Pages: [1] 2   Go Down

Author Topic: Screwdriver versus loop for base station locations in HOA  (Read 603 times)

KK4GMU

  • Member
  • Posts: 366
Screwdriver versus loop for base station locations in HOA
« on: February 19, 2023, 07:40:17 AM »

Among "compromise antennas", what are the pros and cons between "Screwdriver" and "Mag Loop" for base station HF antennas in highly regulated HOA-type locations?  My examples will be a screwdriver with full auto controller versus something like the  MFJ-1788 or 86 mag loop.

I'll list a few as I understand it:

* Price:  The MFJ would be a few hundred $$$ less than the full complement screwdriver.
* Directionality/gain: The loop is directional; the screwdriver is an omnidirectional vertical.  Rotating the loop would be necessary (manually or remotely) whereas not needed with the screwdriver.  However, the gain would be better with the loop, once positioned.
* Counterpoise/radial.  The screwdriver requires radials.  The loop does not.
* Positioning:  The loop is more portable.  Can be easily moved along with its mounting tripod. The screwdriver will usually be more permanent.
* Power handling: The loop is generally limited; most to 15 to 20 watts; the MFJs 150 watts.  The screwrivers can usually handle much greater wattage, many to 1500.
* Stealthiness:  The screwdriver is much taller but it has a very slim profile that the unaware might consider a generic pole or lightning rod.  The loop, which performs well mounted 4 or 5 feet off the ground, may not be noticed at all or could be disguised as a vine or whatever.
* Band coverage:  The screwdriver covers a wider range of bands while the loops generally are limited to 10 to 30 or 15 to 40 meters.
* Easy tunability: I don't know.

Other thoughts?

I will add this concerning availability.  I would have owned the MFJ loop by now if they were available when they said they would be.  I ordered one in October, promised for December, and as of this date (mid-February) there is no sign of availability from either HRO or MFJ.  Scanning HRO/Gigiparts websites, screwdrivers also appear to be in short supply.
« Last Edit: February 19, 2023, 07:44:06 AM by KK4GMU »
Logged
IC-7100, RSPdx, AT-D878UVII-Plus HT, TGIF Spot

K1KIM

  • Member
  • Posts: 1556
    • HomeURL
Re: Screwdriver versus loop for base station locations in HOA
« Reply #1 on: February 19, 2023, 08:01:05 AM »

The only screwdriver antenna I would buy is the Tarheel. It is a proven design with great resale value for your purposes or mobile installation.

Its not cheap by any means when all the bells and whistles are added, but worth it in my opinion.

I was going back and forth between the Tarheel and the Hustler 5-BTV and decided on the Hustler because I could "hide" the vertical in a copse of woods behind my house with all my wire antennas.

Fortunately my rear and side neighbors think the hobby is great and are always asking me if I have worked a new contact or country. They are fascinated about the space station coms.
Logged
So Many Toys.......So Little Time!

N2ZD

  • Posts: 429
    • HomeURL
Re: Screwdriver versus loop for base station locations in HOA
« Reply #2 on: February 19, 2023, 08:39:42 AM »


I have three loop antennas.
 
The Ciro Mazzoni baby Loop which is 40m-10m

The Ciro Mazzoni MIDI loop which is 80m-20m

The MFJ 1786 which is 40-15m

All work awesome, the MFJ is touchy to tune but gets you on the air.

 I’ve worked all over the world with 100 watts on my base rig and 20 watts on an SGC SG 2020 and 5 watts on an 817.
   Truly a remarkable design for sure.

 I’m also in an HOA and simply wheel out the Mazzoni’s or plant the MFJ and I’m good to go. It’s not permanent so what can they say? It’s on a tripod so I usually take it down when not in use.
   Screwdrivers need a little more care, you need to lay down a bunch of radials and bury them if you plan on making it a permanent install. Then run buriable coax and a control wire back to the shack.
  You can place a pvc tube in the ground and drop a mast in it when in use, attach radial field and coax/control wire and you’re on the air.
   The MFJ loop btw, just needs the coax. It’s powered thru the coax simplifying things.
   The Ciro Mazzoni needs a control wire and coax like the screwdriver since there is no bias tee to power it up for tuning.

Both setups will serve you well. I prefer the loops as they are amazing to mess around with and work like magic for me. Both are a compromise, but do what’s important, they get you on the air..

Regards Richy N2ZD
Logged

KK4GMU

  • Member
  • Posts: 366
Re: Screwdriver versus loop for base station locations in HOA
« Reply #3 on: February 19, 2023, 09:08:43 AM »

Good comments, N2ZD.  Thanks for sharing your experiences with mag loops.  I may still consider a loop in the future if/when I am sure I won't run out of retirement money.  Until then, the MFJ's aren't available anyway.
Logged
IC-7100, RSPdx, AT-D878UVII-Plus HT, TGIF Spot

K6SDW

  • Posts: 527
    • HomeURL
Re: Screwdriver versus loop for base station locations in HOA
« Reply #4 on: February 19, 2023, 10:16:47 AM »

A loop antenna, being hi-Q" is very directional and narrow banded as well.  I've read a loop is abert equivalent to a dipole in performance. Each antenna you mention has its pros and cons......

GL/73
Logged

AK5B

  • Member
  • Posts: 137
    • homeURL
Re: Screwdriver versus loop for base station locations in HOA
« Reply #5 on: February 19, 2023, 10:26:58 AM »

I have built several STLs capable of 650-watt PEP QRO operation for when I lived in a HOA condo; here at the newer QTH I am using wire antennas as well as an upcoming  elevated screwdriver installation in my back yard.

My second Scorpion SA-680 is on its way to me as of yesterday (Ron just moved his machine shop and had a slight backlog of orders to catch up on) and I plan to mount it @9 or 10 feet above ground.  Elevated  thus will only require two tuned radials per band and this one will be dedicated for (primarily) 80 meters dxing running legal-limit ssb.

My other Scorpion is atop my truck's toolbox so I have it available for fixed portable ops by the saltwater here.

I thoroughly can recommend using a taller radiator as well as a DIY or K8UZZ cap hat for better performance with any screwdriver, too.  Elevating them reduces the radials requirement unless you must ground mount one.  Mesh or screen is good for that and be sure to bond it well to whatever ground plane used.

More info in the QRZ Forums (with photos), too.

73,

Jeff, AK5B

P.S.  I never use any kind of auto-tune device with my Scorpion---just up/down switch and tune for maximum noise + watch SWR dip on rig---quick and easy!
« Last Edit: February 19, 2023, 10:30:23 AM by AK5B »
Logged

AI5BC

  • Posts: 456
    • HomeURL
Re: Screwdriver versus loop for base station locations in HOA
« Reply #6 on: February 19, 2023, 02:00:12 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.
Logged

KK4GMU

  • Member
  • Posts: 366
Re: Screwdriver versus loop for base station locations in HOA
« Reply #7 on: February 19, 2023, 04:07:54 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.
Sometimes over the top exaggeration can be funny.  Other times it just sounds like the exaggerator doesn't know how to use the device.
Logged
IC-7100, RSPdx, AT-D878UVII-Plus HT, TGIF Spot

KL7CW

  • Member
  • Posts: 1162
Re: Screwdriver versus loop for base station locations in HOA
« Reply #8 on: February 19, 2023, 06:11:19 PM »

Since you live in an area probably with many significant RFI sources near, it is possible that your biggest problem MIGHT be RFI noise on RX.  So do some listening in various places with a temporary RX antenna.  Noise MAY be worse on the omnidirectional vertical, and the loop may be quieter on RX.  It also depends on your band and mode.  If you can receive "ok" your biggest obstacle will be getting your signal out so power with maximum radiation is probably your main objective.  Sometimes when I have operated in noisy urban settings, RX was a major problem which made operation nearly impossible, but my 1 to 5 watts of CW could be heard even with marginal tx antennas.  SSB or AM with reasonable power may be your primary objective.  If a mag loop, or even just a RX loop are necessary, you could possibly use a different TX antenna, perhaps something like a stealth random wire, EFHW, etc. very probably will be a better choice than the screwdriver, or mag loop for TX in most cases.  So before you spend significant you need to do more research.  A mag loop or short vertical, will possibly or probably be one or two S units down from a "reasonable" size antenna. I have had good luck with QRP CW in many portable operations in rural and urban settings with even my 26 foot piece of wire on 20, 30 and 40 meters with a good antenna tuner, my rough guess it probably is often better than a short vertical or mag loop (for TX) in many situations. 
          Good luck on your research,   Rick  KL7CW
Logged

WB6BYU

  • Member
  • Posts: 20896
    • Practical Antennas
Re: Screwdriver versus loop for base station locations in HOA
« Reply #9 on: February 19, 2023, 06:28:03 PM »

Whether or not the directivity of the loop is an issue depends
on the distances you are trying to work.  There is a sharp null
in the pattern at low angles, but not at higher ones.

The null maybe useful for nulling out interference if it is
coming from a single source, but won't help if it is radiating
from power lines, for example, because nulling out one
point will still pick signals from others.  But for shorter
distance work on 40m and 80m at higher angles of radiation,
you may not have much need to rotate the loop.

Even at low angles, the peak of the loop is relatively broad
(similar to a dipole).  The null is less than 10 dB down at
a 20 degree elevation angle, and less than 3 dB down over
at least half the compass.

K6AER

  • Member
  • Posts: 7159
Re: Screwdriver versus loop for base station locations in HOA
« Reply #10 on: February 19, 2023, 07:03:42 PM »

Biggest difference are verticals are much more sensitivity to man made interference. I typically see a 3-4 S unit increase between the vertical and the center fed Zep antenna.

Ninty five percent of man made electrical interference is vertical in polarization.
« Last Edit: February 19, 2023, 07:07:00 PM by K6AER »
Logged

KL7CW

  • Member
  • Posts: 1162
Re: Screwdriver versus loop for base station locations in HOA
« Reply #11 on: February 19, 2023, 07:20:35 PM »

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.  For example if your MAIN interest is 75 meter local or regional SSB nets, where RX signals are often strong, one type of advice is relevant. If you want to work some DX on 20 meter CW other approaches may be appropriate.
    For example, when I operated portable CW from my daughter's house in urban area of California, the noise made operation impossible with any antenna near her house.  I laid a wire dipole on her back yard wooden fence cut for 40 meters, average height around 4 feet.  I think I shortened one or both legs a bit with loading coils, and/or zig-zags.  (it was a few decades ago).  It was a very good quiet rx antenna which was at least 20 or 30 feet away from any houses.  Had many very nice QSO's out to a few hundred miles with 2 watts of CW.  As a tx antenna it was not great (RST 549, etc.) but had some long rag chews.  Now this was probably back when propagation supported this type of operation.  If I had to operate from that location for an extended period, I would put up a separate TX antenna, even near a house, which might even work for some DX. This idea may work for CW or digital operation, but SSB or AM may not.
      One idea is to build a simple (wire ?) antenna for a single band and see how it goes before you spend money and time.  For DX  20 or 17 meters might be a start.  For shorter range 40 or 80 may be useful.  You will gain very useful information for designing your ultimate antenna.  Think outside the box.  A wild example, when I operate portable from various states and Europe, usually I just hike up a trail, or city park, or whatever.  It is fun, usually rx noise is low, but when I operated from northern Norway, or even England it the winter, it was a bit rough, but still fun in my warped mind, but I am still young at 81 years old.
           Cheers, Rick  KL7CW,  Palmer Alaska
Logged

K7JQ

  • Member
  • Posts: 2602
Re: Screwdriver versus loop for base station locations in HOA
« Reply #12 on: February 20, 2023, 08:07:04 AM »

I can't speak for a mag loop...never used one...but I do have extensive experience with screwdrivers at my HOA location.

For the past 10 years, I've been using a Tarheel M200-HP, ground mounted on a hill behind my house with 60 radials stapled to the ground. Four years ago, I added another one of the same model mounted on a 70'x6' steel fence in my backyard, using it as the counterpoise to operate SO2R in contests. I run a KW to the one on the hill, and 100W to the one on the fence. I use the simple up/down switch on both...uncomplicated, accurate, and fast to tune. You can see the installations on my qrz.com page.

Someone on here said they'd rather use a paper clip or a dummy load (actually a "dummy" comment) than a screwdriver. Well, in the 10 years, I'm closing in on 300 DXCC entities worked, and some fairly decent contest scores using them. Even the one on the fence contributes well to the contests. They both achieve 1.5:1 SWR or less from 10-80M. Broad-banded on 10-17M and 30M, a little moving adjustment from the CW to SSB segments on 20 and 40M, and narrow-banded on 80M. No tuner needed. Very easy to install, and require little/easy maintenance (I clean the coils once a year for tip-top performance).

The only mag loop that can handle real power is the Precise RF unit, but a lot of circuitry involved in the tuning process, and quite expensive. That's my experience and $.02 on the subject. Good luck with your choice!

73,  Bob K7JQ

Logged

AI5BC

  • Posts: 456
    • HomeURL
Re: Screwdriver versus loop for base station locations in HOA
« Reply #13 on: February 20, 2023, 09:29:42 AM »

I can't speak for a mag loop...never used one.

Someone on here said they'd rather use a paper clip or a dummy load (actually a "dummy" comment) than a screwdriver. Well, in the 10 years, I'm closing in on 300 DXCC entities worked
Bob sorry to hear you have no experience with antennas. Why are you giving advice? If you had erected a proper antenna or at least one with usable efficiency, you would never recommend using a screwdriver for any application except for mobile to a ham you do not like.

Mag Loops OTOH have efficiencies comparable to a dipole, but a terrible PIA to use. To handle anything over 100 watts will be very expensive, and many have bandwidths so narrow make them only usable for CW. If you have a radio with a bandscope is useless with a STL. The antenna is stone death to all frequencies except the one it is tuned too. In that respect is equal to the screwdriver.

OP there is a third option. What if you could have an antenna that requires no frigging hocu pokus ground, directional, and 300% more efficient than a screwdriver? Sound good? Still a POS antenna but leaps and bounds better than being screwed. Consider Hamsticks configured as a Dipole. You can get the parts at any CB shop or Mississippi Fine Junk. Orient it vertically for omni directional, or horizontal on a turnstile or rotor for directional.

Do you have an attic? You can hide a dipole in the attic.

Good luck.

Logged

K7JQ

  • Member
  • Posts: 2602
Re: Screwdriver versus loop for base station locations in HOA
« Reply #14 on: February 20, 2023, 12:17:39 PM »

I can't speak for a mag loop...never used one.

Someone on here said they'd rather use a paper clip or a dummy load (actually a "dummy" comment) than a screwdriver. Well, in the 10 years, I'm closing in on 300 DXCC entities worked
Bob sorry to hear you have no experience with antennas. Why are you giving advice? If you had erected a proper antenna or at least one with usable efficiency, you would never recommend using a screwdriver for any application except for mobile to a ham you do not like. 

Do you have an attic? You can hide a dipole in the attic.


Yes, sixty-four years as an active ham, and have had no experience with antennas. But since you're an expert on everything, far be it for me to question your comment about using a paper clip or dummy load in preference to a screwdriver ;). My "paper clip/dummy load" just produced 832 (DX only) Q's, limited time effort in this past weekend's ARRL CW DX contest.

The op asked for opinions, so I gave him mine based on extensive screwdriver antenna experience in a fixed location, with no comment on mag loops (never used one). Is there something wrong with that? They work for me based on my available space and HOA restrictions.  But it's up to him to make his own choice.

I also have mono-band dipoles for 10, 12, 15, 17, 20, and 40 meters in my attic...remotely switched. With all the consumer electronics now in the average house, the junk receiving noise is deafening, along with transmitted RFI to some of those devices. With A/B comparisons, the outside screwdrivers win every time on received noise and signals received on the other end. Just my experience, YMMV.
Logged
Pages: [1] 2   Go Up