SB-104 Talkback fix

[Domenic M. Mallozzi]

MODIFICATION FOR TALKBACK ON THE SB-104 / HW-104 SERIES

( WARNING  -  THE FOLLOWING MODIFICATION WAS PROVIDED BY HEATHKIT MANY YEARS 
AGO TO CORRECT A TALKBACK PROBLEM ON A FRIEND's SB-104. I PUT THE MODS IN HIS 
RADIO AND IT WORKED FINE. THE MOD IS NOT ON HEATHKIT LETTERHEAD NOR IS IT 
DATED,  BUT IS RATHER A PHOTOCOPIED SHEET THAT IS STAMPED AND SIGNED RON 
NICKERSON-COMMUNICATIONS. I TAKE NO RESPONSIBILITY FOR THE MODIFICATION OR 
ANY PROBLEMS IT MAY CAUSE YOU.   N1DM)

(SB Series)

Step 1

Disconnect gray wire from lug 2 CW switch and reconnect to lug 3 of the tune 
switch.

Step 2

Disconnect the jumper from lug 3 of the tune switch to lug 2 of the CW 
switch.

Step 3

Disconnect the white-violet wire from lug 4 of the CW switch and reconnect 
this wire to lug 6 of the high switch.

Step 4

Disconnect the jumper running from lug 6 of the CW switch and lug 6 of the 
lower sideband switch.

Step 5

Disconnect the gray wire running from lug 6 of the CW switch and reconnect it 
to lug 6 of the lower sideband switch.

Step 6

Install a 100 ohm, ½ watt (I-3) from the high switch lug 6 to the CW switch 
lug 3.

Step 7

This is an orange wire running from F19 to the relay pin 11. Disconnect this 
wire at the relay pin 11 and reconnect it to pin 3 of the relay.

Step 8

Connect another orange wire from F19 to lug 4 of the CW switch.

Step 9

Connect a third orange wire from lug 6 of the CW switch to pin 3 of the K 
board.

Step 10

Install a 1 Kohm (I-95) from pin 19 of the F board to ground.


END OF MOD


This mod is also posted in the technical articles section of the Natick 
Emergency Radio Net's homepage (which I maitain):

http://publish.hometown.aol.com/dmallozzi/myhomepage/index.html

Dom N1DM

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