Antenna Adjacent channel causing reception problem

Richard · Post by **Richard** » Sun May 23, 2004 7:57 am

Grumpy,

I had another Atlantan contact me about this and both of you are using the same antenna in the same conditions.

From that email...

Actually that is what I said, too much power from WTBS is causing tuning
problems with the weakling WGCL right next to it. Your receiver keeps seeing
the lobes of WTBS in the WGCL channel incresing the noise floor especially if
the WGCL is already noisey. As Gain increases so does direction and
selectivity. The antenna I suggested would solve your problem by:

By not using a preamp you have reduced noise

By increasing the gain of WGCL you have reduced noise even with a preamp

By adjusting the antenna you might detune WTBS reducing adjacent channel
interference and noise on WGCL

FACT: your antenna does NOT have enough gain regardless of how well it has
performed up to now.

FACT: most folks do not have enough antenna and are compensating with preamps

Grumpy, you won't know until you do it. It will cost you $50. I have a 4228 laying around here but considering how far apart we are...

Just order it.

kq6qv · Post by **kq6qv** » Sun May 23, 2004 3:05 pm

Richard- I believe none of your suggestions will work. I gave this problem a lot of thought for a Washington case (KEPR) and I concluded that when an adjacent channel station is too powerful (by a factor of more than 20 or so), if the towers are separated by less than one degree, there is no practical way to receive the weaker station.

I am not sure whether the failure is due to out-of-channel emissions by the strong station or if it is an AGC failure in the receiver. -Ken

Richard · Post by **Richard** » Sun May 23, 2004 3:48 pm

Ken,

We have a had a fairly rough week in Atlanta over this and the engineering staffs are already overwhelmed and quite aware of the complaints.

On the other hand they have proven for themselves time and time again by actually showing up at the customers location that the antenna system is ALWAYS marginal and by installing the correct one the problem(s) is solved.

I calibrated Grumpies display, I have seen his house and his antenna and he was marginal before WTBS increased their power. I told him then I was surprised the system was working and he did go on to explain all his consistency problems but since he does most of his viewing at night he was not concerned since it seemed to cooperate during those hours.

I am in multipath hell running a very high gain antenna and have not had the first problem. Most antenna systems installed by end users are designed to get by, keep it off the roof, or put where they really do not belong due to poor appearance and are marginal. That is never a problem until things like this come along...

The Atlanta group also provides a free loaner CM4228 but it is in a crate to protect it and is not setup for actual installation on a roof. Many have used it only to buy one for themselves having great success in the end.

kq6qv · Post by **kq6qv** » Sun May 23, 2004 4:23 pm

I retract the claim that none of your suggestions will work. I had assumed that WTBS was far above the power limit that would allow WGCL to be received. There is the possibility that WTBS is only marginally too powerful. I had considered that unlikely, but it appears to be the case in Atlanta. In such a case, the added reception difficulty can cause marginally working antenna systems to fail. (I

chuckken · Post by **chuckken** » Sun May 23, 2004 4:39 pm

KQ6QV...This is off subject, I just noticed that you live in San Jose...My wife and I just moved from there about a year and 1/2 ago...We lived in San Jose, Saratoga, Campbell, Los Gatos...My stomping grounds were around Hamilton Ave and Lawrence Expressway...By the Malls...

How do you like those gas prices?...Just for your own info...We moved because the housing was so ridiculous...The house we bought here in Acworth Ga. would have cost 1.5 Million in San Jose...We only paid 210,000.00 here!...plus gas is the cheapest in the U.S here...anyways, glad to hear from a fellow San Jose-an...

akirby · Post by **akirby** » Sun May 23, 2004 8:11 pm

I've got a 4228 in the attic with a CM preamp about 20 miles from the towers and I'm getting both TBS and WGCL just fine.

Grumpy_Bob · Post by **Grumpy_Bob** » Mon May 24, 2004 8:19 pm

Richard,

All the other stations are still fine. It's not the $50 that is stopping me, it's the $150-200 that an installer wants to go up there... As you may recall, the backside of my house is down a STEEP hill, so it's a three story drop to the deck below, and the guy that installed the current antenna had a hard time balancing on the awkward ridge up there - and he was a pro! There's no way I'm crawling up there. Not for just CSI. I'll miss the football, but the rest of CBS just isn't worth a possible broken pelvis. And after spending $500 on the T165, $1000 on the Lumagen, and $$$ for the calibration (I omit the exact number out of courtesy to Richard - it was a fair price), I can't justify spending any more on TV right now.

Allen, I'm in Ellenwood, near Stockbridge, about 20 miles SE of Midtown. Yes, I have two pickup trucks - one beat up one for six days and a clean one for Sunday. I have cows grazing in the center of my subdivision.

Richard · Post by **Richard** » Tue May 25, 2004 12:28 pm

It's not the $50 that is stopping me, it's the $150-200 that an installer wants

Oh.

I get it.

akirby · Post by **akirby** » Tue May 25, 2004 12:31 pm

Grumpy_Bob wrote:Richard,

All the other stations are still fine. It's not the $50 that is stopping me, it's the $150-200 that an installer wants to go up there... As you may recall, the backside of my house is down a STEEP hill, so it's a three story drop to the deck below, and the guy that installed the current antenna had a hard time balancing on the awkward ridge up there - and he was a pro! There's no way I'm crawling up there. Not for just CSI. I'll miss the football, but the rest of CBS just isn't worth a possible broken pelvis. And after spending $500 on the T165, $1000 on the Lumagen, and $$$ for the calibration (I omit the exact number out of courtesy to Richard - it was a fair price), I can't justify spending any more on TV right now.

Allen, I'm in Ellenwood, near Stockbridge, about 20 miles SE of Midtown. Yes, I have two pickup trucks - one beat up one for six days and a clean one for Sunday. I have cows grazing in the center of my subdivision.

That's the other reason mine is in the attic. I'm glad I didn't have to go outside. Mine is also 3 stories in the rear with a concrete patio below most of it.

Grumpy_Bob · Post by **Grumpy_Bob** » Tue May 25, 2004 5:18 pm

Richard,

What do you think of trying a 4228 in my attic? I figured It'd be too low, but for $50 and 50 feet of RG6... I could keep both, and switch between them as needed...

Ken, any advice on what to look for in a simple A/B switch?