• To anyone looking to acquire commercial radio programming software:

    Please do not make requests for copies of radio programming software which is sold (or was sold) by the manufacturer for any monetary value. All requests will be deleted and a forum infraction issued. Making a request such as this is attempting to engage in software piracy and this forum cannot be involved or associated with this activity. The same goes for any private transaction via Private Message. Even if you attempt to engage in this activity in PM's we will still enforce the forum rules. Your PM's are not private and the administration has the right to read them if there's a hint to criminal activity.

    If you are having trouble legally obtaining software please state so. We do not want any hurt feelings when your vague post is mistaken for a free request. It is YOUR responsibility to properly word your request.

    To obtain Motorola software see the Sticky in the Motorola forum.

    The various other vendors often permit their dealers to sell the software online (i.e., Kenwood). Please use Google or some other search engine to find a dealer that sells the software. Typically each series or individual radio requires its own software package. Often the Kenwood software is less than $100 so don't be a cheapskate; just purchase it.

    For M/A Com/Harris/GE, etc: there are two software packages that program all current and past radios. One package is for conventional programming and the other for trunked programming. The trunked package is in upwards of $2,500. The conventional package is more reasonable though is still several hundred dollars. The benefit is you do not need multiple versions for each radio (unlike Motorola).

    This is a large and very visible forum. We cannot jeopardize the ability to provide the RadioReference services by allowing this activity to occur. Please respect this.

Tuning a duplexer for a range of frequencies rather than just one pair

sbraun46b

Newbie
Premium Subscriber
Joined
May 11, 2016
Messages
1
Location
Lancaster, wi
I'm in the process of building portable repeaters for use on the national interoperability channels. In UHF, that would include UTAC41-43. Those frequencies range from TX 453.4625-453.8625 and RX 458.4625-458.8625. I've assumed that I'll need three duplexers and will have to swap them out depending on which frequency pair I want to use. However, I came across this duplexer on ebay, tuned for the whole GMRS range, and it made me wonder if I could do the same in UHF with a similar portable duplexer. Any advice on whether this is an acceptable practice, or should I steer clear? Can you tune most of these portable duplexers to pass/reject this wide of a range ( 0.4mhz)? In your opinion would the downfalls of doing that (decreased functionality) outweigh the benefits? I'm just getting started in the world of duplexers--everything I've ever used was notched for a specific frequency pair, not a range. Any advice would be appreciated.
 

Attachments

  • s-l1600.jpg
    s-l1600.jpg
    167.3 KB · Views: 17

Project25_MASTR

Millennial Graying OBT Guy
Joined
Jun 16, 2013
Messages
4,284
Location
Texas
It can be done but it's very dependent on the frequencies being used and the minimum separation between the lowest uplink frequency and highest downlink frequency. Using the same concept though, some 800 MHz duplexers are not field tunable because of the 45 MHz offset.
 

RFI-EMI-GUY

Member
Joined
Dec 22, 2013
Messages
7,046
You will almost certainly have worse rejection performance when you tune for 0.4 MHz . You can stagger tune the three reject notches (center plus near two edges.) within that 0.4 MHz, but it will result in worse rejection than when tuned on a single center frequency. I would sweep the duplexer as now tune for GMRS to see how well it performs and where the notches are placed.. If it is sufficient for your application, then tune for your new frequencies.
 

prcguy

Member
Premium Subscriber
Joined
Jun 30, 2006
Messages
15,692
Location
So Cal - Richardson, TX - Tewksbury, MA
Flatpack duplexers have some inherent bandwidth and they should cover at least 100KHz of BW with some useable up to about 200KHz as you saw with the GMRS ad. The isolation will peak in the middle of the band and degrade at the edges and you have to tune and test them for bandwidth including testing the repeaters over wide range to make sure there is no desense.

If your repeaters are low power like 10w or less you might get away with just two duplexers to cover your needed 400KHz bandwidth.
 

12dbsinad

Member
Joined
Mar 15, 2010
Messages
1,973
DO NOT buy cheap Chinese flatpack ebay duplexers, they are total trash. Ask anyone with radio knowledge and they will tell you. If you insist on a mobile duplexer find a Celwave one. Personally I'd tune a duplexer for each frequency and when deploying them don't stick them on busy RF sites because it probably will puke and won't work worth a beans. A nice quiet site with not much around if you're only planning on using a mobile duplexer.
 

kayn1n32008

ØÆSØ
Joined
Sep 20, 2008
Messages
6,703
Location
Sector 001
You should have no issue getting a duplexer to pass 400KHz of band width. If you have the room, I would look at getting a Sinclair ResLoc BpBr duplexer and stay away from the mobile duplexer.
 

rubidio

Newbie
Joined
Apr 2, 2024
Messages
1
DO NOT buy cheap Chinese flatpack ebay duplexers, they are total trash. Ask anyone with radio knowledge and they will tell you. If you insist on a mobile duplexer find a Celwave one. Personally I'd tune a duplexer for each frequency and when deploying them don't stick them on busy RF sites because it probably will puke and won't work worth a beans. A nice quiet site with not much around if you're only planning on using a mobile duplexer.
Thanks for the tip, as I'm starting to learn about duplexer.
 

jeepsandradios

Member
Feed Provider
Joined
Jul 29, 2012
Messages
2,164
Location
East of the Mississippi
We have 2 "tac" repeatersi n command posts that have all the UTACS in them and use a single Sinclair Duplexer. Tune in the middle and it works ok. For site repeaters I would do seperate for each but for most TAC stuff it works well enough. The channel we go to is the one we tuned for most of the time but has ability to move if needed.
 
  • Like
Reactions: fog
Top