print  
Author Topic: The Kilowatt Curtain  (Read 3553 times)
SCUBA
Member

Posts: 74




Ignore
« Reply #15 on: July 06, 2008, 05:09:12 PM »

Hi K9NW,

QRV, as in contesting? Not me. I'll gladly support someone else who is participating, but I have no plans to compete.

RE: "Compromise antennas"

Before I spend any money, please clarify which of the above mentioned antennas are considered compromise antennas.  

The Ventenna HFPD I presently have.
The Mosely Mini-33-A-WARC beam I'm considering?
The Cushcraft MA5B beam I referred to?
All 3 of the above?

Thanks for replying,
Jack

Logged
KB9CRY
Member

Posts: 4284


WWW

Ignore
« Reply #16 on: July 06, 2008, 05:49:04 PM »

I'll gladly support someone else who is participating, but I have no plans to compete.


Jack, I sense you don't understand contesting.  Yes, there are a few stations that compete against each other for first place in whatever category.

However, 99% of the stations are not doing that and are only in the contests to had out points, rack up a bunch of new countries, improve their operating, etc.

Contests are where even the El Grande QRPers, like yourself, can be efficient.  Your competition is yourself; whatever goal you set is what you're up against.  It's the best way to do the above.  Phil

Look at a Force 12 antenna or a Steppir before the Mosley, and all are better than the Cushcraft you listed.
Logged
KY6R
Member

Posts: 3133


WWW

Ignore
« Reply #17 on: July 06, 2008, 06:11:06 PM »

Mr. Scuba,

I went from that Force-12 Sigma 5 to an MA5B, and it was fantastic - and I understand your choice(s) - they are the same as mine years back. I needed something stealthy with gain.

When I could put up something a little bit larger, I went with a Force-12 C3SS, and finally a 2 element SteppIR.

Funny thing - my 2 element K1WA wire array - on 20M and 30M performs exactly like the 2 Element SteppIR and the C3SS. The MA5B is not far behind these at all - in fact, on 20M, its the same thing.

After rotating 2 element yagis for the last 5 years, I've ended up on phased arrays using a DX Engineering switch. I'd MUCH rather switch than rotate.

Oh - I have also had a 20M 4 square and a 2 element 40M end fire and broad sided array, and they were awesome.

The K1WA array cost about $400 - with that superb DX Engineering 8 position switch. The 2 element SteppIR - almost $1000. The MA5B - about the same as the K1WA array .

You DON'T always get what you pay for!

Have fun - you will love the MA5B after using a Ventenna!
Logged
N3OX
Member

Posts: 8853


WWW

Ignore
« Reply #18 on: July 06, 2008, 06:51:45 PM »

"
The Ventenna HFPD I presently have.
The Mosely Mini-33-A-WARC beam I'm considering?
The Cushcraft MA5B beam I referred to?
All 3 of the above? "

"Compromise antennas" lie on a continuum, that is, everyone compromises on the price/complexity vs. performance front.

You can just go bigger and bigger and higher and higher and still see performance increases every time.

But I'd say this:  to decide what's a compromise and what's not, compare to a simple half wave dipole.  A half wave dipole installed up at least a half wavelength in the clear radiates nearly 100% of the power you feed to it and so it makes a good reference.  Every time you build one, you can be pretty sure it works exactly the way a half wave dipole works.  You can start adding elements in beam arrays, squeezing your radiated power in a given direction for some improvement.  Sometimes that actually leaves you with an antenna that radiates slightly *less* power (has slightly more loss) but that still has "gain" in the sense that the power you do radiate is very tightly focused toward your desired station.

An antenna that has too much efficiency loss, so it has negative gain with respect to a dipole, but still has a good pattern is considered to be "directive," and would be good for recieving, but the dipole would be better for transmitting!  I have an antenna I use on 160m that has 43dB loss relative to, say, a 1/4 wave vertical, I add a 20 dB preamp to make the relative loss  -23dB or so, and it works great for receiving.  If I tried to transmit on it, no one would hear me.

The small beams you've referenced are likely to be in the middle category, they're not *quite* as *efficient* as a dipole, but they're probably not lossy enough to have negative gain.  They just have less positive gain than *big* beams.

The HFp antenna has NEITHER directivity or gain w.r.t. a dipole.  The pattern is almost exactly the same, but because it's short and loaded by  somewhat lossy means, it's worse on transmitting and no better on receive than a dipole.  

The size and cost of arrays for continuing major improvement tends to be more or less exponential.  You double the size of your array, you get a fairly obvious improvement.  Eventually you get to a point where people don't feel like they need any more antenna.  There aren't a whole lot of 6x6x6 20m arrays out there that use six towers with stacks of six  six element yagis each, for example, because by the time you've got a few stacked 20m monoband yagis 5 elements long on a hundred foot tower, well, you can work anyone ;-)  Bigger arrays just cost more money and make you unnecessarily loud at distant points.  So any station I'm ever going to build is some sort of signal compromise ...

For a simple, straightforward, popular definition based more on the average ham than the insane station builder, I would say a "compromise antenna" is anything that significantly underperforms with respect to a half wave dipole a half wave above ground on the bands above 30m, or that falls significantly short of a 1/4 wave ground mounted vertical over a good radial field on 30m and down (or perhaps an inverted L on 160m).  I think this is kind of what people mean when they glibly use the phrase "compromise antenna."

A good small beam is not something I would term a compromise antenna as long as it meets these criteria:

1) *some* positive gain over a dipole.  
2) a clearly directive pattern with enough rejection in other directions other than off the sides that's actually useful for knocking down QRM.  Say at least 10dB F/B at worst, preferably peaking higher.

I don't know how the beams you're looking at stack up in this regard, but if you don't meet #1, all you're doing is installing a receiving antenna, and you should keep a full size half wave dipole for transmitting, and if you don't meet #2, there's no point in spending big bucks for a beam when you could just build a rotatable multiband dipole.

73,
Dan



Logged

73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
SCUBA
Member

Posts: 74




Ignore
« Reply #19 on: July 06, 2008, 09:05:51 PM »

Hi Dan,
Many thanks for taking time to provide a verbose reply.

Yes, cost and size define the stopping point, especially in my case.

RE: "A good small beam is not something I would term a compromise antenna as long as it meets these criteria:

1) *some* positive gain over a dipole.
2) a clearly directive pattern with enough rejection in other directions other than off the sides that's actually useful for knocking down QRM. Say at least 10dB F/B at worst, preferably peaking higher. "

The Cushcraft MA5B seems to meet both based on subjective forum reviews and the testimony of local hams who have owned them for some time.  

The Mosley MINI-33-A WARC, according to the manufacturer, meets that (for front to back ration) at 20,15 and 10, but not 12 and 17, otherwise, the fwd gain at 20, of 3.5, may or may not cut it.  I need to read up more on the relationship between fwd gain and front to back ratio.

The basis for my purchasing the Ventenna in the first place is
http://www.eham.net/reviews/detail/2737
although I haven't tried it in the vertical configuration yet.

An interesting Ventenna observation was made by K6TTD, where he reconfigured his Hfp-D as a "L" with remarkable improvements.  I'll give it a try.
http://www.eham.net/reviews/review/71536

Nice website, Dan; I bookmarked it.

Thanks again,
Jack

Logged
N3OX
Member

Posts: 8853


WWW

Ignore
« Reply #20 on: July 06, 2008, 09:48:25 PM »

Jack,

I built a magloop:

http://n3ox.net/projects/magloop/magloop1_lg.jpg

I used it for Field Day this year just on 40m, though it tunes 60m through 15m (up through 21.300 at least)

I set up my deep cycle marine battery, hooked up the FT-857D to the magloop, and made about 70 QSO's just answering people's CQ FD calls.  With maybe one or two exceptions, each  station came back first call, from Illinois to California to Arizona.  

When I first built this antenna, I fired up on 30m and got a 539 report out of ZL1ALZ.  I got on 40m and had a long QSO with a guy in Texas who was absolutely astonished that I was running a 4 foot octagon loop.  If I bought this and reviewed it like the typical eHam review, this thing is a 5/5 success story for sure, just based on the anecdotal evidence above.  Domestic, DX, easy QSOs, etc etc.

But... the punchline.  It probably radiates, at most, something like 12W of my applied 100W on 40m, maybe 21W on 30m.  When I compare it against my other antenna options, it falls down flat.  I was in QSO with PA7MM on 20m with this antenna and switched to my Moxon, and Bert said the difference was like "turning on the light."  

My point is if it works "OK" then people will rate it very high. 5/5 Eham antenna reviews generally reflect more on how great ham radio is than they tell you how well an antenna works ;-)  I worked a lot of DX in college with a 20 foot wire fed against my window frame. You wouldn't pay $89.99 for that, I'd expect ;-)

If I were buying an antenna, I'd put the most stock in reviews that say things like "the MA5B is consistently 2 S-units stronger than my HF6V on 20m," or compare to a dipole or simple ground plane vertical... because people who only have one antenna have no idea how well or poorly it's working.  It's unfortunate but true that many antenna reviews are just useless because of this.


73,
Dan



Logged

73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
N3OX
Member

Posts: 8853


WWW

Ignore
« Reply #21 on: July 06, 2008, 10:11:36 PM »

"otherwise, the fwd gain at 20, of 3.5 may not cut it"

If you had 3.5dB gain over a dipole (dBd) on 20m, you'd be happy.

Unfortunately, I don't think a 3 element beam with 1/2 size (16 foot) elements on a six foot boom on 20m can actually make 3.5dBd gain!  I think that number is actually really fishy.  

The MA5B on a 7.3 foot boom claims 3.6dBi. (dBi is dB over an isotropic radiator, which means dB gain vs. spraying your radiation *totally equally* in all directions)  That's roughly 1.5dBd, and THAT is realistic, in my opinion.  That's a very subtle and probably not very useful amount of gain over a *dipole* , but it's not *worse* than a dipole, and probably quite a bit of gain over what you're running right now.  And, the MA5B has a directive pattern to it that will out-hear a dipole.

The 3.5dBd gain the Moseley is claiming is approximately the gain that my 20m Moxon has.  My Moxon is 25 feet wide and has a "boom length" of 9.3 feet.  

And to top it all off, a 2 element *full length element* yagi design from a pretty reputable source (DK7ZB) gives just 4dBd on 20m on a 7.5 foot boom.  

http://www.qsl.net/dk7zb/2-Ele-Kurzwelle/2-Ele-details.htm

Full 33 foot wide elements from a reputable, non-profit website, and somehow Mosely has managed to get within 0.5dB with a half size design?

73,
Dan





Logged

73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
AA6YQ
Member

Posts: 1551


WWW

Ignore
« Reply #22 on: July 07, 2008, 12:07:19 AM »

Jack wrote "Many members of a local radio club have commented on the formidible kilowatt curtains, namely, The California Kilowatt Curtain  The East Coast Kilowatt Curtain that both are barriers to central US hams attempting to work overseas DX. This is not my inference, many hams around here have brought up the subject and shared their experiences at trying to penetrate these kilowatt curtains."

This is a bunch of whining, and you should ignore it before you too become infected. As the great DXer's have said -- and on more than one occasion -- "you can't whine and work new ones at the same time".

Yes, west coast stations have an advantage over the rest of the continental US when working Oceania and Asia, but for them Africa and Europe can be a real struggle. In those pileups, they're "the sufferin' sixes". And while  east coast stations have an advantage to Europe and Africa, Asian and Oceanian pileups are tough for them to crack; few on the east coast even heard the last Spratly operation.

One could argue that midwest stations have the advantage because they can hear Africa and Europe better than their west coast competition and hear Asia and Oceania better than their east coast competition. No matter where you are, some other DXer seemingly has it better.

Previous responses have offered several good suggestions: improve your antenna, use CW, and read W9KNI's "the Complete DXer". To those I will add "learn about HF propagation". Knowing when and where the openings occur, and being there before the competition will give you a big leg up. Here's an excellent introduction by Bob NM7M:

http://www.astrosurf.com/luxorion/Radio/nm7m-hf-propagation-tutorial.doc

And there is much to be learned from the DXing lore in

http://www.ve1dx.net/Stories/stories.html

DX is!

    73,

       Dave, AA6YQ
Logged
K0OD
Member

Posts: 2527




Ignore
« Reply #23 on: July 07, 2008, 03:01:00 AM »

"The feedline is LMR-400 with a 1db line loss. Another ham told me to switch to Heliax Hard Line,"


That's the most hilarious piece of advice I've ever heard given to a new HF DXer.

Lots of quality advice given by posters here. I've worked every country but two with simple antennas. I too would suggest trying a dipole, and adding 40 CW to your arsenal. Use internet spotting websites.

My QTH is in Missouri, btw.
Logged
K0OD
Member

Posts: 2527




Ignore
« Reply #24 on: July 07, 2008, 09:01:31 AM »

"Many members of a local radio club have commented on the formidable kilowatt curtains..."

--
More comments because the info you're getting from your club mates is really off base. (what kind of club is that? Local repeater group?)

 *** Texas is on a coast... the South Coast! ***

Texas is a great place to work long path over-the-pole DX... Russians, northern Europe and more.  Propagation is generally better from southern latitudes.

Have you worked everything to the south? Peter I Island, South Sandwich, South Georgia? You haven't mentioned South America or a bazillion countries in the Caribbean and Central America. In terms of propagation, you should be thankful you're not in Minnesota.

As for working DX higher in the bands, contests are the very best time to do that. On 40 (which I've often contested on) you'll hear tons of DX up to 7080 or so in the CQWW.  
Logged
WW5AA
Member

Posts: 2088




Ignore
« Reply #25 on: July 07, 2008, 12:49:41 PM »

I have always considered myself lucky here in the middle of the country. On any day I can work the Pacific rim or EU on 20/17. It just depends on pointing the beam E or W. Same with a wire on 160/80. The key is a good antenna systems both for TX and RX. I very seldom use the amp on 20 and above, but it's nice to have 1.5K on 160/80. Have fun!

73 de Lindy
Logged
KE5OKQ
Member

Posts: 191




Ignore
« Reply #26 on: July 07, 2008, 04:20:29 PM »

AA6YQ:

Why must you denigrate a member's post as whinning?  Your admonishment would be more credible if you were running 100 watts thru a dipole in Arkansas rather then your AL-1200 amp and tower in PA.  Have empathy for the little guys in the central states and enjoy your membership in the kilowatt curtain with some grace.
Logged
WB3ERE
Member

Posts: 118




Ignore
« Reply #27 on: July 07, 2008, 04:56:33 PM »

Mr. Sherman, I do believe that you failed to completely understand Dave AA6QY's response "Jack wrote "Many members of a local radio club have commented on the formidible kilowatt curtains, namely, The California Kilowatt Curtain The East Coast Kilowatt Curtain that both are barriers to central US hams attempting to work overseas DX. This is not my inference, many hams around here have brought up the subject and shared their experiences at trying to penetrate these kilowatt curtains."

This is a bunch of whining, and you should ignore it before you too become infected. As the great DXer's have said -- and on more than one occasion -- "you can't whine and work new ones at the same time"."

------------------------------------------------------

He called the responses by un-named members of a local radio club whining not and hence did NOT "denigrate" Jack's post.

We need to improve our reading comprehension before attacking each other.  Perhaps you can follow this up with a well deserved apology to Dave, come on be a man, be a Marine ex or otherwise.

73
Ed
Logged
AA6YQ
Member

Posts: 1551


WWW

Ignore
« Reply #28 on: July 07, 2008, 05:29:18 PM »

KE5OQK said "Why must you denigrate a member's post as whinning? Your admonishment would be more credible if you were running 100 watts thru a dipole in Arkansas rather then your AL-1200 amp and tower in PA. Have empathy for the little guys in the central states and enjoy your membership in the kilowatt curtain with some grace."


Please re-read my post more carefully, Curtis. I did not characterize Jack's post as whining, I characterized the advice given him by his radio club members as whining, and suggested that he ignore it.

Were there truly a "kilowatt curtain" on the east and west coasts, then DXers from the central states wouldn't occupy three of the top ten slots in the ARRL's De Soto Challenge (10-band 3-mode DXCC) -- as do K5UR (Arkansas), W9ZR (Ohio), and K8MFO (Ohio). Another three top-ten slots are held by east coast DXers (W4DR, W1JR, and W1NG) -- but none are held by west coast DXers.

see

http://www.arrl.org/awards/dxcc/listings/dxccCHAL.pdf

With a competent antenna and good knowledge of propagation, one can enjoy DXing at any level of power. One of my proudest moments is working a station in the then-USSR from Northern California with ~1 watt using a Heathkit HW-8 and an A3S tribander. A few months back, I spent two weeks as 8P9RY with a 100w ic-706 and a slingshot-launched multi-band palm tree doublet; I worked 93 countries (including Ducie) and had a blast!

So stop fretting about "curtains" and the rest of those lame excuses. Focus on improving your knowledge, your skills, and your station.

    73,

        Dave, AA6YQ
Logged
KB9CRY
Member

Posts: 4284


WWW

Ignore
« Reply #29 on: July 07, 2008, 07:11:45 PM »

Have empathy for the little guys in the central states and enjoy your membership in the kilowatt curtain with some grace.


Hey, I used to be one of those Midwestern 100w guys and after a season of yelling into the pileups, I upgraded my station and became one of the regulars.

Life is too short for QRP.  
Logged
Pages: Prev 1 [2] 3 4 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!