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Metal roof rental, 2m\70cm, new Tech, long sorry :(

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KC1MUR, Mar 22, 2020.

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  1. KC1MUR

    KC1MUR Ham Member QRZ Page

    Just passed my Tech test a few weeks ago after wanting to do it since I first heard about amateur radio as a Cub Scout in the mid-70s (yes, I'm slow :D ). Been doing a lot of reading on many subjects, the one I am not 100% sure what my best option I'm asking for advice now. I apologize for the length, I hope that I am providing enough information to prevent a long back and forth thread because I left something out :). Yes, this is my first post.

    I'm in a rental house in Maine, drilling or modifying the house isn't an option. It is still very much winter up here so opening a window in the main part of the house really isn't great either. It is an old (200 years or so) house, small (800sqft) in the middle of nowhere :). It has a metal roof on the main part of the house, on the front of the house is a porch with asphalt. The two slopes of the metal roof face east and west, the porch is on the front of the house, roof just below the bottom of the main roof and is unblocked E,W, N. The "local" repeaters are mostly not south of me. I have access to the attic with a window right at the middle of the porch roof and power just below the window.

    I've been listening in the house on the main floor on a UV5r with a dual band 2m\70cm plopped on top of my freezer that is in front of a west-facing window during the day while I work, on top of a Monitor heater facing east at night. Neither, obviously, are ideal - nor is the radio but I got it - like many - as it was cheap to get my feet wet plus I can use it as a scanner (I'm a volunteer EMT up here, I know not to use my radios on the county network, I have a C200 Motorola provided by the service for that but it doesn't work in my location even to receive so I listen on the ChiCom). Receive is eh, but for the most part usable. Transmitting I haven't tried yet as I'm still listening to get the hang of how things flow, though I suspect I won't be heard with the little radio. I have an old Radio Shack HTX-212 on 2m. There's so much noise from my computers in the daytime location (I'm a Sr Sys Admin working remotely for a software company, I have 5 systems running 24/7) that it is useless. If I go outside and clip it to my SUV with the same antenna on the roof, I can hear all my repeaters programmed in like they are next to me so I know the radio - if given a chance - would work. Ok, so here's my question...

    What would be my best choice using the HXT with that antenna in the house? Options as I see them are:

    1) put the antenna on one side of the main roof, though I assume that would negate using any of the repeaters coming from the other direction, even if I could get it high enough to reach over the top of the peak.
    2) Put the antenna on a metal plate on the porch roof, though it is below the main roof so would that not work out either?
    3) Put it on one of the old satellite dishes mounted on either end of the porch, flipped so the dish is horizontal?
    4) Try to run a simple dipole off the tree that is on the east corner of the porch (white maple) that does extended above the roof, but unfortunately is right at the street so visible and subject to frequent truck drafts from logging trucks that pass by.
    5) Wait until spring and just sit in my truck :)

    Thank you in advance for anyone that is sharing knowledge and has in the past, I'm learning a lot just reading old posts. RadioHousePic.JPG
  2. AK5B

    AK5B Ham Member QRZ Page

    Height is might with VHF and above; if I were in your situation (and HAD to install the antenna on the house instead of a tall mast in the yard) I'd mount it atop the satellite dish since it's around the tallest part of the house.

    Thanks for providing lots of info in your first post---that's often lacking in about 80-90% of the posts or questions posed here.:)


    KC1MUR likes this.
  3. N7WR

    N7WR Premium Subscriber QRZ Page

    Another option. Buy or make a ground plane antenna. throw a rope up high on the big tree to the left in the picture. Hoist the ground plane up high. It won't matter if it touches branches. Use good quality, low loss coax. Should work fine
    AK5B likes this.
  4. WA7ARK

    WA7ARK Ham Member QRZ Page

    I would just try an NMO magnetic antenna base with a suitable dual band NMO whip. Those NMO bases usually come with ~15 to 20ft of RG58 coax. Just drop the mag mount on the house roof near the ridge line, just above the dormer window in your picture. Extending the coax another 10 to 20ft is ok. Should work unless the metal roof is aluminum:(

    That the antenna leans a bit due to the roof pitch likely wont matter.
    K0UO likes this.
  5. KC1MUR

    KC1MUR Ham Member QRZ Page

    Roof is steel :)

    That's what I'm using inside and was hoping to use outside. :) Snow for the next few days, then it is supposed to warm up a bit. I'll try all of the suggestions given and report back with what I find so that if someone else in the future has a similar dilemma, it might help them.

    Thanks everyone!
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Anything outside on VHF-UHF usually works better than anything inside.

    Since the roof is steel, a mag mount should stick to it just fine and provide a good enough ground plane, probably better than your truck -- and up higher.

    Since it's winter and cold and you don't want to leave a window open for the coax, there are effective "coax pass-through" products on the market that allow you to pass coax from outside to inside while closing the window on them and locking out the cold and snow (or rain, and bugs, or anything).
    KC1MUR likes this.
  7. KC3HUM

    KC3HUM Ham Member QRZ Page

    Look up slim jim antennas made with 450 ohm ladder line. Purchase one off line (forget what ham makes them) and throw it up into the tree to the left and run the coax into the window from the tree. Just make sure the ladder line is positioned vertically so the signal is radiated properly. Or use the mag mount 1/4 wave or 5/8th wave on the peak of the roof... Have fun. vhf and uhf u want it as high as you can possibly get it while keeping the coax run as short as possible.
  8. KM3F

    KM3F Ham Member QRZ Page

    I note two things you have.
    1. All the computer systems creating interference.
    2. Outside clipped onto your SUV antenna hears all your desired repeaters.
    This is key for what to do.
    If you have interference, the antenna needs to be far enough away and still hear the repeaters using a longer coax feed line.
    The repeaters are all likely to be transmitting at 50 watts or greater...and hear your HT at 5 watts or less due to their height.
    I would consider a base type antenna with some gain placed outside the most practical distance from the computer area and high on a support pole.
    Use LMR 400 coax as the feed line.
    The signal strengths both transmit and receive should be more than compensate for the 'coax length loss' by the gain antenna and it's height outside.
    Its always a compromise or balancing act you have to solve for satisfactory end result.
    For the antenna consider a 'Co-Linear' design. they are longer in order to get the gain. Look up the gain charts for the antennas. Don't pay attention to whether the gain is absolute or not, but the fact is they have gain over a simple mobile type.
    A mobile antenna for your 'operating situation' is not the preferred type to use even if it works outside somewhat better.
    Plan it all out, and get the equipment and install it
    You won't be disappointed over what you have now.
    If it's worth doing, do it the best you can.
    Good luck.
    Last edited: Mar 25, 2020
    AK5B likes this.
  9. KM3F

    KM3F Ham Member QRZ Page

    Additional, your HT s not meant to be other than for short distance applications on a Duck antenna.
    Coming off LMR 400 or similar type will need to use an adapter to small flexible coax cable so you can either hold it in your hand or use a hand mike.
    Better to consider mobile unit and power supply with higher power output, better selectivity and be near immune to signal overload.
    Good luck.
    AK5B likes this.
  10. KC1MUR

    KC1MUR Ham Member QRZ Page

    Ok, following up on this, today was in the mid-30s and I needed to clean and organize the attic as my "isolation room," pretty much decided that getting COVID is more of a "when" than an "if" so setting up this space to minimize infecting the better half when the time comes. While up there, I decided to do some tests.

    I have a ps that is surplus from our dispatch room at the station. So, tried the antenna I have (unfortunately, that is what I'm limited to at my location currently, I've ordered a better one but shipping is delayed due to the current crisis) and no matter where I located it, performance with the HXT was no different than it is with the antenna inside the house, and when I key the mic, I get a decent hum through the speaker. The mic is an ICOM rewired for the HXT. This behavior doesn't exist when outside on the car. Attached the antenna to my UV5 (have SMA-to-PL256 adapter) just for giggles, and after trying several different options, determined the best overall reception is on the eastern sat dish (set horizontally, it's a few feet higher than the west side dish). If I want to get best performance for the repeaters to the west, then the west side roof is slightly superior to the dish, likewise for the east roof\east repeaters. So location question answered.

    Great. So the crappy little HT works but the HXT not so much, even though out on the car it is quite good. The location in attic is about as far away from any obvious RFI items, the only wiring up there is for the single outlet and one overhead light (IC). After some research and looking at my equipment, I'm thinking both my issues with the HXT are ground-related (electrical). The power supply has the third prong snipped off, which I didn't really pay attention to initially because, well, I just didn't :(. All the outlets in the house except for two - bathroom and microwave in the kitchen - are old two prong, the wiring old enough to have braided insulation, and except for the previously mentioned two GFCI, are still connected to a fuse panel :(. I'm going to replace the PS cord this weekend with the proper cord, then try it in the kitchen and see how it goes. When at the car, no issues with a hum, I'm guessing that is because I have good earth being directly connected to the battery and frame of the SUV? Eventually, this radio will be going in my VW Bus, but I'll still need some solution for inside that isn't the little BTech. I'm racking up overtime being in EMS right now, so I'm tucking away that money for better radio(s). I'm waiting for permission from my landlord to erect something in the backyard, so this entire solution is - hopefully - temporary and I'd like to experience some of the other bands eventually.

    Thank you all for your input!
    KB0QIP likes this.

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