Attic antenna

[N1XDS]

Question, I live in a deed restricted neighborhood so no outside antennas so it leaves me the attic where I have my scanner antenna put up. I am trying to access the MotoTRBO repeater in my area which is about 10 miles away from me and was wondering what type of antenna would I need to make it work the best? Vertical or Yagi antenna? I would think Vertical work best?

I was looking at the Diamond Antenna F-718A vertical antenna in mind I just need to buy the LMR-400 coax with the correct connectors on the ends of the coax. Which is N and Mini U on my XPR 5550 and SMA on my XPR 7550 handheld or I could go with the Comet DS-150S discone antenna if it will work?

Diamond Antenna F-718A: Ham & Amateur Radios - Equipment, Parts and Supply | AES

Comet DS150S Discone Scanner Antenna

 

[Netdewt]

Attic antenna for beginner

I am remodeling my 1.5 story attic and have HAM aspirations. The sheetrock will soon be on, so I am trying to plan ahead.

I don't have a lot of room, but there is some, maybe 15x25 ft with 3 ft max heigh at one end. I have a space I could run something vertically down the center of the house. There are power wires, and other signal wires (phone, ethernet, cable) nearby.

Is there an ideal, inexpensive antenna set up that would work for the space I have and could get me going when I am licensed? I know very little about how the different antennas work. Given that I'd just have a Technician license, I'd be on 2M.

If this is a really stupid question, sorry... and I'll just leave it alone.

 

[Thunderknight]

Make sure you have 15 feet of clearance in the attic (the height of that Diamond F-718A).

If you only want to hit 1 repeater, a yagi pointed in that direction will have more gain than an Omni (although the vertical with 11dB is still pretty good). However, if it's only 10 miles away, you might not need much gain and by going with a vertical, you get coverage in all directions.

Did you try hitting it with the 7550 with the stock antenna from the attic already?

 

[popnokick]

If you take the 7550 handheld into the attic and can bring up the repeater with the stock antenna (rubber duck, I assume?).... then EITHER the vertical or yagi (properly aimed) will work. And of course will work much better than the stock antenna on the handheld. Failing that, I would estimate that at 10 miles the yagi is a certainty if pointed at the repeater. The vertical should work, but if there was a way to test it prior to mounting it permanently, you should do so.

 

[popnokick]

If nothing else, be sure to run some good quality coax from the attic... preferably at opposite ends.... down to the lower floor(s). That will leave you some options for antennas and experimenting.
Your post is similar to another one today in this forum asking whether to use a vertical or a yagi in the attic. I have a different suggestion than in the other post: Build (or buy) a 2M ground plane. They are dirt simple to make using an SO-239 coax plug chassis mount and 5 19" pieces of good stiff copper wire. My 1st 2M antenna was exactly that and worked very well for a long time. Plans abound here on RR and on the Internet in general.
On the other coax (you did run two cables down, right?) install a 2M yagi/beam. If you can, put a rotor on it. If not, point it in the direction of most interest for you.
And one more possibility is a J-pole... another type of omnidirectional antenna that will fit in the attic.

 

[ermin]

I am remodeling my 1.5 story attic and have HAM aspirations. The sheetrock will soon be on, so I am trying to plan ahead.

I don't have a lot of room, but there is some, maybe 15x25 ft with 3 ft max heigh at one end. I have a space I could run something vertically down the center of the house. There are power wires, and other signal wires (phone, ethernet, cable) nearby.

Is there an ideal, inexpensive antenna set up that would work for the space I have and could get me going when I am licensed? I know very little about how the different antennas work. Given that I'd just have a Technician license, I'd be on 2M.

If this is a really stupid question, sorry... and I'll just leave it alone.

Hello NetDewt

This is NOT a stupid question. Everyone starts at 0. They only way I learned was from lots of questions.

I use the Radio Shack 20-176 scanner antenna. Works great for 2 meters and 70 Cm. I live in a 1 story duplex and with my 5 watt HT get into repeaters over 20 miles away (great for here in FLAT South Florida). My Icom mobil goes a lot farther. and the antenna will last many years. I now use the Tram 1465 Land Mobile Base Ground Plane Kit Radio Shack # Model 1465 with a Hustler MX-270 fed with some LMR-400 and it is the best non outdoor setup I've ever had. Experiment! That's what us hams do.

73
Ermin

 

[Netdewt]

The coax I have installed now just goes to the HDTV antenna. 1 down, 2 back up to jacks. I have easy access through the center of the house, not so much at the ends.

I don't have an area of interest at this point. Lots of repeaters in my area, closest one is 3 mi due NW.

It's all still open so I can run more cable. If something doesn't work or is expensive, I just won't worry about it for now.

Something like this for a ground plane? I've seen the build plans but having never done it before, I'm not sure I follow 100%.
Base antenna, 2m, 2ft, w/ground plane

Just use typical coax?
Amazon.com: Mediabridge 50 feet Triple Shielded Coaxial Digital Audio Video Cable F-Pin to F-Pin with Easy Grip Connector Caps: Electronics

 

[AK9R]

Merging similar threads, both asking about VHF/UHF ham antennas in attics, that were created within 5 minutes of each other.

 

[mmckenna]

I just need to buy the LMR-400 coax with the correct connectors on the ends of the coax. Which is N and Mini U on my XPR 5550 and SMA on my XPR 7550 handheld

Don't do this.

The mini-UHF connectors on the back of the Motorola commercial radios will not stand up to the stress put on them by heavy coaxial cable. Even the SMA connectors on the portables can easily be damaged by attaching heavy cable to them directly.

If at all possible, use type N connectors on your antennas and coax. When you get the coax down to where your radio will be, use a short jumper made of flexible lightweight coaxial cable to make the connection to the radio. Even a piece of RG-58 will work fine.

Even though places like Radio Shack will sell you a UHF to mini-UHF adapter, resist the temptation to use those. Even Motorola knows this and will happily sell you a female N to male mini-UHF adapter cable.

Spending the money on the adapter cable is a whole lot cheaper than the hassle of replacing the connector on the back of your radio.

 

[Netdewt]

Merging similar threads that were created within 5 minutes of each other.

Not really the same question... now I just feel like I wrecked this other guy's thread.

 

[mmckenna]

Not really the same question... now I just feel like I wrecked this other guy's thread.

Not your fault, but I agree, the two different questions confused me. Not sure why they needed to be merged. I didn't know what the timing had to do with it.

 

[N1XDS]

Thank you Mmckenna, for the information and the help. For your suggestion I think it's going to be best is get N connectors on the antenna which the Diamond F-718A comes with I would just need the N connector on the end of the coax and use the mini uhf to sma connector I have had for awhile. For my XPR 7550 I would need the BNC to mini UHF antenna adapter? I was told by a local MotoTRBO owner/Ham I would need the BNC to UHF adapter for me to be able to use the XPR 7550 handheld.

Don't do this.

The mini-UHF connectors on the back of the Motorola commercial radios will not stand up to the stress put on them by heavy coaxial cable. Even the SMA connectors on the portables can easily be damaged by attaching heavy cable to them directly.

If at all possible, use type N connectors on your antennas and coax. When you get the coax down to where your radio will be, use a short jumper made of flexible lightweight coaxial cable to make the connection to the radio. Even a piece of RG-58 will work fine.

Even though places like Radio Shack will sell you a UHF to mini-UHF adapter, resist the temptation to use those. Even Motorola knows this and will happily sell you a female N to male mini-UHF adapter cable.

Spending the money on the adapter cable is a whole lot cheaper than the hassle of replacing the connector on the back of your radio.

 

[N1XDS]

Not really the same question... now I just feel like I wrecked this other guy's thread.

Not your fault, but I agree, the two different questions confused me. Not sure why they needed to be merged. I didn't know what the timing had to do with it.

No problem.

 

[N1XDS]

Few minutes ago I took the XPR 7550 with the stock antenna to the attic it brought up the MotoTRBO repeater with one bar on the signal indicator on the left side of the LCD screen if that makes since. I think I need a higher antenna and it put it in the attic will work the best for me. My Comet D150s discone antenna scanner antenna works great.

If you take the 7550 handheld into the attic and can bring up the repeater with the stock antenna (rubber duck, I assume?).... then EITHER the vertical or yagi (properly aimed) will work. And of course will work much better than the stock antenna on the handheld. Failing that, I would estimate that at 10 miles the yagi is a certainty if pointed at the repeater. The vertical should work, but if there was a way to test it prior to mounting it permanently, you should do so.

 

[mmckenna]

Thank you Mmckenna, for the information and the help. For your suggestion I think it's going to be best is get N connectors on the antenna which the Diamond F-718A comes with I would just need the N connector on the end of the coax and use the mini uhf to sma connector I have had for awhile. For my XPR 7550 I would need the BNC to mini UHF antenna adapter? I was told by a local MotoTRBO owner/Ham I would need the BNC to UHF adapter for me to be able to use the XPR 7550 handheld.

It really doesn't matter, BNC or N, whichever you prefer on the end of the coax from the antenna. I personally prefer N connectors. Motorola used to make/sell an adapter cable just for this purpose. A mini-UHF to BNC adapter would work with a short jumper cable to the feed line if you secured it well.

Few minutes ago I took the XPR 7550 with the stock antenna to the attic it brought up the MotoTRBO repeater with one bar on the signal indicator on the left side of the LCD screen if that makes since. I think I need a higher antenna and it put it in the attic will work the best for me. My Comet D150s discone antenna scanner antenna works great.

The nice thing about digital is you just need to get enough signal into the repeater for it to work. You will need to overcome your feed line losses, but a gain antenna should work just fine for that. A vertical would still allow you to use simplex and hit other analog repeaters. A discone would work, but they have no gain. I use one on VHF and it works just fine, but it's not the best antenna for the job.

 

[N1XDS]

The Diamond F718A has a N connector on the bottom of it so I will need a N connector on the coax that connects to it and Mini UHF for my radio. If I use my handheld I will need a BNC to N adapter is that correct? Just trying to learn what I will need. I went over to where the repeater site is and saw a bunch of trees from where the repeater is to my house where I live. The repeater is on a very,very,very tall commercial tower. Only issue I see maybe not a issue is the trees?

It really doesn't matter, BNC or N, whichever you prefer on the end of the coax from the antenna. I personally prefer N connectors. Motorola used to make/sell an adapter cable just for this purpose. A mini-UHF to BNC adapter would work with a short jumper cable to the feed line if you secured it well.




The nice thing about digital is you just need to get enough signal into the repeater for it to work. You will need to overcome your feed line losses, but a gain antenna should work just fine for that. A vertical would still allow you to use simplex and hit other analog repeaters. A discone would work, but they have no gain. I use one on VHF and it works just fine, but it's not the best antenna for the job.

 

[mmckenna]

Trees won't be an issue at those frequencies.

Not sure what the fitting is on top of the XPR portable, but if it's like the other Motorola's, it's an SMA male, so you'll need an SMA Female to N to attach it to your feed line. Many amateur grade radios use BNC's so that might be the confusion.

If you must use adapters to connect the short/flexible cable to your main feed line, use good ones. Hint: Radio Shack doesn't sell high quality adapters. If you really need to use an SMA to BNC adapter on that radio, go with a good brand. Pasternack is a good source. You'll pay more, but you'll get a good product.

 

[FKimble]

Just use typical coax?
Amazon.com: Mediabridge 50 feet Triple Shielded Coaxial Digital Audio Video Cable F-Pin to F-Pin with Easy Grip Connector Caps: Electronics

No, no no and heck no. You need 50 ohm coax not 75 and you need low loss coax for the vhf and higher frequencies. At least LMR 400 regular or the flexible version.

 

[wbswetnam]

I use the Radio Shack 20-176 scanner antenna. Works great for 2 meters and 70 Cm.

I bought one of these for just $14 on a well-known website (named after a large river in South America) from a 3rd party seller. With shipping, I got it into my hot little hands for under $20! I put it on a mast, away from other metal objects, connected up a length of coax and hooked up the antenna analyzer. I got 1.1:1 to 1.2:1 across the entire 2m band, and 1.3:1 on 446.0 MHz (the center of the 70cm band for FM repeaters). While not specifically intended for low-power transmitter usage, it will certainly work for that purpose. I also put mine in the attic and it works great for local (<30 miles) repeater traffic.

 

[popnokick]

[Replying to Netdewt] The Radio Shack 20-176 is likely to outperform a homebuilt 2M ground plane if you've never built one before. And maybe even the MFJ-1740 in the GigaParts link you provided. And you have some good testimonials right here on the 20-176.
If you can more easily run coax from the center of the house to the distant ends of the house (in the attic)... and can hide the coax more easily, then do a couple of runs now even if you don't use them. But if you don't care if those runs are visible in the attic, then no need to install them now.
I was suggesting two widely separated runs so that you'd have more options if you start using two antennas, e.g. separation so they don't affect each other TX/RX, having more flexibility to select optimal placement in the attic, etc.