Tech talk on YAESU CAT & audio

Marijan.Miletic at Marijan.Miletic at
Wed Apr 20 15:31:00 EDT 1994

Hi Contesters,

While reading recent discussions on Heil & CAT problems with YAESU,
I got a feeling that nobody reads electrical diagrams any longer!

FT-1000 dual audio output for headphones is generated by pair of transistors
with 1 KOhm in emiter, supplied from +9V via 100 Ohm & 100 uF and biased by 
100 kOhm .  Assuming optimal colector current of 4 mA, such a stage gives 
maximum of 16 mW output power in linear class A but to the 1 kOhm load.  
This is about 100 times less (- 20 dB) than available from final audio 2 W 
amplifiers.  They use 1 uF coupling capacitors which makes nice 10 kHz 
high-pass filter with standard 16 Ohms headphones and greatly rejects hum!

Yaesu CAT electrical interface consists of + 5 V emiter follower TX and
10 kOhm pull-up with diode in series for RX.  Interfacing with RS-232 
computer serial port can be done by directly connecting CAT TX output to 
RS-232 RX input.  Additional 3.3 kOhm resistor to the ground is recommended.  
RS-232 TX output can be connected to CAT RX input via 3.3 kOhm serial resistor.  
CAT input should be protected from RS-232 negative voltage by small diode of
1N4148 type with anode connected to the ground. 

ICOM & Kenwood use inverted RS-232 levels and therefore need MAX-232!

I wish you a very good luck with Yaesu CAT protocols as they take ages to 
service the simple computer request of radio frequency.  FT-1000 is supposed 
to do that fast with ROM version 6.  Unfortunatelly, I am not able to get this 
free of charge item in 6 month via K7JA!

73 de Mario, S56A, S57MM, N1YU, ex YU3EA, YU1PCF.

email: Marijan.Miletic at IJS.SI

>From Bruce Herrick <bdh at>  Wed Apr 20 14:39:46 1994
From: Bruce Herrick <bdh at> (Bruce Herrick)
Date: Wed, 20 Apr 94 8:39:46 CDT
Subject: Dayton!
Message-ID: <199404201339.IAA19778 at>

The Society of Midwest Contesters would like to welcome all amateurs to our
9th Annual SMC Hospitality Suite in Rooms 1201-1203 at Stouffer's in
downtown Dayton.  We will open around 8 P.M. on Friday and Saturday nights.

This year we are going to designate Room 1203 as the official CQ-Contest
Suite.  We will have a sign-in sheet for all you internet types, as well as
the usual refreshments and camaraderie.  Come and meet your fellow netters
and contesters!

SMC members take note:  If you are interested in a special Internet badge,
contact me at one of the phone numbers below, or send me e-mail.  Badges
will be paid for and picked up at the suite.  Cost is unknown at present,
but will probably be 3 or 4 bucks.  Order cutoff is Friday afternoon.  Sorry
for the short notice - I've had trouble posting to the reflector.  

Thanks, and see you all there!

73, Bruce WW1M & Gary W9XT
1994 SMC Suite Hosts
Bruce D. Herrick               bdh at      Home:   414.462.1270
Pryon Corporation                                  Office: 414.253.5678
N93 W14575 Whittaker Way                           Fax:    414.253.2772
Menomonee Falls, WI  53051                         PacketCluster: WW1M > NB9C

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