Flexradio and OCF 80-6m multi-band (Windom) - thoughts/experience?

Dave - N6XVZ

Not yet an owner but seriously looking!
I live in a deed restricted/hoa area so an attic antenna is path of least resistance.  Two story with a peak of 30ft.  Upstairs attic fairly open except within it the cube/shell of my upstairs mancave/shack (just 1 room upstairs).  I can fit an OCF Dipole that spans 68 feet if I invertVee it and fold the ends by a few feet.  Can't quite get it to best mount of 35ft for SWR minimization but it will be close.

Question:  Is that a good type of antenna to feed a Flexradio to get band coverage across 40-6m?  I realize there's lots of options but looking to maximize the hearable bandwidth with such a capable radio and just don't yet have the need for dual antennas/diversity.  Or is there a better attic antenna for maximizing a Flexradio?

I'm liking the OCF/Windom so I don't have to have traps and can get the multi-band out of a dipole since it's unbalanced.  Mag loops look intriguing but don't quite cover the bands I want - maybe in the future.

I can't think it's a bad idea but looking for a blind spot in my research/logic.  Ideally someone who's done this and any learnings/concerns would be greatly appreciated.  

Thanks!
Dave

Bill English

I have an OCF for 80-6m that has given me good results. Made a lot of QSO's on 30m using the ATU, not a bad antenna. I put it up mostly for 80 and 40, but have made a lot of QSO's with it on 6m. You won't be disappointed.  

DaveC

Had a 80-6m OCF up for about 3 years with the vertical radiator. Tuned great 80-6. (with internal ATU) including 60m. Took it down because I moved. Of course, mine was outside up about 50'.

Bill English

I had one of those as well some years back, with the vertical radiator. It was up about 90 feet and worked surprisingly well. It was a good one.

Wayne

I have an amerirton sda100 1200 watt screwdriver antenna mounted on my roof. Its only about 6ft tall and remore tuned via control box from my shack covers 80m thru 6m all you would need is a few counterpoise wires from the base of ut across the attic, does really well on my roof and with just the antenna i get about 1.5 to 1 swr then i occasionally use the flex tuner to further match it to 1.2 swr or better. Had it up ther for over a year outside with no issues so in the attic it should do even better out of the weather. The only downside is it is about $450 new with everything needed.

Rick - W5FCX

I’m using the Ni4l OCF Windom and it works very well. The Buckmaster is also quite popular. Make sure you don’t have aluminum backed heat shielding in the attic, as it would negate your efforts (my new HOA house has it). Inside the attic steer clear of large metallic objects and house wiring, if possible, to prevent SWR and RFI issues (even if it means not running elements perfectly straight). I’ve had severe issues with GFCI breakers popping on 40 meters above 75 watts. Also if you’ll be running any power, antenna element insulation and clearance matters to prevent arcing and potential fire hazards. As always, verify maximum permissible exposure levels inside the rooms below the attic for safety, esp if running power, as the antenna will radiate inside the attic and beyond. Good luck. Let us know how it works out.

KF4HR

OCF antennas work fine.  I tried an attic antenna years ago.  I wasn't impressed with its performance.  I switched to a flag pole vertical (well in the clear) and achieved considerable better reports.  Part of the issue with attic antennas are they are in fairly close proximity to house wiring, gutters, and such. 

N8SDR

I have a 40M OCF and it works very well, HOWEVER- OCF's are prone to RF issues esp when there inside and near other types of metal objects, with that in mind I would recommend you build you own and use the Balun Designs Hybrid OCF balun, I currently use this balun as one leg on my OCF is only around 12 feet from an attached carport. and the other side horizontal except the last 4 feet which hangs horizontal over a tree limb ( using insulated wire), I find this balun which has a doubled Stacked design of a 4:1 followed by a 1:1 RF choke works very well in odd or less then optimum installs. And possible another 1:1 RF choke balun at the rig:  Give Robert of Balun Designs a call and ask his advice,  The best advise I can share  with you when using a OCF is the BALUN will Make or break antenna performance use a good balun there are many cheap baluns which when put under pressure such as you intend to do will cause high voltages on one side and possibly lead to saturation of the balun, you'll notice increasing SWR. The Balun Designs products are well made but there a bit more costly, again you get what you pay for.

https://www.balundesigns.com/model-4116-4-1-hybrid-balun-1-5-54mhz-3kw/

N8SDR

An OCF with a vertical radiator isn't really an OCF its a windom

AA0KM

Search here on the forums:

Stealth antenna


Hoa antenna


TX antennas

Antenna for Restricted

And any other combination of antenna searching. 

Lot of user experience in the forums.

Good luck.

73 Jeff

Mark WS7M

Hi Dave,

I also live in an HOA and have managed to slide by with an outslide wire loop.  A large one actually 280 feet of wire strung between trees.

While I think we all do what we can do I suspect you will be disappointed with an attic antenna.  If it is your only option then so be it.

Another thing to consider is to buy simple wonder poles from Amazon and build yourself a 20m vertical for the back yard.  They are almost invisible and with a reasonable tuner you can load it up on 40m as well.

https://www.amazon.com/Shakespeare-TSP20-Six-Piece-Wonderpole-Fishing/dp/B000FFQOSW/ref=sr_1_4?ie=UT...

You simply run a wire up to the top of it and provide some radials, upto 16 would be great but 4 will do.  It can mount on a simple stake pounded into the ground.  

Just giving you some options!

Another reasonable option is the EF antenna. These work well:

https://myantennas.com/wp/product/efhw-8010/

You can mount the feed point near your house and run it as a sloper up into a tree.

Dave - N6XVZ

I've been eyeing the Ni4L as well.  I basically have a plywood deck but noticed two sections along the ridge that have aluminum foil about 1x4 ft - not sure why it's there but worries me for blocking part of the signal close to the balun.  The only other worry in the attic is the large volume of foil air duct (It's Texas) piled up onto the top of the mancave cube, a bit close to the peak....

I plan on a max of 100w but the concerns are valid to consider.

Thanks so much for the response and input!

Dave - N6XVZ

Thanks for the observations.  I suppose with an OCF I'd at least be on the air but with band conditions it might be quieter than I'd hope.  Ugh....  Great input - just what I'm looking for - real world input vs all the debates/information.  Thanks!

Dave - N6XVZ

Wow great stuff.  Thanks.  I'll check it out.  I wasn't aware of the RF issues so the 1:1 RF chock would be good input to have!

Thank you.

Dave - N6XVZ

Mark-
Hmm..  I do have a 30ft peak and could do a sloper from there out to the yard.  It would have to bisect to trees (18ft) that are only 17ft apart.  They themselves aren't great for hanging wires from (Chinese Pistachios) and are not marked by a tall single structure like an evergreen or even a big oak.   I greatly appreciate the input -stuff I haven't yet come across and will research!

I do like the idea of having the wire outside of the house...

Thanks!

Rick - W5FCX

That will be best if you can pull it off.

I made my own ZS6BKW, an improved GR5V, using #26 poly stealth black insulated wire - it’s practically invisible against the backdrop of houses. It works okay as a compromise antenna, in that it’s apex is only 20’ from the eaves of 2nd story with both elements sloping down to around 10’, terminated with 8 pound invisible monofilament to back fence corners. Nobody has ever said anything in my HOA neighborhood about it and there are no trees blocking it...you just don’t notice it if you don’t know to look for it.

If you can run a two element antenna from 30’ sloping down to 18’ it will work okay - not great but much better than inside the attic.

EDIT 1

Adding photos of how the antenna is mounted and appears. One can only see the #26 polystealth wire elements when contrasted against white or gray cloud background. From the street behind my yard, it’s virtually invisible against the house background.

As you can see, it's completely non-optimal - running right out past the gutters... and it's trimmed to 1.1 to 1 SWR on 20 meters and tunes 1.4:1 on 40 and works across many bands with a tuner.  It's certainly a compromise, but it beats the heck out of no HF at all.  I have worked all over the USA, EMEA and South America with it on all modes with 100 watts or less.

I was surprised by how stealthy a black #26 wire and 8 lb. monofilament can actually be... hiding in plain sight!

DaveC

Did not know that. Learn something new everyday.

Jim Ricker

Dave
two thoughts. I served in the Marine Corps for over 30 years and used the following two antennas very successfully .

Dipole  running on the inside of the facia .  You can use small electrical tie/ties and a staple gun I  would use a small 1to 1 balun the size of a old film canister. I would use small coax with bnc on both end. Kept the power down to about 65 watts.Ran the coax back to the shack via a side vent.

A single wire from the roof to a supporting pole or tree in the back yard. I used small 16 gauge black wire. Yes it would break, Just restrung it . Watch your neighbor hood. If its retirement community and everyone is home all day. Do your work (safely) at night. If your neighbors all work during the day Take a day off and install NEVER NEVER do any major work on a  weekend everyone is home. 
Pushed my luck on this one and a neighbor turned me in. I was off the air for over a year. Also if you can a wire on the top inside of the fence these work great. 


Jim
K6CEF

Ken - NM9P

Other options....

1) A secret "Flagpole" antenna - feed a 29-33 ft. flagpole at the base, with buried radials.  If you have an auto-tuner that can be concealed at the base with landscaping, all the better.  Just remember to fly your flag on the right days!

2) I like the wire under the facia/soffet dipole.  A 40 meter dipole will work on 15, too.  You can feed another with the same feedline on 20 meters with a couple inches separation (more separation is better). 

3) A clothesline antenna...either a dipole, or one of those umbrella types may make a good loop on 10 or 15.

4) An inverted L under the overhang. - begin with the feed at the corner of the house...go up to the soffit, and then run along the under edge of the soffit until you have a total of a 1/4 wave or so.  Feed like a ground mounted vertical, with a couple of radials buried or just on the surface of the grass and let the grass grow over them.

5) and under the facia loop - like the dipole idea, but enclose a whole loop under the facia....

6) on top (of just behind) your privacy fence.  either a dipole,  or a loop around the whole yard if you can go up and over any gateway --- perhaps by building a nice entry arbor or canopy.

I have run a variety of homebrew 80 and 160 meter OCF's for several years that tune most of the bands, in addition to my log periodic.  The important thing to remember is that they are inherently unbalanced, and need both a good 4:1 current balun AND a good coax isolation (either a ferrite isolator, or a multi-tuen coax coil near the feedline, in order to keep common mode RF energy OFF of the feedline and out of the shack.   This may be a larger problem with an attic antenna.

In the attic, I would rather use a balanced dipole than an OCF.  But that is my own preference.

Good luck,

Ken - NM9P

szawrotny

I swear by OCF dipoles. I have three, 2 80-6 and a 160-6. The 80-6's work VERY well with SWRs  below 2:0 on most bands. I do not use a tuner other than the atu on my 6600M. They are easy to build. Use a good 4:1 balun at the top and a 1:1 at the shack. Even better at the top is an rfi choke. I have worked the world (DXCC) with 100 watts.

Bill -VA3WTB

I tried one for a while and found it to be noisy,,not sure why... I went back to my linear loaded 40 and 80m dipole.

N8SDR

Like SZawrotny- I have had very good results with OCF's but like I mentioned they require the correct and a well made balun to work well. If its nosier than you dipole hung in same location its the balun your using, a good well made balun will help negate noise

N8SDR

Yes very stealthy: only two things would concern me if placed in this type of arrangement.

1) Breakage due to high winds, icing or an occasional bird/squirrel incident
2) 26ga wire and high wattage radios or amp and an non tuned antenna with high current /voltage and fizzle like a fuse and your off the air.  

N8SDR

Or make/buy a couple bird houses and build a tall wooden support for them staple the wire on the outside of it, place your ground radials and a 4:1 UNUN under at feed point and your good 6-20 M, Optionally you could use say a metal fence top rail for the support pole and some good PVC tubing and a mount for the base to insulate it from ground and load it up as well,  

Rick - W5FCX

Yeah. Have had one breakage incident in 2 years but in Houston area ice is quite rare (except in our iced tea and occasional libation). The most I have run is 100 watts. Anything more and I get GFCI breakers popping, touch screen lamp ghosts and whistling gun safes. Signal reports are good, too

szawrotny

Why use 26 ga. It has a breaking point of only 25 lbs. 18 ga - 280 , 16 ga 381, 14 ga - 550 lbs. 18 or 16 ga is hard to see.

Rick - W5FCX

It’s stealthy and strong enough. The key requirement in this use case is stealthiness, not strength. The wind load against #26 wire is negligible. It’s field-proven at this point.

Ken - NM9P

You can use a length of mini bungie cord as a stretching strain relief and reduce the risk of breakage, too.

Rick - W5FCX

Interesting idea.  That's why I chose the 8 pound monofilament line as the insulator to bridge from end of #26 wire antenna elements to the fence - it stretches easily and rebounds with quite a bit of elasticity.  A bungee cord might be better except for how visible it is.

The one breakage incident I had was before I started using monofilament. I originally used 30 pound Spiderwire, which has virtually zero elasticity, because it was all I had available at the time.  After the break incident, I switched to the monofilament and no more issues since.

szawrotny

You can string wires around facia and fences around Christmas time without too much suspicion, as long as you add some decorations too. Plan ahead.

Dave - N6XVZ

Now I'm thinking outside is better than inside the attic.  I have a HOA wording that says "only approved by board" and no neighbors behind me so chances seem higher.  So OCF with coax feed seems best for what I want.  The latest questions are:

1)  I only have about 8 feet of clear space between brick veneer of house and the tree.  I hope to hang a messenger wire from peak of roof (30ft) to tree (15 ft) and midpoint the balun along that at appx 20 ft.  That would give me about 4 feet from brick.  Not perfect but not a showstopper right?

2)  I worry about having an eyebolt drilled into the veneer/stud at the peak and tied to a moving tree.  I will build a shock system into it but don't want to rip a weak part of the fascia or something else off with a big tree hanging off the roof.  Any ideas on a small mount idea that has some give?  Maybe I use Rick's monofilament tip for hanging the brick on the end of the messenger wire that will yield at some point beyond normal storm sway?  Or something up top that would give appropriately?

3)  I worry I can only get the ends of the antenna 9ft high.  The rope/monofilament from that point would go to a 6ft pole as that's the height of the fence.  9 ft seems a tad low - everywhere I look it seems 10ft is prudent.  The answer to #1 might sway hanging it closer and getting more height.  Is 10ft above ground for antenna end the target I need to stick to (100w max)?

Thanks all- really great bunch of answers and support - I appreciate it!