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Old 6-Jun-2013, 10:47 AM   #23
tripelo
Senior Member
 
Join Date: Jan 2010
Location: Dallas, TX
Posts: 127
Jerrold/Wade VIP-306 for VHF-11

Previously mentioned was that the stacked YA-1713’s on the main tower were not much use after WKYT moved from Channel 13 to Channel 36. Then, it was realized that for part of the time, a Louisville KY VHF station could be received and was occasionally watchable. The station:

WBNA (ION) Channel 8, 24.5 kW, at ~80 miles, TVfool Noise Margin -7.0 dB

And also interesting, for short periods of times, Louisville’s WHAS channel 11 (16.4 kW, at 101 miles) could be received, but was not actually watchable.

The signal goodness indication on a CM-7000 DTV converter was calibrated using a Signal Level Meter (~1.5 dB per each 10% indication for channel 11). This calibration of CM-7000 was used to help evaluate the two stations’ signals, hoping to make antenna changes for potentially better reception. For several weeks, reception of these two stations was checked daily.

An additional two YA-1713’s were purchased for possibility of a installing a quad stacked arrangement of YA-1713’s.

Analysis of signal data suggested:

An additional gain of 7 dB, above that provided by the stacked YA-1713’s, may be required for reliable reception of WHAS-11.

This required amount of increased gain (7 dB) essentially ruled out a quad stack of YA-1713’s.

A quad stack of YA-1713s (2 horizontal, vertically stacked above 2 horizontal, or even a diamond stacked quad) would at best provide ~3dB gain above a dual stack.

At the time, the highest gain for commercially available VHF antenna was Jerrold/Wade VIP-306 (specified gain of 12 dB on Channel 11). The VIP-307 version had a bit more gain but was no longer available.

That VIP-306 gain listing was dBd. In the late 1960's when the VIP series were designed, computer simulation (dBi) was virtually non-existant. So dB values were commonly provided in dB, as actually measured, with respect to a dipole (dBd).

A pair of VIP-306’s was purchased for evaluation and potentially for stacking.

Below, is an image of a single VIP-306 installed at the test location, aimed towards the main tower.




Over the next few weeks, other VHF antenna configurations were mounted on the test mast and reception observed.

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Attached Images
File Type: jpg VIP-306 at Test Location.jpg (120.0 KB, 6811 views)

Last edited by tripelo; 7-Jun-2013 at 1:52 AM. Reason: clarify
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