Thanks for everyones help regarding this duplexer. By combining the information in each reply, can I assume I could have a good shot at tuning this duplexer to the bottom end of the 2m repeater bandplan if (1) The duplexer is factory tuned slightly below the 2m band (below the 145 split mentioned by one reply) and it there has been no attempt by anyone else to retune it?
I'm assuming a lot, but if it's only a couple of megs off now, I'm thinking it may only need a minor "tweeking" rather than major adjusting of the coupling loops, etc. Does this sound reasonable also assuming I have the tuning instruction??...Thanks again.....N5MZQ...Don --- In Repeater-Builder@yahoogroups.com, allan crites <[EMAIL PROTECTED]> wrote: > > Don, > The manual I have for a Celwave 5042M-1-2-3 does not spec a power rating for use at less than 1.0 MHz of 200 W. > It indicates the unit is tunable from 132 to 174 MHz with a band split at 145 MHz requiring different loop assemblies. > Since there are 3 ranges I assume there are three different cable assemblies but nothing is indicated in the manual to confirm this. > The individual cavities are shortened coaxial resonators with a pass dual notch coupling circuit mounted on a rotatable loop plate. > Notch placement relative to the pass band frequency is accomplished with variable capacitors on the rotatable loop assemblies. > Improper adjustment of the variable capacitors can and will easily destroy them. > Persons not familiar with the tuning procedure have been known to rotate the caps too far and thus damage the loop assembly. > What else would you like to know? > 73 Allan Crites WA9ZZU > > Gary Schafer <[EMAIL PROTECTED]> wrote: > I don't know that particular duplexer. The close spacing capability is not > an indication that it is a band pass/band reject or a straight notch type > unit. It could be either. > > The difference in the smaller mobile type or smaller rack mount type > duplexers is usually in the insertion loss. The smaller the cavity the > higher the insertion loss will be for a given set of operating parameters. > It is usually not a problem getting enough rejection in the notch but it > comes at the cost of higher insertion loss with the small cavities. > > The mobile type duplexers are usually notch only type and the other problem > is that they usually have fixed capacitors in the internal loops that you > can not change. So when you move them any great distance in frequency the > insertion loss ends up even higher than the original spec because you can't > change the loop capacitors. > > 73 > Gary K4FMX > > > -----Original Message----- > > From: Repeater-Builder@yahoogroups.com [mailto:Repeater- > > [EMAIL PROTECTED] On Behalf Of Don Spivey > > Sent: Monday, January 07, 2008 2:51 PM > > To: Repeater-Builder@yahoogroups.com > > Subject: [Repeater-Builder] Celwave 5042-1 > > > > Has anyone had any experience with a Celwave 5042-1 duplexer? I've > > very skeptical of any rackmount VHF duplexer although specs on the 6 > > can version (this one) shows it capable of 500kc spacing at 100 watts. > > I've seen several of these in recent months and mow I'm getting > > curious. I haven't located tuning instructions either, and some of the > > Celwave mobile duplexers can be a bear to tune, so I've heard. For > > that spacing I would assume this must be a band pass/band reject > > design too...73 & Thanks...N5MZQ....Don > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > >
