Duplexer Question

[KG4LHQ]

Hello,

Went to a site a couple days ago to exchange a TKR-720 repeater out for a MTR2000 and noticed they have a small duplexer Sinclair is the make.

The dimensions are about 18"x4"x4" and on the back plate where the model number is listed had damage, the only thing I could make out was R-29 on the plate.

Any idea what this may be and what the power handling of this small duplexer would be?

The TKR-720 was right at 50 out to the duplexer and they have ran this fine for several years but want to make sure it will handle 85-95 watts out of the MTR before I hook it up.

[Bill_G]

Links and pictures would help.

[maxkelley_kc2spy]

These little "mobile duplexers," as they call them, are really meant just for "mobile" power levels... essentially up to 50-60w. If you're running these power levels., that should be fine. Get up into the 90W range, and I'm not sure that's a great idea. Take a look at a similar telewave duplexer: http://www.telewave.com/pdf/TWDS-6022.pdf . Power handling is specifically 50 watts.

As far as the TKR-720, they're not rated for 50W continuous, FYI (I know you're replacing it...). In fact, 25W continuous is still a bit ambitious, but hey, if it was working for you, I guess it was working, then, wasn't it!

Hope that helps...

[fineshot1]

Possibly a Sinclair MR series mobile duplexer ?

http://www.repeater-builder.com/sinclai ... tuning.pdf

[tvsjr]

Definitely a mobile duplexer. It won't handle 100 watts...

[Mikey]

Buy a good TxRx Duplexer and be done with it. Those are rock solid

[RFguy]

Take a look at a similar telewave duplexer: http://www.telewave.com/pdf/TWDS-6022.pdf . Power handling is specifically 50 watts.

That's far from a "similar" duplexer.

The one that the OP asked about was 18" wide, 4" high and 4" deep (the 4" deep part has me confused, but the rest is a standard RezLoc base station repeater size).

The telewave is only 7" x 4.5" x 1.4" high.

[RFguy]

but want to make sure it will handle 85-95 watts out of the MTR before I hook it up.

Just curious, are you licenced for an increase in power? Just asking.

[KG4LHQ]

Mobile radios are licensed for 50W and Fixed Operation is Licensed for upto 110W.

Not sure what that has to do with the question but thanks for your interest in my post.

[RFguy]

Mobile radios are licensed for 50W and Fixed Operation is Licensed for upto 110W.

Not sure what that has to do with the question but thanks for your interest in my post.

I assume that's ERP, so a 90 watt transmitter with an antenna of any gain will exceed the licensed ERP and put you in violation of your licence.

What's it got to do with your post? Just trying to help. FCC fines tend to be steep.

No need to thank me

[escomm]

Mobile radios are licensed for 50W and Fixed Operation is Licensed for upto 110W.

Not sure what that has to do with the question but thanks for your interest in my post.

I assume that's ERP, so a 90 watt transmitter with an antenna of any gain will exceed the licensed ERP and put you in violation of your licence.

What's it got to do with your post? Just trying to help. FCC fines tend to be steep.

No need to thank me

Unless of course you have insertion loss from the duplexer, cable loss from the hardline, etc. Is this thread about FCC licensing or mobile duplexers? Are you an FCC field enforcement officer or something?

[KG4LHQ]

Mobile radios are licensed for 50W and Fixed Operation is Licensed for upto 110W.

Not sure what that has to do with the question but thanks for your interest in my post.

I assume that's ERP, so a 90 watt transmitter with an antenna of any gain will exceed the licensed ERP and put you in violation of your licence.

What's it got to do with your post? Just trying to help. FCC fines tend to be steep.

No need to thank me

Ya know what happens when you assume? In this case its made an ass out of you.

The license calls for 110W or 245w ERP - Thank you now if you have nothing to contribute to this thread which you have failed to do so then please do not post on here.

The question wasn't asked about wattage as it pertains to an FCC license because I knew it was fine in that respect it was a simple question about the power handling of a duplexer and you came in then ran your mouth about crap that I already had taken care of.

Good day.

[Will]

So did you get a photo of the existing duplexer?

[KG4LHQ]

The county judge executive has authorized me to buy another duplexer that will run the spec'ed wattage.

Thanks Will.

[Bill_G]

The original description said it was 18 x 4 x 4 suggesting it was a small bandpass duplexer that could handle 100w without a problem. Have you looked through Sinclair's website for similar equipment?

Sinclair duplexer catalog

[KG4LHQ]

I did and even tried to call the company with such small information but was stopped both ways.

I will probably end up with the TKR-720 and the small set of duplexers out of the deal.

If I get it then I will post a better picture to get your guys thoughts.


ON the other hand just curious, coax jumpers from the duplexer to the repeater - What is acceptable? 155mhz range.

I will need to install these duplexers on the floor while the repeater is at the top of a rack cabinet so there will be a somewhat long run of coax from the repeater to the duplexers - Suggestion for good jumpers to make it from the repeater to the duplexer cans installed on the floor?

[Jim202]

The jumpers need to be a good quality, double shielded or "heliax" type cable. Do not even think about using any LMR type coax any place on the repeater system. This includes the feedline going to the antenna. You will regret it while you try to locate the noise it will cause over time.

Jim

I did and even tried to call the company with such small information but was stopped both ways.

I will probably end up with the TKR-720 and the small set of duplexers out of the deal.

If I get it then I will post a better picture to get your guys thoughts.


ON the other hand just curious, coax jumpers from the duplexer to the repeater - What is acceptable? 155mhz range.

I will need to install these duplexers on the floor while the repeater is at the top of a rack cabinet so there will be a somewhat long run of coax from the repeater to the duplexers - Suggestion for good jumpers to make it from the repeater to the duplexer cans installed on the floor?

[KG4LHQ]

They have hardline going to the antenna so no problems there.

For some odd reason the company that does all the radio stuff installation uses these small jumpers that looks like to me would be really lossy.

I, of course, want my install to be better then that.

Reading to find that RG-400 or RG-142 is about the standard for this type of install.

[KG4LHQ]

Looks to be the standard for jumpers are RG-400 or RG-142 coax jumpers.

Anywhere I can get these w/ N connectors already installed?

If its one thing I suck at is attaching connectors to coax

[gtriever]

TESSCO can fix you up with pre-built jumpers.

[KG4LHQ]

I ordered 2x 15 feet of TWS400 ( RG-400 ) jumpers with N connectors installed.

Thanks for all the help, I just want my install to be better then the others I see installed in there.

[escomm]

TWS400 is not RG400....I think it's more like LMR400

[KG4LHQ]

We'll go with it and if it generates noise then I will definitely replace the coax. I've already purchased so might as well go with it and see if it generates any issues.

[tvsjr]

As it's been explained to me, LMR - and any coaxial cable - will generate noise when used in a full-duplex application (transmitting and receiving simultaneously). This occurs due to internal heating from the transmit power causing miniscule movement within the cable, which generates noise on the RX side. Thus, for anything duplex, you want to use hardline.

However, for anything not full-duplex, such as jumpers from duplexer to RX, duplexer to TX, TX to amp, etc., a coaxial-type cable should be just fine. I've used LMR-240 for jumpers inside a cabinet with no trouble whatsoever.

One caveat - when rebuilding duplexer harnesses, it is critical to use the exact type of coax specified by the manufacturer, as slight variations in the coax can alter the duplexer's performance.

TWS400 is an RG-8 type cable - a knockoff of LMR400, similar to Belden 9913 (without the "garden hose" feature), etc. It's not RG-400.

Installing connectors is *not that hard*, at least on garden-variety coax. Anyone who's going to play radio tech should be able to install a connector. Get a few cheap connectors and practice... start with an Xacto and some electrician's scissors, a ruler, and a printed out spec sheet of the connector you're attempting to install, plus crimpers with crimp dies offering the sizes required by the connector's spec sheet. Once you get good at that, you will probably want to move up to an automatic coax prep tool. LMR400 and it's ilk is exceptionally easy... they sell an automated prep tool that works like a giant pencil sharpener, and the center conductor is large enough that you won't have any problems attaching the center pin.

You'll pay for the tools and the time in short order, compared to purchasing pre-built jumpers.

[motorola_otaku]

For the duplexer-transmitter side it's a good idea to run a RG8-size cable for 50 watts and up. RG142/400 tends to get a little warm at that power with repeater keying cycles. You can use LMR400/Ultraflex on VHF/UHF and on 800/900 use LMR600/Ultraflex or FSJ4-50B Heliax. And for the duplexer-receiver side RG142/400, Teflon RG58, and LMR195 are all excellent choices.

I can do pretty much any RG58-size crimp connector in the world with a utility knife and a $20 pair of crimpers from a local electronics shop. Like anything else, you just have to practice to get good at it.