Jim jlboockh at earthlink.net
Sun Aug 7 11:46:45 EDT 2005

Tommy and Dave-

What I have in mind is identifying a button I don't use, disconnecting 
it from its intended circuit, and using it to switch the roofing filter. 
It doesn't have to be the FM or VOICE buttons. I don't want to use PROC 
since I occasionally use it.

For example, I will probably never again use an auxiliary receive 
antenna. I could disconnect the ANT switch and solder the MAIN antenna 
permanently in the circuit. Then use the ANT pushbutton to switch in 
13.5 v from somewhere, such as the Aux 13.5v jack on the rear panel. 
This switch would connect to J5 on the roofing filter board.

Tommy, when you used the PROC button for this, how did you set the four 
switches on S1 of the roofing filter board?

Thanks for the suggestions.

			Jim  N4AL

Tommy wrote:
> Jim,
> You don't actually disable the processor, you basically 'steal' a 
> positive voltage from the pc board for the PROC switch.  The reason I 
> used the PROC switch is only because I very seldom operate SSB. If 
> you do use SSB and the processor, this is probably not where you want 
> to switch the filter on/off. You need just a few milliamps of 
> positive current to turn on the transistor that switches in the 
> roofing filter relay.
> This idea, which really simplifies then roofing filter installation, 
> was originated and shared by K1FK.
> Tommy - W4BQF
The FM and VOICE buttons (nor any other button on the main keypad) 
CANNOT be used directly for this function.  They have a different logic 
interface with the main µProcessor and would require a buffer in order 
to drive another load, such as the Inrad roofing filter mod.

73, Dave, K1FK
Fort Kent., ME
ARRL Life Member

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