Batboard

Hi all...

I've got my hands on a few Sinclabs MR3332 Duplexors. I'm wanting to build a small portable repeater out of a couple of Maxtrac radios - both of which are UHF. These duplexors are currently on 413/417. I'm wondering what would be the maximum frequency I could tune them up to. A quick Google search shows these do 406-512 so I'm hoping they'll tune up to my needs (450/455).

Any assistance would be great!

Many duplexers are spec'd to cover a wide range, i.e. 406-512. The individual CANS will tune over that range, but to get a working duplexer, the interconnection cables are cut to a specific length for a much narrower band. So there might be cables 11 inches long to cover 450-470 but 11-1/2 inches long to cover 430-450, etc. Mobile duplexers, being much smaller, often use rigid coax that's soldered into place and can't easily be fooled with out in the field.

If you can get ahold of Sinclair, they might be able to give you the exact frequency range the unit is capable of, if given the full model and serial number.

Bob M.

Uh, scuse me, these appear to HAVE no interconnecting cables

Here's some info from


http://www.repeater-builder.com/rbtip/a ... #duplexers


http://www.repeater-builder.com/sinclai ... -specs.jpg


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


73, W7DJM

If you look real closely at pictures of mobile duplexers, including the one posted above, you'll see tubes, maybe 1/8 inch in diameter or slightly bigger, that run from section to section. There's some insulation and a center conductor inside these, forming a coaxial assembly, and they do connect the sections together electrically. Some manufacturers use flexible coax and solder it in place, then paint it black. If you don't want to call them cables, that's fine with me. They're installed during manufacture and are not removable or easy to change. They're mass-produced to cover the frequency range, then the sections are tuned and they get shipped. I never said these could be moved to another frequency band, and in most cases, it's not worth the effort to even try.

On bigger, base-station duplexers, there ARE cables, usually made from RG-214, and these CAN be changed. I could not tell what the original poster had, just from his model number, so I gave a broader answer. Maybe my information will help someone else some day when they're in a similar situation.

Bob M.

The duplexer will tune up for you, it just won't be pretty. If it is not for professional use, or you don't need the exact performance specs, then tune her up. If it is for a customer or the like, then call Sinlcair and have them send you a tuned harness for the duplexer and frequency you are using. It will be cheaper then getting a new duplexer.

Sinclair cans will do the whole band, it is just the critical length cables that are inportant.

It's for a portable Ham repeater.

Currently, it's tuned up around 413/417MHz.

I've abandoned my plan of using it for a commercial repeater as the need for that is no more. So, it'd just have to tune up 444/449.

Thanks!

If you look real closely at pictures of mobile duplexers, including the one posted above, you'll see tubes, maybe 1/8 inch in diameter or slightly bigger, that run from section to section. There's some insulation and a center conductor inside these, forming a coaxial assembly, and they do connect the sections together electrically. Some manufacturers use flexible coax and solder it in place, then paint it black. If you don't want to call them cables, that's fine with me.

Ok, I won't I haven't, and I don't--call them cables. When I said that

Uh, scuse me, these appear to HAVE no interconnecting cables


I was stating that in context with what you said--from which one can infer that the cables can be lengthened, shorted, replaced. I sure won't try that on one of these, and I can't imagine, given the type of duplexer that they are, that one would need to

have them send you a tuned harness for the duplexer

evidently, we all are talking about some completely different duplexers here?

evidently, we all are talking about some completely different duplexers here?[/quote]

I was just mentioning getting a new harness for general info on most duplexers.

I'm sure we are all aware that the "flat pack" mobile duplexers' harness cannot be changed or modified too easily without screwing them up.

The duplexer you have will go to the freq you want to put in it. You shouldn't experience any problems and they will still perform well there. You will probably experience better performance putting them in the 450 area, because it is closer to the middle of the band. Of course, the only can with this typr of duplexer is the limited Q.

Good Luck
Cheers

http://antennasystems.com/PDFs/Sinclair/mr3332.pdf

The MR3332 mobile duplexer comes in 5 different band splits. Since yours is in the lowest split (406 to 430), it may just barley go into the ham band (the 430 to 450 split). If it doesn’t you can open it up and take some turns of the helical resonators.

MR354 and MR346 mobile duplexer models come in three different band splits that are wider and will tune the ham band split.

Nand.