So...I'm going to show stupidity here. Nothing new...so bear with me, please. Anyway...looking to use the DMK dongle to key a radio whose PTT is a simple key to ground. Think normal HF or vhf rig like a 7900 or even a KenYaeCom HT, where the ptt basically closes a circuit. Hooking up a meter between ground (pin 20) and pin 1 (PTT) on the DMK, and issuing a command to key the dongle gives me close to a 0 ohm reading, but not quite; still at about 10 ohms. (and I know how to hook up a meter...fwiw, it's a simpson 260, not a digital, so, I can see the needle swing...). This obviously is not what I'm looking for. Yes, I know what the circuit is rated for (not much) and it's an open collector... So, the question is...is this pin basically a contact closure (which IS what I'm looking for), or some other logic level that I'll have to convert? If so...any pointers or ? I freely admit that digital logic (or lack thereof...) especially at this level (pretty basic, huh?) escapes me...but am willing to learn. TIA. Bryan WB0YLE Allstar 27294/27295 Echolink WB0YLE-R
So, the question is...is this pin basically a contact closure (which IS what I'm looking for), or some other logic level that I'll have to convert? If so...any pointers or ?
It's like a contact closure, except it will not pull the voltage all the way to ground and it will not handle much current. It works fine for radios that use logic-level kinds of signals. That is the vast majority of ham radios. I have had to add an additional relay and/or transistor externally to switch big things (like my Motorola Nucleus 300 watt paging transmitter). 73 Ken PS: see http://www.dmkeng.com/images/GPIO_Relay.pdf http://www.dmkeng.com/images/HIGH_CURRENT_PTT.pdf
On 2/19/2011 7:56 PM, Ken wrote:
So, the question is...is this pin basically a contact closure (which IS what I'm looking for), or some other logic level that I'll have to convert? If so...any pointers or ?
It's like a contact closure, except it will not pull the voltage all the way to ground and it will not handle much current. It works fine for radios that use logic-level kinds of signals. That is the vast majority of ham radios.
I have had to add an additional relay and/or transistor externally to switch big things (like my Motorola Nucleus 300 watt paging transmitter).
Relays...now, that's something I can sink my teeth into...turn on the mic here in my broadcast recording studio, and you can hear them clunking all over the place...shutting off speakers and turning on 'On Air' lights. Guess it's time to pick up a small 12V relay, 2n4401, couple diodes (need to replace the rectifier bridge on a VU meter, too...) and get the iron warmed up.. Which one would you prefer for the ptt line off the dongle? Basically just going to pull the relay in when the thing goes to transmit...and use the contacts to close the PTT circuit on the rig. 73 (and good talking with you last week...) WB0YLE
participants (2)
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Bryan D. Boyle -
Ken