View Single Post
Old 16-Sep-2015, 7:28 PM   #4
Retired A/V Tech
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,738
When I click on the CHCJ callsign in your report I see the escarpment:

I then did another profile using different software based on your estimated location (I don't have your exact coordinates) which puts you about 1 block SSW of Shanghai Chinese Food and Rosedale Sports Bar and Eatery:

The escarpment is definitely in the way, and UHF signals can't make it over a peak by diffraction as well as VHF.

Tell us about your yagi. I wonder if tilting the front end up would help?

And then I did an FM FOOL report which shows some very strong FM signals that might interfere with TV reception, if the filter in the 7778 isn't sufficient; see attachment 3. Canadian DHC forum member roger1818 told me that the FM Fool database isn't up to date for Canadian FM stations.

I suggest you make some tests with each antenna in its respective direction without combining. If it can't get what you want alone, it can't do it combined.

Try the yagi for channel 35 with a UVSJ (high and common ports) between the antenna and the preamp. If that doesn't give you CHCJ try inserting an attenuator between the UVSJ and the preamp to reduce any possible spurious signals created by IMD. Then try a similar test with the 8-bays.
•Attenuation values 1, 3, 6, 8, 10, 12, 16, 20dB (FAM)
click on 1 dB for other values; the up and down arrows are faint

If you want a short course on overload and IMD, ask me.

Attached Images
File Type: jpg 4.6 ExplorerTVFprofile1.JPG (60.6 KB, 2249 views)
File Type: jpg 4.6 ExplorerTVFprofile2.JPG (124.6 KB, 2718 views)
File Type: jpg 4.6 ExplorerTVF FM est.JPG (107.1 KB, 844 views)
If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 16-Sep-2015 at 10:11 PM.
rabbit73 is offline   Reply With Quote