The Official AVS Antenna and Related Hardware Topic! - Page 583 - AVS Forum | Home Theater Discussions And Reviews
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post #17461 of 17920 Old 10-25-2018, 05:57 AM
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Quote:
Originally Posted by rabbit73 View Post
To expand a little further on the answer to how low can you go, the practical limit would be a signal with an actual Noise Margin of -15 dB (-106 dBm, -57 dBmV, 1.4 µV across 75 ohms) as defined by TVFool.

The signal coming out of the terminals of an antenna with a gain of 18 dBd, as shown in the diagram below, would be -88 dBm (-39 dBmV, 11 µV across 75 ohms).

And finally, as you requested, the signal to the preamp input would be -89 dBm (-40 dBmV, 10 µV across 75 ohms).

The Noise Margins listed for weak 2Edge signals are known to be less accurate than for LOS signals, because of software limitations. Also, OTA signals constantly vary in strength and Tropospheric Propagation can temporarily enhance a weak signal. For consistent reliable reception you would want a Fade Margin greater than the one dB indicated in the diagram.



The above diagram assumes that the ambient noise level is at or below -106 dBm. To receive weaker signals, you would need an antenna with more than 18 dBd gain, which is possible, but not easily done.
Speaking of low loss baluns.

I read in a post some where that the early baluns were tuned more towards VHF and had less loss in those frequencies than baluns produced later on.

Has anybody put that to the test?
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post #17462 of 17920 Old 10-25-2018, 12:59 PM
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Quote:
Originally Posted by MSev View Post
Speaking of low loss baluns.

I read in a post some where that the early baluns were tuned more towards VHF and had less loss in those frequencies than baluns produced later on.

Has anybody put that to the test?
What you say is true. When I was comparing the gain of a CH3 folded dipole to an FM dipole on channel 3, I noticed that the readings were different when I changed the balun on the FM folded dipole. But, because the ambient noise level was so high on VHF-Low, it didn't make a difference in the SNR. The change in the reading of the gain was equal to the change in the reading of the noise level.

I noticed the same problem on VHF-High with an indoor antenna. I substituted a 30-2475 for a folded dipole. My marginal channel 9 was much stronger, but so was the noise; channel 9 stayed at the Digital Cliff with an SNR of 13 to 14.



Often, the answer on VHF is to reduce the noise, not look for more antenna gain.

"Don't raise the bridge, lower the river."

I measured the loss of 3 different baluns on channel 3 by connecting two in series and dividing by two as I had previously done on UHF.





This inexpensive Jensen MR-550 AM/FM portable radio has been useful in finding noise sources. Tune to a vacant frequency at the low end of the AM broadcast band and then at the high end. The built-in AM loop antenna is directional, which helps in finding the source of noise. Noise on the AM broadcast band often indicates that there is also noise on VHF TV. The AM mode works better than FM when locating noise sources. A portable radio that includes the Aircraft band will also work; that's AM too.

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Last edited by rabbit73; 10-25-2018 at 04:33 PM. Reason: corrected typo
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post #17463 of 17920 Old 10-25-2018, 07:25 PM
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Quote:
Originally Posted by rabbit73 View Post
What you say is true. When I was comparing the gain of a CH3 folded dipole to an FM dipole on channel 3, I noticed that the readings were different when I changed the balun on the FM folded dipole. But, because the ambient noise level was so high on VHF-Low, it didn't make a difference in the SNR. The change in the reading of the gain was equal to the change in the reading of the noise level.

I noticed the same problem on VHF-High with an indoor antenna. I substituted a 30-2475 for a folded dipole. My marginal channel 9 was much stronger, but so was the noise; channel 9 stayed at the Digital Cliff with an SNR of 13 to 14.



Often, the answer on VHF is to reduce the noise, not look for more antenna gain.

"Don't raise the bridge, lower the river."

I measured the loss of 3 different baluns on channel 3 by connecting two in series and dividing by two as I had previously done on UHF.





This inexpensive Jensen MR-550 AM/FM portable radio has been useful in finding noise sources. Tune to a vacant frequency at the low end of the AM broadcast band and then at the high end. The built-in AM loop antenna is directional, which helps in finding the source of noise. Noise on the AM broadcast band often indicates that there is also noise on VHF TV. The AM mode works better than FM when locating noise sources. A portable radio that includes the Aircraft band will also work; that's AM too.

Good to know.

Ever play with any Jerrold and later Dehi baluns?
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post #17464 of 17920 Old 10-25-2018, 08:03 PM
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Quote:
Originally Posted by MSev View Post
Good to know.

Ever play with any Jerrold and later Dehi baluns?
No

If you can not measure it, you can not improve it.
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post #17465 of 17920 Old 10-26-2018, 07:32 AM
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Quote:
Originally Posted by MSev View Post
Good to know.

Using an AM radio to look for noise sources on high VHF is not a reliable method. Lots of electronic devices generate noise at 1 MHz but not at 174 MHz and up. A radio that covers the aircraft band is a much better method.

I've driven around a lot listening on the AM radio and the aircraft band. It's very common to hear terrible noise on AM radio and silence on the aircraft band. Sometimes it works the opposite way.

If you use the AM radio band to look for noise on high VHF you're going to get a lot of false positives.
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post #17466 of 17920 Old 10-26-2018, 08:03 AM
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Originally Posted by Calaveras View Post
Using an AM radio to look for noise sources on high VHF is not a reliable method. Lots of electronic devices generate noise at 1 MHz but not at 174 MHz and up. A radio that covers the aircraft band is a much better method.

I've driven around a lot listening on the AM radio and the aircraft band. It's very common to hear terrible noise on AM radio and silence on the aircraft band. Sometimes it works the opposite way.

If you use the AM radio band to look for noise on high VHF you're going to get a lot of false positives.
What inexpensive method, other than a low SNR that some users can't measure, do you suggest to measure noise interference on VHF?

If you can not measure it, you can not improve it.
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post #17467 of 17920 Old 10-26-2018, 08:48 AM
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Rabbit.
What is your opinion of that stellar labs antenna?
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post #17468 of 17920 Old 10-26-2018, 09:22 AM
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Quote:
Originally Posted by rabbit73 View Post
What inexpensive method, other than a low SNR that some users can't measure, do you suggest to measure noise interference on VHF?

I never said that there was an inexpensive method but an AM broadcast band radio is not a substitute for listening near the frequency you're having trouble with. Properly diagnosing these problems is often not easy or cheap. That's just the reality of the situation.
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post #17469 of 17920 Old 10-26-2018, 11:20 AM
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Originally Posted by Calaveras View Post
I never said that there was an inexpensive method but an AM broadcast band radio is not a substitute for listening near the frequency you're having trouble with. Properly diagnosing these problems is often not easy or cheap. That's just the reality of the situation.
Read my post again. I did suggest the Aircraft band, which is a nearby frequency.

Are you saying that if you can't do testing the "perfect" way, you shouldn't even try anything else?

You seem to have a lot of reasons why something shouldn't be done, but few ways it can be done. I thought it was the ham spirit of innovation to find a way, even if you don't have the ideal equipment for the job.

Chuck's Rules of Forbidden Actions discourage experimentation. Sometimes people have to find out for themselves that it doesn't work. In the case of budh9534, you discouraged him from trying what he wanted to try, which was combining two UHF antennas in different directions with a splitter in reverse:
Quote:
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As far as I'm concerned #2 is a no go for the reasons I've already stated. "Significantly different directions" doesn't make two antennas combined onto one feedline work as you can see in my spectrum analyzer display.
He got it to work because his location was ideal for that method of combining which has a poor record of success.

Why did you think it was OK to discourage him by calling it a "no go" and deprive him of a learning experience?

Wouldn't it have been more constructive to tell him that it doesn't usually work, but that he should try it.?

The only benefit your negative advice gave him was that it made him even more determined to make it work.
____________________________________________

A used Sadelco 733C Super signal level meter covers VHF TV and cable frequencies, but no UHF. It costs less than $100. It can measure the strength of VHF signals and the noise level.

Would that be good enough? It, and my used 719E which covers UHF and VHF and cost $75 including shipping, work just fine for me to diagnose a problem.

The MFJ 852 and 856 power line noise meters (135 MHz AM) cost more and have poor quality control; it's a gamble on getting a good one.

If you can not measure it, you can not improve it.
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post #17470 of 17920 Old 10-26-2018, 01:16 PM
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Originally Posted by MSev View Post
Rabbit.
What is your opinion of that stellar labs antenna?
Good price for a well made antenna that performs well. It didn't help with my marginal VHF channel, but that wasn't the fault of the antenna, it was the fault of the antenna location.

I think the two sections of the boom could fasten together a little more securely. The female coax connector on the balun doesn't grab the male pin of the coax connector tightly, but it hasn't caused a problem.

niv, on the TVFool forum, seems to be very happy with his 30-2475 for VHF. JoeAZ and I had to post for him from PMs because he was never authorized to post.
http://forum.tvfool.com/showpost.php...0&postcount=33



crank it up

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post #17471 of 17920 Old 10-26-2018, 06:41 PM
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On a quick side note re: The pictures of that antenna setup: Holy Crap! That is an unbelievably ambitious setup. I wonder what the cost and construction problems and/or permits were needed for that setup. :-) I feel for him on the whole TV Fool forum problem. I registered at least 8 months ago and never received my authorization for forum posting either.

Back on topic: I have the Stellar Labs 30-2475. In my very remote area, I only have realistic access to 3 channels -- ABC from about 68 miles away (2-edge), Fox about 12 miles away (LOS), and CTV about 50 miles (2-edge). (I suppose if I had an antenna setup like niv, broadcasts from the Moon might be in play). :-) The 30-2475 does a great job on all. Of course, I can't get both CTV and ABC at the same time due to their being in complete opposite directions, but pointed at one or the other pulls them in just fine. Next spring, I may explore some kind of combining -- although I've read wildly varying accounts of whether that will be successful. But as for High-VHF, the 30-2475 performs really well. I actually ordered both the Clearstream 5 and the Stellar Labs antenna to test against each other (and perhaps combine the two). When testing each one for signal, the Stellar Labs performed on a higher level than the Clearstream 5 for me. Given the significant difference in cost between them, I will probably be looking at introducing a 2nd 30-2475 model in the spring.

One final note about the 30-2475: The assembly instructions for the antenna are bad. I mean *really* bad. If you know what you're doing in antenna assembly (or are generally pretty handy), I suppose you wouldn't have a problem. Since I had never assembled one before (and being 'handy' isn't really a skill-set of mine) - I had a couple of mis-steps along the way. Assembly really turned into looking at a picture of an assembled antenna and trying to make my pile of parts look like that. My last mistake during the assembly was finally having it put together ... looking like the picture online ... and then realizing I hadn't put the mast clamp on. Even correcting that, I realized while attaching it to a hillbilly setup of a pvc pipe in a 3-legged tripod that I had the adjustable clamp placed on the antenna in an upside-down position, so I could tilt it downwards, but not upwards. :-) Next spring when the whole setup is looked at again with the 2nd antenna added, I'll need to correct that also.
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post #17472 of 17920 Old 10-27-2018, 04:32 AM
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Thank you for your interesting story. The assembly instructions are really bad, and the instructions for the bigger 30-2476 show two different locations for the mast clamp.





Quote:
Originally Posted by eherberg View Post
In my very remote area, I only have realistic access to 3 channels -- ABC from about 68 miles away (2-edge), Fox about 12 miles away (LOS), and CTV about 50 miles (2-edge). The 30-2475 does a great job on all. Of course, I can't get both CTV and ABC at the same time due to their being in complete opposite directions, but pointed at one or the other pulls them in just fine. Next spring, I may explore some kind of combining -- although I've read wildly varying accounts of whether that will be successful.
Combining 12, 7, and 8 that are in three different directions is possible, but it will not be easy.
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post #17473 of 17920 Old 10-27-2018, 04:48 PM
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What inexpensive method, other than a low SNR that some users can't measure, do you suggest to measure noise interference on VHF?
Software Defined radio USB dongles like the RTL-SDR can be had for under $20 and there are free pieces of SDR software such as SDR#.
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post #17474 of 17920 Old 10-27-2018, 05:09 PM
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Software Defined radio USB dongles like the RTL-SDR can be had for under $20 and there are free pieces of SDR software such as SDR#.
Good idea for those that are comfortable dealing with software.

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post #17475 of 17920 Old 10-27-2018, 05:31 PM
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SDR software isn't all that complicated.

Besides looking at noise and TV signals, they can be used for looking at/listening to/recording LW, AM, Shortwave, CB, Air, Weather, FM, Ham, trunked radio, certain satellites, etc.
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post #17476 of 17920 Old 10-27-2018, 05:37 PM
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Originally Posted by rabbit73 View Post
Good price for a well made antenna that performs well. It didn't help with my marginal VHF channel, but that wasn't the fault of the antenna, it was the fault of the antenna location.

I think the two sections of the boom could fasten together a little more securely. The female coax connector on the balun doesn't grab the male pin of the coax connector tightly, but it hasn't caused a problem.

niv, on the TVFool forum, seems to be very happy with his 30-2475 for VHF. JoeAZ and I had to post for him from PMs because he was never authorized to post.
http://forum.tvfool.com/showpost.php...0&postcount=33



crank it up

Wow, he even has an Advantage 2 weather station on that tower.
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post #17477 of 17920 Old 10-28-2018, 05:23 AM
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Wow, he even has an Advantage 2 weather station on that tower.
Davis Vantage Pro 2...not sure if it has the solar and/or UV sensors. Good consumer weather station workhorses. One of the best updates they've done to this model are the integrated bird spikes, they *really* help!
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post #17478 of 17920 Old 10-28-2018, 07:55 AM
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Read my post again. I did suggest the Aircraft band, which is a nearby frequency.

Are you saying that if you can't do testing the "perfect" way, you shouldn't even try anything else?

You seem to have a lot of reasons why something shouldn't be done, but few ways it can be done. I thought it was the ham spirit of innovation to find a way, even if you don't have the ideal equipment for the job.

Chuck's Rules of Forbidden Actions discourage experimentation. Sometimes people have to find out for themselves that it doesn't work. In the case of budh9534, you discouraged him from trying what he wanted to try, which was combining two UHF antennas in different directions with a splitter in reverse:

He got it to work because his location was ideal for that method of combining which has a poor record of success.

Why did you think it was OK to discourage him by calling it a "no go" and deprive him of a learning experience?

Wouldn't it have been more constructive to tell him that it doesn't usually work, but that he should try it.?

The only benefit your negative advice gave him was that it made him even more determined to make it work.

Hey man, what is your problem? I give the best advice that I know how to give. If you don't like it then don't say anything. You post stuff all the time that I think is unhelpful but I rarely say anything about it because we're allowed to post whatever advice we feel is good.

I didn't deprive anyone of anything. They can do whatever they want. My goal is to always suggest what is most likely to work. Many times I've told people they can try the two antennas in different directions with a simple combiner but I always tell them it often doesn't work. I've even posted exactly why it usually doesn't work. You even liked my post! What changed?

https://www.avsforum.com/forum/25-hd...l#post56833878

When I give someone advice it's very likely to work. But often the best solution is not the easy solution. People are lazy and want a magic solution. This is not my problem and I don't want to waste my time on people who are not really interested in solving their reception issues.

I still think there needs to be a scale in one of the stickies to gauge how interested someone is in solving the problem.
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post #17479 of 17920 Old 10-28-2018, 08:48 AM
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Hey man, what is your problem?
You criticized my post #17462 that was addressed to MSev.

I posted my rebuttal to defend my advice.

Did you think I wouldn't say anything?

If you don't want to see my rebuttal, don't criticize my post.

If you can not measure it, you can not improve it.
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post #17480 of 17920 Old 10-28-2018, 11:40 AM
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Quote:
Originally Posted by rabbit73 View Post
You criticized my post #17462 that was addressed to MSev.

I posted my rebuttal to defend my advice.

Did you think I wouldn't say anything?

If you don't want to see my rebuttal, don't criticize my post.

It came across as a general rant about the way I construct my posts.

Looks like there have been some deletions and post renumbering so I'm not exactly sure what you're referring to. If you're referring to my post currently numbered 17465, the post is 100% accurate. An AM broadcast band radio is a highly unreliable way to find noise at high VHF. No one should be recommending this even if you can find the oddball case where it did work. The advice in your signature is spot on. "If you can't measure it, you can't improve it." What's measured at 1 MHz is not what's present at 174 MHz and up.

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post #17481 of 17920 Old 10-28-2018, 12:12 PM
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I do not agree with you.

My wife and I have been married for over 50 years. To make it work, we learned that it is OK to disagree.

You and I are not married, but we live on the same forum.

If you can't learn how to agree to disagree, there will continue to be problems between us.


If you insist on proof of my concept, I can give you a link that shows a car radio that was tuned to the AM broadcast band located a battery charger that was causing interference to VHF-Hi.


If your mind is closed to new ideas that don't agree with your old ideas, how can you learn anything new?
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post #17482 of 17920 Old 10-28-2018, 12:48 PM
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Quote:
Originally Posted by rabbit73 View Post
I do not agree with you.

My wife and I have been married for over 50 years. To make it work, we learned that it is OK to disagree.

You and I are not married, but we live on the same forum.

If you can't learn how to agree to disagree, there will continue to be problems between us.


If you insist on proof of my concept, I can give you a link that shows a car radio that was tuned to the AM broadcast band located a battery charger that was causing interference to VHF-Hi.


If your mind is closed to new ideas that don't agree with your old ideas, how can you learn anything new?
I came across this some time back and it is similar to your advice so it can work in some situations:

http://dennysantennaservice.com/vhf-...erference.html

As you say, you do have to try various things to solve problems.
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post #17483 of 17920 Old 10-28-2018, 03:42 PM
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I came across this some time back and it is similar to your advice so it can work in some situations:

http://dennysantennaservice.com/vhf-...erference.html

As you say, you do have to try various things to solve problems.
Thank you for the link to an excellent example of an AM radio finding VHF-High interference from a heated pet blanket. That's even better than my example of an AM car radio finding power line noise that led to a battery charger and a laptop power adapter that were causing VHF-High interference.

http://forum.tvfool.com/showpost.php?p=52500&postcount=5

Mike's review of battery charger

https://www.harborfreight.com/15-amp-three-stage-onboard-battery-charger-maintainer-99857.html

Mike

August 10, 2015 one star, last page of reviews

BAD RFI from this charger, ruins radio and VHF tv reception

Quote:
This charger does charge batteries well. However, it really pumps out radio interference! I can pick it up well over 200-300 feet away from where I had one plugged in in my garage.It caused AM radio interference, and ruined my OTA VHF channel reception for my tv set.Be aware of this, if you are trying to become a cord-cutter, and are hooking up a tv antenna for OTA tv channels. If some of your channels are still VHF, you may have problems caused by this charger.
That's two documented cases, so far.

I owe you a debt of gratitude, jkeldo.
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www.megalithia.com/elect/aerialsite/dttpoorman.html

Last edited by rabbit73; 10-28-2018 at 03:58 PM.
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post #17484 of 17920 Old 10-28-2018, 04:52 PM
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From the FCC:
https://www.fcc.gov/consumers/guides...ephone-signals

Interference with Radio, TV and Telephone Signals

Electrical interference and your TV
Electrical interference appears on the audio and video portion of television programming. Short bursts of interference may be caused by hair dryers, sewing machines, electric drills, doorbell transformers and garage door openers. If the pattern is on continuously, it may be caused by equipment that is in use full time, such as aquarium heaters and fluorescent lighting.

Electrical interference may be caused by power lines or electrical equipment in your home. Interference caused by your power company’s electrical equipment is normally continuous and your power company should be notified.

A simple method of determining the location of electrical interference is by using a portable AM radio tuned to a quiet frequency at the lower end of the dial. You should hear static or a buzzing sound as you get close to the source of the interference. The closer you get, the more intense the static will be.
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www.megalithia.com/elect/aerialsite/dttpoorman.html
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post #17485 of 17920 Old 10-29-2018, 12:25 PM
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Quote:
Originally Posted by rabbit73 View Post
Thank you for the link to an excellent example of an AM radio finding VHF-High interference from a heated pet blanket. That's even better than my example of an AM car radio finding power line noise that led to a battery charger and a laptop power adapter that were causing VHF-High interference.

http://forum.tvfool.com/showpost.php?p=52500&postcount=5

Mike's review of battery charger

https://www.harborfreight.com/15-amp-three-stage-onboard-battery-charger-maintainer-99857.html

Mike

August 10, 2015 one star, last page of reviews

BAD RFI from this charger, ruins radio and VHF tv reception



That's two documented cases, so far.

I owe you a debt of gratitude, jkeldo.
Thank you as well. Your posts are very informative and help many here looking to improve reception and for antenna choices.
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post #17486 of 17920 Old 11-07-2018, 07:50 AM
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New Channel Master Balun

Channel Master has come out with a new balun:
https://www.channelmaster.com/TV_Ant..._p/cm-3203.htm



Quote:
Replaceable Leads with Weather Seal
They don't show the Replaceable Leads or how much they cost; they have a special connector.

At $29.00 for ONE balun, I think I will let somebody else do the testing.
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If you can not measure it, you can not improve it.
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www.megalithia.com/elect/aerialsite/dttpoorman.html

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post #17487 of 17920 Old 11-07-2018, 08:07 AM
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Quote:
Originally Posted by rabbit73 View Post
Channel Master has come out with a new balun:
https://www.channelmaster.com/TV_Ant..._p/cm-3203.htm




They don't show the Replaceable Leads or how much they cost.; they have a special connector.

At $29.00 for ONE balun, I think I will let somebody else do the testing.

Financing available.


Any word on when Monster is coming out with any new jumper cables?
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post #17488 of 17920 Old 11-07-2018, 09:44 AM
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Maybe this $30 balun will sell with some sucker consumers, but there's no way I'd consider it. Maybe at $10. No other decent balun costs more than $5!!! Of course all the new stuff I install have built-in baluns, so it's not like I go through a lot.

What sells to my customers is that their antenna setup receive channels all reliably - they couldn't care less about brand names. What sells to me is reliability and price/performance. I'm not going to double or even triple the cost of hardware for a system so I can say it's name brand. Nobody cares.

Sure, 30+ years ago the CM name might've carried some weight with installers and consumers. It was a reputation well earned. They advertised, they had a dealer network, a FULL line of top quality products and a huge install base (Quantum combos especially). But going the Monster Cable route...

Last edited by mattdp; 11-07-2018 at 03:09 PM.
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post #17489 of 17920 Old 11-07-2018, 12:49 PM
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It looks like the leads section of that balun "unscrews" .. perhaps with some sort of internal quick-release connector for quick replacement ( .. 50 years later when needed ) ....
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post #17490 of 17920 Old 11-07-2018, 01:46 PM
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Quote:
Originally Posted by rabbit73 View Post
Channel Master has come out with a new balun:
https://www.channelmaster.com/TV_Ant..._p/cm-3203.htm




They don't show the Replaceable Leads or how much they cost; they have a special connector.

At $29.00 for ONE balun, I think I will let somebody else do the testing.

$29.00 for a balun, they are OUT OF THEIR MINDS! Though this is probably marketed at people that pay $110 for a "150 mile antenna" that's worth about $5.00.
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