What kind of repeater and ID'er are you using? And where in the transmitter
audio circuitry is the ID audio being injected?
I've dealt with several problems, mostly with commercial-band repeaters,
where a cheap CW ID'er was hooked up to a run-of-the-mill repeater (Micor,
Mastr II, MSR2000, etc.), and rather than coming up with a clean way of
mixing the CW ID audio with the transmit audio, someone injected the ID into
the tx audio stages after the limiter/LPF. The IDer's produced something
resembling distorted square waves. Even though the deviation may be tame,
the high-frequency components pushed the modulation sidebands out far enough
to cause adjacent-channel splatter. Remember, the bandwidth you occupy is a
function of both deviation and maximum modulating frequency. Something as
un-clean as a square wave tone (rich in odd-order harmonics), or an
unfiltered synthesized speech generator, will cause you to spill over onto
adjacent channels even if the peak deviation is under 5 kHz.
--- Jeff
--------------------------------------------
Jeff DePolo WN3A - [EMAIL PROTECTED]
Broadcast and Communications Consultant
> -----Original Message-----
> From: [email protected]
> [mailto:[EMAIL PROTECTED] On Behalf Of Dave VanHorn
> Sent: Saturday, June 25, 2005 5:14 PM
> To: [email protected]
> Subject: Re: [Repeater-Builder] Splatter?
>
>
> At 04:10 PM 6/25/2005, Dave VanHorn wrote:
> >At 03:15 PM 6/25/2005, Eric Lemmon wrote:
> >>Dave,
> >>
> >>You have done all of the right things, except you did not
> mention how much
> >>deviation your IDer is causing, or how pure its signal is.
> >>
> >>Many IDers deviate much more than is necessary. My
> personal preference is
> >>something around 1 kHz, and no more than 2 kHz deviation. When I
> >>set up an IDer,
> >>I first set the code speed as slow as it will go, like one word per
> >>minute, so
> >>that a Morse dash lasts for several seconds and makes it
> easy to set the
> >>deviation.
>
>
> It's a voice unit, set to 3kHz average deviation, IOW it's roughly as
> loud as a user's voice.
>
>
> >>Another thing to look at, if you tweaked the PA, is to make certain
> >>that your PA
> >>is not generating any spurious signals. Since you did adjust the
> >>duplexer tuning,
> >>the load impedance seen by the PA may have changed enough to cause
> >>PA instability.
>
> That's a thought, but then I should pick it up on my radio, sitting
> near the repeater.
>
> >>Finally, is it certain that your repeater and the complainers'
> >>radios are exactly
> >>on frequency? Even if your repeater output is right on frequency,
> >>one or more of
> >>the complainers might have a radio that is off far enough
> that it picks up a
> >>fringe of your channel.
>
> Well, I know the repeater was set to a calibrated SM within the last
> couple months.
> The user's radios were last calibrated in Japan.
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
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>
>
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