Satgen68  More Receivers for Uosat3 9600 bps FSK    by GM4IHJ  17 July 90

I am still being asked " If the receiver audio for reception of 9600 FSK
from Uosat 3 Oscar 14 ,can be taken from the receiver phone socket or its
recorder socket" ? THE ANSWER IS NO. Because the high keying speed needs
both a wide bandwidth ( not available in most receiver audio circuits),
and, the signal must not be distorted by de emphasis, ( a feature present
in most FM receiver audio circuits ). To avoid these problems 9600 Rx
Audio must be taken out at the Rx discriminator before bandwidth filtering
and de emphasis occur. This means in almost all cases that you must carry
out a "Do it Yourself " DIY mod on your Rx to bring out this signal. But
see 4a and 4b below.

Several people are I know looking for old UK CB receivers to modify for
9600 reception. This is a good route with a 435/27 converter if you are
familiar with DIY mods. For those who dislike large scale modification of
equipment there are other methods available depending on what sort of
equipment you have :-
1.  Using an HF FM Rx . Eg Trio Kenwood R2000 - Use a standard commercial
converter ( Microwave modules 432/28 - 434/28) to get Uosat3 435.07 to
29.07MHz to the Rx. Then modify the receiver to get Rx Audio from
discriminator ( R2000, Wire screened lead from common point R207, R209,
R210 , C200 to additional jack socket at Rx back plate).
2.  Using a 144MHz transceiver or receiver. Eg Yaesu FT211R. Use standard
432 to 144 converter to get 435.07 as 147.07MHz. Take output from Rx
discriminator from card PB-1463(FM IF) connection 2 to one of unused relay
sockets at Rx rear, after disconnecting unused relay connection.
3.  Using UHF Rx Eg ICOM R7000 - No converter necessary simply take Rx
audio from FM discriminator on IF unit at common point of R97 and R96 to
spare socket on Rx back plate. Or - Yaesu FRG 9600 Rx take screened lead
from pin 9 IC MC3357 FM discriminator on N.FM UNIT F26821011 accessory
board near middle of Main board, to recorder socket at Rx rear after
removing existing recorder signal feed via R53.
4a.  Do it Yourself. Build a converter for 453 to 10.7MHz and feed output
to the 10.7MHz IF in a circuit using a MC3357 FM discriminator chip. Take
Rx audio from pin 9 of this chip.
4b.  To avoid any work inside your Rx. Take a suitable comverter to feed
your Rx ( 435/29 or 435/147 or none if UHF Rx ).Extract 10.7 MHz signal
from your Rx via usual back plug outlet for this signal. Then feed this
10.7MHz signal to a DIY home made circuit using an MC3357 chip , taking Rx
audio from pin 9 of the chip. Hopefully if 9600 bps reception becomes
popular , commercial manufacturers will eventually produce a 10.7MHz to Rx
audio out add on circuit which can be plugged into the back of most Rxs, (
many of which already carry a 9v supply on their 10.7MHz outlet for this
sort of attachment). There is potential in this method for providing
automatic frequency control over the 22KHz of doppler shift of the signal.
73 de John GM4IHJ@GB7MAC 17th July 90