RE: [Repeater-Builder] Celwave 5042-1

[Eric Lemmon]

Don,

The Celwave PD5042-1 Duplexer was made in two versions, the PD5042-1-05, and
the PD5042-1-50.  Both versions are described in the Celwave and Motorola
catalogs as "dual pass-notch" duplexers.

The PD5042-1-05, AKA the Motorola RDD4900A, was intended for a minimum TX-RX
separation of 500 kHz.  It had an insertion loss of 1.8 dB, an isolation of
60 dB, and a power rating of 100W.

The PD5042-1-50, AKA the Motorola RDD4906A, was intended for a minimum TX-RX
separation of 5 MHz.  It had an insertion loss of 1.0 dB, an isolation of 90
dB, and a power rating of 350W.

These duplexers are very good, but they were essentially made-to-order.
They will NOT work to spec over the entire 138-174 MHz range; they must be
optimized by the factory to work at the frequencies specified by the
customer.  In other words, the advertised specification is a range that
Celwave can manufacture the duplexer; it has nothing to do with ranges over
which an existing duplexer may be tuned.  The coupling loops must be
optimized for the customer's frequencies.  Normally, a duplexer originally
made for a commercial frequency pair in the 150-160 MHz range will not work
properly in the Amateur 2m band without factory rework.  I know of several
cases where a fellow re-tuned one of these duplexers to the Ham band, and
thought that is was "working just fine."  Not!  Once one of these duplexers
was properly reworked by Celwave to the 2m band, the performance was
significantly improved.  As always, YMMV.

73, Eric Lemmon WB6FLY
 

-----Original Message-----
From: Repeater-Builder@yahoogroups.com
[EMAIL PROTECTED] On Behalf Of Don Spivey
Sent: Monday, January 07, 2008 11:51 AM
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