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Author Topic: Decibel Duplexers ???? 220 Mhz.  (Read 10255 times)
WB2NGX
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Posts: 90




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« on: September 18, 2017, 09:32:49 PM »

I'm guessing that the company that makes these is long gone.
I have model DB4100BPR-D 220 Mhz. duplexers. I'm trying to find documentation on them.

Joe WB2NGX
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W1VT
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Posts: 2530




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« Reply #1 on: September 19, 2017, 07:19:13 AM »

http://www.repeater-builder.com/antenna/ant-sys-index.html
This site has an amazing amount of repeater hardware documentation.

Zack W1VT
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K4JJL
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Posts: 835




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« Reply #2 on: September 19, 2017, 07:51:18 AM »

Decibel got bought out in the early 90s by Allen Telecom, which was then bought out by Andrew, which was then bought out by CommScope.

On most sets of Decibel duplexers, the plunger adjusts the bandpass and the small screw adjusts the notch.  Sometimes there's a way to adjust the insertion loss, usually by twisting the RF connectors.  Other than that, I'd need to see a pic of them.
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WB2NGX
Member

Posts: 90




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« Reply #3 on: September 19, 2017, 09:01:42 PM »

Thanks for all the info guys. I don't know how to post a picture to this forum.
These duplexers have 2 large cans for the TX and 6 smaller ones for the RX. I tried to find a picture of them by searching the model number but had no luck.

Joe WB2NGX
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WB2NGX
Member

Posts: 90




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« Reply #4 on: September 19, 2017, 09:03:27 PM »

Decibel got bought out in the early 90s by Allen Telecom, which was then bought out by Andrew, which was then bought out by CommScope.

On most sets of Decibel duplexers, the plunger adjusts the bandpass and the small screw adjusts the notch.  Sometimes there's a way to adjust the insertion loss, usually by twisting the RF connectors.  Other than that, I'd need to see a pic of them.
If you give me an email I'll send you a picture of them.

TNX........
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WW7KE
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Posts: 609




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« Reply #5 on: September 19, 2017, 09:31:55 PM »

Decibel got bought out in the early 90s by Allen Telecom, which was then bought out by Andrew, which was then bought out by CommScope.

Andrew/Decibel is now owned by WISCO International of Miami.  I have no idea when the Decibel office in the DFW area closed.  I worked in their Chicago-area plant in the early '90s, but that location was closed by Allen Telecom in 1992, a few months after I left the company.

http://www.wiscointl.com/decibel/
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He speaks fluent PSK31...  One QSO with him earns you 5BDXCC...  His Wouff Hong has two Wouffs... Hiram Percy Maxim called HIM "The Old Man..."  He is... The Most Interesting Ham In The World!
K0UA
Member

Posts: 1466




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« Reply #6 on: September 20, 2017, 07:14:55 AM »

And I can help a bit with the picture posting.  Pictures must be hosted offsite and linked to here.  One very easy place is to use postimages:   Here is the site:  https://postimages.org/

Drag and drop an image onto their page.  Then choose the 5th choice down  which is thumbnails for forums. and highlight that URL and do a right mouse click, copy and then right click over here in the reply box and do a paste to get the image in your text.



That is all there is to it, and it seems to work well.
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WB2NGX
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Posts: 90




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« Reply #7 on: September 20, 2017, 08:01:06 PM »

Like this...........??

Here they are..........



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W9IQ
Member

Posts: 1718




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« Reply #8 on: September 20, 2017, 11:57:54 PM »

It appears to me that these duplexers were set up for split band operation. Do the smaller cans contain a model number?

- Glenn W9IQ

 
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
WB2NGX
Member

Posts: 90




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« Reply #9 on: September 21, 2017, 06:02:08 AM »

There are no other stickers of identification on the small cans. Just the one on the big can that you can read if you enlarge the picture.
None of the repeater guys around me have seen a set up like this. The TX side seems to be OK. SWR is OK, insertion loss is about 5 watts coming out of the TX cans to the antenna with 20 watts in.
The receive side is questionable..... the repeater can talk a lot farther than it can hear and given my location and height of the antenna some of the guys think there may be an issue with the RX cans. So I'm trying to find some documentation on these so I will know exactly what I have.

Joe WB2NGX
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WB2NGX
Member

Posts: 90




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« Reply #10 on: September 21, 2017, 07:43:26 AM »

It appears to me that these duplexers were set up for split band operation. Do the smaller cans contain a model number?

- Glenn W9IQ

  
If these are split band duplexers what frequency would you suspect the 6 smaller RX cans are for ?? UHF ?? and if so would they be able to have  been tuned for 220??  Can this be determined by the size ??

Joe WB2NGX
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K4JJL
Member

Posts: 835




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« Reply #11 on: September 21, 2017, 10:11:43 AM »

There are no other stickers of identification on the small cans. Just the one on the big can that you can read if you enlarge the picture.
None of the repeater guys around me have seen a set up like this. The TX side seems to be OK. SWR is OK, insertion loss is about 5 watts coming out of the TX cans to the antenna with 20 watts in.
The receive side is questionable..... the repeater can talk a lot farther than it can hear and given my location and height of the antenna some of the guys think there may be an issue with the RX cans. So I'm trying to find some documentation on these so I will know exactly what I have.

Joe WB2NGX

Do you have a spectrum analyzer with a tracking generator (or access to one)?  That'll tell you the whole story immediately.
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WB2NGX
Member

Posts: 90




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« Reply #12 on: September 21, 2017, 10:17:12 AM »

There are no other stickers of identification on the small cans. Just the one on the big can that you can read if you enlarge the picture.
None of the repeater guys around me have seen a set up like this. The TX side seems to be OK. SWR is OK, insertion loss is about 5 watts coming out of the TX cans to the antenna with 20 watts in.
The receive side is questionable..... the repeater can talk a lot farther than it can hear and given my location and height of the antenna some of the guys think there may be an issue with the RX cans. So I'm trying to find some documentation on these so I will know exactly what I have.

Joe WB2NGX

Do you have a spectrum analyzer with a tracking generator (or access to one)?  That'll tell you the whole story immediately.
No I don't but the guy that originally set these up did, but he also suspected that there may still be an issue with the RX side.

Joe WB2NGX
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W9IQ
Member

Posts: 1718




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« Reply #13 on: September 21, 2017, 12:57:52 PM »

Perhaps posting some good pictures of the small cans would lead to someone identifying them.

- Glenn W9IQ
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
WB2NGX
Member

Posts: 90




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« Reply #14 on: September 21, 2017, 01:28:33 PM »

OK Glenn here is a picture of the back. Not much to see.

TNX..... Joe WB2NGX

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