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Hi Folks,
I got up on the roof this morning and played around for a couple hours with things.
Disconnected Pre-Amp
- No change at current mast location (0 strength)
- Found a portion of the house above the garage where it did receive signal (~40% strength) enough to pick up football with no issues.
Re-connected Pre-Amp in this new location
- Increased strength by ~10% (to 50+%)
I then moved incrementally around the roof varying the antenna height/orientation. This exercise demonstrated:
- A band (10-20') wide on the roof where I picked up signal. This band tended to be weaker the higher I raised the antenna from the roof, with a sweet spot being ~3' above the roofline. As I got to the fringe of the area the dropoff was quick from ~30% to 0%.
Since the Pre-amp increased my strength previously I left it connected and disconnected the VHF antenna. I then incrementally moved around the roof with the antenna. Strength levels were similar to what they were when both were connected; however there may have been a slight gain.
Upon completion of the testing I re-installed the antenna on the existing mast and took photos from two vantage points that are attached.
Existing Mast Location (Current Mast Location.jpg)
Where I picked up KTMF (Pickup Location.jpg)
Based upon my experiments I'm thinking my set up has some combination of the following:
1) Poor mast location for KTMF
2) Inadequate UHF antenna
3) Potentially inadequate gain/pre-amp
Moving forward it would appear I could
A) Install a mast where I can pick up signal (This option would require a lot of work on my part, require mounting/runs on a roof that may need to be replaced soon, and could upset neighbors)
B) Experiment with a different Pre-Amp to increase gains at current location
C) Experiment with merging 2 different antenna signals at current location
Options B & C have the definitive risk of doing nothing if current mast location is in a blind spot.
In performing the tests I found it very strange how there was such a limited window (with the existing antenna) where I could reliably get signal, and that raising the antenna much above the roof-line seemed to generally hurt reception.
I guess my questions are:
1) Is there a good explanation on why raising the antenna would hurt reception? (I thought KTMF was LOS, for which higher is better)
2) What is the likely hood I can pickup signal at my existing mast location by playing with antenna/pre-amp choices?
3) Is there any additional tests that I can do with my existing equipment to help provide clarity?
Again, I appreciate all the time and help that folks have put in to this point.
FC
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