80m EFHW Sloper Possible?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KE8SZX, Nov 25, 2021.

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  1. KE8SZX

    KE8SZX Ham Member QRZ Page

    Like every antenna installation, I have a unique situation. I'm new to amateur radio so I'm looking for opinions on what I'm considering is even possible.

    Goals / Requirements:
    1. Access to the 80 & 40 m band - I don't intend to hit the world but was just hoping for good activity
    2. Currently 100 Watts of Power but the ability to add more power at a later date
    3. Must be able to set up and take down in a reasonable amount of time (30 minutes)
    4. Must be sturdy enough to remain up for 3-4 days under normal weather conditions
    a. Normal weather conditions meaning a range from 70F & Sunny to Hard Rain and 17-20 mph Winds

    What I'm considering (see the picture)
    An 80 m EFHW is attached at the top of a ~40' guyed mast with the coax connector at the lower end.
    The lower end would be suspended in the air ~12' and being fed by RG-8X which runs into the house.
    The box with the coax connector would be attached by a rope that would run through a pulley attached to the side of my house.

    Questions and Concerns:
    1. Will this even work.
    2. I can't find much information about people using 40' masts and how reliable it will be. One of the masts I'm considering is quite expensive and I'd hate to find out it just won't work. Remember, I only plan on guying it from 4 sides at relatively low height and I intend to leave it overnight but take it down if any severe weather is predicted and put it up and take it down many times throughout the year.

    Equipment I'm considering:
    Masts:
    MFJ-1917 - MFJ Lightweight Telescoping Fiberglass Masts
    MFJ-1906HD Heavy Duty 38ft Telescoping Fiberglass Mast with Quick Clamps (Sturdier but most expensive)
    Antennas:
    MyAntenna EFHW-8010
    MyAntenna EFHW-8010-2K-Plus
    MFJ MFJ-1982HP, END FED, 1/2 WAVE, 80-10M, 800W, WIRE ANTENNA (Cheaper Lower Power Rating)
     

    Attached Files:

  2. AK5B

    AK5B Ham Member QRZ Page

    Everything works! How well do you want it to work is the crucial question to ask.

    You will make contacts in that proposed scenario---but even a flat-top dipole at 40 feet is too low for even 40 meters, let alone 80 meters (although it will suffice for local or regional work somewhat. With one end down close to the ground... be aware of something called ground loss.

    I would look into other antennas like a Hustler BTV series vertical monopole with lots radials for any chance at working dx.

    100 watts on those bands is OK if you you are using CW or digital modes, not so much on phone.

    Hope this gets you started, and getting your hands on the ARRL Antenna Book (librairies have; older editions fine) is also highly advisable. We always have lots to learn, especially at first.

    73,

    Jeff

    PS: Forgot to mention: Spiderbeam makes excellent fiberglass masts in lots of different lengths and they're called SpiderPoles---my recommendation if you go with fiberglass. Their 12m model would be a good one for your application.
     
    Last edited: Nov 25, 2021
  3. WA7ARK

    WA7ARK Ham Member QRZ Page

    Most of the 40ft masts will not take that much side pull without a "backstay" on the opposite side of the mast to the radiating wire.

    The radiation from a properly constructed (80m resonant, ~136ft) EFHW fed through a 50:2450 Ohm autotransformer is identical to that from a resonant dipole. I think it would be better to use the mast to hold up the center of the wire. That way you have a built-in backstay.

    Since the goal is 80/40m, then if you end-feed the dipole, that creates resonances both at 80m and 40m (and higher harmonics). A 80/40m resonant EFHW requires a critical wire length (~136ft, depending on your desired 80m design frequency.

    What actual frequencies would you like to operate on?
     
    WA7F and AK5B like this.
  4. KE8SZX

    KE8SZX Ham Member QRZ Page

    ARRL Antenna Book I already have, just have to dig into it.
    The Hustler BTV looks like an option. Just a quick review of the manual, it looks like a lot of work upfront but I could get nearly everything underground and then use the tilting base take to out the antenna when needed.
    Also, the pricing is comparable to what I was already considering. Thanks for pointing out that system.
     
    AK5B likes this.
  5. KE8SZX

    KE8SZX Ham Member QRZ Page

    ALL OF THEM! I'm kidding of course. I realize there are always sacrifices.
    But seriously, I'd like to work 80/40/20 just because I see so much activity. With what I have now I have seen a fair amount on of activity on 15m as well.
    The dream goal would be to do some DXing but if that's not in the cards that is fine as well. I enjoy hitting most of the United States like I've been doing so far.
    The at Hustler 6 BTV looks pretty impressive and might give a shot at DX plus it can take more power once I get around to adding power.
     
  6. WA7ARK

    WA7ARK Ham Member QRZ Page

    Check the swr bandwidth of the 6BTV on 80m.
     
    AK5B likes this.
  7. AK5B

    AK5B Ham Member QRZ Page


    You're welcome. If you enjoy dxing as I do, you will likely fare a bit better with a vertical of some sort (as long as you don't live on very sandy or rocky ground). Do take into account the very narrow bandwidth as WA7ARK just pointed out---that is the big price you pay on the lower bands like 80m with any sort of trap vertical. You can tune the antenna for a narrow portion of the great big band---and that's that, end of story. :eek:

    If you find the lure of dx on 80 meters beckoning you you'd want to aim for the 3.750 to 3.800 MHz portion (IIRC you'd have about 50KHz to play with using a BTV) as well as add an amp when you could.

    The tilt-over feature is useful if you need to keep a low profile in your neighborhood, too. But if you could mount it on your roof (via roof tripod or quadpod), you could get by with only two opposing radials per band (approximately 1/4 wave-length long)---otherwise 32 to 64 random-length radials are de rigeur for ground-mounted installations. Short radials are fine as long as you lay a good number down, too.

    73,

    Jeff
     
  8. WG5ENE

    WG5ENE Premium Subscriber QRZ Page

    I have the identical antenna that you specify - the MyAntennas EFHW-8010. There's no reason why it wouldn't work as a sloper, but my preference is as an inverted vee. I'm using a ROHN 9H50 telescoping mast (metal). I put a pulley and rope on it and use that to hoist the center of the antenna up. Makes it easy to bring the wire down if I need to without disturbing the mast. The balun is mounted on a fence pole I sunk right near the house, about 6 feet tall. The other end of the wire is attached to nylon rope - which is tied off to a fence post aways down. I get out just fine. You can work the world on FT8 with it. I've done some phone to Europe with it on 20m - not that bad for a end fed dipole.

    I really do think the an end fed half wave dipole is a great "first" antenna as it lets you work a lot of bands. After one finally decides where one wants to be in the HF world then they can spring for more specialized antennas.
     
    WA7ARK likes this.
  9. W1VT

    W1VT Ham Member QRZ Page

    It can be a lot of work, but I've worked DX in SSB contests running low power and QRP.
    It helps if you have the skills to quickly tune in stations before they are spotted.
    Unlike CW, I'm not aware of any automated robots that spot voice signals, so there can be a lag between when a station shows up and when he is spotted on voice.
     
    AK5B likes this.
  10. KE8SZX

    KE8SZX Ham Member QRZ Page

    Thanks for your reply. I’m going to add this set-up to my list of possibilities. I’m assuming the pulley is plastic or some non-conductive material? Or it doesn’t matter?
     

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