[1000mp] Computer Interface

[Joe Subich, W4TV]

Doug, 

The FT-1000 series of radios seem to have higher current in the 
PTT circuit than most other rigs.  There are two things you can 
do ... 

  1) use a high performance optoisolator - one with a high current 
     transfer ratio.  Generally that means an optoisolator with 
     a darlington output. 
  2) Use the optoisolator with an external transistor.  A 
     2N2222 connected collector to the optoisolator collector 
     base to optoisolator emitter and emitter to ground should  
     increase the current capability significantly and still 
     maintain the galvanic isolation. 

73, 

   ... Joe Subich, W4TV 
       microHAM America, LLC 
       www.microHAM-USA.com 



> -----Original Message-----
> From: 1000mp-bounces at mailman.qth.net 
> [mailto:1000mp-bounces at mailman.qth.net] On Behalf Of Doug Rehman
> Sent: Monday, August 29, 2005 1:45 AM
> To: 'All about Yaesu 1000mp'
> Subject: [1000mp] Computer Interface
> 
> 
> I just finished building an interface for my Field for both 
> CW and digital modes. I used the circuit found at 
> http://www.qsl.net/wm2u/interface.html
> for both the CW key and the PTT. The CW key works perfectly 
> from the computer, but I am having a problem with the PTT 
> line. The PTT line is connected to Pin 3 of the "Packet" connector.
> 
> When keyed by the computer, the PTT voltage drops from 13.4 
> volts to about 2.7 volts- not enough to key the radio. If I 
> parallel 50 ohms across the opto isolator's output, it works 
> like it is supposed to (the standby voltage on the PTT line 
> drops to about .7 volts, but the radio isn't keyed until the 
> computer keys it).
> 
> I've tried to use the CW key output for PTT, but it does the 
> same thing so I don't think it's a wiring or component issue.
> 
> I've also checked the ground connection- no problem (.1mV 
> difference according to my DVM). 
> 
> It won't key the radio from the  PTT connector on the back either.
> 
> I've used this exact same circuit before on a Kenwood TS-430S 
> and TS-2000 without any problems.
> 
> Any ideas? Anybody experienced this before?
> 
> Hanks,
> Doug
> K4DDR
> 
> 
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