RE: FT100D not transmitting

Hi Keith,

 

If you are using a 1k resistor to ground to operate the PTTY it won’t work. There are two control lines from the Mic to the radio being the SW1 and SW2 lines. These must have different resistances to ground for their various functions.

 

Have a look at http://k0lee.com/mic.htm which shows the basic wiring of the mic buttons for the various functions. As you will see PTT requires a 27k series resistor to ground and each subsequent button requires progressively higher resistance values thus the SW1 line has PTT, Down, Up and Acc buttons on it and, obviously the one with the lowest resistance to ground will win every time so PTT has the highest priority followed by Down, then Up and finally Acc.

 

Sorry if this is not the problem you are having but it is a trap which many have fallen into over the years. Much less than the 27k to ground and nothing happens.

 

73….Eric VK2VE

 

From: [email protected] <[email protected]> 
Sent: Wednesday, 31 October 2018 17:12
To: [email protected]
Subject: [FT100] FT100D not transmitting

 

  

I have an FT100D which will not transmit on any band. It doesn't even go into TX mode which means it will continue to RX when the PTT has been pressed complete with receive audio. The PTT signal gets to the appropriate input pin on the CPU, going from 4.5 V to about 1 volt. Pulling it to ground with a 1 K makes no difference. The appropriate output pin, HF/50TX or V/UHFTX doesn't change state. If anyone has any ideas, I would appreciate hearing them. The only thing I can think of is that the CPU is faulty but the receiver works fine.





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