Don,
The Celwave 5042M and the 5042-1 are the same duplexer which was
manufactured by Celwave in Phoenix AZ for Motorola.
The 5042M was supplied to Motorola with the Motorola part no. 01 V 85417xxx
for use in Motorola base stations. They were supplied tested and tuned to a
stock freq. from Celwave and were re-tuned by Motorola contract employees to
the freq. required in the base stations at the Motorola factory.
The 5042-1 Celwave duplexers referenced by Eric Lemmon were sold under the
RDD4900A Motorola Parts Dept.no. having a revised spec. negotiated by Bryan
Corley of Motorola with Celwave for the 500 KHz spacing, higher insertion loss,
and the higher power.
The 5042 duplexers, while able to be used over a freq. range of 132 to 174
MHz, had 6 different loop assemblies depending if the unit was for low
pass-high notch or high pass-low notch, and 3 different cable assemblies
required to operate in this range.
The Motorola parts dept. would take an order from a customer for a duplexer,
sent the operating freq's, and other parameters to Celwave, who tuned the
duplexer and drop shipped the unit to the customer direct.
As Celwave's OEM Support Manager to Motorola in Schaumburg in the 1990's, I
had occasion to observe the Celwave factory personnel tune these duplexers when
I was at the Celwave factory in Phoenix.
I then later myself tuned, trained & instructed Motorola factory personnel
of the methods necessary to tune the 5042 duplexers, who after destroying many
loop assemblies, were able to do the alignment properly. Unfortunately for
Motorola the personnel changed around regularly and retraining was an ongoing
process because of the loop assembly destruction.
Alignment tuning of the duplexer requires the cable harness to be removed
and each cavity be tuned separately, the harness then is reassembled to the
cavities and optimization of the input and output of both legs "may" be needed
to get the best return loss.
I caution you that this comprehensive realignment needs to be performed even
tho you are moving only a MHz away from the original tuning. A network analyzer
or such similar test equipment is mandatory if the optimum benefits of the
duplexer is to be realized.
I suggest you obtain the 5042-1 instruction manual from Celwave ( now known
as Radio Frequency Systems ) in Connecticut.The manual I have is 44 pages and
not for the 5042-1.
73 Allan Crites WA9ZZU
Don Spivey <[EMAIL PROTECTED]> wrote:
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
> >
> >
> >
>
