Quiz time

Is a duplexer required to build a repeater?

  • Yes

    Votes: 4 26.7%
  • No

    Votes: 11 73.3%

  • Total voters
    15
  • Poll closed .
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KC0QNB

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If you are a Technician class ham and you want to build a repeater for 2 meters do you need a duplexer?
I put this on this forum because it is related.
Explain your answer in as few words as possible.
 

chrismol1

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I say if you find a right priced Duplexer, go ahead and install it, will make it better overall, or you can just use 2 antennas like someone said before
 

WouffHong

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Jawjuh :)
Repeater Question

As mentioned - a duplexer with a single antenna is the 'gold standard" for most repeaters.

The idea is to keep the transmitter output (only 600 KHz away from Receiver input frequency) from Desensing (overloading) the receiver making it short-range and of little use.

Two antennas, widely separated, and with minimum coupling between the cables and Repeater equipment in the shack will also work but a bit touchy to effectively max out the separations to prevent desensing..

IMPORTANT: You must coordinate the Frequencies you are going to use with the local or state Repeater Coordination Council before firing up a system that COULD mess up other systems!! :)

Also: you must have (or be) a monitoring control Operator 24/7/365..

Good luck and enjoy - Tom, W4NOV

Sorry - a few words didn't hack it. :D

If you are a Technician class ham and you want to build a repeater for 2 meters do you need a duplexer?
I put this on this forum because it is related.
Explain your answer in as few words as possible.
 
Joined
Dec 24, 2004
Messages
799
Location
Emporia, KS
As mentioned - a duplexer with a single antenna is the 'gold standard" for most repeaters.

The idea is to keep the transmitter output (only 600 KHz away from Receiver input frequency) from Desensing (overloading) the receiver making it short-range and of little use.

Two antennas, widely separated, and with minimum coupling between the cables and Repeater equipment in the shack will also work but a bit touchy to effectively max out the separations to prevent desensing..

IMPORTANT: You must coordinate the Frequencies you are going to use with the local or state Repeater Coordination Council before firing up a system that COULD mess up other systems!! :)

Also: you must have (or be) a monitoring control Operator 24/7/365..

Good luck and enjoy - Tom, W4NOV

Sorry - a few words didn't hack it. :D
The emporia ks repeater got moved to a new site and went from 2 antenans to the new site at 1 antenna. they jacked the output up and got some desense untill they did something with the duplexer. don't know if they still got the power at 80watts.
 

Grog

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While 600 KHz is the standard offset, it is not always required. Some sites run an odd offset, although it is not very common.
 

scrotumola

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So. Texas
As mentioned - a duplexer with a single antenna is the 'gold standard" for most repeaters.

The idea is to keep the transmitter output (only 600 KHz away from Receiver input frequency) from Desensing (overloading) the receiver making it short-range and of little use.

Two antennas, widely separated, and with minimum coupling between the cables and Repeater equipment in the shack will also work but a bit touchy to effectively max out the separations to prevent desensing..

IMPORTANT: You must coordinate the Frequencies you are going to use with the local or state Repeater Coordination Council before firing up a system that COULD mess up other systems!! :)

Also: you must have (or be) a monitoring control Operator 24/7/365..

Good luck and enjoy - Tom, W4NOV

Sorry - a few words didn't hack it. :D
Tom, W4NOV <=- What he said.

While 600 KHz is the standard offset, it is not always required. Some sites run an odd offset, although it is not very common.
This reiterates the necesity for vertical and/or horizontal separation in a 2 antenna system. Avoiding desense is a major factor. If you have the vertical real estate, the receiver should be the highest antenna, with the transmitting antenna at a predetermined distance below. (I read the formula somewhere, but I couldn't find it.)

In not so many words.
 
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KC0QNB

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I already know the answer have known for years, but I wanted to test the waters, there are a lot of good answers so far.
roughly 12 hours to to.
 

KC0QNB

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NO you don't need a duplexer, of course most of you know that, so. how far apart do the antennas need to be to work correctly?
You guys let me down, I was expecting more replies than that.
 

dkostrey

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FN31
License class has nothing to do with the equipment required to operate a repeater (now that there is no longer a Novice class license). If you can get by without a duplexer, great then do it. If you need a duplexer, it could get a bit expensive. As far as spacing, you could put both antennas on the same tower if the tower is tall enough to get the proper vertical spacing.

73
 
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Grog

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License class has nothing to do with the equipment required to operate a repeater (now that there is no longer a Novice class license).

http://wireless.fcc.gov/services/index.htm?job=about_3&id=amateur

No new Novice, Technician Plus, or Advanced Class amateur service operator licenses will be issued. These licenses, however, may be modified or renewed. Technician Plus class operator licenses will be converted to Technician Class licenses if renewed. Technician Plus class operator licenses will also be converted to Technician Class when modified to show a vanity call sign.
 

KC0QNB

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The two repeaters I mainly use do not have duplexers one used to, but the club chose to remove it from service and go with a two antenna system vertically spaced on the tower. It works better than it ever did with a duplexer.
 

dkostrey

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I stand corrected sir. No 'new' novice licenses are 'issued' (I understand what you are saying, because I have an Advanced class license. Same difference. Thank you for clearing that up). Since Novices have no two meter privileges, the chances of them operating a two meter repeater are slim. Otherwise, from Tech up repeater stations are permissible. Coordination etc. is another story.
 

KC0QNB

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Location
Gothenburg, NE
I stand corrected sir. No 'new' novice licenses are 'issued' (I understand what you are saying, because I have an Advanced class license. Same difference. Thank you for clearing that up). Since Novices have no two meter privileges, the chances of them operating a two meter repeater are slim. Otherwise, from Tech up repeater stations are permissible. Coordination etc. is another story.
Well at least someone was paying attention to the class reference, I was trying to through a curve and you caught it good job.
 

rescue161

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Unless you have access to a large tower and are willing to spend a lot of money on feedline and connectors, then a duplexer is the way to go. I tried to use a two antenna setup a while back on UHF, but didn't have enough room to seperate the antennas. Ended up having to use a duplexer and all the desense went away. It may appear more expensive at first, but when you start looking at the cost of feedline and all of the hardware to mount it, it adds up real quick.
 
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