[Elecraft] K3 PTT with DEMI Transverters

[Ken Arck]

Hi Ken

I too use a DEMI xvtr and used the following circuit to exploit the 
K3's capability to set a logic bit on the ACC connector based on band

Ken




At 09:33 PM 7/17/2016, Ken Kontor via Elecraft wrote:
>Gentlemen,
>
>I am looking for a circuit that one of you K3 users may have 
>designed to automatically switch the K3 PTT line between multible 
>external transverters as the K3 is switched from band to band.
>
>I presently use the K3 PTT line to key my 6m amp driven with 30 w from my K3.
>
>I recently purchased a DEMI 2m HP transverter to drive my 2m 3CX800 
>amp. The DEMI puts out 50 w with 1 mw of drive from the K3. The 
>problem I have is when I key the DEMI Transverter from Pin 10 on the 
>K3 15 Pin accessory socket, the K3 PTT out on the back of the K3 
>also Keys my 6m Amp even though the K3 is set to 2m. I need a 
>circuit that will decode the BCD output from the K3 15 Pin connector 
>to key the 6m Amp when I am on 6m and automatically switch the PTT 
>line to the DEMI Transverter when I am on 2m. A manual switch would 
>be very inconvenient for VHF contesting as one need to quickly QSY 
>between bands with one station for multiple points. Also in the 
>future I might add a 432 Transverter and would like to auto 
>switch  the PTT for it also. I would only require three outputs as I 
>would only switch between 6m, 2m and 70 cm.
>
>I am a Mechanical Engineer with limited Electrical knowledge. I did 
>build  a K2 and can breadboard stuff from a schematic and parts 
>list, but I am not a circuit designer and have no knowledge of 
>digital logic stuff other than I know it exists. I am in need of a 
>designed and tested circuit that is know to work reliably. Given the 
>circuit diagram and a parts list I could then reproduce it.
>
>Your help is greatly appreciated. Thank you in advance for any 
>information you can provide.
>
>73, Ken - W8KEN
>
>
>PS: you may contact me off line at w8ken at yahoo.com
>
>
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