[Hackrf-dev] Still hoping for PTT

[Gavin Jacobs]

Dominic
Thanks for that offer/suggestion, but it’s already done! I found the TX mode signal that drives the TX LED, and it was already brought out to P5. So All I had to do was solder some ribbon cable to P5 socket (which is not populated). I have it connected to my power amp such that it energizes whenever the Hackrf is in transmit mode.

Jake


On Jun 26, 2018, at 10:59 AM, Dominic Spill <dominicgs at gmail.com<mailto:dominicgs at gmail.com>> wrote:

I'm not certain, because I don't want to break portapack or other add on boards, but it may be possible for us to toggle a GPIO pin on one of the headers when we switch to TX mode, if that would help?

Dominic

On 20 June 2018 at 17:55, Gavin Jacobs <apriljunkbox at hotmail.com<mailto:apriljunkbox at hotmail.com>> wrote:
Chuck,
I have used the bias-t voltage on the hackrf to power an upconverter but it isn’t easy to turn it on and off. The only method I know is to use hackrf-transfer - but that doesn’t work when switching to/from rx & tx.

Meanwhile I have brought the tx LED signal out from P5, and it is switching the power amp on and off just fine.

Jake

On Jun 19, 2018, at 7:02 PM, Chuck McManis <chuck.mcmanis at gmail.com<mailto:chuck.mcmanis at gmail.com>> wrote:

FWIW the idiomatic way to achieve this as far as I can tell is to send a bias-T signal on the RF cable, basically its a DC offset on the cable which the PA picks up and switches on. This lets you have short cables between the PA and the antenna and its only one line to hook up (the antenna coax)

On Tue, Jun 19, 2018 at 5:04 PM Gavin Jacobs <apriljunkbox at hotmail.com<mailto:apriljunkbox at hotmail.com>> wrote:
Bernie
That’s a great idea! I looked on the hackrf schematic and the signal for the TX LED is brought out to a (DNP) header - all I have todo is bring that signal out to my PTT circuit. Thanks for the suggestion!

Jake


On Jun 15, 2018, at 5:32 AM, Bernard Kobier <bernardkobier at tpg.com.au<mailto:bernardkobier at tpg.com.au>> wrote:

I admit I have not tried this but what about using the TX LED to drive an optocoupler to switch the amp?

Bernie



On 11 Jun 2018, at 00:53, CJ Hicks <cjhicks at dadelus-engineering.com<mailto:cjhicks at dadelus-engineering.com>> wrote:

Why not leave your exciter on and only PTT your power amplifier (PA)?  Or use an RF to shunt your exciter signal into a dummy load.  Just a couple of random thoughts.

CJH

From: HackRF-dev [mailto:hackrf-dev-bounces at greatscottgadgets.com] On Behalf Of Gavin Jacobs
Sent: Saturday, June 09, 2018 5:57 PM
To: hackrf-dev at greatscottgadgets.com<mailto:hackrf-dev at greatscottgadgets.com>
Subject: [Hackrf-dev] Still hoping for PTT

Has there been any progress on implementing digital i/o from/to the hackrf One. I'm hoping that someday the hackrf can supply a PTT signal to an external amplifier.

Jake

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