Comet H-422 - mount height off roof ridge

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KG7OSA, Nov 14, 2017 at 5:44 AM.

ad: L-HROutlet
ad: l-rl
ad: Subscribe
ad: L-rfparts
  1. KG7OSA

    KG7OSA Ham Member QRZ Page

    I'm looking at the Comet H-422 to compliment my ICOM 7300 which will come home with me later this week. Excited to upgrade from my FT60 and have the general exam to study for. :D

    Regarding the mounting of the H-422, I have a roof ridge which is 31ft off the ground and roughly 40ft long. No trees around me. Would I be okay to mount the H-422 just a few feet above the ridge? Should I ponder a rotor for this antenna?

    Was also looking at the Comet CHA-250B vertical however heard that the horizontal antennas produce less noise? Also read that this vertical antenna requires a counterpoise likely in the form of a mast.

    Appreciate any input.

    Hans
     
  2. K6BRN

    K6BRN XML Subscriber QRZ Page

    Hans (KG7OSA):

    Consider mounting the Comet H-422 rotatable trap dipole in its "V" configuration with the base at least 8-16 feet above the peak of your roof, where it should work very well. Higher is better and this is a light antenna with minimal wind cross section, so a long mast is practical. It can be easily turned by a light duty Yaesu G450A rotator in a mast mounted configuration. This antenna has a bi-directional pattern. Frequency coverage is 10, 15, 20 and 40M, so if you want to work the WARC bands,, like 12M, 17M, and 30M, you'll need to supplement it with another antenna, like a MyAntennas EFHW-8010-2K multi-band wire antenna.

    Neal, N6YFM, has exactly this arrangement, with the EFHW-8010-2K strung in a horizontal "L" shape to fit his very tight lot, up about 15 feet. I helped install and adjust both antennas. He's made thousands of contacts with them over the last two years. You may want to look him up on QRZ and email or PM him - he will probably have lots of insights.

    I have the Comet CHA250B, up about 30 feet, and rarely use it because all of my other antennas far outperform it. Instead, I rely on an EFHW-8010-2K wire antenna at about 23 feet height in a horizontal "V" configuration (it's wire can be strung in many shapes and still be effective). I'm on the wire right now on 40M making numerous contacts with Japan using FT-8. The EFHW-8010-2K is backed up by a Mosley TA-33-M-WARC Yagi antenna up just 35 feet or so, and the combo works very well. I switch back and forth between the two depending on band propagation and noise conditions.

    Brian - K6BRN
     
  3. KD6RF

    KD6RF XML Subscriber QRZ Page

    Congrats Hans :D

    When going to the trouble of putting up antennas, it really helps to define your goals first, if possible. If you are more interested in local-ish type comms and NVIS -or - if you are more interested in DX chasing, then the choices are different. And being in a solar cycle minimum, the lower bands take on more importance.

    As said above, there are better choices than the rather inefficient CHA. And what you do with your dipole, or any other antenna(s) (hopefully several new antennas !!! :cool:) is influenced by your goals.

    Anyway, if you are more interested in optimizing near-in comms, then low horizontal antennas are fine. Of course, you'll make DX contacts as well, but low horizontal stuff is not optimum by several dB.

    I'm a casual DX chaser so like many others, live by the rule-of-thumb: "Verticals and Inverted-Ls for the Low Bands – Horizontal Antennas for High Bands" If interested, you can read more at ===> http://vtenn.com/Blog/?p=221#more-221



    The take away is that a vertically polarized antenna outperforms low mounted horizontal antennas by several dB at those low angles where DX is most often found ===>

    [​IMG]

    What the graph means is at those low elevation angles, the red-ish patterns for vertically polarized antennas outperforms by an S-Unit or 2, the radiation patterns of the low 30 ft high mounted horizontal half-wave antennas.


    The HF bands are a lot of fun, and it pays to think through your goals (if you know what they are at this point), and plan ahead !!!
     
    NH7RO likes this.
  4. KG7OSA

    KG7OSA Ham Member QRZ Page

    I appreciate this information. DXin'g will be my purpose with this. My brother lives 600 miles to the South of me in the bay area. Chatting with him will be on my hit list as well as DXing.

    KD6RF, what vertical antenna would you suggest I look at?

    I will look into mounting a 10' mast on my roof then the 422 on that in the vee configuration as K6BRN noted as well.
     
  5. KD6RF

    KD6RF XML Subscriber QRZ Page

    There are plenty of verts available, and I'm sure other folks could comment with relevant info on all the other good choices that are out there.

    My fav is the Inverted-L - I use a 45 x 45 footer and some 23 x 22 footers for 160 M - 10 M and 80 M through 6 m respectively. Both are non-resonant designs that use tuners as I like to work all band / every band. This is pretty much true for ANY antenna type - if you want to work the entirety of each band, then a tuner is used to mitigate SWR extremes.

    If you're interested in Inverted-L, here's some info on a non-resonant design ===>

    "End/Base-Fed Inverted-L, 45 ft version, Elevation and Azimuth Radiation Plots" http://vtenn.com/Blog/?p=110

    "End/Base-Fed Inverted-L, 90 ft version, Elevation and Azimuth Radiation Plots" ===> http://vtenn.com/Blog/?p=83


    But don't forget that horizontal antennas, when up a good half wavelength or so do very well, so it's not uncommon to have both types as the title of the article above says.

    One of the interesting about Invested-L's is that they have attributes of both verts (on the low frequencies) and horizontal antennas (on the higher bands.
     
  6. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    600 miles is an easy shot on 40m, you shouldn't have any problems there.

    For "DXing," the higher, the better until the antenna is up very high, much higher than you're discussing.

    A 10' mast isn't enough for the H-422 because to rotate it, unless you have a tower with a rotator mounted inside the tower, takes two masts: One to support the rotator, and another one above the rotator to turn the antenna -- and the H-422 definitely should be rotated. As stated, a G-450 Yaesu or Hy-Gain CD-45 will be okay for that antenna, but still use strong masts and not 1-1/4" diameter "TV antenna" masts -- they won't handle it.

    If you can get it up about 50 feet above ground, 40m should provide DX during dark hours and 20m will provide it during daylight hours but everything's a surprise when it comes to "wireless." That's what keeps it interesting!
     
  7. K6BRN

    K6BRN XML Subscriber QRZ Page

    The roof ridge (peak?) Is 31 ft off the ground. Add a 10 ft mast, rotator and 3 foot top mast, with the H422 mounted halfway up, and tbe bottom of tbe antenna is at 43 feet. Not too shabby. Can easily be attached to the peak using a 4x4 mount and fence lost clamps. And the tips of the antenna in a V config are up another 12 feet or so. It'll likely work very well, especially on the digital modes. Higber is better, but a bare mast that extends beyond 15 feet (1-7/8 pipe, tubing or similar) is going to require a lot more work to put in.

    Brian - K6BRN
     
  8. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    An 8' roof tower straddling the peak (like a Glen-Martin RT-832 or similar) with a rotator mounted inside the tower and a 10' mast will put the antenna at >45' at the feedpoint and be very secure, and you won't need two masts.:)

    I've installed those on every kind of roof imaginable, even old homes with slate roofs from the 18th century, like the place I had in Boston.

    "Modern" roofs are easier.:p
     
  9. KG7OSA

    KG7OSA Ham Member QRZ Page

    What hardware are you referring to to mount it to my roof? Pics or links appreciated. :)

    The Glen-Martin is a nice looking tower but out of my budget at this point. Appreciate the suggestion.
     
  10. N8CMQ

    N8CMQ XML Subscriber QRZ Page

    If you do a vertical antenna, the counterpoise should not be the mast or feedline.

    If the vertical is elevated, a minimum of four radials for each band of operation is the minimum required. You want it a minimum of 1/2 wavelength above ground for the lowest band used for best performance.

    If the vertical is ground mounted, then the radials have no set length due to the detuning effect of the earth.
    The radials should be a minimum of 1/8 wavelength for the lowest band used, and you need a minimum of 60 radials for better efficency.
    More radials are better, as you are heating the ground otherwise.

    The band conditions will actually set the skip zone and ground wave coverage of any antenna. So you may see better operation with a vertical one moment, and a horizontal the next, and the third moment, neither antenna is working.

    Noise is not antenna dependant, noise is either in your home, or external of your home. The internal noise you can hunt down and eliminate at the source. External noise is harder to deal with.
    But you can eliminate external noise by hunting it down and seeing if it is power line or neighbor related. If your neighbor likes welding, nothing will help that, but power line noise can be reported to the power company.

    There is more, but this is the basics for a vertical.
     
    NH7RO likes this.

Share This Page

ad: Schulman-1