The Celwave PD633-6A-2N mobile duplexer is designed for the 450-470 MHz band. The similar PD633-6A-1N mobile duplexer is designed for the 406-450 MHz band. Although they are identical on the outside, the coupling loops inside are quite different, and account for their inability to be tuned much outside of their respective bands. Even though a dash 2 duplexer may seem to be working well at 70 cm, a test with a network analyzer usually proves otherwise. I have a dash 1 duplexer in a portable 440 repeater that works quite well, whereas a dash 2 duplexer was mediocre. Nevertheless, some dash 2 duplexers will work well enough at 440 to satisfy the noncritical user. As Paul pointed out, YMMV.
I suppose one could dismantle a dash 1 duplexer to see what the difference is that makes it work so well on 440, and then use that knowledge to field-modify a dash 2 duplexer- or better still, publish that information for the benefit of others. Any takers? 73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Paul Plack Sent: Thursday, April 02, 2009 8:21 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Celwave 633-6A-2N Tuning down to 441 / 446 I've never had much luck getting the little mobile duplexers that far out of band. I was able to get enough isolation for a 2-watt repeater, but loss was pretty bad. A friend who ordered a new one for the ham band had far better results. The only real difference appeared to be lengths of the interconnect jumpers. I sure wish they worked better...they're a dime-a-dozen at some hamfests. But, YMMV! 73, Paul, AE4KR ----- Original Message ----- From: bbe...@aol.com To: Repeater-Builder@yahoogroups.com <mailto:Repeater-Builder@yahoogroups.com> Sent: Thursday, April 02, 2009 8:34 PM Subject: [Repeater-Builder] Celwave 633-6A-2N Tuning down to 441 / 446 Hi all! I have a Celwave 633-6A-2N duplexer with a bandwidth of 450-470. Has anyone had any luck/success taking this down to 441tx/446rx? This is a 6 cavity, band reject 50w mobile duplexer. Thanks Again! 73, Brian ________________________________ Feeling the pinch at the grocery store? Make dinner for $10 or less <http://food.aol.com/frugal-feasts?ncid=emlcntusfood00000001> .
