Did you tune it with a 50 ohm pad on each port? When I tune
a duplexer I put a 50-ohm 6db passthrough pad on the generator,
on the analyzer, and a 50 ohm termination on the 3rd port. Not
having the 3rd port terminated gives really strange readings and
results in an unusable result.
At 01:11 PM 03/02/07, you wrote:
Not a mobile, it's a celwave rack mount 99147 6 cavity, we tuned
pass first and then notch,. Into a 50 ohm load,
-----Original Message-----
From: [email protected]
[mailto:[EMAIL PROTECTED] On Behalf Of Ken Arck
Sent: Friday, March 02, 2007 12:06 PM
To: [email protected]
Subject: Re: [Repeater-Builder] repeater problems, duplexer etc.
At 03:38 AM 3/2/2007, you wrote:
>Picked up a vertex VXR 7000, and a Celwave 6 cavity duplexer. (VHF)
<---What type? One of those mobile notch-only type? How about a model number?
>Using Celwave pd-220 3a, with 25 feet lmr.
<---Some folks recommend against using LMR in a full duplex system
(this topic has been beaten to death on this list by the way but
there are good articles at the RB website explaining why)
>We have spent hours tuning the duplexer, and find that it makes the
>system deaf.
<----Keep reading...
Using an HT to generate and notch the signals, (as well as a power
meter and a swr meter) all looks good until hooked up and its deaf. A
user a half mile away can barely hold the repeater on an ht at 5
watts.
<----An absolutely HORRIBLE way to tune a duplexer. But still I'll
ask - what type of duplexer and,if a notch-only mobile type (which
those small ones are), did you tune for notch or pass? And I bet you
didn't use 50 ohm pads when you tuned?
>Using an HT to generate and notch the signals, (as well as a power
>meter and a swr meter) all looks good until hooked up and its deaf. A
>user a half mile away can barely hold the repeater on an ht at 5
>watts.
>
>I fully understand that there is attenuation inherent in duplexers,
>but this is way too much. freq pair is 4 mhz split, antenna system
>and cabling is excellent, rx and tx on the repeater is great,
>duplexer is in excellent shape.
>
>Anyone have any ideas? Are our crude methods of tuning the duplexer
>too crude? we tune the high to pass the high and notch the low (and
>vice versa on low side) but the duplexer seems to attenuate much
>more than expected.
<---See above
