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Old 13-Mar-2020, 3:34 PM   #1
shoman94
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Removing DB4e reflector

How would removing the reflector change the gain? How would it look compared to the reception graph of the DB4e?
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Old 13-Mar-2020, 5:13 PM   #2
Tim
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Originally Posted by shoman94 View Post
How would removing the reflector change the gain? How would it look compared to the reception graph of the DB4e?
Hollands posted the gain figures and pattern for the Antennas Direct DB4 with no reflector a few years ago. The DB4e should be similar.

Basically, removing the reflector decreases the gain somewhat and makes the antenna bi-directional.

https://imageevent.com/holl_ands/mul...tienoreflector
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Old 13-Mar-2020, 5:36 PM   #3
shoman94
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Originally Posted by Tim View Post
Hollands posted the gain figures and pattern for the Antennas Direct DB4 with no reflector a few years ago. The DB4e should be similar.

Basically, removing the reflector decreases the gain somewhat and makes the antenna bi-directional.

https://imageevent.com/holl_ands/mul...tienoreflector
Thanks for that....

Ouch what a huge hit below 530mhz.

I don't think that would work for me.

https://www.rabbitears.info/searchma...study_id=69426

I aimed at 331 TRUE and only have some issues with 26-1.

Last edited by shoman94; 13-Mar-2020 at 5:46 PM.
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Old 14-Mar-2020, 1:01 AM   #4
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Thanks for that....

Ouch what a huge hit below 530mhz.

I don't think that would work for me.

https://www.rabbitears.info/searchma...study_id=69426

I aimed at 331 TRUE and only have some issues with 26-1.
I think the gain figures for the DB4e are much better at the lower end of the band than they were for the DB4.
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Old 14-Mar-2020, 2:51 AM   #5
Tower Guy
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Do you get WMTW on RF channel 8 or RF channel 26?

Can you receive PBS on WENH (RF channel 11)?
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Old 14-Mar-2020, 10:22 PM   #6
ADTech
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Ouch what a huge hit below 530mhz.
As noted by Tim, that was for the old DB4 which was discontinued many years ago.


Get the tech data sheet for the DB4e off the website, print out the horizontal polar pattern, draw a new curve 2-3 dB inside the existing curve (on the "hot" side), then mirror that to the other side. You'll be right in the ballpark as to what would be expected.
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Old 15-Mar-2020, 3:08 AM   #7
shoman94
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Originally Posted by Tower Guy View Post
Do you get WMTW on RF channel 8 or RF channel 26?

Can you receive PBS on WENH (RF channel 11)?
I get it with RF channel 8. I have a di-pole kit for it.

I do not get channel 11 or 10 PBS's.

Last edited by shoman94; 15-Mar-2020 at 3:13 AM.
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Old 15-Mar-2020, 3:11 AM   #8
shoman94
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Originally Posted by ADTech View Post
As noted by Tim, that was for the old DB4 which was discontinued many years ago.


Get the tech data sheet for the DB4e off the website, print out the horizontal polar pattern, draw a new curve 2-3 dB inside the existing curve (on the "hot" side), then mirror that to the other side. You'll be right in the ballpark as to what would be expected.
So I will likely lose maybe 2-3 db on the front end on each of the 4 patterns?

Also what do you think would happen if only one reflector was removed?

Last edited by shoman94; 15-Mar-2020 at 3:19 AM.
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Old 15-Mar-2020, 4:26 PM   #9
shoman94
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Originally Posted by ADTech View Post
?
I could try adjusting the backside lobe to line up with 246 degrees and the front side would end up at 16 degrees. Or do you think removing the reflector and adjusting the front side to 331 or 357?

https://www.rabbitears.info/searchma...study_id=69987
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Old 15-Mar-2020, 6:07 PM   #10
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So currently if I aim directly or near directly to the Fox/CBS tower (they are on the same tower) I get all kids of errors and glitches. CBS is glitch free. The height I changed by about 2ft and it doesn't change anything.

I'm gonna try without a preamp and see if the signal are just too strong now.
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Old 15-Mar-2020, 9:03 PM   #11
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I took off the juice preamp and everything is coming in better now. Even PBS is watchable now but it does have a 12ish% error rate with the sun out so I'll see what happened tonight.

Last edited by shoman94; 15-Mar-2020 at 10:45 PM.
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