Tony Brock-Fisher, K1KP
The basic problem is that the AL-1200 relay is a bit slow. I have developed a circuit that can be built and installed in the external keying line to the AL-1200 which will significantly increase the speed of the stock relay. No modifications are required to the AL-1200. The cricuit works by charging a cap from the keying line, then using this stored charge to give the relay an extra ‘kick’ on closing. I use it with the AL-1200 and an IC-765.
Here goes:
^ key line to amp
|
|
|_________________
| |
| |
| |/ c
| ______| TIP47
| | |\ e
| \|/gnd |
\ / 1N4004 |
v |
--- |
| |
<------------------||----------
to rig + 47uF |
|
\ /
V
--- 1N4004
|
|
\|/ gnd
Disclaimers:
1. This will increase the switching noise of the relay.
2. This must not be used on any amp that uses high voltage for relay actuation such as SB-200, SB-220 etc. This must not be used on any amp where the keying line goes to other circuitry besides the keying relay (such as bias, EBS, etc.).
3. This has been tested only on an AL-1200.
4. No liability for use is assumed/implied by K1KP.