Msg Nr.     : 205433
Da          : PE1DNA
Per         : 9K6   @WW      
Tipo/status : BF
Data/ora    : 0621/0224
Dimensione  : 3758
Bid (Mid)   : 91610_PI8ZAA
Titolo      : Modifica 9600 baud per TM733

Hello,
John, ZS5J wrote :

----------------

Hi and thanks for reading this message. I recently bought
a Kenwood TM 733A 9600 ready vhf/uhf rig, and a Kantronics
KPC 9612 9600/1200 baud tnc, and have the new WISP software
for working the pac sats. I have been trying for weeks to
get this setup to work - I get a very good signal from the
satellites, but I can't get my system to communicate with
the satellites. I had my KPC 9612 set for the proper deviation
with a deviation meter, so that shouldn't be the problem.
Any help would be appreciated. If you are using the same
or similar system and have it working, please let me know
your experiences.
Please leave mail for me, John ZS5J @ ZS0WTE.NTL.ZAF.AF
------------------

Well John, i'm sorry i have to say this but the Kenwood TM733 is
definitely NOT suited for 9600bd operation. It has several
serious design bugs. 

- PLL modulation, thereby giving very bad Bit Error Rate figures because
of the bad lf response of the modulation circuits. At 64 Hz, there is a
4.5 dB rise.

- Slow tx<>rx switching. The TM733 needs 100-150 milliseconds to
turn around. If your opponent (satellite or earth station) is faster
with replying you keep on missing his first packet.

These problems are very common in the current generation '9600bd ready'
transceivers. The Icom IC281/481, Yeasu 5100 and many others suffer
from these problems.
The Kenwood TM733 has another design bug :

- If you try to make more than about 2.5 KHz deviation via the data port,
the modulation gets very distorded. This is not easy noticable, since
9k6 modulation sounds like noise, and distorded 9k6 also sounds as noise..
This problem is seen at more than one TM733, throughout Europe.

I sure hope you can send this thing back and get your money back, John.

73 Joop, PE1DNA @ PI8ZAA