Riktar

While I do believe all information and suggestions have importance in varying degrees... In this case, I have moved from the residence in my original post. The suggestions are well stated for anyone trying to determine best location and mounting practices for home/base antenna and cable choices.

Just to toss in what I am using, a DB404 would fit nicely in your attic.

When you are trying the antenna in the attic, did you try having your friend drive in multiple directions? Do a range check with a direction that is parallel to the roof line. Then do a check perpendicular to the roof line. If you find a notable increase in range when you are parallel then I would guess that you have some metal barrier in the underlayment. Just a thought.

50 watts is the max output on the channels listed for GMRS simplex and repeater channels. I get that. What I am wondering is if that 50 watts is specific to what is coming out the back of the radio itself or is that the maximum that can be applied from the first connection of the coax/antenna cable? IE: If a repeater is setup using a duplexer, there is wattage lost going from the output side of the radio to the first coax connection point. Is it a general fact that duplexers soak up half of the wattage from the radio? So even with a full 50 watt radio/transmitter, if a duplexer is used, only 25 watts are going to be available at the first connection of the coax going to the antenna yes?

I went through this a few summers ago in my former residence. It was 120+ degrees and I spent almost a whole day (This place had a BIG attic) finding the best position to put my antenna. Felt like I sweated a gallon of water before the day was through. Good Luck!

Be aware that most mag mount moble antennas use the vehicle chassis as a ground plane. If you experiment with this make sure you have some type of 'groundplane' to attach the mag mount to. A large baking pan or pizza pan should suffice. I don't recall the minimum diameter you should use but I am pretty confident a 12" pizza pan should work.

FWIW I have tried my DB-404B outside my house with an approx height of 22 feet as well as placing the antenna in the attic at (roughly) the same height. My house is a 2 story Lanon Stone with Asphault shingles that are doubled up since the last roofing job was not a full tear off. Is there a difference? Yes but it is so minimal I decided to stay with the attic mount since I can reach out and hit every repeater in the area without a problem and my simplex range with the mobiles was not enough of an increase (We are talking about less than a couple mile(s) difference) to warrant the added work to properly secure and ground/bond the system for the outdoors. All that being said, how big is your attic? The CA-712EFC is nearly 10 feet tall. Not sure I have ever seen an attic with that kind of headroom.

Specifically the antenna. While the installation presently has a mag mount I am going the drill route (Center of the roof) for max performance. If nobody has, I am still going to do this and will post back with the results.

Noted for future reference. Thanks!

That should not be a problem since I have a specific set of mixed (repeater and simplex) channels that I seldom change. The ability to set volume control for either speaker is paramount to this project.

Thanks for confirming the volume question! I never considered that possibility. I will check the back the manual for my TK-8180 and see if the back ports have that same capability!

If I am running a KRK-6DH with a TK-890 head unit (Single radio controlled by 2 separate control heads) is the volume able to be set independently from either control head? Or does changing the volume level on control head "a" also change the volume level on control head "b"? Reason for asking is for the consideration of having one radio service the upstairs and downstairs of my home.

Aside from putting 13.8 to the yellow wire you also have to provide the same 13.8 volts to the red wire. Have you taken the front faceplate off and (gently) checked the ribbon cable that connects the faceplate to the radio body? The reason I ask is that one of the TK-8180 radios I purchased was listed as non working. Which it was until I checked the ribbon cable and found it wasn't inserted fully into the body. I surmised that someone previously had the KRK-10 remote kit in use and when converting the radio back, they did not fully insert the ribbon cable back in. Just a thought. Good luck!!

Then how does the DB-404 work? It consists of 4 folded dipoles which are combined by what appears to be a phasing harness. And they are not pointing the same way. Or is that because the folded dipole design allows that while the Yagi design does not?

Pretty close to 150 degrees. I did some searching on how to make a phase harness. If I understand the theory I need 2 75 ohm coax feeds to the antenna(s) and a 50 ohm feed that get connected to a coax splitter/combiner of sorts which is then connected (via the 50 ohm coax) to my radio. All the sites I found that mention how to do this are referencing VHF frequencies for the math and measurements. Still looking for someone who has done the math in the 462-467 range.

It wasn't the $$$ amount of the DB404 that was the egads part. It was the cost of the splitter I was commenting on. And yes on the 2 yagis. I do have a coax switch already from a prior setup. I just thought it would have been convenient to have both antennas "on" at the same time without having to remember to flip the switch on the coax switch. But for that price, I will bear with the added effort of flipping a switch.... ?

Thanks for the reply. As to the power level, I am using a Kenwood TK-8180H so 45 watts output. And EGADS that is an eyewatering price!! Not to mention the 3db loss....

Most of my needs (at distances over 10 miles) are in 2 specific directions. Using just a single yagi pretty much covers my "local" (under 5 miles) needs. So instead of using a rotator on a single antenna I was wondering if it would be simpler/more efficient to have two yagis pointing at 2 individual compass points?

Fascinating idea! It would definitely take some advanced planning to make it practical. I think the 1/2 mile hops that were mentioned earlier were in reference to people using bubble pack HT's. My experience has shown 4 (Suburban) - 12 (Rural) mile simplex range between my base (TK-8180) and my mobile (TK-8180H) radios. Now this has been achieved by listening to all the advice and experience of this forum's members as well as doing A LOT of reading on the subject. Anyone in SE Wisconsin care to try setting something like this up?

Thanks for the replies. Since I didn't mention the cable type I have run the following: Started with 50 feet of LMR400 and later found a 30 foot length of FSJ4-50B with N connectors already install that made a noticeable difference. So for the sake of seeing what would happen if I went "cableless" to the antenna I considered this. I did not consider the ground. Is that to say I should ground the antenna itself aside from the grounded power supply to the radio body?

I am considering moving my TK-8180H radio right next to the antenna in the attic since I have a spare KRK-10 kit which would allow me to put the head unit right on my desk. And it would eliminate any power loss from using 30 feet of coax cable I am currently using. Would there be any need to shield the body of the radio from RF since it would be right next to/below the antenna? The antenna I am using is a Commscope DB404-B.

Thanks. Will give that a go...

I will be changing my DB-404 antenna from Omni to Elliptical and according to the manual I am suppose to use Aluminum backed tape to resecure the antenna feed cable to the mast when done with the procedure. They mention using Scotch #425 as an example. I am having trouble sourcing the tape locally and was hoping to finish my project this weekend. Has anyone done this and used an alternative aluminum backed tape that specs out like Scotch 425 that I could find at a local Menards/Home Depot/Lowes/etc? Thanks for any advice.

THANKS!!!

Thanks for the reply. I have taken the faceplate off and compared the ribbon cable in the radio to the 2 listed on Pacparts website and neither matches the numbers/specs I have on my existing cable. This is why I am not confident in ordering either. I suppose I could just order both since they are only 6 bucks and change for each. But it would be nice to just order the correct one and be done with it...