I am still in the processing on setting up my "shack". I have a few questions:

1. The shortest run would be from the radio to the peak of the gable roof. It would be about a 20' run. My wife wants to hide the antenna on the back of the house, that would make it closer to a 100' run. What would I lose by going the addition 90'ish feet? It's a 2M/70CM rig.

2. How strong are gable mounts? I live on the OR coast, and we get strong winds somewhat often. Is there a better alternative?

3. Is there any issue running the coax in the same conduit as CAT6? What about in the same conduit as electrical wire used for a solar panel?

4. I am thinking about a Tram 1480, it would be mounted on my roof (in some undetermined fashion). How much of a performance increase could I expect over a mobile right a 1/4wave NMO mount (assuming the radio and other variables are the same)?

Losses of UHF and VHF is for a 100 foot run is crazy.

RG8X 20 foot run 50w input......

out: 144Mhz 41.456 Watts
out: 440Mhz 34.370 Watts

RG8x 100 foot run 50w input......

out: 145Mhz 19.591 Watts
out: 440Mhz 7.637 Watts

LMr400 20ft run 50w in.......

out: 145Mhz 46.681 Watts
out: 440Mhz 44.243 Watts

LMr400 100ft run 50w in.......

out: 145Mhz 35.467 Watts
out: 440Mhz 27.123 Watts

So as you can see there is substantial loss, even on LMR400 at 100ft runs. Anything over 50 feet on VHF/UHF hardline is a must. Keep in mind there is loss on the signal as well. 100 foot run on LMR400 you loose nearly half of the power out and half of the RX signal strength.

Sounds like there is gonna be an ugly antenna on the side our garage

Gable mounts are not all that strong, they can take some wind load, but a roof tripod would work better.

There will be no issues running the coax in conduit, since it is shielded there should be no RF out, how that works using high loss coax is anyone guess. Other may be able to chime in.

As far as antennas go, the Tram has 6db of gain that is huge when compared to a 1/4 wave that is a 0 gain so to speak. But keep in mind hiding the antenna on the backside of the roof will reduce performance. The name of the game for VHF is as high as possible and in the clear. I have had sucesses with attic mount and indoor antenna's so dont let anyone tell you it cannot be done.

It sounds crazy but I would use a short run of coax and a battery and radio to test different locations to see where the best location is. I honestly would try to talk the XYL into allowing the gable or roof mount. When done correctly they dont look that bad. Plus they get used to it.

Check out my thread for some large antenna's that mine was not too happy about, but I give here executive authority to do what she wants with the house. I get the shed, the roof, and my man cave. It works well for us! Stanprophet's 432 EME Thread

With a 20 foot run Belden 9913f7, 50w and gain you are looking at........

144Mhz ERP 185.4 Watts,
440Mhz ERP 277.1 Watts

At VHF and UHF frequencies vertical coax has no loss.  

Here' a chart I ran up a while ago....

Attached File

Thanks for everybody's input. As I understand it, gain applies more to TX, rather than RX, correct? My issue is that I live at base of a 150ft hill (the top of the hill is 150ft above sea level, and I am at sea level +/- a few feet).

With my mobile rig, using a 1/4 wave nmo mount, I only have maybe 1 mile of simplex to a HT and 1/4 wave whip

I am afraid that a bigger and higher antenna won't gain me much, which is disappointing because there are quite a few hams in town and I would like to do some simplex QSOs.

You already have some.... somewhat misleading information in the thread.

Gain (and other antenna performance characteristics) applies equally to reception and transmission, it's called the law of reciprocity in antenna theory.

Your location is very tough for radio propagation, yes. It's not a complete block to communications, there is something called knife edge diffraction, plus you get some reflections off mountains and such but you're in a big hole both figuratively and literally.

In your specific case a higher gain antenna may not necessarily be better. A high gain omnidirectional antenna works by taking signal away from upward angles and compressing it at the horizon (or should be at the horizon, which is a problem with some antenna designs, but I digress). In your case you might well do better with a lower gain antenna that puts more signal at the mountaintops to take advantage of the diffraction. Or you may just be out of luck entirely
With a 150 foot hill in the middle, that is probably doing well.
Well, this is why there are repeater stations on the VHF & UHF bands.

Something to consider is that different VHF bands respond differently to knife edge diffraction and other non-typical propagation modes. You might find better performance out of 70cm than 2m for example. Or 6m might be better. Or 220, although few have 220 equipment.

Posting wattages is the typical scare tactic of people scared of transmission line loss. What matters is decibels (dB).
Here is a link to an online calculator for line loss for various types of coax.
http://timesmicrowave.com/calculator/?productId=52&frequency=146&runLength=100&mode=calculate#form
As an example, using your 100 foot cable length at 2 meters shows a line loss of 1.5dB and a cable assembly loss of 1.7dB. Adding connectors adds a little bit of loss, and if they're PL259/UHF types the loss will likely be a little more than that. By comparison a 20 foot run has loss of 0.4dB, so the shorter run saves you 1.3dB roughly. In amateur VHF FM, its usually impossible to distinguish by ear a difference in signal strength of less than 2dB.  The difference on 440MHz is greater, at 2.1dB which might be detectable, but barely. A poor quality connector installation could easily make more difference.

I would not let the fear of line loss dictate your antenna installation.

One thing to consider is access to your antenna... as one thing I would suggest is that you try some different antennas to find something that will hopefully work for you. It's entirely possible that a simple 1/4 wave ground plane would be the best option at your location.

To paraphrase Gamma762,

I would not let the fear of spouse dictate your antenna installation.

Put your antenna where you want it, where it is best mounted.