At 9/28/2004 03:35 PM, you wrote:
>What's the best way to adjust the transmit deviation for a repeater.
Depends on what your goals are. If you're not highly bandwidth-constrained
(not on a 12.5 kHz UHF or 15 kHz 2 meter channel) & are running unlimited
hifi audio, you'll want to adjust for 1:1 repeat deviation ratio. The
method you suggest should work fine, as the deviation of the two sources
will add linearly in that case.
If you are using a deviation limiter, you need to make sure that the TX
deviation remains below the maximum deviation allowed by your coordination
to avoid causing adjacent-channel interference. Using a 1 kHz tone may not
be sufficient if your limiter is not flat over the audio passband. Voice
or white noise from the repeater receiver driving the TX at a high level
(>> 1:1) will assure that your deviation limiting is adjusted
properly. Once that's done, you can reduce the repeater TX drive level
from the controller to set the deviation ratio to 1:1 or maybe a bit higher
depending on your preference.
When adjusting the deviation ratio, the repeater TX's CTCSS encode needs to
be off. When adjusting the peak deviation (limiter or IDC), the CTCSS
needs to be on.
I hope this wasn't too confusing; I just wanted to cover all the bases
since there are differing philosophies of how repeat audio should or
shouldn't be processed.
Bob NO6B
>I was thinking of doing it this way.
>
>Setup the service monitor for duplex mode and hook the cable up to the
>antenna port on the duplexer.
>
>Manually key the transmitter and adjust the PL for .6 kHz deviation.
>
>Then adjust the generator for a 1k tone at kHz deviation with a PL tone at
>6khz deviation.
>
>Then watching it on the duplex monitor adjust for 3.6 kHz (with .6 being the
>TX pl) on the transmitter.
>
>-Tim
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