These are the 28-37-11E, 6" duplexers, 3 on each side with 85 dB Isolation per channel, rated at 400 Watts. But if what one mentioned that it should be about 120 watts out, then I am not to far off. As for the meter, I used a Yaesu YS-500 meter, that I have ran along a Bird 43 meter and specs were so close that I could not argue with it, but now I have a Bird 43 here to work with, so will run the test with that on Saturday. As for the slug, I have the 250 watt slug that I will be using. I'm going to make some changes in the cable's that goes from the amplifier to the duplexer and see if I notice any changes there. Over all, the performance of the system had improved as to the reason I went after the duplexers.
For some strange reason one of the duplexers lost it's tunning, and started getting some decense. And after the tunning process, the repeater now transmit's just about as far as it can receive, so
back to more of a balanced system. What was happening was I could hear users about 40 miles away, but they could only hear the repeater about 25 miles away, and got real noisy at that. Maybe an s-unit or two, but very noisy. Before I did anything to the duplexer's, it was running at about 90 watts, hardly enough to make such a differnce, but it did.
Mathew
skipp025 <[EMAIL PROTECTED]> wrote:
You guys are missing something... no one asked
him what size cavities he's using. If they are the
smaller TX/RX units... the reported lower power
output values are probably normal when using the
higher insertion loss settings with smaller
cavities.
cheers,
skipp
> "Jeff DePolo WN3A" <[EMAIL PROTECTED]>wrote:
>
>
> > The other thing.... All of the RF power being produced at
> > the 200 watt
> > level may not be on the operating frequency. Remember that a
> > watt meter
> > reads total power, not just the power on the repeater
> > frequency. If the
> > transmitter or PA or both are spurious or dirty to some
> > degree, you may
> > actually have less power (on your transmitter frequency) than
> > you think,
> > even though the power 'reads' higher. Since the duplexer provides
> > filtering, the power leaving the duplexer may show less due to the
> > removal of the spurious energy.
> >
> > Kevin Custer
>
> And to add to that, bear in mind that if you only have one wattmeter
and you
> use it to first measure the input power to the duplexer, and then
disconnect
> it and move it to the output of the duplexer that you've changed the
> electrical length of the cabling between the devices. Unless
everything is
> tuned and operating at exactly 50+j0, changing the effective length
of any
> of the cables is going to change the Z that the transmitter sees.
To get
> around this problem you have two options:
>
> 1. Make up a short patch cable with the same connectors as your
wattmeter,
> and substitute it in place of the wattmeter to maintain a constant
> electrical length when moving the wattmeter between devices in the
system.
> The cable must be the same electrical length as the wattmeter's
effective
> electrical length. For something like a Bird 43, the length is
known (and
> published by Bird) making this easy. For other wattmeters, particularly
> non-thruline types, this becomes more difficult.
>
> 2. Use two wattmeters, calibrating the differences in readings by first
> connecting the two back-to-back (preferably without an jumper cable).
> Transmit through the wattmeters into a dummy load and record the forward
> power readings of both wattmeters. Determine the error between the
two in
> dB. Then put the wattmeters into the system at their appropirate
locations,
> determine the measured loss based on their readings, and then
correct that
> value by the difference you originally recorded.
>
> --- Jeff
> --------------------------------------------
> Jeff DePolo WN3A - [EMAIL PROTECTED]
> Broadcast and Communications Consultant
>
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