开云体育

ctrl + shift + ? for shortcuts
© 2025 开云体育
  1. YaesuFT847
  2. Messages
Single Messages Topics Expanded

Re: disable ptt function on rear DATA jack in the presence of isolation transformers?

 

开云体育

Sorry skip that…… I just couldn't decipher that on a mobile phone …. So small. There should also be a 2k resistor if the equipment uses and external PTT and does not reply on the high side signal I don’t see that in your drawing.

? If you want to disable PTT then use the TX inhibit lines. If you see the attached image of the Tuner socket then you can use a resistor I believe to tie this TX inhibit to a pull up but you need to ask Andrew Lenton this as ?I believe as it was he that told me about this. I often work remote and when my PC starts up it sometimes pulls RTS or DTR (which one I’m not sure) ?high and puts the radio in TX. I?wanted this to stop as the radio could be out of band listening to something like AM broadcast etc and certainly didn’t want TX there so came up with the idea of inhibiting the TX with a remote relay and resistor. I went with a different solution I the end as my tuner was always inline unless using the CAT connection.

? Sorry for the mixup but I’ve been reading another thread and couldn’t quite get my head around something.

? Hope this helps as the TX inhibit can easily be sequenced to enable and disable.


De Spence G5STO


image0.jpegimage1.png
Sent while portable! please excuse typos.

On 5 Jan 2025, at 16:40, Spencer Tomlinson <unavailable.equal@...> wrote:

?I don’t see a 10uf capacitor in the FSK out lines?

De Spence G5STO

Sent while portable! please excuse typos.

On 5 Jan 2025, at 14:19, Rob MW0CQU via groups.io <mw0cqu@...> wrote:

?
Afternoon all ,?

Checking my understanding of a perceived challenge here with you all:
before buying the bits and prototyping a cable...?

It seems that plugging the 847's rear 3.5mm data jack into anything with audio isolation transformers
at the far end (thereby effectively dc grounding the tip of the 3.5mm plug) forces the rig into
constant TX irrespective of any remote PTT settings (correct?)?

And therefore, interfaces like the SCU-17 which feature such isolation, require something like a 10nF
blocking cap (depicted as C-BLOCK --||-- below) like (hope this scales) :

RIG END? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? PC INTERFACE END

? ? ? ? ? ?|----------------------------------------|
TIP |RING|EARTH|------------------|EARTH|RING|TIP|
?|----------------------||-----------------------------|
? ? ? ? ? ? ? ? ? ? ? ? ? ? ?C-BLOCK

inline to stop this constant PTT (correct?)?

is there any other way (I cannot see one in the menu?) to disable that data port PTT without rig surgery ?

many thanks and 73 de

'CQU
Join [email protected] to automatically receive all group messages.