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Old 19-Apr-2017, 5:59 PM   #16
lifespeed
Junior Member
 
Join Date: Dec 2016
Posts: 14
Quote:
Originally Posted by rabbit73 View Post
You can add the antenna gain to the NM to make it more positive.
Yes, that is how it works. The UHF antenna gain is 12 to 14 dB, so even with a noise margin of 10 dB (KBCW RF45 VC 44.1) I still get error-free reception. So (10+12)-15 leaves about 7 to 9dB for coax loss and tuner noise figure. Both of these must be doing OK, as I get this station clearly.

Quote:
Originally Posted by rabbit73 View Post
Nice photo of your antennas, but it makes your thread hard to read because the posts are very wide. I try to limit my images to about 800 pixels wide.
Fixed and clickable.

Quote:
Originally Posted by rabbit73 View Post
It impossible to receive signals with a NM lower than -15 dB; they are buried in the thermal noise floor below -106 dBm.

If you are able to receive a signal with a NM lower than -15 dB, either the TVFOOL report is wrong or the signal has been
enhanced by Tropospheric Propagation.
That was a hyphen, not a minus sign. Not clear, edited to "sub 20 dB".

Quote:
Originally Posted by rabbit73 View Post
With so many factors involved, try the easy way first with the UVSJ down below.

If you are concerned about the insertion loss of the UVSJ for UHF, you have a choice of two UHF antennas to combine with the
VHF antenna; pick the one that will do the least harm to UHF reception.
In hindsight this seems obvious, good idea! The way to maintain tuner quantity, as opposed to dedicating an entire dual tuner to VHF to receive two channels, would be to diplex VHF with the DB4e aimed at Fremont 12 miles away. Although this antenna does not receive all the San Francisco stations like the Big Yagi it does receive quite a few perfectly. This would help with the occasional DVR wanting more tuners issue. Unfortunately I don't have room for three antennae on that mast. Three antennae, something doesn't seem right here. Anything worth doing is worth overdoing.

Last edited by lifespeed; 19-Apr-2017 at 6:04 PM.
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