Kosmic Superquad VS Channel Master 4228 VS Channel Master 4221 shootout!

[Fringe Reception]

Just like back in the 1980s when I setup my VHF I used my pad attenuator as a poor-man's signal strength "meter" and dialed in attenuation until each channel dropped off on all three antennas. Here's a link to the method: http://www.megalithia.com/elect/aeri...ttpoorman.html There is a photo of my attenuator in one of my my photo albums here.

*NOTE: this attenuator is virtually transparent at VHF frequencies, but it presents its own
loss at UHF frequencies, however, its loss at any given channel is constant regardless of which antenna is being tested. Signal strengths are reported by the onboard Sony Bravia diagnostics in the TV set. The Channel Master 4228 and 4221 are old versions. The channels referred to here are 'real' channels: 13, 14, 26, 27 (and later, discovered and tested 9 and 11!)
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Channel 13:

4228: 60 strength / S:N ratio 25 / added attenuator, -- 60 strength added 40 db attenuation, signal dropped to 10/drop off

KSQ: 60 strength / S:N ratio 25.5 / added attenuator, -- 60/54 strength added 41db attenuation, signal dropped to 10/drop off

4221: 71/65 strength / S:N ratio 26.5 / added attenuator,-- 60/54 strength added 36db attenuation, signal dropped to 10/5/drop off


Channel 14:

4228: 93/87 strength / S:N ratio 31 / added attenuator, -- 87 strength added 36db attenuation, signal dropped to 10/drop off

KSQ: 98/93 strength / S:N ratio 32 / added attenuator, -- 93 strength added 48db attenuation, signal dropped to 10/drop off

4221: 98/93 strength / S:N ratio 31 / added attenuator,-- 87/82 strength added 44db attenuation, signal dropped to 10/5/drop off


Channel 26:

4228: 60/54 strength / S:N ratio 25 / added attenuator, -- 43 strength added 7db attenuation, signal dropped to 10/drop off

KSQ: 32 strength / S:N ratio 21 / added attenuator, -- 21 strength added 3db attenuation, signal dropped to 10/drop off

4221: 38/32 strength / S:N ratio 21 / added attenuator,-- 16 strength added 3db attenuation, signal dropped to 10/5/drop off


Channel 27:

4228: 93/87 strength / S:N ratio 31 / added attenuator, -- 76 strength added 16db attenuation, signal dropped to 10/drop off

KSQ: 98/93 strength / S:N ratio 32 / added attenuator, -- 93/87 strength added 23db attenuation, signal dropped to 10/drop off

4221: 98/93 strength / S:N ratio 32 / added attenuator,-- 93/87 strength added 24db attenuation, signal dropped to 10/drop off

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Just for giggles, I pointed the KSQ east toward the channel 9 and 11 towers, thru the neighbor's garage wall to see if by chance either VHF 9 or 11 came thru and when I went back inside, a picture briefly popped up on 9! That's a first from that low/compromised antenna mount. So, I rotated it around the clock and when pointed NW it 'saw' the signal again, although not useable. Strange! So, the test wasn't over:

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Channel 9:

4228: 0 strength / S:N ratio 0

KSQ: 16 strength / S:N ratio 17 added attenuator, -- 16/10 strength added 27db attenuation, signal dropped to 5/drop off

4221: 16/10 strength / S:N ratio 17 added attenuator, signal went to zero


Channel 11:

4228: 0 strength / S:N ratio 0

KSQ: 5/0 strength / S:N ratio 16 added attenuator, signal went to zero

4221: 27/21/16 strength / S:N ratio 18 added attenuator,-- 16/0 strength added 0db attenuation, signal dropped to 5/drop off

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Pointing to the northwest ? ? I went back and forth switching the KSQ and the 4221 and the KSQ was better on 9 and the 4221 was better on 11. The setup was dicey: 9 came in better with either antenna mounted 6" lower than the 'hot-spot" for 11 (6" higher). Julie and I played with capturing 9 and 11 for over an hour, then we sat down to watch a show on 11. 15 minutes later, both channels vanished! So, it was probably a large moving van or something bizarre reflecting the signals back to us. RATS!

Regarding the odd result on channel 26, I note both the KSQ and the 4221 underperform the 4228 by a large margin. However, all of the antennas love 27! I should also add, when the low numbers showed on 26, I went back and double-checked other channels to see if anything had changed with my setup and all other results were consistant.

So, the results are somewhat confusing but it was a good way to spend a sunny day in Seattle. Your comments are invited. :gossip:

Jim

Edit: PS I just checked and channel 9 is back at a strength of 16, S:N ratio 18. 11 is still missing ... probably available if I raise the antenna 6", but not today in the rain.

 

[EscapeVelocity]

Could be that the 4 Bays were out of the sweet spot on 26, where the 8 bay provides a 4 bay either side of the centerline, could be that, that little bit of offset helped.

Those are the old American made Channel Masters right. All the antennas did well. Thanks for sharing your testing results.

 

[Fringe Reception]

EV,

Per my experience last year attempting to capture Channel 48, where it was only present within a 2 foot height range (absolutely no higher/no lower) and last weekend seeing the amazing signal strength changes on 9 and 11 within only 6 inches of height change ... you might be on to something.

The testing mast I used cannot be moved sideways at all do to trees and if the wider 4228 was partly in a 'hotspot' whereas the half-sized 4221 was not, that could explain the result between those two antennas.

... However ... the Kosmic SuperQuad is sized like a 4228 which puts its' reflector in the same space as the 4228. What say you (and others) now? Best regards,

Jim

PS A reminder to readers ... this was my first test of the SuperQuad, literally "right out of the box" and EV ships his antenna with additional parts to alter its configuration to change its reception characteristics, depending on the channels in a buyer's area.

 

[EscapeVelocity]

Dont know, it just seems odd that both of the 4 Bays dived together in virtually the same amount. So that would tend to discount a some impedence dropout or some other electrical anomaly on that channel....if it was just the KSQ or the CM 4221.

 

[EscapeVelocity]

The old American Made discontinued Channel Master 4221 really held its own. Pretty impressive.

 

[rabbit73]

Hi Jim,

Interesting tests using an attenuator and your Sony. The 4221 is an old but good design, in spite of the fact that it needs to be rescaled to 14-51.

Just like back in the 1980s when I setup my VHF I used my pad attenuator as a poor-man's signal strength "meter" and dialed in attenuation until each channel dropped off on all three antennas. Here's a link to the method: http://www.megalithia.com/elect/aeri...ttpoorman.html There is a photo of my attenuator in one of my my photo albums here.

That's one of my favorite links; I hate to see it broken.
Selecting and Siting your TV aerial: Measuring Signal Quality - The Poor man's DTT meter

DTT is Digital Terrestrial Television, the UK term for OTA.

Best regards,
rabbit

 

[Fringe Reception]

Rabbit! :bunny: LTNS.

Thank you for supplying a working link to the megalithia website ... I'm not sure why the one I chose turned out to be a dud. After I trim trees I will test a side-stacked pair of 8-bay Antenna Craft Hovermans on the same testing mast.

Best regards, Jim

 

[FOX TV]

Hello all,

I found a UHF sweet spot in my living room for our most distant transmitter. It is only 6 inches difference in height, and is almost like a go / no go situation. Put any antenna at the max height and you have good signal, but drop it 6 inches and nothing. Even the stream analyzer, which is much more sensitive than a DTV receiver, sees a dramatic drop in signal strength, even though it does still see some signal, it would not be enough for a receiver to decode, and the bit error rate goes off the scale.

 

[FOX TV]

http://www.megalithia.com/elect/aerialsite/dttpoorman.html

That link worked for me....

 

[Fringe Reception]

FOX,

Interesting. It worked when I first posted it, Rabbit found it didn't work and he added a link that does work, today it worked for you and again today, it doesn't work for me. Let's blame Al Gore - after all, he invented the internet!

Error 404 - Page Not Found
Sorry, there seems to be a problem with the page you requested

Jim

 

[rabbit73]

....again today, it doesn't work for me. :confused.....

It is possible that the site was down when you tried it.

You had me worried (again); I thought that one of my favorite links wasn't working.

The last part of the link that Jim posted:
com/elect/aeri...ttpoorman.html

The last part of the link that I posted:
com/elect/aerialsite/dttpoorman.html

See the difference?

What confuses the issue is that the link is shortened when it appears in the post, but when you click on it the full link is used.

http://www.megalithia.com/elect/aerialsite/dttpoorman.html

It still works for me.

There are two ways that I can copy a link:
1. Select, copy, and paste from URL address bar at top of screen after clicking on link
2. Right click on link given in post and click on properties; select, copy, and paste URL from properties box

As a double check, when I move the mouse pointer to a link in a post, the arrow changes to a hand and the Status bar at the bottom of the screen displays the address of the page associated with the link.

 

[tballister]

Jim:

I'd like to say thanks for the data you posted in your "Kosmic Superquad VS Channel Master 4228 VS Channel Master 4221 shootout!" post!

The results are indeed perplexing; not intuitive. If the communinity accepts the results now posted for the Old vs New CM4228 Comparison I've finally published at HDTV Antenna Comparisons then we can assume the old and new CM4228 design produce very similar results for UHF, but slightly improved Hi-VHF response for the new CM4228.

Therefore I have no explanation for our differing results; they are clearly conflicting. I can also think of no elctro-mechanical reason why the 4221 should outperform the 4228.

From the description of your test bed I do wonder how much multipath is a factor? One thing I know is that signal "quality" readings on various TV sets follow no standard. My observation is that "Quality" numbers as displayed on various manufacturer's sets is some arbitrary manufacturer-specific algorithm combining AGC Level, Error Rate, corrected frame rate, peak-to-peak "flatness" across the channel, and so on. I really wish there were a standard. But what I can tell you of my own observations across Sony, Panasonic, Toshiba, and Sharp sets that I have is that some react to 3 to 6 dB changes in pure RF level and some actually don't!

I have several of Jeff Kitz' preamps, which have a 1 dB NF and a convenient gain pot. I've measured them indendently and their response is flat as a pancake across the VHF/UHF spectrum. You put a little screwdriver in there and rotate it counter clockwise, reducing the gain about 5 dB or so, and then wander around the house and check the changes in "Quality", and they're all over the map! Irritating.

So one question your set up raises is "what criteria is the Sony Bravia's 0 to 100 scale most sensitive to?". E.g., what are those 0 to 100 scale numbers exactly based on? I sure can't tell. On my Bravia I can rotate the Kitz gain pot counter clockwise even 1/2 turn (about a 10dB gain reduction) and on my strongest channel none of the S/N ratio, AGC, or Quality figures change.

On my weakest channels (for this 1/2 turn - 10 dB reduction) I am able to observe significant change in AGC level, but accompanied by only a 1 dB S/N change and no Quality change. That has brought me to have a little respect for the Bravia because of the usefullness of that AGC metric. I suspect that the "Quality" numbers on the Bravia are heavily dominated by Signal/Noise ratio, and that metric is very often dominated by multipath. E.g., it is the receivers ability to equalize the peaks and valleys in the channel signal (ideally flat) that often come in to play.

I wonder what your results would show if you captured the AGC levels for each measurement?

Nevertheless your figures are thought provoking. Perhaps a 4228 vs 4221 comparison is in order on my part?

 

[Fringe Reception]

Tom,

Yes, the strange results on channel 27 are perplexing and I agree, it is probably a multipath issue. I tested the antennas on the same mast at the same height which is under my roofline in my backyard. When facing south, my neighbor's garage is to its side and there is a hill behind it. It is located under my roofline in my back yard, invisible to any neighbor or passerby. My guess is the KSQ and 4228 larger reflector screens are catching something the 4221 is comparatively immune to. Perhaps if I moved the 4221 a foot to the side it would 'see' the same multipath.

If you have a 4221 handy, a shootout between it and a 4228 would be terrific!

Jim

 

[Fringe Reception]

Hi all,

I got together with my neighbor today and we cut space in our common trees to allow me to exchange my CM-4221 with my 16-Bay Hoverman: it has been parked on my deck for several months awaiting "tree surgery" to allow it to be tested for the first time.

Per the results of my testing other antennas in above posts and per the messages from others, I am a bit surprised the Hoverman is NOT outstanding on all of the above tested channels.

This report is not a test using my attenuator, but simply the very first result after getting the antenna in the air. Using the Hoverman, channel 26 has a useable signal in the 30's. (The translator is LOS around 17 miles away)

Compare that to the results from the other antennas (unattenuated). Prior results are below:
-----------------------------------------
Channel 26:

4228: 60/54 strength / S:N ratio 25 / added attenuator, -- 43 strength added 7db attenuation, signal dropped to 10/drop off

KSQ: 32 strength / S:N ratio 21 / added attenuator, -- 21 strength added 3db attenuation, signal dropped to 10/drop off

4221: 38/32 strength / S:N ratio 21 / added attenuator,-- 16 strength added 3db attenuation, signal dropped to 10/5/drop off
----------------------------------------
As a comparison, KBTC 28 (27) is a solid 98 which appears to be better than the KSQ, 4228 or 4221. A detailed test and comparison is forthcoming.

The one surprise was pointing it east-ish, thru the neighbor's garage, another neighbor's home and thru the hillside and for the first time EVER the KMYQ 22 (25) signal was detected and seen! Woohoo! It's not yet stable so more tree cutting tomorrow and a bit more elevation is in order.

Jim

PS Just like the KSQ (the only antenna to date that could 'see' 9) the 16-Bay Hoverman also detected VHF-9 ... however, unlike the KSQ the signal is stable around 10-15 on the Bravia diagnostic screen. Double woohoo!

 

[tballister]

Hi All.

Maybe not so appropriate to post here, but since the discussion involves the CM4228HD I thought I'd let this forum know my latest hack was to implement Ken Nist's harness recommendations for the CM4228HD. You can find a link at my Antenna Hacks page.

Merry Christmas!
t

 

[Fringe Reception]

Tom, Merry Christmas!

Aside from poorer performance receiving VHF, how does the "Nist improved" 4228-HD compare to the old version CM-4228 or CM-4221? I find it interesting that the left and right side harnesses are located so closely to each other near their attachment points. The photos (9 and 10) suggest less than 1/4" gap.

As an imagineer I'm shooting from the hip, but would a greater gap work better by using one longer screw at each attachment point (staggering the harness) or does this gap establish impedence matching? Also, might it be better to use nylon tubular spacers rather than aluminum spacers to reduce potential interaction with the antennas' frame?

Jim

 

[tballister]

Aside from poorer performance receiving VHF, how does the "Nist improved" 4228-HD compare to the old version CM-4228 or CM-4221?

Hi Jim. On my Antenna Comparisons page you'll find a link to an old vs new 4228 comparison. Over the UHF band the two are comparable, with a few 1-2 dB differences noted there for specific frequencies. In general then, since a CM4228HD fitted with a Nist Harness would outperform a stock (new) CM4228HD over the high end, it would likely also outperform the Old CM-4228 over the high end. At the low end of the UHF spectrum I'd expect a modified CM4228HD to be just about the same as the old CM-4228.

I find it interesting that the left and right side harnesses are located so closely to each other near their attachment points. The photos (9 and 10) suggest less than 1/4" gap.

Hmmm.... I assume you meant something like "... surprised the rails of the (horizontal) harness are so close to each other at the left and right side?" Perhaps the viewing angle of these photos is misleading? The 'B' spacing of 0.714" of the two rails at the outer ends of the (horizontal) harness expands at the ends to 1.75", bending and rotating forward to where they attach to the vertical transmission line terminals. The closest spacing of the 20" spans of the rails is 0.255", which occurs across the 'A' section at the center of the horizontal span.

As an imagineer I'm shooting from the hip, but would a greater gap work better by using one longer screw at each attachment point (staggering the harness) or does this gap establish impedence matching?

I'm not sure which gap you're thinking of here. There is a 'longer' screw involved, a 2.5" screw that passes through the terminal block, through the 1.5" spacers, through the circle formed at the ends of the .1" aluminum wire, and then through a nut. This moves the connection point to the vertical transmission lines about 2" towards the rear, so that the horizontal secion can be connected without touching the vertical boom. The 1.75" spacing between the rails of the vertical transmission line is not something I wanted to modify. By definition, then, this requires a transition from the .714" spacing of the (end) 'B' section to the 1.75" spacing of the vertical transmission line.

Above all, I wanted to keep the electrical center point of the two rails at the physical center of the horizontal span, so that the center conductor and shield of the coax could be attached at the same mid-point with minimum exposure of the center conductor, and thus minimum effect on the impedance of the coax at its end point. It did occur to me that a different a single common shape for each horizontal rail could be implemented, and that each rail could be attached to the vertical terminals without the complex backward turn to the inside terminal. But that would leave 1.5" of rail unbalanced at each end, and I did not want to take the chance of introducing anomolies. It would also not have conformed to Ken's recommendation. E.g., the two conductors I used for the rails are exactly the same length, and each has exactly the same distance from its center to its corresponding terminal, thus maintaining a balanced transmission line. I would accept that my arbitrary choice of shapes for the one bend out, and one bend in, might not be optimal, and would welcome any recommendation.

Also, might it be better to use nylon tubular spacers rather than aluminum spacers to reduce potential interaction with the antennas' frame?

Yeah.... perhaps. Whatever that interaction is though, it would be common mode because both left and right sides are equidistant from the frame (vertical boom). So I'm not sure any effect would be significant to the balanced impedance. One thing I do realize is that using .25 diameter spacers takes the conductor diameter from .1" to .25" for that 1.5" span from horizontal conductor to terminal, and that could probably introduce some anomoly. If I elect to try optimizing further I might implement your suggestion.

Mainly, however, my goal was to provide some emperical results that either validated Ken's recommendations, or not. It does seem that the result substantially verifies his assertions.

t