Recent TV antenna inconsistencies

[mikenowo]

We have had a TV antenna on our roof for several years now, but most recently (past few months) the reception has been abysmally inconsistent.
On some days, all channels will play well for hours; on others turning the rotator unit indoors to ANY location (N, S, E, W, or any combinations) result in bad or no reception on all or most channels!
A baffling example was today when in the morning keeping it at EAST all channels came in fairly well, then after a few hours all were gone. After minutes of frustrating back and forth rotation, WEST finally got the channels back. Then after half an hour they were gone or many lost again!!
Turning it to SOUTH (once again after many tries) and all was well until about 7 PM. Readjusting yet again to SW helped up to now, 11PM. For the moment, it is still working, knock wood. I might be tempted to say it is worse during colder weather, but it is 20 below right now and all is working well, so that can't be the reason. Also it is not specific to a particular time of day (yesterday I could not tune anything in at 11PM, unlike today).

Once again, this started about 3 months ago and has been ridiculously inconsistent since then. WHAT could possibly cause this? We have tried BOTH rotator units (ARCHERATOR: model 15-1225 and model 15-1225B) and the problem persists on both. Nothing has changed regarding the connections indoors or outdoors and as far as we know nothing has been built around us recently to interfere with reception.

What should we be looking for regarding rectifying this situation? Can both rotator units be failing (do they even mean anything regarding reception or do they simply rotate the antenna)? Is there a problem with the antenna itself? If so, what part is most likely the culprit? We have boosters on all TVs as well, so that shouldn't be a problem.

Any suggestions as to possible things to look for regarding a fix would be most appreciated. Getting reception these days is like rolling the dice (and it seems they're loaded)!

Thanks for your help.

[Mike]

Your antena could be oxidised (corroded) especially if you live near the sea or any source of pollution
However it is more likely that your coaxial downled is damaged maybe rain has got in it a tiny amount of water can destroy a whole length of cable or ther is a bad connection of break in it

[StormiNorm]

UNUSUAL FM RECEPTION, EXPLAINED...
No doubt you have read several postings to Airwaves Journal about some very unusually long-distance FM reception reports. As a Radio Engineer and LONG-TIME DX'er, I thought I would give you a little explanation on what is going on. During the warmer (especially the Summer) months, two types of long-distance FM reception can occur. The first is what we call "trops" or in other words... tropospheric ducting. This happens mainly during temperature inversions. During the day, the ground absorbs the heating rays of the sun. At night, radiational cooling occurs where that absorbed heat rises from the earth and goes straight up into the atmosphere to about 1-3 miles up to the higher areas of the troposphere. If the conditions are ripe, mainly during times of high humidity, the troposphere can act like a mirror, a sort of waveguide. Trops are more prevalent during the late night, early morning hours. Since the ducts are 3 to 4 miles above the earth, the line of sight can be roughly 100-500 miles around. If a stalled weather front occurs, that ducting can bring stations over 1000 miles away. I witnessed such an occurrence in 1993 when I got local reception of WHTK/99.7 in Port Royal, SC , over 800 miles away from my vantage point here in the Boston area. UHF- TV also can get into the act during trops. A viewer in Tulsa, Oklahoma got a perfect picture of Boston's WSBK-TV, Channel 38 in 1979 and got it verified!

Now, the fun part. The other type of long-distance reception is called "E-skip" or Sporadic-E. This happens during the months of late-May through late-July. But it can happen at any time of the year but on a very limited scale. This involves the "E" layer of the Ionosphere, roughly 50-100 miles above the earth. E-Skip mainly occurs during times of high thunderstorm activity. Without getting technical, if you are getting a station from South Florida (and you live in Massachusetts, for example).chances are there is a band of severe weather somewhere between those two locations. The highly powerful electric activity of these thunderstorms has been linked to the occurrence of E-skip. In 1991, during a VERY powerful batch of T-storm activity in MY area, I was getting some very usual skip conditions. I was getting WBVE-FM "Beaver 96.5" in Hamilton (Cincinnati), OH clear as a bell and WKDD-FM (96.5) from Akron, OH started coming in a few minutes later. After the storm abated, I was getting WMT-FM (96.5) in Cedar Rapids, IA and WDZQ-FM (95.1) from Decatur, IL. And just before the skip died, I was getting KKDL-FM from Fargo, North Dakota (95.1). There is NOT a way to predict E-Skip (as far as I know). But you can get a hint of a chance that E-skip is going to occur. If you have a police scanner, capable of LOW band (30-50 MHz), set one of your memories to one of several paging channels NOT being used in your area or a police channel NOT being utilized in your area. My one is 42.12 MHz (Missouri Highway Patrol, and others). If you are beginning to get some activity on that channel, chances are the bands are going to "open-up". After that, check the any low band TV channel that is not very active (Channels 2-6) in your area. If you are beginning to see some video or if you experiencing some co-channel interference on that channel, you've got SKIP! SKIP conditions move up in frequency depending upon the strength of the opening. The highest frequency where skip occurs is called the MUF (maximum useable frequency). Sometimes it can level off at Channel 2, or it can level off upwards to 107.9 and maybe beyond!

Have FUN!

73's Peter Q. George, N1GGP Randolph, Massachusetts USA