On Thu, Dec 09, 1999 at 08:55:48PM +0100, Thomas Sailer wrote:
> Bob Nielsen wrote:
> >
> > On Wed, Dec 08, 1999 at 03:45:40PM +0000, Patrick Ouellette wrote:
> >
> > > Most of the newer mobile radios from the major manufacturers include
> > > 9k6 ports.
> >
> > Have you found any of these to actually work (low BER, txd < 30 ms or
> > so)?
>
> Good question. Henning DF9IC has measured a couple of mobile
> transceivers
> claimed '9k6 capable' about 3 years ago, and none was satisfactory.
> I've heard of new allmode transceivers (one ICOM model) that works well
> with 9k6, that is however >$2000.
That was my point. I believe QST came to a similar conclusion. The
allmode transceivers tend to use a heterodyne scheme for transmit so
that you modulate a crystal oscillator stage rather than the PLL. As I
recall, an early Azden FM transceiver did this as well and had
reasonable 9600 performance.
Otherwise there is a trade-off between poor frequency response (fast
PLL time-constant) and poor T/R switching times (slow PLL
time-constant). There are ways to compensate for the frequency
response, but it's a bit tricky and may not be all that stable in a
production-line radio.
TEKK and some other data radios work fairly well, as do some converted
crystal-controlled commercial radios, such as Motorola Mitrek.
>
> In the end you're probably better off with dedicated designs like
> the T7F kit by Holger Eckhardt.
Do you have a URL for this?
Bob
--
Bob Nielsen, W6SWE (RN2) Internet: [EMAIL PROTECTED]
Tucson, AZ DM42nh AMPRnet: [EMAIL PROTECTED]
QRP-L #1985 http://www.primenet.com/~nielsen
