[aprssig] mobile antenna for D7?
scott at opentrac.org
Wed Mar 14 14:59:29 CDT 2007
I wasn't aware of the D7 issue, but I know the Alinco DR-135 tends to get
some noise on the speaker from the GPS serial data. There's definitely some
crosstalk going on.
Don't forget that even with low-speed serial data, you can have fast slew
rates. A MAX232 will slew from -6 volts to +6 volts in about 1 microsecond.
I wonder if adding some capacitance to the line would help... just dampen
the slew rate out until it's just good enough for the RS-232 receiver in the
radio to work reliably.
> -----Original Message-----
> From: aprssig-bounces at lists.tapr.org
> [mailto:aprssig-bounces at lists.tapr.org] On Behalf Of Mark Earle
> Sent: Wednesday, March 14, 2007 1:24 PM
> To: TAPR APRS Mailing List
> Subject: Re: [aprssig] mobile antenna for D7?
> Tyson S. wrote:
> > One thing to keep in mind is that NMEA data entering a D7
> from the cable will degrade your reciever. There are various
> web sites that explain how you are usually transmitting
> better than you think while mobile. But I use a regular dual
> band antenna on my truck with an adapter from SMA to BNC and
> it works pretty good.
> Huh? I'm not trying to pick a nit, but low speed serial data causes
> receiver degradation how?
> What do you mean degradation? Reduced sensitivity? Reduced
> Intermodulation distortion? Overload?
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