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My secret little CM4221HD hack.
[note: this hack has been tried and true over a dozen times]
Just thought I should share something with those of you who are stuck on the performance benefits of that old reliable CM4221 antenna design.
Here’s a little hack that I have been doing for a while now in order to beef up the new CM4221HD antenna design.
It appears that whoever it was at PCT in China that was responsible for the re-design of the new CM4221HD was more concerned with the cosmetic values of this newly designed antenna than it’s overall performance values.
There has been some concern among many about the lacking performance of the new CM4221HD antennas as compared to the old CM4221 antenna design. There are a few simple revisions that can be made to the CM4221HD that will restore those overall performance values and restore the familiar characteristics that the old CM4221 antenna had.
‘V’ ELEMENT OBSTRUCTIONS:
There are some cute little 1” plastic covers that hide a portion of the elements at the connection points of each ‘V’ element on each bay. Remove these 8 cosmetic plastic caps and just toss them away, as they actually shorten the overall calculated length of each ‘V’ element by almost 2”.
RESIZE THE REFLECTOR GRID WIDTH:
The next thing that will need some adjustment is the width of the 24” wide reflector grid. The new CM4221HD reflector grid is 24” wide and the old CM4221 is only 20” wide. To do this, just carefully remove the plastic side retainers from all of those grid rods. Then cut exactly 2” off each of the aluminium grid rods and then reinstall the plastic side retainers.
BALUN TO BOOM CLEARANCE:
The flat bars that the balun box is connected to are too close to the boom, so simply pull the balun assembly outwards and make sure that those flat bars are at least ½” away from the boom. I believe this may have just been an oversight that should have been mentioned within the antenna assembly instruction sheet.
[I believe this inward positioning of the balun was intended to accommodate the slim packaging dimensions and to reduce the risk of shipping damages]
You will now have the same basic dimensional and performance characteristics of the original CM4221 antenna design.
[note: this hack has been tried and true over a dozen times]
Just thought I should share something with those of you who are stuck on the performance benefits of that old reliable CM4221 antenna design.
Here’s a little hack that I have been doing for a while now in order to beef up the new CM4221HD antenna design.
It appears that whoever it was at PCT in China that was responsible for the re-design of the new CM4221HD was more concerned with the cosmetic values of this newly designed antenna than it’s overall performance values.
There has been some concern among many about the lacking performance of the new CM4221HD antennas as compared to the old CM4221 antenna design. There are a few simple revisions that can be made to the CM4221HD that will restore those overall performance values and restore the familiar characteristics that the old CM4221 antenna had.
‘V’ ELEMENT OBSTRUCTIONS:
There are some cute little 1” plastic covers that hide a portion of the elements at the connection points of each ‘V’ element on each bay. Remove these 8 cosmetic plastic caps and just toss them away, as they actually shorten the overall calculated length of each ‘V’ element by almost 2”.
RESIZE THE REFLECTOR GRID WIDTH:
The next thing that will need some adjustment is the width of the 24” wide reflector grid. The new CM4221HD reflector grid is 24” wide and the old CM4221 is only 20” wide. To do this, just carefully remove the plastic side retainers from all of those grid rods. Then cut exactly 2” off each of the aluminium grid rods and then reinstall the plastic side retainers.
BALUN TO BOOM CLEARANCE:
The flat bars that the balun box is connected to are too close to the boom, so simply pull the balun assembly outwards and make sure that those flat bars are at least ½” away from the boom. I believe this may have just been an oversight that should have been mentioned within the antenna assembly instruction sheet.
[I believe this inward positioning of the balun was intended to accommodate the slim packaging dimensions and to reduce the risk of shipping damages]
You will now have the same basic dimensional and performance characteristics of the original CM4221 antenna design.