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Author Topic: Various HF antenna choices for restricted location  (Read 17368 times)

Mark_Hastings

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Various HF antenna choices for restricted location
« on: October 30, 2012, 05:05:41 PM »
All,

First of all let me start by thanking those of you who are taking the time to read my questions and in particular who are going to take the time to respond.

I have been an amateur radio operator for almost 15 years.  Recently I find myself living in a ground floor apartment in CO while I work on a year contract.  I would like to be able to remain active in MARS during this time (frequencies as low as 4Mhz) but the tight restrictions of my community give me little hope.  :(

I need some advice and suggestions.

Here are the options I am considering.  Any opinions?

1.   TW2010 Traveler antenna with 80M coil
2.   Scorpion SA-680 Screwdriver antenna
3.   Buddipole
4.   Super Antenna
5.   Chameleon Antenna (CHA HYBRID Base plus V2L)
6.   A 30 foot Dipole with an SGC 230 Tunner

Obviously there are quite a few options here.  I am concerned mainly with visibility, RFI (it needs to be in close proximity to the building, and other electronics) and performance.

Thanks again,  ;D

Mark




RadioRay

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Re: Various HF antenna choices for restricted location
« Reply #1 on: October 30, 2012, 05:47:59 PM »
Hi Mark,

Before giving some suggestions, it would help to have some information:

1. What specific band do you need to use at what distances (average)?
Example: 80m for in State at night.   20m out to 1,000 miles.

2. Are you allowed an antenna, or shall we run you as a clandestine station?   8)  (BTDT)

3. What modes are you planning on using?

4. What is the general layout of your available space?

I've operated a lot of HF radio from apartments and always did it clandestine, because it's always better to beg forgiveness    :'(  than to ask permission   :-[  .  Also, if those around you know that you have a radio transmitter, then you'll be the cause of every electronic disturbance as far as the rumors flow - regardless of whether you're on the air or not at the time. Best to keep it unknown, in my experience.   :-X

Never Say Anything




de RadioRay ..._ ._

« Last Edit: October 30, 2012, 05:58:39 PM by RadioRay »
"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry

Mark_Hastings

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Re: Various HF antenna choices for restricted location
« Reply #2 on: October 30, 2012, 06:15:40 PM »
Hi Ray,

Thanks for the response.....

My answers:

1) you are correct.  Mainly 80M for in state. Longer range - I'm in Denver area - would like to reach south Texas.

2) I am leasing so I figure I need to keep it well hidden.  No point in even having to address it unless I have to.

3) Mainly SSB voice.  Some digital.  No CW.

4) Very limited.  I have my gear setup next to a patio door.  Outside I have a small ground floor patio and some length along the building (but never ) further then about 8 feet from a wall.  There is a very large green belt that I look out on but a sidewalk separates me from the promised land. That coupled with very limited vegetation means it is unlikely I can hide much.  I have a fence line about 100' away across the field but I have no idea how I would reach it. 

Ideas?

Mark

Mark_Hastings

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Re: Various HF antenna choices for restricted location
« Reply #3 on: October 30, 2012, 06:28:24 PM »

gil

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Re: Various HF antenna choices for restricted location
« Reply #4 on: October 30, 2012, 06:56:51 PM »
Hello Mark,

The Buddipole, Super Antenna, and I suspect all such shortened antennas won't do any good for 80m. I have a Buddistick, it works great down to 30m. I haven't had any success with it yet on 40. You might want to look into a PAR end-fed dipole, if you can string it up somewhere. It doesn't have to be straight...
Another option would be a magnetic loop. You would need a fairly large one for 40m, and they require an expensive variable capacitor. They are also dangerous because of very high voltages and RF. They do work.

Gil.

RadioRay

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Re: Various HF antenna choices for restricted location
« Reply #5 on: October 30, 2012, 08:21:34 PM »
OK - Let me 'percolate' on this a bit, but to start with, let's do this in two steps - easy one first:

Co-Tx:  I ran a plot from Denver area to San Antiono, Tx area.  Texas is a big place, so YMMV, but in general:

VOAPropagation software shows:

20m band is a good bet for your voice & data : 15-22HRs GMT. 
30m is a good DATA/CW band , a few hours on each end of this block with some overlap.


>>>  I would make you sked including BOTH of these - usually Pri: 20m,  Sec: 30m  (have some 'slide' in there for QRM)  + 10 KHz is always good. Have the STRONG station call you - not vice-versa) . If you miss the sked, come-up on the next hour, that gives you time and freq diversity - if you can.

BUY THE GUY ON THE FAR END AN ALARM WATCH FOR CHRISTMAS AND PROGRAM IN YOUR SKED TIMES BEFORE YOU SEND IT!   ha ha ha   ;D

Emergency contact for prepping purposes: The MMSN 14300 Daylight/early evening for relaying SHORT QSY messages in a grid down situation and etc.

Warning: Voice is the mode MOST likely to compromise you by it's tendency to be 'envelope detected' by nearby electronics. Voice also requires many times more power than a digital or CW signal for the same intelligence transfer. Digital modes like even basic PSK-31 are a 'smooth' envelope and less prone to 'accidental rectification/detectin/. On 20m , even a whip antenna like the quick-up/down BuddiStick antenna, would put a copiable signal into Texas, especially in digital modes, when voice is virtually undetectable. Even a mobile whip clamped to a railing or chain-link fence would work well on twenty. Gil and I have worked CW between Florida and Virginia using an indoor antenna clamped to a coffee table. You might want his thoughts on that. Probably your best bet for a quick up/down antenna for  20m, is the BuddyStick, rather than a wire & antenna coupler, which you might not have time for. Another suggestion is an automatic antenna coupler a 16 foot, el-cheapo , telescopic 'Crapie pole with a wire to it's top. This is a full 1/4 wave vertical on twenty meters - either at home or on the road. 
toss a couple of 'counterpoise' wires on the ground fed to the 'ground side of the antenna coupler. Collapse it when not used. VERY effective from a stationary mobile.

20 meters MOBILE is another solution.  Get into your car and drive to make your skeds. This also eliminates one of the WORST problems in condos/apartments: electrical noise from all of your neighbors, wiping-out your reception.  There is a cure for most of that, but first things first.

OK - there's a start for 20m out door antennas and 'phoning home' when there are no phones  . . .  An indoor antenna for twenty is very doable and I used to use indoor antennas fed with an antenna coupler from south Aurora, Co. to contacts in State and in Washington State with a nearly 100% QSO rate.

QQQ1: Do you have metal rain gutters?

QQQ2: Do you have any fencing around any part of your patio or etc?


YouTube and look-up VK3YE for cool fun and ideas. 
"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry

gil

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Re: Various HF antenna choices for restricted location
« Reply #6 on: October 30, 2012, 08:31:57 PM »
Quote
Gil and I have worked CW between Florida and Virginia using an indoor antenna clamped to a coffee table.

Yep, Buddistick! And for one contact on 30m, I inadvertently was using only 2W!

Gil.

Paul

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Re: Various HF antenna choices for restricted location
« Reply #7 on: November 05, 2012, 10:36:38 AM »
Several thing in no particular order.

In general, 20 meters is a 'day time' band, long in the daylight.  Short after dark.  80 meters is the opposite, long at night, short in the day light.  The higher the frequency (HF) the longer in day light, sorter after dark.  Pick the band that suits the time of day.

If you have a choice between ground -rods- and radials, the radials will provide more use for RF (and safety grounds too).  'Deep' doesn't necessarily make 'better'.  The same length of 'rod' laid horizontally just under the surface of dirt does as well as if it's straight down.  Dirt is lossy so the more metal in contact with it the better.  All kinds of variables in that, but it's still 'true' in most cases.

The 'best' antenna for YOU is the one that's most practical for you.  The more you 'shorten' an antenna the less effective it will be.  Think in terms of radiation patterns since that's why any particular antenna is good/bad, where it can put a signal.
I think the Scorpion screwdriver antenna is probably the best you can have (can you tell I have one??).  Their biggest draw-back is that they are expensive.  You have to see one to understand their quality and workmanship.  Another thingy about them is that they are NOT 'fly-weight' antennas.  They build up enough momentum when moving to make inadequate mounting very, very possible.  (Tore a metal tool box loose from the truck bed...rats.)

all I can think of right now, so better get back to what I'm supposed to be doing.
 - Paul

cockpitbob

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Re: Various HF antenna choices for restricted location
« Reply #8 on: November 05, 2012, 06:04:32 PM »
I have a 180' long wire in an inverted L config.  It goes 60' straight up to a tree, then 120' to another tree.  It's 12AWG brown insulated Home Depot wire (~$50 for 500).  The only thing you can see without really trying is the insulators.  I used black Dacron cord in the trees.  It used to be 100' long and I can't tell that the extra 80' did anything at all.

I just use a manual cross-needle tuner (MFJ-949E) and can work anything from 160M to 10M, though of course performance is a compromise.  From my shack in the basememt I have 20'  of RG8X going through the wall to a 1:1 current balun (ferrite beads over the coax).  The shield side goes to my ground rod and the center goes to the long wire.  Very stealthy.

I also have a 10M/6M dipole in the attic that works pretty well.

White Tiger

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Various HF antenna choices for restricted location
« Reply #9 on: November 05, 2012, 06:11:30 PM »
I have a 180' long wire in an inverted L config.  It goes 60' straight up to a tree, then 120' to another tree.  It's 12AWG brown insulated Home Depot wire (~$50 for 500).  The only thing you can see without really trying is the insulators.  I used black Dacron cord in the trees.  It used to be 100' long and I can't tell that the extra 80' did anything at all.

I just use a manual cross-needle tuner (MFJ-949E) and can work anything from 160M to 10M, though of course performance is a compromise.  From my shack in the basememt I have 20'  of RG8X going through the wall to a 1:1 current balun (ferrite beads over the coax).  The shield side goes to my ground rod and the center goes to the long wire.  Very stealthy.

How much would the performance of the inverted "L" suffer if you could only raise it to 30'?

I also have a 10M/6M dipole in the attic that works pretty well.

Any RF/EMF issue inside the house due to this? Is the 10m/6m dipole configured in an inverted "v" in the attic?

Thanks for the information cockpitbob!
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cockpitbob

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Re: Various HF antenna choices for restricted location
« Reply #10 on: November 05, 2012, 07:06:56 PM »
How much would the performance of the inverted "L" suffer if you could only raise it to 30'?

I also have a 10M/6M dipole in the attic that works pretty well.

Any RF/EMF issue inside the house due to this? Is the 10m/6m dipole configured in an inverted "v" in the attic?

Thanks for the information cockpitbob!
I'm far from an antenna guru, so I can only guess that lowering the inverted L antenna will make 40M and longer act more like NVIS.  I'm down in a hole so might be a good thing for me.  some day I'm going to install EZ-NEC and play with simulating antennas.
 
For the 10M/6M in the attic, it is strung straight and flat.  I haven't noticed any EMI issues, but I don't use that antenna much and it's a 2 story house with nothing but bedrooms upstairs so there's not much to be bothered besides smoke detectors, alarm clocks and a TV.  I'm only transmitting a barefoot 100W.

White Tiger

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Various HF antenna choices for restricted location
« Reply #11 on: November 05, 2012, 11:10:58 PM »
Thanks cockpitbob - I ask because I am interested in possibly mounting a 10m dipole in my attic - unfortunately my house is NOT a two story, so I'm afraid it wouldn't be high enough off the ground to work - and far enough from PEOPLE to meet exposure limits!

I think I can get the center insulator up around 20' but the legs of the antenna would only extend almost 15 feet on each side and extend downward at around 13'...which would seem to give me the worst of all possible set-up's...a NVIS at 10m...

...except a local radio club runs a 10m net around my house every evening at 8pm...so since I have a 10m rig Should be interesting to see if it actuallyworks!?
« Last Edit: November 06, 2012, 02:25:18 PM by White Tiger »
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cockpitbob

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Re: Various HF antenna choices for restricted location
« Reply #12 on: November 06, 2012, 08:07:18 AM »
Gil also mentioned a magnetic loop.  They don't have to be large.  MFJ sells one that is 3 feet square and does 15M - 40M.  It's not cheap, but it gets fairly good reviews on eHam.net.  I'm sure you can make a manually adjusted one that would be cheap except for the HV variable capacitor.

gil

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Re: Various HF antenna choices for restricted location
« Reply #13 on: November 06, 2012, 01:37:17 PM »
Right, see my article on the antenna board. I got an air variable capacitor for $65. The vacuum ones are more like $200...

Gil.

Lamewolf

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Re: Various HF antenna choices for restricted location
« Reply #14 on: November 11, 2013, 12:25:28 PM »
You might want to try an Eagle One Vertical from  www.w8afx.com

Its a telescopic vertical that is 31' tall and will work 40 meters as is, but I feed mine at the base with and Icom AH4 autotuner for 10 thru 80 meter operation and it does quite well !

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Re: Various HF antenna choices for restricted location
« Reply #14 on: November 11, 2013, 12:25:28 PM »