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Terms of Use have been amended effective October 6, 2019. Make sure you are aware of the new rules! Please visit this thread for details: https://www.mibuzzboard.com/phpBB3/view ... 16&t=48619
Search found 45 matches
- Sun Sep 22, 2019 6:09 am
- Forum: Engineering & DX'ing
- Topic: WWJ signal problems? (+ WJR audio distortion)
- Replies: 79
- Views: 14645
Re: WWJ signal problems?
Hopefully, Rich will check in on this. As I have heard, WJR still has two tube 50 kW transmitters out there in Riverview, and they sound better than the solid state ones. ... Well, better most likely is the subjective conclusion of listeners based on what their ears tell them, and which for them, t...
- Fri Sep 13, 2019 7:59 am
- Forum: Engineering & DX'ing
- Topic: FCCdata.org Now Has Skywave Contours
- Replies: 7
- Views: 2649
Re: FCCdata.org Now Has Skywave Contours
Another approach to showing nighttime contours is to revert to the groundwave contour of that station at locations where its skywave is weaker than its groundwave. Of course that doesn't mean that such signals will not have serious interference from co- and adjacent-channel stations. The plot of the...
- Fri Sep 13, 2019 6:52 am
- Forum: Engineering & DX'ing
- Topic: FCCdata.org Now Has Skywave Contours
- Replies: 7
- Views: 2649
Re: FCCdata.org Now Has Skywave Contours
Thanks for update about FCCData.org.
Surprising that the 0.5 mV/m nighttime skywave contour for WWJ and I suppose other nighttime DAs appears on the map for very short distances from the transmit site where a returning skywave is virtually zero, though.
Surprising that the 0.5 mV/m nighttime skywave contour for WWJ and I suppose other nighttime DAs appears on the map for very short distances from the transmit site where a returning skywave is virtually zero, though.
- Thu Aug 08, 2019 5:43 am
- Forum: Engineering & DX'ing
- Topic: Shortwave - WBCQ new 500kW transmitter on 9330kHz
- Replies: 8
- Views: 3536
- Tue Jul 30, 2019 6:54 am
- Forum: Engineering & DX'ing
- Topic: Reduced ERP from "Overheight" FM Stations
- Replies: 18
- Views: 5262
Re: Reduced ERP from "Overheight" FM Stations
Additional: The mounting environment of an FM transmit antenna has a very significant effect on its radiation patterns, as the tower structure and other re-radiators near the antenna aperture become part of the antenna system. The image below shows these effects for one case by comparing the radiati...
- Mon Jul 29, 2019 9:20 am
- Forum: Engineering & DX'ing
- Topic: Reduced ERP from "Overheight" FM Stations
- Replies: 18
- Views: 5262
Re: Reduced ERP from "Overheight" FM Stations
The radiation pattern on the left side of the image below shows an extreme example of the pattern distortion than can result from mounting a stock, "omnidirectional" FM antenna on the side of a large-faced tower.
- Mon Jul 29, 2019 8:18 am
- Forum: Engineering & DX'ing
- Topic: Reduced ERP from "Overheight" FM Stations
- Replies: 18
- Views: 5262
Re: Reduced ERP from "Overheight" FM Stations
Remember that there are only one or two azimuths of a DA that have the full measured maximum field ratio. All other directions are less than maximum, regardless of the licensed pattern envelope field ratios. That is true. Directional FMs are licensed for the maximum ERP they may radiate in the hori...
- Wed Jul 24, 2019 6:19 am
- Forum: Engineering & DX'ing
- Topic: Reduced ERP from "Overheight" FM Stations
- Replies: 18
- Views: 5262
Reduced ERP from "Overheight" FM Stations
FM stations with antenna heights greater than the HAAT permitted for their Class of station must reduce their ERP to provide a radius to their 1 mV/m field contours equal to that of a station exactly meeting the maximum ERP and HAAT authorized for that Class. As an illustration of this, below is a c...
- Mon Jul 22, 2019 8:57 am
- Forum: Engineering & DX'ing
- Topic: Another Good Resource On Indoor vs. Outdoor Antennas
- Replies: 4
- Views: 1836
Re: Another Good Resource On Indoor vs. Outdoor Antennas
Proper orientation of a directional TV receiving antenna will ensure optimal reliability... True, and sometimes the most useful orientation is not in the direction one expects. For example, when I lived at the north end of Lincoln Park along the Lake Michigan shoreline in Chicago (late 1960s) and a...
- Mon Jul 22, 2019 4:56 am
- Forum: Engineering & DX'ing
- Topic: Another Good Resource On Indoor vs. Outdoor Antennas
- Replies: 4
- Views: 1836
Re: Another Good Resource On Indoor vs. Outdoor Antennas
... Preamps are noisy, and don't give you gain like noise free gain from antenna placement and gain Another benefit can result from using a directional outdoor antenna. It can reduce interfering signals arriving from co- and adjacent-channel stations with compass bearings well away from the directi...
- Sat Jun 15, 2019 10:06 am
- Forum: Engineering & DX'ing
- Topic: WJR vs. WWJ Fields at Utica, MI
- Replies: 22
- Views: 5165
Re: WJR vs. WWJ Fields at Utica, MI
Here is a study using NEC4.2 set for an Earth conductivity of 8 mS/m: The WWJ 186° radiator at 8 Mile Rd used alone, and driven with 5 kW would generate about a 20.6 mV/m field in Grosse Pointe, MI (a 14 mile path at N107°E). The 186° radiator used alone and driven with 1 kW would generate a field o...
- Fri Jun 14, 2019 6:22 pm
- Forum: Engineering & DX'ing
- Topic: WJR vs. WWJ Fields at Utica, MI
- Replies: 22
- Views: 5165
- Fri Jun 14, 2019 6:45 am
- Forum: Engineering & DX'ing
- Topic: WJR vs. WWJ Fields at Utica, MI
- Replies: 22
- Views: 5165
Re: WJR vs. WWJ Fields at Utica, MI
... I think it shows what the FI would be along points of a circle equidistant from the old WWJ tower, about 14 miles away. Correct. I don't know why the first circle is 0 and not the center of the graph. I set the lower limit of the scale to less than zero field to give more resolution to the lowe...
- Thu Jun 13, 2019 11:54 am
- Forum: Engineering & DX'ing
- Topic: WJR vs. WWJ Fields at Utica, MI
- Replies: 22
- Views: 5165
Re: WJR vs. WWJ Fields at Utica, MI
(Corrected for 5 kW at common point) Below is a NEC4.2 study showing the nighttime groundwave fields at a radius of 14 miles from WWJ using their tx site on 8 Mile Road (if I did it right). The array parameters were taken from the links provided earlier in this thread by CK-722. I didn't bother rot...
- Wed Jun 12, 2019 2:06 pm
- Forum: Engineering & DX'ing
- Topic: WJR vs. WWJ Fields at Utica, MI
- Replies: 22
- Views: 5165