Purely a guess on my part: I suppose 3 or more dB would come off the one direction and be added to the other side as you change to a figure-eight reception pattern.

I'm basing my guess on what I've read about the relative differences in patterns between the same antenna with and without a reflector: the Delhi 4BT-1483 and the reflector-less Delhi SL-4BT version.

In a perfect world, the reflector should double (a 3dB gain is approximately double the signal) the amount of signal received from the front and eliminate the signal received from the back, so removing the reflector should in theory cut the forward gain in half and make the reverse gain equal to the forward gain. However, since we don't live in a perfect world, real life experience trumps the theoretical any day.

How should the balun be connected to a CM-4221?
I tried different way with different result, I guess there a way that is "The way".

First where the coax should go down?
1-Between the reflector and the bow ties.
2-pass in the plastic part that old the reflector
3-In front of the reflector.

The Balun long leg (I use the one from CM)
1- form a V to connect to each connector.
2- Form Y (Connect each leg and then back together.)
3- Form a M with the leg.

http://i200.photobucket.com/albums/aa19/jajoflo/Balun.jpg

I had time to make some test, and the winner is Y.

If you are handy with tools you can buy a CM4228 and section it in half (into 2 CM4221s). I'm referring to one of those CM4221 halves as a "side":

drill out the rivets on one side of the thin galvanized steel support brackets of the back reflector screen
drill out the rivets on one side of the steel cross members
leave all the riveted parts of the other side intact
remove the antenna lead cross connectors so that one of the CM4221 halves comes right off
leave the antenna lead cross connectors of the other side intact
load the sectioned CM4228 parts into the attic
reverse the process by reassembling the 2 halves
replace the drilled out rivets with galvanized or stainless steel machine screws, or with nuts & bolts with lock washers

Hi! After weeks of research and reading many threads here I have finally decided to experiment with going completely OTA. I purchased a CM4221 for $39.99 from a local online store. I don't know what to expect of these antennas in terms of build quality and craftsmanship, so I do have a few questions about the one I purchased.

First, I noticed that the wire running down the length of the antenna on the left was slightly bent out of shape near the bottom. I didn't think it looked right, so I took some photos and bent it a bit straight, just like the opposite one. Don't worry, I left the 1/2" gap between the wires as they cross, it's just above that for about 4 or 5 inches that the wire was significantly bent.
http://i221.photobucket.com/albums/dd206/pilotantenna/IMG_3158.jpg

Also, I noticed that one of the brackets at the top back of the antenna was bent backwards. Again, I took some photos and bent it back to what it looked like it should be set to.
http://i221.photobucket.com/albums/dd206/pilotantenna/IMG_3159.jpg
http://i221.photobucket.com/albums/dd206/pilotantenna/IMG_3161.jpg

Finally, I noticed that the space between the crossarm and mesh at the bottom of the antenna was greater than at the top. This gives the antenna a slight downwards tilt.

Should I be concerned about any of these? I was wondering if it's possible that the antenna I purchased has been either used or mishandled. Should I consider returning the antenna?

Thanks!

Hi pilot007 and welcome here - antennas can sometimes move about in their cartons before arriving at the dealer or into your hands, but looking at the photos you posted I can see that you have only to straighten out the various bends and you'll have a perfectly good CM4221.I noticed that the wire running down the length of the antenna on the left was slightly bent out of shape near the bottom.Line it up with a straight edge, bend it with some pliers, and you'll be fine.one of the brackets at the top back of the antenna was bent backwardsAgain, a pair of pliers and a gentle touch will bend it into proper shape.

All in all I don't see any show stoppers with what you've got. A few minutes with a steady, gentle hand on the pliers and you'll do great! :)

Thanks stampeder! I have bent those pieces back into place and they look good now.

So is there supposed to be a slight downward tilt to the mesh? I measured the distance between the mesh and the bottom of the crossarm, it is ~6cm, vs. ~4.5cm near the top. Is this ok?

Also, the distance from the mesh to the tips of the bowties on the left is about 9 - 10cm on average, whereas some bowtie tips on the right vary between 10 - 12cm from the mesh.

Should I be at all concerned about these? Again, I could do some bending here to get them to be a bit more symmetrical, however I'd rather have an antenna that is in good shape to start. Especially since I don't know what to expect.

Ideally the back screen should be flat and all clearances the same. Having said that, I have a very old Delhi 4-bay that has been bent and rebent so many times that nothing is truly straight on it anymore, yet it does great as long as I make it as straight and flat as possible.

On my 4221 the top and bottom are the same spacing from the mesh. (6 cm)

As for the bowties, mine are all about the same. (10-11 cm from the mesh)

It seems to me that something heavly was placed on your antenna (the last pic is the clue) and it got bent. Just straighten it out as best you can.

When I bought my 4221 one of the clips that attaches the pole to the mesh was almost as bad as yours, and I just bent it back. All is fine now.

Thank you stampeder and ASA. Based on your information and my measurements, I think I will initiate the process of exchanging or returning my antenna.

Does anyone have any close up photos from the side and bottom of the CM4221? I'd like to have some photos of good CM4221's in case I encounter any trouble with the return process.

Thanks!

I'll try and post a couple tonight for you.

by the way, the bends you have are not that bad. The box the 4221 comes in is not padded with packaging material and I have a feeling the new one you get may not be perfect 100% either. Mine wasn't and I was still able to bend the problem areas back into shape. The only thing I would be worried about are the rivets holding the brackets to the pole. If they are loose there isn't much you can do except exchange the antenna, or drill out the loose rivets and replace them with a nut/bolt.

An alternative method would be to find a bedroom clothes closet that runs parallel to the ceiling joists or a bedroom clothes closet that is so big that it doesn't matter which way the ceiling joists run.

Next; slice open the ceiling drywall so that the CM4228 fits easily up into the attic.
NOTE: It is easier to cut from above. MEASURE TWICE, CUT ONCE! Also, measure twice, cut once.

anyidea on the performance of CM 4220 compared if i buy the Silver Sensor? Due to its 'small' size, I can put it indoor against the window in my condo in yonge/sheppard area... Is it a good antenna compared to the silver sensor?

anyidea on the performance of CM 4220 compared if i buy the Silver Sensor? Due to its 'small' size, I can put it indoor against the window in my condo in yonge/sheppard area... Is it a good antenna compared to the silver sensor?

The CM4220 should perform similarly to the AntennasDirect DB-2 (though I susspect it will be slightly better for the lower channels). If you look at HDTV Primer (http://www.hdtvprimer.com/ANTENNAS/comparing.html) you will see that the DB-2 is better than the silver sensor so it would be a good alternative as an indoor antenna.

I took the plunge and bought the CM 4221...

Will its performance be affected if I paint it black or grey? I want to blend it with the colour of my balcony's wall....

boumbo, I don't recommend painting it, and here's my answer from a previous post:

http://www.digitalhome.ca/forum/showpost.php?p=282342&postcount=81

:)

Just ordered a 4228 from Stark electronics. The screen is painted with an enamal type paint. Is this normal? Aslo the screen has a concave curvature to it because they ship in a slightly smaller box. I was reading that it needs to be perfectly flat. Will this cause any problems? as well can I reinforce it any way . Thought of putting some tie wraps in some critical points.

Thanks

It has a... greyish almost greasy coating on it.. not really paint, but that could be what you're referring to.
and the back screen isnt vital for reception, its the bowties. The bowties should be straight and aligned to one another (like X's if you look at pairs)
The back screen will be fine as long as you flatten it out a bit.
Keep in mind it normally has the two edges bent forwards (the side with the bowties)

when stacking two 4228 antennas will VHF-Hi (7 - 13 ) still be good or better
or not work? Anyone try!