Paul, Full-size BpBr cavity duplexers can easily be detuned with rough handling, especially when the box is dropped on its side- which puts sideways shock loads on the center tuning element. Notch-only duplexers of the "mobile" type are, by design, far more resistant to vibration and rough handling. The Celwave 5085-1 duplexer I cited is a notch-only duplexer that is about 50% larger in all dimensions than a typical "mobile" duplexer, but it should be nearly as rugged. I don't expect this portable repeater to be bouncing around in the bed of a pickup; it will likely be strapped to a shock-mounted storage shelf in my RAV4, along with magnetic mount antennas and a telescoping mast.
A simplex repeater on an existing repeater pair is an excellent idea. I already have one in service, being tested on a coordinated pair assigned to me. It is a Motorola SM50 VHF radio connected to a Zetron 19B "Simplexor" simplex repeater controller. It listens on the repeater input frequency and plays back on the repeater output frequency. A Comm-Spec ID-8 performs the identification functions while the repeater is in use. It gets used a lot by Hams who want to hear how their radio sounds. I will be the first to admit that a simplex repeater (isn't that an oxymoron?) gets to be tiresome to use real fast, and some users get annoyed by hearing everything twice. But, hey, in an emergency it works. One of the posters commented that it would be chaos while everyone tried to reprogram their radios to the special wide-split portable repeater frequency. Not! The majority of the Hams who will use this portable repeater are fully-trained ARES members who test their equipment on a weekly basis on several nets, and all of their personal radios are pre-programmed. One of the local ARES groups has a cache of Motorola HT750 portable radios which are already programmed with every local repeater, including the wide-spaced portable. We take emergency preparedness seriously in my neck of the woods, and we don't expect or need to have a sudden influx of clueless people who don't know how to program their own equipment. It is a requirement that each ARES member have in his or her possession a valid Disaster Services Worker identification badge issued by the County Office of Emergency Services. Mandatory refresher training, including CPR, is routine. 73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of Paul Yonge Sent: Monday, May 08, 2006 6:20 PM To: [email protected] Subject: Re: [Repeater-Builder] Portable Repeaters Eric - Thanks for the comments on duplexers. When I started this in January, I remember reading some comments about some duplexers getting "out-of- tune" from bouncing around (mainly in shipping) and that's what got me thinking about simplex repeaters and, now, about cross-band repeaters. Is subjecting the duplexer to vibration and shocks in a truck on a rough road really something about which to worry? One of the comments I received when I proposed using simplex repeaters was that, if a fixed-repeater went off the air because of power failures, it would be possible (with the permission of the repeater owner/trustee) to tune the simplex repeater to the fixed- repeater frequencies as a temporary measure until the fixed-repeater could be returned to service. What do you think of that? Paul W2ARK Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
