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Author Topic: Screwdriver versus loop for base station locations in HOA  (Read 598 times)

KK4GMU

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Re: Screwdriver versus loop for base station locations in HOA
« Reply #15 on: February 21, 2023, 10:58:34 AM »


Bob sorry to hear you have no experience with antennas.

Bob never said that.  AI5BC:  You have a terrible habit of distorting posts by others and creating a worst case false scenario.  Emotional maturity would be a big help.
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IC-7100, RSPdx, AT-D878UVII-Plus HT, TGIF Spot

N2ZD

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Re: Screwdriver versus loop for base station locations in HOA
« Reply #16 on: February 21, 2023, 11:46:33 AM »


  In both posts I see the same two complaints.

1. “A loop is deaf when untuned to the frequency.”

   Not true, it is just as dead as any untuned antenna on the band. It will hear slightly less than a screwdriver or other out of tune antenna. Not much to write home about here.

2. “A loop is highly directional and must be turned to work properly.”

   Also not true, when I deploy my loops my house faces North south and I use the loop facing east west. I still can work Canada and South America or Europe or Western US with a lower signal to the area out of
Favor.
   You can use a rotor to squeeze a few more out of it, but it’s not always necessary. It doesn’t have to be very high to work right either. Whereas a screwdriver works better elevated as was mentioned due to the amount of ground radials needed

  I’ve used screwdrivers and have 4 as we speak. The Ameritron SD-100, the little tar heel II, the ATAS-120A, and another big one that takes near legal limit (I forgot the brand but they make the piranha)   
   They work great, some can take gobs of power, don’t look like antennas, can be easily hidden and tuned.
    The loop on the other hand attracts attention with its looks but can be disguised somewhat. But in my opinion does much better than a screwdriver watt for watt and surprises me every time with the contacts I make .

   This is only my opinion. But I’m having lots of fun working the world with them.

Regards Richy N2ZD
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KA4WJA

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Re: Screwdriver versus loop for base station locations in HOA
« Reply #17 on: February 21, 2023, 10:44:53 PM »

Jerry,

1)  I don't want to start posting redundant things....but, I think I can put some fine points on, and highlight some, things....and some might be redundant from my responses in your other thread....so forgive me....it should be helpful.


2)  As we've been discussing with you for about a year, your local receive noise level on HF is going to be your limiting factor in successful HF comms....being in a townhouse with strict HOA rules, makes this one of the most important things to look at, BEFORE even looking at antennas to buy/build/install....

Hmmm....or huh?, how? you say.....okay, the point is you should throw a wire (a very thin, and practically invisible wire) out a window and across a shrub, or over a tree branch, or along a fence, or over a patio umbrella, etc. etc. etc.....plug this wire into the center hole of your IC-7100's HF antenna jack (its SO-239 jack, for HF), sitting inside....and listen to your noise levels on 40m and 75m, daytime and nighttime (and 20m as well)....this can be a quick test, so even if you're worried about neighbors seeing what you're up to, it won't take but an hour in the morning, maybe an hour in the afternoon or evening (and a few minutes at night, if possible)...

Listen in to some local daytime nets (South Cars on 7251 most of the morning....WaterWay Net [and Hurricane Watch Net] on 7268 at 7:45am-8:45am...as well as a couple on 75m/80m etc. etc...)....and, if you can hear some stations well, and/or your noise level is fairly low and you can hear many stations from all over, count your blessings and then start to consider antennas!
Keep your Pre-Amp OFF!!
  (please know that while there ARE some antennas that can improve your receive S/N, in your situation it's unlikely that even the wicked-expensive small loops would provide you with significant improvement in actual real-world receive S/N....but, let us know the results of your receive tests, and we can go from there!)

If you're unlucky, you'll need to spend the time/effort doing RFI mitigation / elimination, BEFORE you start looking at buying/building/installing antennas...(and, as I wrote, while there are some antennas that can improve your receive S/N....they are NOT a panacea, and unfortunately even if you had the room for them, you may not want to spend the $$$$ on them!)  So, in your situation, eliminating / reducing your local RFI is going to be the single most important aspect in striving for success in HF comms, with antenna choice a distant second place...

Rick, KL7CW mentions this....but everyone seems to have ignored him....please don't.  :(


{Also, while signal levels of stations on 40m (daytime) and 75m (nighttime), within ~ 200 miles of you should be fairly strong, and if you get your local receive noise levels low, you should have decent receive S/N ratios....but....

But, remember two things:

---  other stations might not always be so strong, especially on emergency-power or on temporary antennas...

---  and, the most important thing here:  Natural Noise, mostly constant thunderstorm-induced, with higher "static crashes"...here in central Florida we have some of the highest incidences of thunderstorms (the inland area between Gainesville and Leesburg, within 20 miles east and west of I-75 has the highest yearly incidence of T-Storms in the US....heck, the Univ of Florida's lightning research center is just north of Leesburg, 3 guesses as to why, and the first two don't count....and close second place is a tie between the SW Coast from Naples to Sarasota, and the SE Coast from Miami to WPB)...and, guess what, those areas are all within close NVIS range of Ocala...of course, the whole US Gulf coast from FL to Texas, and many areas of the SE US also spur T-Storms all summer long, but we have 'em day and night, and while it might "clear-up" inland, you can see lightning offshore a ways, until late at night, especially over/near the Gulf Stream (in Atlantic as well as the Gulf Stream feeder currents in the Gulf and Yucatan), so our summertime 75m (and 40m) noise levels here are significantly higher than in most of the rest of the US!

Meaning that while "the books" are correct that NVIS signal levels using normal 100 watt ham rigs and simple dipoles are "strong", the fact is that we unfortunately have some of the highest natural noise levels to contend with here-abouts....so, using compromise antennas down here, for 75m is fraught with frustrations!  If you ever wonder why some folks say that they love their EFHW, or small transmit loops, etc...and some ridicule them....remember that you get different results in different locales / different applications!  (btw, Dale reminded me of this just a little while ago....where they have significantly lower nighttime "critical freqs" up north than we do down here, especially with low sunspot counts...) }



3)  Highlighting something else of what Rick wrote:  "If you give us more info on your PRIMARY band(s) and mode of operation, we could give you some good ideas since many of us have over 60 years of ham experience, often from many states and countries."

This (after getting your local RFI under control) is the second most important aspect here!

The good news Rick, is that Jerry (KK4GMU) has mentioned previously that his primary focus is EMCOMM operations, and that here in Florida that is almost exclusively on 40m and 75m for coverage from 50 - 300 miles, and on 2m for more local coverage.

When activated, The Hurricane Watch Net is on 7268 on 40m (and, nationwide on 14325 on 20m)...and they also use 75m at times (the National Hurricane Center used to be on 14325 and 3850 from 48 hours prior to landfall, until no longer needed)....now they're on 14325 and 7268...and 3815 for Caribbean stations, 3940 for south Florida stations and 3950 for north Florida stations....and, I have personally provided them with wind and pressure data during 2004 and 2005 hurricanes ---- Frances, Jeanne, and Wilma on HF---- they now are publicly on 7268 and 14325, and use their 75m freqs when announced and/or as needed....and, yes they did use 75m at night, this past year..

So, here in Florida (north-central Florida) Hurricane Watch Nets on 7268 and 3940/3950 (and on 3815, along with the Caribbean Weather and Emergency Net)

The North Florida ARES Net (and N. FL Phone Net) is on 3950 primary (with 7242 and 7247 secondary)....the Florida Statewide Phone Net is on 3940...(fyi, there is also a Bahamas Weather Net on early mornings, on 3696 and 7096...not typos, they use SSB just below the US Phone band)

The Gulf Coast Hurricane Net is on 3935 (night), and 7290 (day)...

The South Florida ARES Net is on 3940 nighttime (and 7242 daytime)...

Regional ARES Net (and West Central Florida ARES Net) is on 3911 nighttime (and 7281 daytime)

South CARS is on 7251...

So, while there is some occasional use of 20m for emergency comms, here in Florida it is not used much (as the skip zone doesn't allow 20m comms within the state), and since the National Hurricane Center is in Miami (~ 250 miles from Jerry) and state emergency management is in Tallahassee (~ 150 miles from Jerry)...and local EMCOMM is on local 2m repeaters....the "primary" HF bands needed here for EMCOMM are 75m and 40m, for comms from ~ 50 miles out to ~ 250 miles...

And, here at 25 degrees to 29 degrees latitude, with operations on 40m and 75m (especially the upper end of 75m), for coverage of ~ 50 - 200 miles, this is all going to be F2 Skywave (via NVIS)....so, high angles of radiation are used.

So...so, the worst antenna choice would be a vertical (a vertical of any type....but a small, loaded vertical is even worse)....
Have a look at one of Dale's pages, where he has some easy-to-understand info that might help explain this....
https://practicalantennas.com/applications/nvis/

The best antenna choice here is a horizontal antenna, like a dipole or doublet, or a remote-tuner-fed horizontal zepp / random wire....(if you had the room there are other antenna choices, but lets limit this to what will fit in a small yard, with HOA restrictions)...

If you need to cover both 40m and 75m, and have severe HOA restrictions (where a "fan dipole" or a multi-band/trap dipole, might be too obtrusive?), you can use a remote-auto-tuner feeding a wire or two, and have a multiband doublet/dipole, and have a damned effective, and fairly efficient, antenna!  :)   The cost of this is just the cost of the AH-4 tuner (~ $300 - $325, new) and the cost of some thin (nearly invisible) wire and the thin rope holding the ends.   The AH-4 can be painted to match your house, patio, shrubs, trash cans, etc....and, can be mounted just about anywhere and still be effective!   (although the best place would be atop of a 25' tall mast, I grasp that this might not meet your HOA restrictions....but, it's about the size of a shoe box and can look like a patio light, bird feeder, etc....or, it can be mounted next-to a patio light and blend-in well...or, under the eave....or, it could be on a flag pole, etc....the list goes on and on...)

BTW, regarding a "flag-pole-antenna", it's a vertical....so, that's a non-starter here.....but, you CAN put up a flagpole to fly the American Flag, so you could use two small (nearly-invisible) wire to hold the flagpole steady in the wind, and who's to say that you could not also use those wires as a inverted-v dipole?  (and, if you put the AH-4 tuner up there, even on a short 10' - 15' high flagpole, you'd have a killer antenna for your application!)

Regarding running some small, nearly invisible, wire....from the AH-4 out and up (?) to somewhere....the lengths are NOT critical!

Now, none of us are there at your house....none of us have seen your yard, patio, etc....so, we don't know where / how to run an antenna out there....but, just know that a vertical is the worst choice you can make for your application.  :)  (and, if you took some aerial pics or made a drawing to scale, etc. of your house/yard/trees/shrubs/patio, etc...it would really help)



4)  Now, as to small transmit loops....they are WICKED EXPENSIVE (one that would cover 75m and 40m, and handle decent power without being overly lossy nor suffer from failure at 100 watts, will cost you ~ $2500!!!  Ouch!!!)

https://www.dxengineering.com/parts/mzz-midi?seid=dxese1&gclid=CjwKCAiA9NGfBhBvEiwAq5vSy8FyhToMvP6PWvRdOOjMJ8srNp90_BNoPSF3mwMAWcQOLA4yHj19MRoCngoQAvD_BwE

https://www.wimo.com/en/blog/post/testreport-ciro-mazzoni-midi-loop

And, at best (using the best, wicked-expensive model), in the best situation / location, it will still be ~ 4db to 6db worse (in zenith gain) than a dipole at the same height would be....and, in many situations/locations it will be even worse than this...so, spending > $2000 more than an AH-4 and a piece of thin, nearly-invisible, wire, and get an antenna that is ~ 6db worse, that just makes no sense to me.  :(

Also, can you disguise it well enough to be HOA invisible?  Hmmm?  That's a good question, that I don't have a good answer to...but suspect the answer is "maybe, but probably not"?

Oh, and the darn thing's 3:1 VSWR bandwidth is just about 3.8khz on 75m!!!  WOW, that is narrow....and this means constant retuning...(that 3.8khz is not a typo!  and on 40m it's only ~ 14khz....again, not a typo!)


5)  Jerry, at the risk of being redundant....here is the last part of what I wrote in your other thread....
3)  Jerry, please take this part in the friendly, helpful way I intend.

a)  there is room for everyone in ham radio, whatever your desires are....whatever niche you find inspires you, there is room for you!  (I have been saying this since the 1970's, and it is still as true today as it was 50 years ago!)

b)  just 'cuz I don't use DMR, etc., I will not try to dissuade you from what you find interesting.

---- BUT  ----

c)  But, if you do decide to get into HF operating from your house (using your IC-7100, etc.), please, please don't spend money on poor / inefficient antennas just because many hams say "I used xxxx, and it worked great" or "I've worked > 150 DX countries using yyyy antenna", etc....this is especially important in your case (both the negative of having serious HOA restrictions, and the positive of having a modern Icom rig), where you can take some small, nearly invisible wire, and string it up in just about any length (>20' and < 150'), in just about any configuration / shape (straight, zig-zag, loop, etc.), at just about any height (above your head, of course), and feed it from an Icom AH-4 tuner (under the eave, or on a post, or even just sitting on a patio table, etc.), and you'd have a decent 80m thru 10m antenna, easy-peasy, that will work much better than any small transmit loop (actually better than EFHW, and other such compromise antennas....and unless you put down a lot of radials in your yard for a vertical, it's going to work better than a screwdriver-antenna in your yard...and, for local/regional coverage, out to 300 - 500 miles, a vertical is the LAST type of antenna to consider!)....with total cost of ~ $300 - $325 new (or ~ $200 used)...

Also, please remember your initial query was about EMCOMM activities, etc....which, here-abouts in Florida are usually on 40m and 80m, with comms paths of ~ 50 - 300 miles....which would necessitate a horizontal antenna, not a vertical antenna (whether a "screwdriver" or a 65' tall full-sized 80m vertical)....a simple horizontal wire antenna will be MUCH better here!
Please take note here that I'm not panning verticals, nor screwdriver antennas....just pointing out that you can spend 2 - 4 times the cost of an AH-4 on some HOA-designed verticals, or screwdriver, etc....and, they'd be 20db - 40db worse than a simple horizontal wire antenna, for 40m and 80m coverage out to 300 miles or so!


{and, btw, remember the AH-4 tuner is well-sought after on the used market, as it is a MUCH better tuner than LDG or MFJ...so, while a ~ $600 - $800 transmitting loop may be a tough sell on the used market, even at 1/3 of its original price ---- an AH-4 can be sold for ~ 2/3 of its original price, in just a day or two....so, the "real" cost of an antenna using the AH-4 is much, much less than the poorer-performing small-transmit-loops!  :) }



d)  And, finally....again, if you do decide to get into HF operating from your house (using your IC-7100, etc.), please get in touch directly....and, whether you heed my specific recommendations or not will be no worry here, as long as you get the advice the choices are of course up to you.....the problem is that much of the advice given (goodness help me for saying this!) ---- much of it is rather anecdotal and misleading, and some of it is just regurgitating of either what that particular ham has heard from others (think of that old game of "telephone"), or just a rehash of the marketing info.

Remember, I'm not selling anything....and, I will usually only share my own experiences with some particular antenna / antenna system, AFTER I've helped explain the science / engineering (don't worry, maybe just the basics!)...


Okay, gotta' go.
Jerry, please take care and enjoy!

73,
John,  KA4WJA


I do hope this helps?

73,
John,  KA4WJA
« Last Edit: February 21, 2023, 10:55:20 PM by KA4WJA »
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K1FBI

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Re: Screwdriver versus loop for base station locations in HOA
« Reply #18 on: February 22, 2023, 04:03:30 AM »

I was previously in the restricted situation for a few years and had luck with loops. I ended up having much better results with the simple EndFedz antennas. They now even make an all band antenna that can handle an amplifier
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K0UA

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Re: Screwdriver versus loop for base station locations in HOA
« Reply #19 on: February 24, 2023, 03:23:50 PM »

I would use a paper clip before i would use a screwdriver antenna as it would be more efficient. A dumb load works better than a screwdriver.

I wonder how I was able to works so many countries with my little Tarheel II ?
Not to mention all over the USA, and this is on SSB with 100 watts.

Hm... mystery

Now I am not saying a screwdriver is a highly efficient or broad-banded antenna, BECAUSE it is NOT either of those.  Adding some extra wire in a fixed location will increase efficiency and broad-banded it a bit also.
« Last Edit: February 24, 2023, 03:30:20 PM by K0UA »
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73  James K0UA
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