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Old 13-Jun-2017, 12:41 AM   #1
rabbit73
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Join Date: Aug 2012
Location: S.E. VA
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New Channel Master Balun

Channel Master has redesigned the 94444 balun, but has not changed the model number, just like what they did with the 7777 preamp. The new model with the ring terminals is not as good.

Some sellers are using the photo of the original balun, but send the new balun.

This is what the new balun looks like:



This is the superior original balun:



see review by
DIYPRO

http://www.homedepot.com/p/Channel-M...4444/203763061

http://www.mcmelectronics.com/produc...94444-/30-2570

Caveat emptor!
Attached Images
File Type: jpg CM94444rings.jpg (94.9 KB, 1119 views)
File Type: jpg CM94444originalBalun2.jpg (26.4 KB, 1087 views)
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Last edited by rabbit73; 12-Feb-2018 at 12:02 AM.
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Old 24-Jun-2017, 11:27 PM   #2
rabbit73
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Location: S.E. VA
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I found some of the original Channel Master 94444 baluns and was able to make measurements of three different baluns. I connected two of each, 300 ohm to 300 ohm, and measured the loss at three frequencies in the UHF band.



For the first measurements, I used a Blonder Tongue HAVM-1UA Frequency Agile Modulator as a stable signal source, and a Sadelco DisplayMax 800 Signal Level Meter. The modulator puts out an analog signal; I used the video carrier for each channel. The Sadelco meter has 0.1 dB resolution.



I was having a problem getting consistent measurements. The Sadelco meter has a built-in calibration reference and at certain intervals will correct its readings. This was difficult for me to deal with when making 0.1 dB resolution measurements, so I switched to my Sadelco 719E meter that has a panel meter with wide 1 dB divisions in the center of the scale that allows me to interpolate to the nearest 0.1 dB.

The Sadelco 719E is on the left; the DisplayMax 800 on the right:



I used the red divisions and the second scale -10 to +20 dBmV.



I would read that as +2.8 dBmV.

To make a measurement, I first connected the modulator to the meter with an F-81 adapter and took a reading. I then substituted the balun pair for the adapter for the second reading. If the loss of each balun is the same, then the loss of one would be half of the pair connected together.

There was an attenuator at the output of the modulator and at the input of the meter to try to keep the line "flat" (low SWR).

Code:
Loss of Three Different Baluns

Ch       Winegard                Channel Master           Channel Master
         TV-2900                 Original 94444             New 94444
          
     F-81  Bal  Dif  Ea       F-81  Bal  Dif  Ea       F-81  Bal  Dif  Ea
     --dBmV---  ---dB--       --dBmV---  ---dB--       --dBmV---  ---dB--

15   7.2   1.5  5.7  2.9      7.2   5.5  1.7  0.9     7.2    1.9  5.3  2.7

28   6.2  -1.0  7.2  3.6      6.2   3.2  3.0  1.5     6.2   -2.6  8.8  4.4

45   5.3  -1.3  6.6  3.3      5.3   2.6  2.7  1.4     5.3   -3.8  9.1  4.6
The Original Channel Master 94444 is clearly the best.
Attached Images
File Type: jpg 3BalunsMeter.jpg (85.2 KB, 2037 views)
File Type: jpg 3Baluns1.jpg (152.2 KB, 1016 views)
File Type: jpg DisplayMaxImg1 (3).jpg (100.4 KB, 1407 views)
__________________
If you can not measure it, you can not improve it.
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Last edited by rabbit73; 25-Jun-2017 at 2:33 AM.
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Old 25-Jun-2017, 12:39 AM   #3
OTAFAN
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Unhappy New Channel Master Balun

I've been following this thread rabbit73. Thanks again for your dogged expertise, albeit apparent bad news for the old adage, "new and improved!"

I have a new CM balun with my RCA751 set up here in SoCal, about 35 miles from Mt. Wilson due south and around 90' of RG6 Quad cable. I haven't noticed any difference in signal quality from my previous address of about 19 miles from Mt. Wilson, with 50' of same cable. Only two channels read less than 100% on my Samsung 40" signal meter. PBS SoCal 50 at about 65%, but they have had technical issues for years now, even though their official power readings show strong. I've concluded from my amateur research it comes down to money issues--doesn't it always? And KDOC 56 I get about 75%, but after having talked to one of their engineers, he politely said that was as good as it was going to get--again their signal output was not as strong as others across the spectrum.

So, I guess I should consider myself lucky with what I thought was the best balun on the market. Certainly its build quality is superior to others I have seen. But your test results have given me a bit of heartburn. I don't doubt them, I just wish it would have proven otherwise.

Therefore, I'm calling on all OTA viewers to boycott all digital TV until we get good quality products like in the old days! I ran across this article recently for recommended reading: https://www.soundandvision.com/conte...g-tv-goes-dark

Time for a six pack.....
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Old 25-Jun-2017, 12:53 AM   #4
rabbit73
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When I was making the measurements of the New CM balun, I noticed the loss readings would vary according to the position of the 300 ohm wires between them. I decided to cut the wires to 2-1/2" before removing the insulation to see of it would make any difference.



I then made measurements of this modified balun:

Code:
Channel Master New 94444 Balun with 2-1/2" Wires

Ch        F-81  Bal  Dif  Ea
          ---dBmV--  --dB---

15        7.3   4.8  2.5  1.3

28        6.4   4.7  1.7  0.9

45        5.6   3.8  1.8  0.9
The loss was reduced and was much less affected by the position of the wires. The long wires formed a transmission line of indefinite impedance.

If you use the new CM balun, I suggest you keep the wires short.

If you need a low loss balun for weak signal reception, I suggest a halfwave coaxial balun.

The PCB baluns in the new UHF antennas have low loss, but they are good for only one band. If you need a balun for UHF and VHF, use a conventional ferrite core balun like one of the above.
Attached Images
File Type: jpg 3Baluns2.jpg (195.4 KB, 1290 views)
__________________
If you can not measure it, you can not improve it.
Lord Kelvin, 1883
http://www.megalithia.com/elect/aeri...ttpoorman.html

Last edited by rabbit73; 25-Jun-2017 at 1:42 AM.
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Old 25-Jun-2017, 1:11 AM   #5
rabbit73
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Quote:
PBS SoCal 50 at about 65%, but they have had technical issues for years now, even though their official power readings show strong. I've concluded from my amateur research it comes down to money issues--doesn't it always? And KDOC 56 I get about 75%, but after having talked to one of their engineers, he politely said that was as good as it was going to get--again their signal output was not as strong as others across the spectrum.
To learn more about the local reception problems in your area, I suggest you visit one of the AVS OTA threads for your area.
http://www.avsforum.com/forum/45-loc...nfo-reception/

Quote:
I don't doubt them, I just wish it would have proven otherwise.
It's OK to doubt my measurements. I don't have lab-grade equipment and my test sample is small. Let your TV tell you what works best.
__________________
If you can not measure it, you can not improve it.
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Last edited by rabbit73; 25-Jun-2017 at 1:16 AM.
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Old 25-Jun-2017, 1:25 AM   #6
OTAFAN
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Smile New Channel Master Balun

A couple of inches on the new CM balun make that much difference, rabbit73? Boy, have I learned something REALLY NEW today.

Alright, back up on the roof soon for technical update.....

Thanks for the link to reception issues in my area. But as far as PBS goes, I've noticed others on TV Fool et al, mentioning similar issues with their local PBS affiliate. Although, if my reception improves after trimming CM balun leads, I'll stand corrected.

Thanks again professor for in classroom training! You're the best!

BTW, boycott on hold for now. I think half of the six pack has helped! LOL!
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Old 26-Jun-2017, 7:01 PM   #7
rabbit73
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Quote:
Originally Posted by OTAFAN View Post
PBS SoCal 50 at about 65%, but they have had technical issues for years now, even though their official power readings show strong. I've concluded from my amateur research it comes down to money issues--doesn't it always?
KOCE will be moving to real channel 18 on a sharing basis.
http://www.rabbitears.info/market.ph...&callsign=koce

Your tvfool report looks good, but is only based on a zipcode, centered on the intersection of Le Grande Ln and Marea Cir, just south of Seal Beach National Wildlife Refuge, so it might not represent your actual location.
http://www.tvfool.com/?option=com_wr...8e03b2e1cc4490

92649 is a big area:



The green signal lines from the North look like they have a clear path:



Your generic FM signal report shows some strong signals from the North that might interfere with TV reception of VHF-High channels KTTV and KCOP:

http://www.fmfool.com/modeling/tmp/b...e/Radar-FM.png

KTTV and KCOP have directional antennas because they are in the Mexican Border Zone, so you don't get their full power sent in your direction.

http://www.tvfool.com/?option=com_wr...ALLTV%26n%3d17

http://www.tvfool.com/?option=com_wr...ALLTV%26n%3d19

When the signals look promising, but they are weak at the TV, I usually need to ask for more information to figure out what is going on. Maybe some photos of the antenna in its location or a closeup satellite view with the green signal lines. If that doesn't do it, sometimes it is necessary to move the antenna to a different location to find a hot spot.
Attached Images
File Type: jpg OTAFANtvfMap2.JPG (161.6 KB, 776 views)
File Type: jpg OTAFANtvfMap.JPG (106.4 KB, 787 views)
__________________
If you can not measure it, you can not improve it.
Lord Kelvin, 1883
http://www.megalithia.com/elect/aeri...ttpoorman.html

Last edited by rabbit73; 26-Jun-2017 at 8:46 PM.
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Old 27-Jun-2017, 12:28 AM   #8
OTAFAN
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Smile New Channel Master Balun

Thanks rabbit73 for all the good logistics and information! You certainly have given me a lot more intel than I could find with KOCE 50 PBS SoCal here locally.

I tried calling them several times today to find out when they actually will be moving to channel 18. But I could not get even their general operator. Always were helping another caller and please leave a message to receive a call back in 24 hours or so, etc. They have some good programming but customer service and technical issues have always been problematic. I know they rely on volunteers but I've never been able to get a real person on the phone over the years. C'est la vie!

As far as KTTV channel 11 and KCOP channel 13, I'm getting 100% signal levels here on my Samsung meter. But the Mexican border zone issue might effect others and it's good to know for future reference. And no FM interference as far as I can tell. If it ever does, I've some filters that might work.

Otherwise, when I get back on the roof to trim my CM balun, I'll report any findings of improved signal on PBS and KDOC channel 56, but as I previously mentioned, their engineer that I spoke with in the past told me the signal strength I was receiving was as good as it was going to get. But you never know with the mysteries of TV electromagnetic waves, as you have said!

Professor, you are a true gentleman and scholar. I have learned so much from your threads here on TV Fool that I just cannot thank you enough! Bless you sir!

P.S. I've got to figure out how to leave a quote in grayscale like you guys do here for any future posts that I might do. I'm checking the FAQs.
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Old 27-Jun-2017, 2:41 AM   #9
rabbit73
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Quote:
You certainly have given me a lot more intel than I could find with KOCE 50 PBS SoCal here locally.
You have to go here for more:
http://www.avsforum.com/forum/45-loc...a-ota-336.html
Quote:
KDOC channel 56, but as I previously mentioned, their engineer that I spoke with in the past told me the signal strength I was receiving was as good as it was going to get.
KDOC is only allowed to send about 30% of its max ERP in your direction because of the border agreement.

http://www.tvfool.com/?option=com_wr...dALLTV%26n%3d8

KDOC is on real channel 32, the channel that is used by the transmitter. If you must use the virtual channel number, please state it as 56.1 to avoid confusion. You are no longer a newbie; use the real channel number, callsign, or both.

KDOC will be moving to real channel 12. That is the channel that will be used by the transmitter. It is the real channel number that determines which antenna you will need for reception.

VHF-Low, real channels 2-6
VHF-High, real channels 7-13
UHF, real channels 14-51

The virtual channel number (like 5.1) is a holdover from the analog TV days to maintain the identity of the station, and is what the TV displays.

http://www.rabbitears.info/market.ph...&callsign=kdoc

Quote:
I've got to figure out how to leave a quote in grayscale
It's easy; select the text and click on the quote icon.

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__________________
If you can not measure it, you can not improve it.
Lord Kelvin, 1883
http://www.megalithia.com/elect/aeri...ttpoorman.html

Last edited by rabbit73; 27-Jun-2017 at 3:34 AM.
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